NationStates Jolt Archive

I am posting this information- along with the links and lectures below- in order to cut down on the uninformed nonsense that frequently appears on the boards. Note carefully that this only applies to real-world modern technology. If you are using fusion power plants, FTL ships, gravitic drives, etc, only the lectures at the end of the post really apply.

Anyone having trouble with the terminology in these lectures can go to the glossary in the first link.

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A large number of the players in the game who roleplay with modern technology make use of satellites, space stations, and spacecraft. Sadly, though they use real-world technology, most of them seem to lack an understanding of real-world physics, particularly orbital mechanics.

All too often some player makes the statement, “Any satellites flying over my territory will be shot down.” There are several problems with this, and I’ll take ‘em one at a time.

Satellite Overflights
There are dozens- if not scores or hundreds- of nations with modern space technology in the game. Each one of these puts several dozen satellites of various types into a wide variety of orbital paths. We’ll pull a bunch of numbers out of the air and say that there are fifty nations with satellites in orbit (using only real-world technology). If each such nation puts up 5 reconnaissance satellites (a reasonably small number, since the USA has a large- but classified- number of advanced spy satellites). That makes 250 satellites. Each one also has 10 communications satellites (far too small a number), for an additional 500 satellites. We’ll also assume each nation has 5 weather satellites (another 250 birds). With these extremely rough numbers, we have over 1000 satellites in orbit. I haven’t even mentioned the GPS satellites, dedicated cell-phone satellites, orbital observatories, et cetera.

A lot of these birds will be in polar orbits. The satellite travels over both poles as the planet rotates beneath them. This allows the satellites to cover the entire planet over time. Other satellites will be in orbits that go slightly north and slightly south of the equator, thoroughly covering the terrain between their northern and southern maximum latitudes. Other satellites will be in geosynchronous orbits (at around 36,000 kilometers, the orbital speed matches the Earth’s rotation, so the satellite stays over the same portion of the Earth’s surface). Most of these will be observing the entire hemisphere that faces them.

Because of these facts, every nation may be reasonably certain that there are satellites flying over their territory at least once/day. Most rational nations agree that their national territorial claims end at the earth’s stratosphere, but I won’t get into International Laws here.

Orbits
Generally speaking, the lower the orbit, the shorter the satellite’s lifespan. In real life, it is very difficult to refuel a satellite in orbit. A satellite at 100 miles altitude will experience orbital decay due to friction with the atmosphere. This can only be countered by using the satellite’s engines to keep the speed up. The engines require fuel. Sooner or later, the fuel runs out. When the fuel runs out, the satellite starts to slow down and the orbit becomes a long spiral into the atmosphere.

Many satellites deal with this issue by spending most of their orbit at higher altitudes. Since few orbits are perfect circles, this is not much of an issue. The orbits resemble an oval (ellipse). The Earth is close to one end of the oval. Most of the satellite’s lifespan is spent far away from the planet, and it only swings close by once per orbit. Since the planet is turning beneath the satellite at the same time, the satellite covers a slightly different path over the surface as it orbits. Eventually, the satellite will fly over every millimeter of the planet’s surface.

Remember the fuel issue? It still exists. These birds are on ballistic orbits. They are NOT under thrust once they establish their orbit. They are still coasting on the initial thrust that set up the orbit in the first place. Changing the orbit takes LOTS of fuel. Few satellites can make more than a small number of MINOR maneuvers during their lifespan- usually to counteract atmospheric drag. Done properly, a miniscule amount of thrust can increase the satellite’s speed enough to counteract atmospheric friction- making the tiny amount of fuel onboard last much longer.


Shooting down a satellite
It CAN be done. The US Air Force built a few specialized missiles designed to be launched by F-15’s to take out low-flying satellites. This missile is nearly as long as the aircraft that carries it. The ASAT mission (AntiSATellite) requires specially-trained pilots and specially-equipped aircraft. Satellites with little or no maneuvering reserve fuel in low orbits are vulnerable to this attack.

In order to destroy a satellite in a higher orbit, actual launch vehicles must be used. Each ASAT mission requires the same preparations and cost as launching the satellite to begin with. Attacking satellites from the Earth is very difficult and expensive- mostly due to the problems involved with overcoming the Earth’s massive gravity. Think of it as trying to shatter some glass jars sitting on the rim of a very deep well. The only way you can shatter them is by throwing rocks. But you are at the bottom of the well. And the glass jars are zooming around the edge of the well at a high rate of speed.

“What about beam weapons- Lasers, and the like?” I hear you ask. Remember that we’re dealing with real-world physics here. The biggest problem with laser ASAT weapons is power throughput. Lasers are beams of light. They’ve been amplified and collimated down to coherent beams, but they’re still light. Light spreads out over distance (I won’t get into the physics of why this happens because it is fairly detailed and I’m trying to keep this simple). Even a beam collimated down to 1mm at the aperture (highly unlikely in a weapon) would spread enormously after traveling through 100 miles of atmosphere. This means that the laser would require enormous amounts of energy to be an effective weapon at that range. Too much of the energy is lost in forcing the air aside in order for the energetic photons to damage the target.

The US military has been working on classified missile defense beam weapons for decades, but they’re still not planning on destroying satellites with ground-based lasers anytime soon. Ground-based lasers HAVE been used to damage satellites. The Soviets routinely tried to blind low-flying spy satellites with laser beams. Anecdotal evidence suggests that they might have been partially successful, but hard data is very hard to come by.

The best way to destroy a satellite in orbit is to use a weapon that is also in orbit. Fire a shotgun shell into the path of a satellite and any pellets that hit will do enormous damage. A satellite or spacecraft-launched missile would be just as effective, and probably have a better chance to hit. Even beam weapons from orbital weapons would have a greater chance for success due to proximity and lack of atmospheric scatter. The SDI (Strategic Defense Initiative) had plans to use one-shot beam weapons to destroy ballistic missiles before they re-entered the atmosphere. Each one of these weapons uses the power of a contained (for a microsecond or two) nuclear explosion to generate the charged particle beam or X-Ray laser that would destroy or “mission-kill” (more on these terms later) the missile warhead. The contemporary plans to use ground-based lasers and orbital mirrors fell by the wayside when the power throughput issue killed the ground-based laser program.

Another possible ASAT concept is the so-called “killsat”, or killer satellite. Launch a bunch of satellites loaded with lightweight self-homing missiles, shotgun-like firearms, or chemically-powered beam weapons and lots of fuel. Put these birds in a high orbit. Whenever you want to take out a particular satellite, deploy the missiles or fire the shotguns or energize the lasers whenever the killsat is in relative proximity to the target satellite and ahead of the target’s orbital path.

Now we get down to the “destroying” satellites part. Space is vast. Even the relatively close quarters of planetary orbit still involves enormous amounts of space. Satellites are tiny by comparison. It is very hard to hit a satellite. Even “smart” or “brilliant” missiles can still miss, particularly if the satellite uses a great deal of fuel to execute a violent maneuver (unlikely in light of the fuel constraints, but technically possible). The most effective means of “destroying” a satellite is the Kinetic Energy Weapon (KEW). KEWs rely on relative velocity and mass to do damage. Basically, it means that the KEW must hit the target satellite. Radar guidance is one method for increasing the precision of the weapon, or any other self-guidance system, but these methods start adding a lot of cost to the already staggering expense of building and launching the orbital weapon or spacecraft to begin with.

The answer of course lies in “area-effect” KEWs. The shotgun effect. If a target satellite is zipping along at 20,000 KPH (a modest speed for space travel), firing a shotgun in the opposite direction from fairly close in front of it would have a devastating effect. Each individual shotgun pellet is a fairly insignificant mass, but the pellets are traveling at 100 meters per second (360,000 KPH) and run head on into a satellite with a mass of 200 kilograms traveling at 20,000 KPH (around 6 meters per second). The satellite would be pretty thoroughly shredded by the impact and the subsequent heating from the friction of the impact. This satellite could reasonably be considered “killed”, since it won’t be doing its designed task in its current state and the change in velocity from the impact (known as “delta v”) would doubtless end up dropping the satellite into a spiraling orbit that results in its eventual destruction during re-entry.

The big problem is how to get the shotgun in front of the target close enough to do this kind of damage. If the shotgun is too far away, the odds against successful impact increase exponentially with distance. In layman’s terms, every meter of distance between the target and the shotgun doubles the chances that the target will be undamaged (this is a rough approximation, used only for purposes of this post). Remember where I mentioned that satellites are hard to hit? Imagine this:

The satellite is zipping along at 6 meters/second. Your killsat is several kilometers ahead of the target, in an orbit two kilometers higher. These orbits are going to be in exactly the same orbital plane for purposes of keeping this example simple (meaning that at any given point in either satellite’s path, they will be covering the exact same territory on the planet beneath). So, your killsat aims directly at the target satellite and fires a shotgun at it. Any duck hunter could tell you what happens next- your shotgun blast misses the target by several kilometers. We’ll assume that the onboard computer has figured out the intercept problem and fires well AHEAD of the target (this is called “leading the target”), so that the pellets will arrive at the target’s orbit WHILE THE TARGET IS THERE. Success, right? Not necessarily. The pellets will spread as they leave the barrel of the weapon. As they travel the several kilometers toward the target, they spread farther and farther apart. Every meter of distance doubles the chances for a miss. The odds of actually hitting the target from that range are pretty slim.

So what is the answer? The weapon system most likely to ensure success would be a radar-guided missile with a shaped-charge fragmentation warhead. Radar from the killsat would track the target, compare orbits, and launch the missile into an interception orbit. Once the missile was in position in an imaginary cone no more than 45 degrees in front of the target’s projected orbit, it would explode. The shaped charge of the missile would direct most of the shrapnel at a high rate of speed into the projected orbit of the target. We get the shotgun effect, the target is extremely likely to be damaged beyond recovery, and will likely drift out of its original orbit.

