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#26 Re: Terraformation » Polluting Mars - Good idea? » 2005-09-13 23:28:56
That is a popular idea. "Polluting" Mars with greenhouse gases would trap heat in the atmosphere and thus warm the planet to a suitible temperature for Earth-like life. That is how global warming works, only here on Earth, it's bad. Algae (not even genetically engineered) that can survive in hostile environments would then be sent to convert the CO2 to O2. With the ice caps now melted, the algae would live in the oceans.
#27 Re: Terraformation » Provide the Moon with atmosphere - oxygen one » 2005-09-13 22:49:19
Before you consider if an atmosphere would be sustainable on the moon, it is desirable to know something about meteorology.
The moon is about 100ºC at noon, and about -173ºC at night. Now say an atmosphere was introduced. The cool air would want to sink, causing high pressure, and the warm air would want to rise, causing low pressure. But because of the major temperature differences, you would have insane pressure systems at both extremes. Since an atmosphere always works to restore equilibrium, air moves into low-pressure areas from the high-pressure areas (always in that sequence). This is more commonly known as "wind." So, on the moon, the air would be RUSHING to low-pressure zones, madly trying to maintain equilibrium in such largely different pressure zones. Such an atmosphere would be very turbulent and therefore very unpleasant in which to live.
On the moon, we should stick to enclosed atmospheres.
#28 Re: Interplanetary transportation » ION Engines » 2005-09-13 22:14:36
What? Are you some kind of a troll?
The exhaust velocity controls the specific impulse, a high-velocity engine typically has a high Isp. It also doesn't offer more "pressure" because there is no gas expansion in an ion engine. There is also a very, very small amount of thrust because the engine trades thrust for specific impulse.
Antimatter would be great, but we have no way to produce or store it in any quantity, so its not very useful. A beam-type photon rocket wouldn't have very good thrust either.
Nuclear pulse engines aren't even going to be very useful because of the fallout and expense of building an arsenal of nukes to push it with.
Antimatter catalyzed fusion engines are also a pretty far-out concept, and nobody has even started concieving how you would build such an engine.
I think it would be wise to research something before making any assertions about it.
Antimatter is produce all of the time in particle accelerators. They then store the antimatter (which are usually antiprotons) in electrommagnetic fields. The photons of a photon rocket come from matter/antimatter annihilation, thus, barely any materials will be needed to produce a LOT of energy (E=MC²) that MOVES AT THE SPEED OF LIGHT (It IS light!). High exhaust velocity and high pressure!
Antimatter-catalyzed fission engines are the MOST "NEAR-IN" concept of matter annihilation propulsion. I couldn't help but notice that you stated that "nobody has even started concieving how you would build such an engine?" Do your homework, my friend. Penn State University has designed a ship called ICAN-II that uses this type of engine, and might I add, they did a pretty fine job.
P.S. I am not a troll. 
#29 Re: Interplanetary transportation » ION Engines » 2005-09-13 20:10:33
The ion engine's exhaust velocity is pretty good, but its specifc impulse is horrible. It would be wiser to use the 80-year-old technology of the rocket that is normally used today than to use an ion engine simply because it offers so much more pressure.
So one may ask what engine offers both high exhaust velocity and high specific impulse. The answer is only engines that involve matter annihilation, like the photon rocket, nuclear-pulse rocket or the matter/antimatter-catalyzed fisson rocket. This is because E=MC². That is a LOT of energy!
I think you mean the thrust is low, not the specific impulse.
"Thrust" is a general term for the propellent. There are two factors of thrust. One is the exhaust velocity, the other is the force, called specific impulse.
Say you are in a 50-ton vehicle. It has a rocket, and its propellent is matter that is travelling at 5 miles per hour, but you have enough to apply 100,000 pounds of pressure. You would accelerate pretty fast, but your speed would be limited to just under 5 miles per hour. Now say the propellent is matter that is travelling at 50,000 miles per hour, but you only have 1 pound of pressure. You would accelerate very slowly, but your top speed would be just under 50,000 miles per hour. The ion engine is more like the second example. Only matter annihilation engines can offer large quantities both factors.
#30 Re: Interplanetary transportation » WARP DRIVE, AHEM! » 2005-09-13 17:28:01
In 1994, the theoretical physicist Miguel Alcubierre published a paper that introduces a method for a warp drive. Surprisingly, it has not made too much noise.
As we know, Einstein established that nothing can travel faster than the speed of light. That is a general statement. Nothing can LOCALLY travel faster than the speed of light.
Take for example the expansion of the early universe. Light was travelling at the speed of light, obviously, but spacetime itself was expanding too. Thus, an inertial observer, not effected by this expansion, would observe that the light is travelling faster that the speed of light.
Now we apply this concept to a warp drive. By distorting the spacetime around a vessel by making an expansion of spacetime behind a ship, and an opposite contraction of spacetime in front of the ship, the ship is "pushed" forward by spacetime itself. This is called a warp bubble. Since the spacetime INSIDE and OUTSIDE of the bubble is uneffected, no time dilation occurs. No effects of acceleration are felt in the ship since the ship is LOCALLY not moving.
There is no known way to induce this effect. Negative energy is needed, which can only come from exotic matter.
There must be a better to explain this spacetime stuff, so ask any questions that you may have.
#31 Re: Interplanetary transportation » ION Engines » 2005-09-13 17:12:10
The ion engine's exhaust velocity is pretty good, but its specifc impulse is horrible. It would be wiser to use the 80-year-old technology of the rocket that is normally used today than to use an ion engine simply because it offers so much more pressure.
So one may ask what engine offers both high exhaust velocity and high specific impulse. The answer is only engines that involve matter annihilation, like the photon rocket, nuclear-pulse rocket or the matter/antimatter-catalyzed fisson rocket. This is because E=MC². That is a LOT of energy!