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Space Transportation Science

Electric Rockets Set To Transform Space Flight 114

Posted by Soulskill
from the flying-to-the-future-at-full-impulse dept.
An anonymous reader sends this quote from an article at Txchnologist: "The spectacle of a booster rocket lifting off a launch pad atop a mass of brilliant flames and billowing smoke is an iconic image of the Space Age. Such powerful chemical rockets are needed to break the bonds of Earth's gravity and send spacecraft into orbit. But once a vehicle has progressed beyond low-earth orbit chemical rockets are not necessarily the best way to get around outer space. That's because chemical propulsion systems require such large quantities of fuel to generate high speeds, there is little room for payload. As a result rocket scientists are increasingly turning to electric rockets, which accelerate propellants out the back end using solar-powered electromagnetic fields rather than chemical reactions. The electric rockets use so much less propellant that the entire spacecraft can be much more compact, which enables them to scale down the original launch boosters."
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Electric Rockets Set To Transform Space Flight

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  • by decipher_saint (72686) on Tuesday February 21, 2012 @05:01PM (#39116085) Homepage

    213 million six foot power strips daisy chained together...

  • by iliketrash (624051) on Tuesday February 21, 2012 @05:12PM (#39116257)

    This piece piques one of my pet peeves, the confusion between scientists and engineers. Scientists do not build rockets--engineers build rockets. Even if a person trained in, say, physics, is designing a rocket, that person is effectively acting as an engineer.

    I object to attempts to glorify certain kinds of engineers by calling them scientists. There is no such need to glorify engineers--they are glorious in their own right. Calling them scientists is a slap in the face and an insult.

    Engineering and science could hardly be different. Engineers put things together; scientists take things apart.

  • by Trapezium Artist (919330) on Tuesday February 21, 2012 @05:28PM (#39116495)

    I've long since given up on there being any semblance of proper research done in such articles, particularly when a nod might have to be given to anyone outside the US.

    I'm no expert in the history of solar electric ion propulsion systems, but believe that NASA's Deep Space-1 mission in 1998 was (I think) the first to use SEP as its primary post-launch propulsion, as several subsequent NASA missions, including Dawn, as discussed in the article.

    However, several European Space Agency missions have also used similar systems, including the ARTEMIS satellite in 2001 to get itself to geostationary orbit, the SMART-1 mission to the Moon (launched 2003, ended in a deliberate crash onto the Moon in 2006), the GOCE gravity-mapping mission, and the BepiColombo mission to Mercury (due for launch in 3 years) will be using one. The Japanese Hayabusa-1 asteroid sample return mission also used one.

    Just trying to set the record at least a little straighter ...

  • by Tumbleweed (3706) * on Tuesday February 21, 2012 @06:08PM (#39116979)

    We are going to get shiny metallic space suits next.
    Robots that flails its arms screaming "Danger Will Robinson Danger !"
    This is great stuff we are back to ION propulsion which is kind of cool. Remember the spaceships that sail like Solar wind and stuff?
    That would be cool too. Perhaps next we can actually get someone to care and fund this stuff and some of it will end up actually mattering in the long run.

    Of all the things in your posting, the last sentence is by far the least-likely. :(

  • by ceoyoyo (59147) on Tuesday February 21, 2012 @06:28PM (#39117183)

    If you're building new drives to experiment with, you're a scientist. If you're following established principles to build a drive then you're an engineer.

    The distinction isn't nearly as clear as you imply, and isn't based on your criteria.

    I have degrees in oth science and engineering. Normally I do science with a bit of engineering, figuring out how to do new things. Sometimes I do engineering with a smattering of science figuring out how to do those new things out in the field.

  • by tp1024 (2409684) on Tuesday February 21, 2012 @06:39PM (#39117303)
    The watt count doesn't matter. It's exhaust velocity (more means more energy use, no matter what technology) of the engine and the total amount of energy carried by the reactor (more energy means more mass, means less speed). 0.1-1% of the speed of light should easily be possible, but I haven't done the math to the point of calculating multiple stages, optimizing the energy budget with respect to the trade-off between exhaust velocity and energy consumption and so on and so forth.

    Hydrogen-Oxygen fuel has an exhaust velocity of about 4500m/s for a final speed on the order of 20km/s with multiple stages (for any significant payload). Simple ion engines can reach 30,000m/s, but final speeds will be less than expected, as the empty mass of the stages is higher. Something on the order of 100km/s with 2-3 stages should be possible. (Let's say 12,000 years to Alpha Centauri.) More sophisticated engines can reach up to 200,000m/s in exhaust velocity (2000 years to Alpha Centauri), but somewhere the energy limitations will kick in and I don't know whether before or after that point. (That's when the Uranium/Plutonium makes up a very significant part of the deadweight - even if you throw some of it over board in the process.)

    Just build some of space ships and a couple of pyramids in a desert to remind people they are on their way.

Reality must take precedence over public relations, for Mother Nature cannot be fooled. -- R.P. Feynman

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