Beam weapons can also “kill” satellites- if they are fired from outside the earth’s atmosphere. Here there is a lot less worry about accuracy, since the beams are by definition traveling at C (light speed- roughly 300,000 kilometers/second), and the target is unlikely to have traveled far between firing and impact (especially in planetary orbit). The problem with beam weapons is that they are unlikely to destroy the target. It’s likely that the laser would heat the satellite up, melt a hole in the hull, or damage the electronics onboard, but the bird would almost certainly remain in orbit. This brings me to the difference between “mission kill” and “destroy”.

We’ve already discussed destruction, so I will focus on “mission kill”. This is a military term meaning that the target is not “destroyed”, but it is incapable of performing its mission. Even if a KEW fails to reduce the target satellite to shredded metal, the impact friction and change in delta v are likely to cause a “mission kill”, because the satellite would be unlikely to be of much value to anyone afterwards. It would not take much of a change in delta v to change a satellite’s orbit enough to make it useless for its owners.

Lasers are good weapons to execute a “mission kill” on a target satellite. If the laser is powerful enough, it could do extensive damage in a few microseconds to the hull, solar screens, antennae, or sensors on the target satellite. The lower the laser’s energy level, the longer the contact with the target must be to do significant damage. Even relatively low-powered lasers (class III) could “blind” a satellite by creating an electromagnetic (EM) field around the target, or overloading the sensors with heat or EM energy.

X-ray lasers, Gamma-ray lasers, and Masers (Microwave Amplified by Sustained Emission of Radiation) are all examples of high-energy beam weapons with enormous potential to damage any target they hit. The problem with such high-energy weapons is the energy requirement. It takes the equivalent of a tactical nuclear bomb to generate enough energy in the extremely short time required to generate these beams. This is essentially what the US Government was looking at for the SDI program.

Put a small nuclear weapon into a casing with an extremely refractive lining. This lining is pierced by the laser emission tubes. When a target is detected, the entire assembly is turned to point toward the target, then the nuke within goes off. For a few microseconds, the nuclear explosion is contained, and the energy is channeled into the laser emitters. These tubes send out X-ray laser beams toward the target. The highly energetic beams penetrate the target (unless it is shielded by thick metal of one sort or another- in which case the beams melt everything) and burn out every electrical circuit onboard. Fuel tanks would rupture or explode from the heat of the beams’ passage. This would be more than enough to “mission kill” any satellite made with modern technology. It would also be enough to do the same for missile warheads.

There are a couple of problems with these. First is the fact that they are one-use weapons. One shot is all you get, because the weapon is destroyed as it fires. Another problem is the fact that nuclear weapons are dangerous. A weapon that would destroy a city on the planet has a lot of potential to create havoc in space. It also creates an Electro-Magnetic Pulse (EMP). A sphere of intense EM energy is released by the explosion, which reacts with and overloads any EM fields it encounters (this effect decreases with distance, of course). Active electronic components are destroyed by en EMP. This will affect the satellite or spacecraft employing the weapon as well as anyone else in the area.

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http://users.commkey.net/Braeunig/space/orbmech.htm

http://liftoff.msfc.nasa.gov/RealTime/JTrack/

Types Of Orbits
For a spacecraft to achieve earth orbit, it must be launched to an elevation above the Earth's atmosphere and accelerated to orbital velocity. The most energy efficient orbit, that is one that requires the least amount of propellant, is a direct low inclination orbit. To achieve such an orbit, a spacecraft is launched in an eastward direction from a site near the Earth's equator. The advantage being that the rotational speed of the Earth contributes to the spacecraft's final orbital speed. At the United States' launch site in Cape Canaveral (28.5 degrees north latitude) a due east launch results in a "free ride" of 915 mph (1,470 kph). Launching a spacecraft in a direction other than east, or from a site far from the equator, results in an orbit of higher inclination. High inclination orbits are less able to take advantage of the initial speed provided by the Earth's rotation, thus the launch vehicle must provide a greater part, or all, of the energy required to attain orbital velocity. Although high inclination orbits are less energy efficient, they do have advantages over equatorial orbits for certain applications. Below we describe several types of orbits and the advantages of each:
Geosynchronous orbits, also called geostationary orbits (GEO), are circular, low inclination orbits around the Earth having a period of 24 hours. A spacecraft in a geosynchronous orbit appears to hang motionless above one position on the Earth's surface. For this reason, they are ideal for some types of communication and meteorological satellites. To attain geosynchronous orbit, a spacecraft is first launched into an elliptical orbit with an apogee of 22,240 miles (35,790 km) called a geostationary transfer orbit (GTO). The orbit is then circularized by firing the spacecraft's engine at apogee.
Polar orbits (PO) are orbits with an inclination of 90 degrees. Polar orbits are useful for satellites that carry out mapping and/or surveillance operations because as the planet rotates the spacecraft has access to virtually every point on the planet's surface.
Walking orbits: An orbiting satellite is subjected to a great many gravitational influences. First, planets are not perfectly spherical and they have slightly uneven mass distribution. These fluctuations have an effect on a spacecraft's trajectory. Also, the sun, moon, and planets contribute a gravitational influence on an orbiting satellite. With proper planning it is possible to design an orbit which takes advantage of these influences to induce a precession in the satellite's orbital plane. The resulting orbit is called a walking orbit, or precessing orbit.
Sun synchronous orbits (SSO) are walking orbits whose orbital plane precesses with the same period as the planet's solar orbit period. In such an orbit, a satellite crosses periapsis at about the same local time every orbit. This is useful if a satellite is carrying instruments which depend on a certain angle of solar illumination on the planet's surface. In order to maintain an exact synchronous timing, it may be necessary to conduct occasional propulsive maneuvers to adjust the orbit.
Hohmann transfer orbits are interplanetary trajectories whose advantage is that they consume the least possible amount of propellant. A Hohmann transfer orbit to an outer planet, such as Mars, is achieved by launching a spacecraft and accelerating it in the direction of Earth's revolution around the sun until it breaks free of the Earth's gravity and reaches a velocity which places it in a sun orbit with an aphelion equal to the orbit of the outer planet. Upon reaching its destination, the spacecraft must decelerate so that the planet's gravity can capture it into a planetary orbit.
To send a spacecraft to an inner planet, such as Venus, the spacecraft is launched and accelerated in the direction opposite of Earth's revolution around the sun (i.e. decelerated) until in achieves a sun orbit with a perihelion equal to the orbit of the inner planet. It should be noted that the spacecraft continues to move in the same direction as Earth, only more slowly.
To reach a planet requires that the spacecraft be inserted into an interplanetary trajectory at the correct time so that the spacecraft arrives at the planet's orbit when the planet will be at the point where the spacecraft will intercept it. This task is comparable to a quarterback "leading" his receiver so that the football and receiver arrive at the same point at the same time. The interval of time in which a spacecraft must be launched in order to complete its mission is called a launch window.

Newton's Laws of Motion and Universal Gravitation
Newton's laws of motion describe the relationship between the motion of a particle and the forces acting on it.
The first law states that if no forces are acting, a body at rest will remain at rest, and a body in motion will remain in motion in a straight line. Thus, if no forces are acting, the velocity (both magnitude and direction) will remain constant.
The second law tells us that if a force is applied there will be a change in velocity, i.e. an acceleration, proportional to the magnitude of the force and in the direction in which the force is applied.

Motions of Planets and Satellites
Through a lifelong study of the motions of bodies in the solar system, Johannes Kepler (1571-1630) was able to derive three basic laws known as Kepler's laws of planetary motion . Using the data compiled by his mentor Tycho Brahe (1546-1601), Kepler found the following regularities after years of laborious calculations:
1. All planets move in elliptical orbits with the sun at one focus.
2. A line joining any planet to the sun sweeps out equal areas in equal times.
3. The square of the period of any planet about the sun is proportional to the cube of the planet's mean distance from the sun.
These laws can be deduced from Newton's laws of motion and law of universal gravitation. Indeed, Newton used Kepler's work as basic information in the formulation of his gravitational theory.
As Kepler pointed out, all planets move in elliptical orbits, however, we can learn much about planetary motion by considering the special case of circular orbits. We shall neglect the forces between planets, considering only a planet's interaction with the sun. These considerations apply equally well to the motion of a satellite about a planet.

Launch of a Space Vehicle
The launch of a satellite or space vehicle consists of a period of powered flight during which the vehicle is lifted above the earth's atmosphere and accelerated to orbital velocity by a rocket, or launch vehicle. Powered flight concludes at burnout of the rocket's last stage at which time the vehicle begins its free flight. During free flight the space vehicle is assumed to be subjected only to the gravitational pull of the earth. If the vehicle moves far from the earth, its trajectory may be affected by the gravitational influence of the sun, moon, or another planet.

Escape Velocity
We know that if we throw a ball up from the surface of the earth, it will rise for a while and then return. If we give it a larger initial velocity, it will rise higher and then return. There is a velocity, called the escape velocity, Vesc, such that if the ball is launched with an initial velocity greater than Vesc, it will rise and never return. We must give the particle enough kinetic energy to overcome all of the negative gravitational potential energy.

Thrust
Thrust is the force that propels a rocket or spacecraft. In this section we will take a look at how the application of thrust affects the orbit of a space vehicle.
A space vehicle in orbit experiences the sensation of weightlessness because the outward force of centrifugal acceleration perfectly balances the inward gravitational pull of the earth. By applying thrust, the space vehicle's velocity can be increased or decreased. If velocity is increased the outward centrifugal force also increases which "pulls" the vehicle to a higher orbit. Decreasing velocity lessens the centrifugal force and gravity "pulls" the vehicle to a lower orbit. Such altitude changes do not alter the inclination of the orbit, they merely reposition the vehicle within the same orbital plane. Applying thrust at right angles to the orbital plane modifies the inclination. These maneuvers, called plane changes, burn considerably more propellant than altitude changes.
For a spacecraft to perform an altitude change, two engine burns are required. To change to a higher orbit, the spacecraft fires its engine to increase velocity, thus placing it in an elliptical orbit with an apoapsis equal to the new altitude. When the spacecraft reaches apoapsis, a second burn is performed to once again increase velocity, thereby placing the vehicle in a circular orbit. For a spacecraft to change to a lower orbit, the procedure is reversed. The craft fires its engine in the direction of travel to decrease velocity, thus dropping the spacecraft into an elliptical orbit with a periapsis equal to the new altitude. When reaching periapsis the engine is fired to decrease velocity further, thereby circularizing the orbit.
When propulsive maneuvers are used to alter the orbit of a space vehicle, engineers calculate the magnitude of the velocity change required to achieve the desired alteration. This change in velocity is called delta v (v).

Drag
Drag is the resistance offered by a gas or liquid to a body moving through it. A spacecraft is subjected to drag forces when moving through a planet's atmosphere. This drag is greatest during launch and reentry, however, even a space vehicle in low earth orbit experiences some drag as it moves through the earth's tenuous upper atmosphere. In time, the action of air drag on a space vehicle will cause it to spiral back into the atmosphere, eventually to disintegrate or burn up. If a space vehicle comes within 80 to 100 miles of the earth's surface, air drag will bring it down in a few days, with final disintegration occurring at an altitude of about 50 miles. This deterioration of a spacecraft's orbit is called decay.

This is an excellent idea. For those designing their own ships, how about we get some basic physics as far as thrust, weight and mass, exhaust velocity? For instance, how to determine:

1 how much thrust (in Newtons, since they're much easier to work with than "pounds" IMO) is required to propell different masses (in kilograms) at 1 g, 2 g, etc.

2 how to determine thrust knowing exhaust velocity and reaction mass per second? Anyone, anyone? Bueller?

Most people dont bother with all this, but I prefer to know how fast my ships accelerate and whatnot, or how much fuel they'll need, and everything else actually.

THANK YOU...again.

Very informative post. now I know everything about shooting down satelites, thanks :D

Hm, I'm currently working on a 90,000ft version of the airborne laser (the 747 with a big laser on it). At 90,000 ft, there shouldn't be much atmosphere to weaken a laser.

Ell: but the problem with the ABL on the 747 is that tests have showed it is nto that effective. Yes, those "Tactical lasers" are possible, but right now they are not that effective.

However, that's another story for us 2010-tech-ers (I RP 2009 tech)

Bump for viewing. :)

I know, I just need a 3Mw source of power that can fit on a 747. (The ABL has 1 Mw)

I know, I just need a 3Mw source of power that can fit on a 747. (The ABL has 1 Mw)
I think that people said the main problem with the 747 ABL is the accuracy, not the power.

Hm, I'm currently working on a 90,000ft version of the airborne laser (the 747 with a big laser on it). At 90,000 ft, there shouldn't be much atmosphere to weaken a laser.

90,000 feet is still less than 20 miles, which is less than halfway up. I'm not sure if it would work or not, but that's still a hell of a long way to go.

Thanks very much for this Evil Overlord. It's always really nice to find an informative and useful thread show up every once in a while ;)

Evil Overlord should be one of the "war exports" in the Mod Squad thing...

OOC: This is very well done, and covers a lot of material, but is hardly all-inclusive. There is a lot that can be done that is not covered here.

But it is a good basis for a lot of stuff. Nice post.

This is definitely not an all-inclusive listing. I was trying to keep the post simple and informative without being too boring (still not sure if I succeeded in that last one).

I tried to limit the subject matter to published modern real-world technology. Not necessarily what is in use in the real world, but published designs that are possible using real-world technology (my orbital bombardment spacecraft Gagarin is based on a design by Engineer/physicist Freeman Dyson from the '60s, for example).

The whole purpose of the post is an attempt to educate people who want to roleplay real-world space tech without coming across as a complete ignoramus. A month ago, I read a post by someone who insisted that everyone re-orbit their satellites so nothing would ever cross his territory. I had to explain to him (with one-syllable words as much as possible) why this wasn't a realistic option.

Hopefully, this post will help clear up a lot of space tech issues.

Bump for further comment

Bump for further comment

I like the mention of the the x-ray power via Nuclear explosion. In fact, I have something like that on a project of mine (that is right now, still top secret, so, shhh, :P)

Bump for further comment

I like the mention of the the x-ray power via Nuclear explosion. In fact, I have something like that on a project of mine (that is right now, still top secret, so, shhh, :P)

Evil Overlord Enterprises deployed X-ray laser weapons in self-defense during the Kish/Westmoon incident.

I know, I just need a 3Mw source of power that can fit on a 747. (The ABL has 1 Mw)
I think that people said the main problem with the 747 ABL is the accuracy, not the power.

With the computers availible nowadays (IC:2006) I think accuracy may be much better.

With the computers availible nowadays (IC:2006) I think accuracy may be much better.

Accuracy is not really the issue. The biggest issue is what is called "thermal bloom"- the loss of power due to atmosphere and the sudden scattering of the laser's energy into atmospheric heat. Even at altitude, the laser is unlikely to seriously damage most satellites. The Air Force weapon system in testing is actually an ABM weapon, designed to destroy the electronics of ICBM warheads already on ballistic trajectory toward their targets.

For that mission, accuracy is more of an issue, but the power throughput requirements are lower. More simply, the "mission kill" on the warheads doesn't require that the laser burn up or vaporize the warhead. All that is needed is to damage the internal circuits enough to prevent the nuclear weapon from successfully forcing a critical mass.

The Navy has been testing an antimissile defense system based on shipborne lasers (I'm not giving away national secrets, here- this is based on published material from public sources). Containers the size of boxcars are mounted on the deck of nuclear-powered ship. The laser is supposed to knock out an incoming missile's electronics (guidance, etc) at a distance of 2+ miles, but no public data has listed the effectiveness of the system. I imagine the "thermal bloom" problem and power throughput are still the overriding negative factors in the system's development.

A few words on the subject of orbital weapons platforms.

Several people in the past have made statements to the effect that they have placed ICBM's in orbit. This undoubtedly derives from the common notion that ICBM = nuclear weapon. The truth is that the ICBM is actually a launching platform for nuclear warheads. Placing the warheads on an orbital platform (with re-entry shields, of course) is not too difficult. Placing a 150-meter tall missile on an orbital platform is almost impossible and totally unnecessary.

Assuming that someone has decided to place warheads in orbit. there is no need to attach booster rockets to the warhead. That enormous 150-meter missile attached to the warhead is onky needed to get the warhead into orbit in the first place. All that an already-orbiting warhead needs is a small amount of thrust to counteract orbital velocity and start dropping into the atmosphere.

Atmospheric friction requires the use of ablative re-entry shielding for each warhead. Once the warhead has burned off the re-entry shielding, it can make a few minor course corrections (using tiny vanes attached to the warhead and controlled by onboard computers) before impact. The key to accuracy from orbit is the warhead's course and speed, it's orbital location when it starts to decelerate, and the amount of decelerating thrust.

Killing a falling nuclear warhead is a difficult proposition. Once the warhead begins its terminal re-entry, it is going to hit the ground somewhere. It is extremely difficult to completely destroy the warhead.

What is far easier is to "mission kill" the warhead. A nuclear weapon is a prety complicated piece of equipment. A large number of things all need to go exactly right in the right order before the weapon goes boom! Damaging the electronics controlling the explosion sequence isa a good means of preventing the weapon from achieving critical mass (lasers are good at this, but KEW's can achieve the same effect by cutting wires and destroying circuits). Another good way to prevent fission from taking place is to deform the subcritical masses (KEW's are designed for this task) so the proper critical mass cannot be formed by the explosion sequence.

Please note the difference between "nuclear" weapons and "thermonuclear" weapons. Nuclear weapons are what used to be called A-bombs or atomic bombs. These weapons use fission (splitting the atom of a dense, radioactive element) to liberate energy in an uncontrolled chain reaction. The weapons used on Hiroshima and Nagasaki were this type of weapon.

"Thermonuclear" weapons are also called Fusion bombs or Hydrogen bombs. These weapons use fusion (combining hydrogen atoms under pressure to create Helium, extra neutrons, and lots of energy), but need a "nuclear" weapon to start the fusion sequence. If you vcan prevent the initial nuclear reaction, the follow-up fusion reaction will not take place.

A tougher, cheaper and cleaner orbital weapon is the so-called KEW (Kinetic Energy Weapon). If you drop a rock from orbit, it would most likely burn up in re-entry (unless it was pretty good-sized or composed of tough materials). If the rock were big enough (say a rough cylinder 3 meters by 5 meters), enough of the rock would survive the friction of re-entry to impact the ground. The fragments that hit the ground would be traveling at enormous speed. This adds up to astronomical amounts of kinetic energy (pun intended). All that kinetic energy will be converted to heat when the ground gets in the way. Take a look at the Moon on a clear night to see what results from such an impact.

Smaller masses can also make good KEWs, if they are composed of extemely durable or refractory materials. The beauty of KEWs is that fact that they are extremely hard to stop. They are nothing more or less than falling rocks, and they're going to hit the ground. The problem with KEWs is the fact that they are completely unguided once they begin re-entry (initial thrust, orbital speed, location, and altitude are the primary factors that affect the accuracy of KEWs and other orbital weapons).

It is technically possible to destroy a KEW. Setting off a thermonuclear weapon almost in contact with the KEW will almost certainly destroy most KEWs. The same weapon a few hundred meters distant will likely deflect the KEW ... but it will still hit the ground somewhere. Lasers and chemical explosives are unlikely to have much effect.

OOC:Being the humble RPer I am, Its going to take some time to digest this. I am one guiilty of letting my imagination and designs run off without a grounding in good physics.....unfortunatley, I failed the Higher so my understanding is limited. Which is why I usually avoid it...

OOC:Being the humble RPer I am, Its going to take some time to digest this. I am one guiilty of letting my imagination and designs run off without a grounding in good physics.....unfortunatley, I failed the Higher so my understanding is limited. Which is why I usually avoid it...

Relax. The whole idea of this thread is to let people take the time to figure out what they want to do. Roleplaying real-world physics is actually a lot harder than roleplaying star trek/star wars/babylon 5/whatever science fiction ubertech.

If you want to roleplay spacetech with real-world physics, read the relevant portions of the links I posted up at the top. If you have questions, feel free to ask. The only thing I ask is that you firmly and completely set aside every single idea you got from every TV show or movie you have ever seen before you roleplay.

bump

In the matter of x-ray lasers, the spacecraft im planning on having in another three to four months will have missiles that contain a nuke ranging from 25 to 200 megatons and between 20 to 50 lasing rods which will form the beams. I wasnt quite sure how the x-ray laser warheads in Honor Harrington books worked since i decided to use those as basis for my space missiles, but now i know. Such missiles would be excellent in space combat because they would have a longer stand-off engagement range than contact nukes for example and they would still do a lot of damage.

A very informative post indeed, and you are very much correct Evil Overlord, RPing space tech with realistic physics is much much harder than simply taking stuff from the known franchises.

A very informative post indeed, and you are very much correct Evil Overlord, RPing space tech with realistic physics is much much harder than simply taking stuff from the known franchises.

Thanks. This was originally intended as a rant against the mindless herds of idiots saying things like, "get all satellites out of my skies or I'll shoot them down". I'm glad a few people have got some use out of it.

IMO, the really important thing- regardless of tech level- is that the rules (trivial things like Newton's Laws of Motion, etc) must be internally consistent. That is the only real advantage established "franchise" tech has- a largely self-consistent technology.

Personally, I prefer to work at the edges of current science- off the wall stuff that no one is building because of cost or whatever. A lot of my best tactics are the result of such non-linear thinking. In Star Trek, no one seems to pay attention to the tactical possibilities inherent in such stuff as inertial dampers, transporters, and artificial gravity- for three obvious examples.

One of these days I'll post something about how things move in microgravity with modern technology. I covered it a little in the OMF City thread, but there are still folks out there who claim impossible things because they haven't a clue how the universe works.

Tag for when I get around to having a space programme...

BUMP

Boooooorrrrriiinnnnggggggg *yawn*

I read the first two lines and fell on my keyboard. I now have qwertycitis! *condition in which "qwerty" appears on face* :lol:

But seriously, quality post. Amazingly short given the amount of information provided. Are you a teacher of some sort, or aspiring to be one? Because you seem to have the knack for short, yet comprehensive explanations (relatively given the level of material we're dealing with here).

Bravo, more, more!

Boooooorrrrriiinnnnggggggg *yawn*

I read the first two lines and fell on my keyboard. I now have qwertycitis! *condition in which "qwerty" appears on face* :lol:

But seriously, quality post. Amazingly short given the amount of information provided. Are you a teacher of some sort, or aspiring to be one? Because you seem to have the knack for short, yet comprehensive explanations (relatively given the level of material we're dealing with here).

Bravo, more, more!

:lol:

No, I am not a teacher, nor do I play one on TV. I personally thought the post was too long. I was really worried when I originally posted this that people would simply bypass it or try to read it and fall asleep- the "qwerty" phenomenon.

I plan on doing an addition fairly soon about Newton's Laws of Motion and their effects on objects in space- not out of a desire to waste electronic space on the forums, but as part of a discussion on logistics in space. Trying to get around Uncle Isaac in space is expensive.

Glad you got something out of it.

TEO

Personally, I prefer to work at the edges of current science- off the wall stuff that no one is building because of cost or whatever. A lot of my best tactics are the result of such non-linear thinking. In Star Trek, no one seems to pay attention to the tactical possibilities inherent in such stuff as inertial dampers, transporters, and artificial gravity- for three obvious examples.
Most of my success comes from the tactical possibilities of artificial gravity and other such technologies; most Menelmacari weapons use it in some way or another. Great fun. \^_^/

Anyway, this is a lovely thread, and even us far-future types can derive many useful things from it (like the orbital mechanics and such). Thanks again.

~Siri

PIn Star Trek, no one seems to pay attention to the tactical possibilities inherent in such stuff as inertial dampers, transporters, and artificial gravity- for three obvious examples.

Is it really so hard to program the computer to automatically do a point-to-point transport into vacuum on any intruders? Eh? Eh? And why not just beam some antimatter onto the bridge of your opposition?

Oh! That's right. The episode would be too short.

Stupid lowest common denominator of the 12-35 demographic....

PIn Star Trek, no one seems to pay attention to the tactical possibilities inherent in such stuff as inertial dampers, transporters, and artificial gravity- for three obvious examples.

Is it really so hard to program the computer to automatically do a point-to-point transport into vacuum on any intruders? Eh? Eh? And why not just beam some antimatter onto the bridge of your opposition?

Oh! That's right. The episode would be too short.

Stupid lowest common denominator of the 12-35 demographic....

OOC: Why can't ST ships simply use their darn phasers and photon torpedoes by actually shooting at their opponents instead of trying to come up with intricate and untested strategies of "beaming over some antimatter" or "beaming away the intruders"? ARGH! Shoot, shoot, and more shoot! That's what the guns are for! Ah...I've created a tangent.

Because shooting would require being able to shoot. And Starfleet officers can't shoot.

~Siri

Because shooting would require being able to shoot. And Starfleet officers can't shoot.

~Siri

OOC: Good point. And Klingons always drop their guns and charge headfirst with their bat'leths.

OOC: Why can't ST ships simply use their darn phasers and photon torpedoes by actually shooting at their opponents instead of trying to come up with intricate and untested strategies of "beaming over some antimatter" or "beaming away the intruders"? ARGH! Shoot, shoot, and more shoot! That's what the guns are for! Ah...I've created a tangent.

Aside from what Siri said, beaming over antimetter would bring the conflict to an end much faster than trying to burn through hull armor with phasers, because, despite the fact that they supposedly put out ubergigajoules of energy, every single alien ship in existence seems to be heavily armed and have equivalently uber armor, even if it's just a civillian sleeper ship from an uber-low-tech race that doesn't even know other sophonts exist.

Meh.

Just a point in regards to transporters......they can't be used on a target if it is still shielded. Thats why they are not transporting anti-matter bombs over, you have to bring their shields down first. That said I like to point out that I hate the idea of transporters anyway and I wouldn't RP with them.

Just a point in regards to transporters......they can't be used on a target if it is still shielded. Thats why they are not transporting anti-matter bombs over, you have to bring their shields down first. That said I like to point out that I hate the idea of transporters anyway and I wouldn't RP with them.
Ditto. But the fact still remains that Star Fleet Captains don't put the technology available to them to very much practical use. And shields just plain suck, too. Along with the uber-armor and weapons, that seems to be another thing that every Star Trek spacefarer has. How in heck are they supposed to work, anyway? How is it that hitting an energy field has any effect on it's generator? And then there's all the lost technology- between now and Star Trek times, it seems that they've lost not only common sense, but also surge protectors and the 'copy' command. Just think how many disasters could've been averted had the bridge not blown up every time some insignificant portion of the bridge was hit, or if they had only backed up data!

Somthing I missed whilst browsing through this post was, that if there are so many sattelites around, what are the chances that you'd have a few splat on the windscreen when launching a craft into space? I'd have thought it'd be quite high but i'm no expert. Oh, and starfleet shields don't work on slow moving unpowerd objects strangly enough, so throw rocks at them!

The problem with the real world is that this may be fun. Militarisation of space does not sound like fun. This is a real possibility. I ain't playing.

The problem with the real world is that this may be fun. Militarisation of space does not sound like fun. This is a real possibility. I ain't playing.

Sorry to rain on your parade, but the militarization of space in RL has already happened. There are already weapons in space. Nuclear warheads haven't been deployed in orbit yet (as far as anyone knows, anyway, but I don't discount the possibility), but there are plenty of real-life weapons systems in place from both the US and Russia (as well as its predecessor- the USSR). There is a fair possibility that the PRC has some weapons in orbit as well.

The US and USSR signed a treaty prohibiting deployment of nuclear weapons in space, but the definition of a nuclear weapon was very finely detailed to alow both sides "wiggle room" in describing their equipment. "That's not a nuclear weapon, old bean. It's just a smallish reactor. Never mind the additional fissile material surrounded by explosive charges, just a safety precaution, I can assure you. No, that isn't re-entry shrouding. It's just a layer of insulation we're testing."

The weapons I'm speaking of are mostly conventional explosives, small guided missiles, and Class II or III lasers. None of these weapons are designed to do damage on the ground (indeed, they probably can't hurt anything on the surface), but are instead intended to damage, disrupt, and destroy "enemy" satellites. These weapons could just as easily be used against manned spacecraft as well.

The problem with trying to avoid militarizing space is that this laudable goal conflicts directly with a longtime military goal: control the high ground. Since NASA gets a huge chunk of its operating revenue from military payload contracts, the military has a lot of say in what space gets used for. This situation holds true whether you're in Guiana, Baikonur, or Cape Canaveral.

Somthing I missed whilst browsing through this post was, that if there are so many sattelites around, what are the chances that you'd have a few splat on the windscreen when launching a craft into space? I'd have thought it'd be quite high but i'm no expert. Oh, and starfleet shields don't work on slow moving unpowerd objects strangly enough, so throw rocks at them!

The debris-impact rate in RL Earth orbit is quite high. Fortunately, most of the impacts involve microscopic amounts of material. Sooner or later, however, we might end up losing a cosmonaut/astronaut/taikonaut/pickyourstupidnameofchoicenaut or two from an orbital debris impact.

RL Earth has been shooting crap into orbit since the 1950's. Most of that stuff (especially the larger objects) has suffered from orbital decay and burned up during re-entry. Unknown numbers of tiny particles are still whizzing around up there (Lest anyone think I am trying to disprove Galileo, the reason the tiny bits are still there while the big chunks have fallen into the atmosphere is not weight- or even mass. The culprit here is atmospheric drag. Big chunks are slowed by the atmosphere at a higher rate than smaller chunks).

NASA has long been concerned about this. There used to be a large project dedicated to identifying POSSIMs (POSSible IMpactors) at NASA, but I think the budget for the program went away during the Clinton Administration.

In NS, my country has positioned several satellites in geosynchronous orbit to track objects in orbit. My personal- though unverified- estimate is that there are enough objects in orbit around NS Earth to cause a serious reduction of sunlight reaching the surface- even accounting for a planet the size of Jupiter.

TEO

In NS, my country has positioned several satellites in geosynchronous orbit to track objects in orbit. My personal- though unverified- estimate is that there are enough objects in orbit around NS Earth to cause a serious reduction of sunlight reaching the surface- even accounting for a planet the size of Jupiter.

TEO

Indeed. I mentioned before in IRC (and most likely not the first person to say this) that there should be a "junk ring" around the NS Earth. I believe at least one other player said he takes this into account everytime he goes into space but then again, like all roleplay, a person can acknowledge it or not.

Indeed. I mentioned before in IRC (and most likely not the first person to say this) that there should be a "junk ring" around the NS Earth. I believe at least one other player said he takes this into account everytime he goes into space but then again, like all roleplay, a person can acknowledge it or not.

It's not as bad as it could be, though. There was a big cleanup back in March (or was it April?). A lot of the material for the Snel Worldring came from that "junk ring", but by now there's probably enough new stuff accumulated to build a second Worldring.

Tag and Query.

Firstly I have to say that I will be looking at this thread time and time again to check my RP and make sure everything is at least explained a little bit. So good job on getting such a detailed thread... I hate randomly searching the web for information, it doesn't work too well.


Anyways, my query is about defending your orbit, alot of large nations are currently doing this or starting programs that do the same... but most of them seem to think they can corner off their region of space (the area above their region for example) and shoot down anything which enters their orbit...

I'm not being clear I know... but basically I think what I'm saying is that alot of people now try to claim that now satalite can entry their region of space (above NS earth) without taking into account that many nations have the same kind of orbits as you pointed out, the kind that cover every inch of earth.

Wouldn't this result in us having to go around that bit of space or do we ignore it unless we are activelly RPing with that nation?


Personally I'd like to think I have some satalites above my nation that have an orbit which keeps the satalite above Iuthia at all times (so it matchs the spin of the earth and so on). That way I can view my own nation and keep an eye on threats from both space and sea...


Opinions?

[sorry about the randomness of the post, I'm a little off due to New Years and all]

Anyways, my query is about defending your orbit, alot of large nations are currently doing this or starting programs that do the same... but most of them seem to think they can corner off their region of space (the area above their region for example) and shoot down anything which enters their orbit

That was largely the reason that I wrote this to begin with.

Any nation that says something to the effect that they want all foreign satellites re-routed so they do not pass over that nation's territory is either:

A) Trying to start a war by pretending to be a moron

B) A moron

It is possible to shoot down satellites. It is possible that there are nations out there willing to go to war over satellite overflights of their territory. For a wide variety of reasons already explained in this thread, it is possible (just barely) to re-route a satellite so that it does not cross a particular nation's territory. It is also extermely difficult, expensive, and significantly reduces the lifespan of the satellite. In other words, countries that make these demands are demanding that the nation owning the satellites throw away hundreds of millions of dollars.

Option (B) up above is looking more and more likely.

If you encounter such a nation, it is entirely possible that they are simply unaware of the science and natural laws governing orbital mechanics. This does not make them stupid, just unaware of the facts. Explain the facts to them as gently as possible, provide them with a link to this thread, and ask them to TG me with any questions.

If they persist in this idiocy after you've done this, you may safely ignore them- or go to war after they shoot down one of your satellites. Since they are very likely to be unaware of the science involved, their attack on your satellites would probably be so poorly thought out that you can get them very, very angry by claiming that the attack failed due to lousy science. Keep doing this until they make an attack with a realistic chance of success. Then declare war on them.

Personally, I try to reason with such nations once. Thereafter, I simply ridicule them to smithereens for their lack of knowledge.

A satellite in geosynchronous orbit (the kind where the satellite appears to stay above the same point on the Earth's surface) is restricted to the space above the equator. If your nation is located more than 15 degrees (roughly) north or south of the equator, you would be better advised to set up a series of satellites with offset orbital periods. In layman's terms, you send up several dozen satellites and place them in elliptical (oval-shaped) orbits. Each satellite spends most of its time far from Earth, but at its closest approach each satellite will be flying over your country. Then you arrange the orbits so there is at least one satellite over your skies at all times. This is pretty much what NORAD has done.

The downside of this method is the cost and difficulty. You'll need a massive space administration to manage and track the satellites, as well as lots of launch vehicles and satellite tenders (small spacecraft designed to maintain and refuel satellites) to keep the satellites in space and in good working order. I think that it is worth the expense, but its your call.

TEO

Junk ring...

Stuff blowing up in my nation...

No resources...

Bingo!

OOC:
This is a really, really, really useful thread. Thank you so much for writing it up!

I have a question, though; several nations (such as Melkor in the Martian war) dropped asteroids from orbit onto ground targets, or have asteroids in orbit for mining purposes (well, at least one, I've got an orbital asteroid).

How difficult would it be in real life to move an asteroid out of orbit in the asteroid belt, back to Earth orbit, and into a stable orbit? Or to drop it on a surface location?

How effective in military terms would an asteroid drop actually be?

OOC:-
Along a similar vain: - what kind of damage would a kenetic missile (coated to survive re-entry) have on the ground? Say one of 6 meters in length?

How difficult would it be in real life to move an asteroid out of orbit in the asteroid belt, back to Earth orbit, and into a stable orbit? Or to drop it on a surface location?

How effective in military terms would an asteroid drop actually be?

The sources I use for this sort of orbital bombardment come from science fiction. Robert A. Heinlein wrote a book called, The Moon is a Harsh Mistress, wherein Lunar rebels dropped 20-tonne bundles of rocks onto Earthside cities. Another novel I use is called, Moonfall by Jack McDevitt, where an asteroid hits the Moon and Lunar debris rains across the Earth. Yet another is Footfall by Larry Niven and Jerry Pournelle, which features a bunch of would-be conqueror aliens dropping a Dinosaur-killer on Earth to cow those pesky primates into submission. Another good source is Nemesis, by Isaac Asimov.

Briefly, a small rock (by asteroid standards) hitting the Earth from orbit would be equivalent to a tactical nuclear weapon ground-burst. There would be heat, flashes of light, and a huge pressure wave.

Let me copy a couple of descriptions of this sort of strike. This comes from a work of mine in progress, called "Tales of the Evil Overlord". The chapter title is, "The Fall of Jeeb".

*****

Contrary to the Science Officer's confident predictions, some of the falling rocks did get stopped…in a manner of speaking.

The first asteroid, a three-kilometer lump of nickle-iron, was shattered into thousands of shards by a series of antimatter explosions. The space-time anomalies that inevitably follow A-M blasts resulted in scores of casualties on Jeeb as some shards wormholed to random destinations within a few light-hours. The remaining shards destroyed several orbital installations before burning up in Jeeb's atmosphere.

Asteroid number two was diverted by carefully-placed nuclear explosions while the asteroid was still several million kilometers from Jeeb. The resulting slight vector shift caused the asteroid to hurtle through the upper reaches of Jeeb's atmosphere- trailing a line of flame across the sky of the northern hemisphere- before plunging sunward.

Asteroid three was bombarded by small A-M missiles from the point it began its ballistic orbit almost into Jeeb's exosphere. The asteroid was shattered by the rain of antimatter missiles only ten thousand kilometers from impact. The shattered rock hit Jeeb's atmosphere like a blast from an enormous shotgun. Much of the clustered rock burned up in the atmosphere, but the bulk of the asteroid fragments plunged into the southern ocean. Many of the islands were completely destroyed, and the tsunamis created by the water impacts scoured clean several more. Thousands died on the islands and the low-lying shorelines of the Jeebs' home continent.

The Destroyer pushing asteroid four was destroyed before getting up to full speed, so that asteroid would take several days before reaching Jeeb's orbit. Since the planet would already have passed by the time the asteroid arrived, everyone pretty much forgot about it.

Asteroids five and six were launched almost simultaneously. Number six followed the smaller asteroid five into the Antimatter Particle barrier by just under 12 seconds. Asteroid six was a huge, nearly spherical lump of solid rock.

Asteroid number five was artificial- a large block of Unobtainium™ from one of the lunar mines orbiting Tim. The dinosaur killer's trail through the A-M Particle field- marked by the violent white spheres of antimatter explosions- was visible to the naked eye all the way out to Tim. Despite losing more than twenty percent of its mass in the firestorm, the slug of ore tumbled toward Jeeb. When it was still three million kilometers from planetfall, a small ship of very strange configuration suddenly appeared and matched orbits with the would-be dinosaur killer. The tiny ship attached itself to the asteroid and ran its engines all the way up in a desperate effort to change the boulder's orbit. The Unobtainium™ slug treated the survivors of the southern hemisphere to a brilliant light show as it burned through Jeeb's atmosphere, missing impact by only two kilometers. The tiny ship that had diverted the asteroid was unable to free itself before both rock and ship entered the atmosphere, and burned up in the re-entry. The glowing lump of Unobtainium™, significantly slowed by its passage through the dense envelope of air, ended up in a long elliptical orbit around its erstwhile target.

Asteroid six was the money shot. The dense ball of rock vanished again and again in a haze of spherical antimatter blasts, but always reappeared- somewhat worse for wear, but steadily riding the gravity well toward Jeeb. The spacetime distortions of the antimatter barrage made observation difficult during the last million kilometers to impact, as the desperate defenders rained destruction on the asteroid. The blinding white globes completely obscured the final descent, but when the sensors and scopes of the EOE fleet cleared a few minutes later, the result was no longer in doubt.

The asteroid had impacted in the northern ocean, 463 kilometers from the coastline of the Zirks' home continent. The planet staggered as its orbit and center of rotation changed.

The megatonnes of rock had completely sundered the ocean and cracked the continental plates under the seabed. The shockwave from the impact caused the ocean to surge over the shores of the continent in a tsunami that swept over the mountains and drowned the industrial heartland of the Zirks. The asteroid- already superheated from its impact in the ocean- shattered the planetary crust. Waters streaming back into the void left by the impact instantly flashed to steam as a hundred-kilometer-wide fountain of molten rock burst from the planet's heart. The meeting of water and lava on such a scale spawned kilometer-wide tornadoes that spun off in all directions across the northern hemisphere. The enormous amounts of air displaced by the impact swept across the face of Jeeb at several times the speed of sound. When the giant air masses collided, sheets of lightning thousands of kilometers long ravaged the air, earth, and seas. Trillions of tonnes of atmosphere surged free of Jeeb's gravity under the force of impact and briefly made the space nearby glow in the diffused light of Epsilon Eridani.

The shockwave of the impact blasted billions of tonnes of liquified rock away from the epicenter. Chunks of molten rock hundreds of meters long were sent into unstable orbits, to return weeks, months, years, or decades later. Larger splashes of suddenly-fluid rock carved gouges out of the sea and land thousands of kilometers from the impact site. Tectonic plates, long held in stasis by pressure from their neighboring plates, shifted suddenly under the pressure of impact, causing massive earthquakes over the whole lithosphere- raising mountains thousands of meters in the span of only seconds. Several plates were shattered by the impact and the massive temblors that followed. The earthshocks each spawned a new series of tsunamis, and the giant waves slashed anew at the land.

The trillions of tonnes of vaporized water swept away from the impact site in the wake of the air shockwaves, bringing further destruction. Torrential rains tore at the new mountains, borne on thousand-kilometer-per-hour winds. The presence of so much water and particulate matter in the atmosphere soon made all observation impossible.

The Evil Overlord waved his viewer off. “What is your conclusion?” he demanded of the Science Peon standing before the Seat.

“Based on these images, my Lord, and the sensor data we can get from Tim, I would estimate that approximately 90% of the sentient population of Jeeb perished during the strike and its immediate aftermath. Survivors will be few and far between, and too scattered and traumatized to organize in any meaningful way.” The Science Officer nodded at the Autocrat of Annihilation's viewscreen as she continued. “Furthermore, the remaining planetary population will be far too involved in their desperate struggles to merely survive to be any threat to anyone except themselves. The computers predict that 97% of all species (flora and fauna) on Jeeb will become extinct in the next hundred standard years. Certainly the Zirks will be no more trouble. They'll be too busy becoming extinct, themselves. In a few hundred million years, something might emerge to cause problems.”

*********

I'll cover moving asteroids in another post.

TEO

We- meaning the pack of smelly primates that occupy this planet as a whole in lieu of one particular tribe- might actually do this at some point in the future. We could probably do it now, because no new science is involved- only a metric buttload of engineering problems that have to be overcome. Sadly, the engineering problems are trivial compared to the political problems of selling such an expensive project to the voters. Someone from Earth will doubtless employ similar methods in the future, but they probably won't be Americans.

Damn NASA to hell.

Grrrr .... sorry. I was starting off on another rant. Back on topic.

The technical problems with moving asteroids are pretty daunting ones. Asteroids are not rotating serenely in a stable orbital plane. Most of them are spinning wildly in at least two axes of rotation. The first task before even thinking about moving them is to determine the exact speed and direction of the asteroid's motion. Once this has been determined, engineers and geologists must be landed on the asteroid to locate the best spots to place the prime movers. Assuming that the asteroid is fairly solid and geologically stable, huge motors can be emplaced to give thrust counter to any unwanted motion and stabilize the whirlygig's movement to a single rotational plane.

There are a variety of other ways of accomplishing this- mainly dependent on the technology level you're using. I'm listing the methods for a modern tech (or close to it) society. Be aware that this will take a lot of time, fuel, and money, as well as an extermely fast and flexible computer.

Once a stable rotation has been achieved, thrust must be applied to move the asteroid out of its original orbit and place it in a lower one. Movement in space is not like movement here on Earth. Every desired motion is really 3 (or more) thrusts: 1 to start the object on its new course (transit orbit) toward its new orbital position. 2 to turn it from its transit orbit to its new positional orbit. 3 to accelerate the object to its new orbital speed.

If you have some power source that doesn't require fuel, then you could use massive ships to tow the asteroid into position. These ships would have to have really huge engines capable of really enormous amounts of thrust to accomplish this. Smaller amounts of thrust over a very long time would do the same thing, of course, but I am assuming that you wished to accomplish thejob during the ship's crew lifetimes.

Another option (described by Robert A. Heinlein in his short story, Misfit, which was published in 1939) would be to use nuclear explosions in specially designed blast pits to drive the asteroid into a new orbit.

So, moving asteroids is not easy. I personally think it would be a pretty good idea, but those fuzzy-headed morons at NASA .... sorry.

A good source of information about asteroid mining and other uses for space is the non-fiction work, Mining the Sky, by John S. Lewis.

Hope this helps,

TEO

If you encounter such a nation, it is entirely possible that they are simply unaware of the science and natural laws governing orbital mechanics. This does not make them stupid, just unaware of the facts. Explain the facts to them as gently as possible, provide them with a link to this thread, and ask them to TG me with any questions.

Fair enough... but I suppose we get into rough ground when we start talking about "Near Future" tech huh?


Eitherway, thanks... I may start having to make a choice of whether I'm going to try and keep my "Near Future" tech status and continue with my low tech version of a space fleet, or choose to disband the idea and go "Modern" tech... which would then make some RP's harder to get into.

Personally I've tried to stick to both worlds as I like RPing with both types of nations... using my advanced technologies against advanced nations and my normal technologies against more normal nations... to be honest I don't even used my advanced tech in most cases, I just maintain a small space fleet I never use and about 200 trained Mobile Infantry from the book "Starship Troopers" by Hienlien (got to love him, he's a great sci-fi writer) which were only threatened once as a RP tool (Blackhawk Down scenario).

I don't know.

Eitherway, great advise, I'll remember it and just keep an eye on satalites that overpass me where possible.

OOC:
This is a really, really, really useful thread. Thank you so much for writing it up!

I have a question, though; several nations (such as Melkor in the Martian war) dropped asteroids from orbit onto ground targets, or have asteroids in orbit for mining purposes (well, at least one, I've got an orbital asteroid).

How difficult would it be in real life to move an asteroid out of orbit in the asteroid belt, back to Earth orbit, and into a stable orbit?
Depends in part on how you move it. A rocket, pushing it into a Hohmann transfer orbit, and then into Earth orbit, would be horribly expensive and unworkable. OTOH, setting up a refinery/smelter, and sending the slag and waste down a maglev rail as the propellent, would be cheaper, get rid of mass you wouldn't want to arrive in orbit, be able to run continuously, and be very efficient. However, it would have a very small acceleration, so you'd send the planetoid inwards in a tight, slow spiral.

Or to drop it on a surface location?
From geosynchronous orbit, you'd need to put it into a Hohmann transfer orbit where the perigee is less than ~6375 km from Earth's center---that is, where the point of the new orbit closest to Earth's center is below Earth's surface.
This requires slowing the planetoid from about 3070 m/s to about 1570 m/s. This takes an energy, in Newtons, of the mass (in kg) times about 3,480,000. This becomes a huge amount if you're talking about "dropping" a moderately sized planetoid.

How effective in military terms would an asteroid drop actually be?
Hard to say, without more information. Certainly (many SF stories to the contrary) it would be extremely difficult to destroy a big rock. Further, it would be travelling fast enough to become a difficult target. Further, if it were "dropped" from geosynchronous orbit, there would be about 10.5 hours to react.

OOC:-
Along a similar vain: - what kind of damage would a kenetic missile (coated to survive re-entry) have on the ground? Say one of 6 meters in length?

A sphere 6 meters in diameter, of rock (assume a specific gravity of 3.5), masses around 400 metric tons. If "dropped" from GEO to just touch Earth's surface, it will (at perigee) be moving about 10400 m/s. Subtracting ~500 m/s for the Earth's rotation, and the rock will hit at ~ 9,900 m/s.

This gives a kinetic energy of ~ 1.96 x 10^13 Joules, or (using 4.15 x 10^9 Joules / "ton of TNT") the power of a 4.7 kton bomb.

Of course, it will take about 4.5 x 10^11 Joules to get it to drop in the first place (about the equivalent of 108 'tons' of TNT; this is also ~ the total energy from burning 3.7 metric tons of hydrogen--remember, useful energy from a hyrodgen+oxygen rocket would be no more than ~2% of total energy).

BTW, it will take ~37,700 seconds to impact, and you'll have to do the slowing down 180 degrees ahead of the impact point.

Also, you'll have to move the rock from whatever orbit it's in, to one that passes over the latitude of the target, and one where the ground-track passes over the target. And that kind of adjustment both takes a lot of energy, and a good bit of time.

BTW, re. moving a planetoid from the planetoid belt to Earth orbit: using a solar sail would take no propellent at all, and would probably be the cheapest way of all.

BTW, re. moving a planetoid from the planetoid belt to Earth orbit: using a solar sail would take no propellent at all, and would probably be the cheapest way of all.

I was under the impression that it was impossible to tack with a light sail, since it would essentially involve trying to sail directly into the the solar wind. If I'm wrong, let me know.

Using a relatively powerful laser mounted on a nearby planetoid ought to work just fine, however.

TEO

You could angle it so as to propel the planetoid opposite the direction of it's orbit, thus decreasing its orbital velocity and causing it to fall inward.

Another question:

If I have a drive which can supply a continued acceleration of 1 Gravity, how long will it take to go a set distance, say half an AU (74,789,350 Km)?

BTW, re. moving a planetoid from the planetoid belt to Earth orbit: using a solar sail would take no propellent at all, and would probably be the cheapest way of all.

I was under the impression that it was impossible to tack with a light sail, since it would essentially involve trying to sail directly into the the solar wind. If I'm wrong, let me know.

Using a relatively powerful laser mounted on a nearby planetoid ought to work just fine, however.

TEO

You could angle it so as to propel the planetoid opposite the direction of it's orbit, thus decreasing its orbital velocity and causing it to fall inward.

Or, adapting from "The Integral Trees"/"The Smoke Ring" by Larry Niven:
Backwards takes you in, in takes you forward, forward takes you out, and out takes you backward
(where in and out are towards and away from the sun, forward is the direction of rotation and backwards is opposite the direction of rotation).

Another question:

If I have a drive which can supply a continued acceleration of 1 Gravity, how long will it take to go a set distance, say half an AU (74,789,350 Km)?

Depends on whether you want to do a fly-by, or slow down and "land".

The base formula is time = (2*distance/acceleration)^0.5.
That is, the square root of (twice the distance being accelerated through divided by the acceleration).

Note, that if you're doing a fly-by, accelerating the whole distance, this is the formula to use. However, if you're accelerating then decelerating, you need to use half the distance, then twice the time. IOW:
time = 2 * (total distance/acceleration)^0.5

For 1 g (=9.80665 m/sec/sec) and 74,789,350 km, you get 174658 seconds (2 days 30 minutes 58 seconds).

Oh, so *that's* what that quote means. I always had trouble with that one.

(edit)

Thanks for helping me with that! It's greatly appreciated.

{Tag; For Reference Purposes}

A few questions.

1. What are the minimum distances between Earth and Mars, Earth and Venus, Earth and etc etc? I'm trying to find this stuff on google but not having any luck.

2. What are the maximum distances?

3. What are the delta v's required for Hohmann transfer orbits between each of the planets? Or I guess, what would be the distance travelled in a Hohmann transfer orbit?

As you can see I'm trying to figure out how long it'll take for me to get from any point in the solar system to another. (Well, major points, Earth, asteroids, whatever.) I ask the Hohmann transfer orbit since I'd think that's the most common, but I ask the plain distances between the planets also since I'm aiming for high-thrust, high-fuel consumption, low time transfers as well and wanna figure out if my ships can hack it.

Thanks in advance.

A few questions.

1. What are the minimum distances between Earth and Mars, Earth and Venus, Earth and etc etc? I'm trying to find this stuff on google but not having any luck.

2. What are the maximum distances?

3. What are the delta v's required for Hohmann transfer orbits between each of the planets? Or I guess, what would be the distance travelled in a Hohmann transfer orbit?

As you can see I'm trying to figure out how long it'll take for me to get from any point in the solar system to another. (Well, major points, Earth, asteroids, whatever.) I ask the Hohmann transfer orbit since I'd think that's the most common, but I ask the plain distances between the planets also since I'm aiming for high-thrust, high-fuel consumption, low time transfers as well and wanna figure out if my ships can hack it.

Thanks in advance.

A few questions.

1. What are the minimum distances between Earth and Mars, Earth and Venus, Earth and etc etc? I'm trying to find this stuff on google but not having any luck.

2. What are the maximum distances?

3. What are the delta v's required for Hohmann transfer orbits between each of the planets? Or I guess, what would be the distance travelled in a Hohmann transfer orbit?

As you can see I'm trying to figure out how long it'll take for me to get from any point in the solar system to another. (Well, major points, Earth, asteroids, whatever.) I ask the Hohmann transfer orbit since I'd think that's the most common, but I ask the plain distances between the planets also since I'm aiming for high-thrust, high-fuel consumption, low time transfers as well and wanna figure out if my ships can hack it.

Thanks in advance.

Do you want physical or temporal distance- or both? You specified a Hohmann orbit, but a lot will depend on the type of drive and the amount of thrust available.


TEO

In the case of Space Based Satellite Killer Weapons, using a small Hydrogen Fuel-Cell Reactor onboard a stabilized Platform would indeed create enough energy for plenty of mini-lasers. Yet, however, mini-lasers are hand-held, and do nothing. So, intern, if we use a Hydrogen Laser, powered by Hydrogen Fuel-Cells, we have a good and conductive Satellite Killer.

Anywho, thanks for the info. I try to keep my weapons as REAL as possible, expections are the few instances when everythings goes right, or when more fun can be induced, when everything goes wrong, lol.

Thanks again.

I wanted the physical distance, since if I know the distance to travel I can fit that in with my ships' stats to figure out the temporal.

Problem is, I know how far a planet orbit tends to be from the sun, but not how far from other orbiting objects. I need either some kind of chart or formula here really.

Ds: orbital radius of outer planet
Di: orbital radius of innner planet.

Maximum distance: Ds+Di
Minimum distance: Ds-Di
Average distance: Ds
For exact distances at any particular point in time, you'll probably need an orrery.

For brachistochrone orbits (max dV requirements, minimum travel time), time in seconds is given by T = 2*sqrt[D/A], and required dV is given by dV = 2*(sqrt[2*A*(D/2)])+sqrt[1.33e20 / Di] - sqrt[1.33e20 / Ds].

Hohmann orbits I'm not sure of.

Thanks, that was exactly what I was looking for.

One question, will that work with any 2 elliptically orbiting bodies?

Thanks, that was exactly what I was looking for.

One question, will that work with any 2 elliptically orbiting bodies?
Well, I am not a rocket scientist, but it should.

Ds: orbital radius of outer planet
Di: orbital radius of innner planet.

Maximum distance: Ds+Di
Minimum distance: Ds-Di
Average distance: Ds
For exact distances at any particular point in time, you'll probably need an orrery.

For brachistochrone orbits (max dV requirements, minimum travel time), time in seconds is given by T = 2*sqrt[D/A], and required dV is given by dV = 2*(sqrt[2*A*(D/2)])+sqrt[1.33e20 / Di] - sqrt[1.33e20 / Ds].

Hohmann orbits I'm not sure of.

Thanks. That's a lot more succinct than the response I was working on (although it is the same answer).

Distance in space is usually more a matter of travel time and fuel expenditure rather than linear distance. Your point of origin is moving, you are moving, and the destination is moving- all at different speeds (and possibly different orbital inclinations). Hohmann orbits are sometimes called minimum-fuel orbits because they get the vehicle to the destination over a long period of time but don't use a lot of fuel in the process. I think that there's a series of equations for the Hohmann orbit in one of the links on the first page of this thread.

For RL physics, travel in space is a trade-off of fuel for time. Reaction engines are inherently wasteful. Use more fuel, get there quicker- but you'll have a lot less fuel for an emergency reserve (read a short story called "The Cold Equations for a ruthless description of how this could affect travel in space). Use less fuel, and it'll take forever to get where you're going- but you'll be a lot safer on the journey.

Most of the time.


TEO

Thanks, that was exactly what I was looking for.

One question, will that work with any 2 elliptically orbiting bodies?

Assuming that they orbit the same primary, yes.

Imagine a system-within-a-system: A gas giant planet has several dozen natural satellites- some of which have natural satellites of their own. All of these are orbiting the primary (the gas giant). Getting from Primary Satellite A- which directly orbits the gas giant- to Primary Satellite B- which also directly orbits the gas giant- is a fairly straightforward calculation with the equation already posted.

If PSA has a satellite of its own, and you wish to get to PSB, the math becomes only a little more complicated (generate the mean distance for the two primary satellites, then add/subtract the distance to PSA's satellite at a given point in its orbit.

If both Primary Satellites have their own satellites, it gets slightly more complicated to figure the distances.

Under the situation above, it would probably be easiest to calculate an orbit to the Primary Satellites, then configure a new orbit for the Secondary satellites once you are near the Primary satellite and have better orbital positioning data.

Remember also that every move you make in space takes fuel, and every mistake costs four times as much fuel.

Makes you thankful for digital computers.

TEO

<Mark>

Found:

Hohmann Transfer Orbit:

dVh = Ve1 * sqrt( R2/(R1+R2) ) + Ve2 * sqrt( R1/(R1+R2) )

dVh = total delta-V (m/sec) of Hohmann transfer orbit
Ve1 = Escape velocity (m/sec) of start body
Ve2 = Escape velocity (m/sec) of end body
R1 = Radius of start body's orbit
R2 = Radius of end body's orbit

Only problem there I have now is, calculating time for that orbit. It's not just the delta V divided by the acceleration or anything, since the Hohmann transfer is (if I'm not mistaken) only burning fuel for some, not all the trip.

Only problem there I have now is, calculating time for that orbit. It's not just the delta V divided by the acceleration or anything, since the Hohmann transfer is (if I'm not mistaken) only burning fuel for some, not all the trip.

You're right, the Hohmann orbit involves coasting most of the way there. But it's really more complicated than that. You also have to acount for the fact that you will be decelerating at the end of the trip. It does you no good to arrive at your destination going thousands of mile per hour (relative to the destination). Your travel time will not include additional time required to match orbits with the destination. Assuming RL physics and reaction engines.


TEO

BUMP

For those nations interested in orbital bombardment, here's a link to a calculator of damage from an orbital strike.

http://www.lpl.arizona.edu/impacteffects/


TEO

For those nations interested in orbital bombardment, here's a link to a calculator of damage from an orbital strike.

http://www.lpl.arizona.edu/impacteffects/


TEO

Holy crap! Thanks man, thus far i have been limited to calculating the newtonian KE of a Kinetic Energy Weapon and then translate that to Megatons and apply it to one Nuclear Explosion effect calculator, but this is far better.

Heeheheehe *giggles hysterically at the prospect of 150 ton missiles hitting at .2c* :twisted:

Um, Evil Overlord what about the testing of such laser weapons by the US military aboard a Boeing 747 to destroy intercontinental ballistic missiles?

Um, Evil Overlord what about the testing of such laser weapons by the US military aboard a Boeing 747 to destroy intercontinental ballistic missiles?

Once again, we're talking about the meaning of destroy.

The 2-megawatt (I think that's the power rating being bandied about at the time) throughput of the laser they're testing will not destroy an ICBM. It is capable of rendering incoming ballistic warheads incapable of exploding- by damaging the circuits of the bombs and guidance gear. It is also capable of causing the boost-phase rocket motors to prematurely explode (which would be pretty close to the textbook definition of destroy, now that I think about it), but that would require the weapon being close enough to do so. Atmospheric attenuation (so-called thermal bloom) will still be a major factor.

The big breakthrough with this new laser is the power throughput- the energy delivered out of the emission end of the weapon. The numbers I've heard are between 1 and 2 megawatts- a significant achievement.

The laser system is designed as a missile defense. The purpose of missile defense is to make sure that the enemy's incoming missiles either miss you completely or in some other way fail to do their intended job. Reports of destroying incoming missiles are most likely to be media hype, military propaganda, misunderstandings by non-technical dweeboid media people, or a combination of all three.

Of course, since all I have to go on are published technical reports (which are by definition heavily censored and/or out of date), I could be wrong. Your best bet is to completely ignore any US broadcast media source and listen to the BBC, Reuters, or some of the Defense Industry house magazines, Space.com, rednova.com, and similar knowledgeable parties.

TEO

OOC: This is a tag.

Bump for the new forums


TEO

I'm not sure if I've .::TAGed::. this already or not, but just to be safe: .::TAG::.

Yeeha!!!

{tag}

Bump


I make no claims to being the all-knowing guru of RL physics, BTW. All of this information is available freely in any good library, or even with a few moments of searching online. If anyone discovers any factual errors, please feel free to let me know.

I just got tired of reading posts about astronauts using RL firearms in microgravity and not suffering the inevitable repercussions; idiotic demands to remove all foreign satellites from such-and-so's airspace; loud announcements of the presence of ICBMs in orbit; and ridiculous claims by allegedly modern-tech nations for the performance of their spacecraft.


TEO

Yet another bump

*TAG for future reading*

Brilliant...

I believe I covered this a bit in my Logistics thread, but I wanted to discuss warfare in space. By this I refer to modern war (invading other planets, ship-to-ship space combat, etc) in the space environment and not the US Air Force program for destroying orbital space assets of other countries with US space assets.

Let's suppose your nation on Earth wanted to invade Mars, and further suppose that there are people of some sort already living on Mars who will probably be unhappy about the invaders dropping in for an extended stay. Using those starting points, and staying within the confines of RL technology, how would one go about invading Mars?

The Earth invaders would have several bad options for invading. The optimal orbital configuration for the invasion only happens every few years, and doesn't last very long. No matter when you decide to invade, it will take a minimum of several months to get to Mars from Earth. Using real world technology, this means that everyone on board will be in microgravity for several months. Your invading troops (and ship's crew) will be suffering from a variety of microgravity-induced physical ailments that will severely reduce their combat capability.

Another bad thing would be the population density of Mars. The Martians are always going to outnumber the Earthmen, and there's no practical way to build enough ships to carry millions of troops to Mars using RL technology. So now the invaders are both outnumbered and physically incapable of fighting well- even in the reduced gravity well of the red planet.

The physical conditions on Mars present another obstacle. Humans can't live there without extensive life-support. The Martians have no such restriction. Furthermore, the life-support mechanisms required to keep humans alive are all fairly easy for an energetic martian to destroy or damage. The lower gravity will also play hell with the invaders' reflexes. Firing guns will require extensive practice in 1/3 the gravity that humans are used to. The thinner atmosphere will let the bullets fly a long way before gravity finally pulls 'em down.

Let's take a look at possible solutions to these obstacles. We can do away with some of them by assuming that Mars has been selectively terraformed- the atmosphere density has been increased, the planetary core has been induced to start sipnning again somehow (Mars does not have a magnetic field like Earth's) to get a planetary magnetic field. We can further assume that the Martians are actually human colonists from Earth. With all of these (currently impossible or impractical) upgrades to the Martian environment, we are still left with some extremely intractible problems involved with invading Mars from Earth.

The transit time will always be a problem using modern technology. The psychological and physiological problems could possibly- although not practically- be dealt with by building enormous ships with some sort of spinning chamber to simulate gravity for muscle and bone conditioning and a large (make that huge) crew and invasion force to deal with psychological problems. You're still stuck with a several-months-long transit time, which only happens every couple of years.

OK. Our putative invading nation will just have to build several dozen of these superships and launch them all within a week or two of each other. They'll all arrive at Mars reasonably close to the same time, and they all go into orbit around the red planet with their thousands of ultra-tough killer troops on board. Now what?

Invade Mars! WOOT!

Hold on there, Sparky. How? Your thousands of elite spaceship Marines are all several hundred kliometers above the planet. How will you get them down?

Well ... they'll go down in sub-orbital shuttles! Invade Mars! Woot!

How many of these shuttles will each ship be carrying, and how many troops will fit in each one? How much fuel will it take to get back up to the mothership from the ground? How much fuel for these trips will the mothership be carrying? As you can see, these superships- already larger than a US Navy aircraft carrier- are growing ever-larger with the answer to each question.

You're no fun anymore.

Welcome to the real world. Remember, even if we postulate a massive global effort to build and equip these warships, the invaders are still going to be horribly outnumbered by the colonists on the ground. Even if they don't have a lot of weapons, the mechnisms required to survive on Mars would put the capability of building effective weapons in the hands of every jack-leg mechanic on the planet.

Thankfully, there is a potential solution to the problem, even using only modern technology:

Mars is considerably smaller than Earth. That said, the planet is still a vast expanse of emptiness. Land your invaders several hundred (or thousand) kilometers from the colonists. Build up a base over several years. Most of those superships just went away, replaced by perhaps three or four ships making regular runs with supplies and personnel over a period of years. When you have enough people in your new colony, you can use them to conquer a nearby colony.

At this point, alot of people will be asking themselves, "Why bother? I already have a colony there. What's the point of conquering another colony?"

My point exactly.


TEO

Bump for November

Evil Overlord should be one of the "war exports" in the Mod Squad thing...

[OOC: The Mod Squad is still going?]

[OOC: The Mod Squad is still going?]


I have no idea. Since the whole "Mod Squad" gig was Before Switching To Jolt (BSTJ), I tend to doubt it.


TEO

Ehh... TEO...

100 meters/second*60*60 = 360,000m/s
360,000 meters/hour =/= 360,000 kilometers/hour

Did you mean 100kps, or did you mean 100m/s?

[OOC: I know it was. I'm curious because, well, I was IN the Mod Squad. So. Um. Yeah. Was curious to see someone talk as if it were still going...]

Ehh... TEO...

100 meters/second*60*60 = 360,000m/s
360,000 meters/hour != 360,000 kilometers/hour

Did you mean 100kps, or did you mean 100m/s?


Not sure what post you're referring to, but you seem to have made an error:

100 meters/second = 360,000 meters/hour = 360 kilometers/hour.

NOT 360,000 kilometers/hour.


TEO

[OOC: I know it was. I'm curious because, well, I was IN the Mod Squad. So. Um. Yeah. Was curious to see someone talk as if it were still going...]

I think that post was from BSTJ.

I wasn't invited to be in the Mod Squad, but I used to visit the website from time to time. Since the switch, I no longer have their website linked in my favorites folder.

Sorry,

TEO

Not sure what post you're referring to, but you seem to have made an error:

100 meters/second = 360,000 meters/hour = 360 kilometers/hour.

NOT 360,000 kilometers/hour.


TEO

I'm refering to your first post where you're talking about Area-Effect KEW's.

"360,000 meters/hour =/= 360,000 kilometers/hour" is read as,
"360 thousand meters per hour is not equal to 360 thousand kilometers per hour."

You might want to note that =/= shows inequality.


Each individual shotgun pellet is a fairly insignificant mass, but the pellets are traveling at 100 meters per second (360,000 KPH) and run head on into a satellite with a mass of 200 kilograms traveling at 20,000 KPH (around 6 meters per second).
There's your problem.

May I just remind everybody that using the expression '!=' for 'inequality' is wrong, since the '!' sign in mathematics stands for 'Factorial'. At least this is what I have been taught in my little continental European college.

http://mathworld.wolfram.com/fimg74.gif

Calculating 360'000! might freeze your little computer's calculator. :)

May I just remind everybody that using the expression '!=' for 'inequality' is wrong, since the '!' sign in mathematics stands for 'Factorial'. At least this is what I have been taught in my little continental European college.

http://mathworld.wolfram.com/fimg74.gif

Calculating 360'000! might freeze your little computer's calculator. :)
Well, I've been taught by a few people throughout 4 years of High school to use ! to show inequality among a set of numbers, and I've been taught to use ! as factorial, as well. That's what you get in US schools with a different math teacher every semester.

Oh well. I'm still trying to practically reset my mind because of the uniformity in the lessons at my (not so) little University of Nebraska...

Note: I tried 360,000! 15 minutes ago... It's still going.

Well, I'm done here. No matter what symbol I used, you're still wrong in your math. 100 Meters per Second does not equal 360,000 KPH, but rather 360 KPH. Just thought you might want to know about that error, because it kind of skewed your credibility.

May I just remind everybody that using the expression '!=' for 'inequality' is wrongIn C++, != is used for inequality.

Off-topic: O.o I don't think I've seen Foe Hammer's name in quite a while.

I'm refering to your first post where you're talking about Area-Effect KEW's.

"360,000 meters/hour =/= 360,000 kilometers/hour" is read as,
"360 thousand meters per hour is not equal to 360 thousand kilometers per hour."

You might want to note that =/= shows inequality.



There's your problem.

I apparently misplaced a decimal. Thanks for catching it.

Note to self: Work harder to catch this sort of thing to avoid looking like an idiot.


TEO

Been a while since this has seen any action, so ...

BUMP

BUMP for March

And a BUMP for May.


TEO

[OOC: Nice thread you have here. Glad to see confirmation that yes, bomb-pumped gamma lasers are feasible... especially since I've started using them in RP. :P]

[OOC: Nice thread you have here. Glad to see confirmation that yes, bomb-pumped gamma lasers are feasible... especially since I've started using them in RP. :P]

Feasible, yes. The science tells us that it will work, and laboratory experiments seem to bear this out. Whether or not anyone has actually built one and tested it outside the lab is probably classified. There is a RL international treaty to the effect that no nation will deploy any nuclear weapons in space. Since the concept has been widely published over the last three decades, I'm assuming that it does work, and began deploying my own version many moons ago.


TEO