What is Digg?84 Comments
- wynja, on 08/08/2008, -0/+34It's good to see advanced rocket engine development spewing over into the private sector.
- suckanucka, on 08/08/2008, -0/+34As long as it has ambient light, it has my approval.
- gametavern, on 08/08/2008, -2/+31when will I see a plasma pistol/rifle/sword?
- trollick, on 08/08/2008, -1/+16SCIENCE!
- Adamlite, on 08/08/2008, -0/+15Mars in 39 days!
- bbqsalad, on 08/08/2008, -0/+10NASA is considering flying a prototype plasma rocket engine designed by a former astronaut to the International Space Station for testing.
- mizarone, on 08/08/2008, -0/+10What could possibly go wrong?
- Jam20621, on 08/08/2008, -0/+9Yah I like how they just kinda tack that on the end as if it isn't a pretty big deal lol
- inactive, on 08/08/2008, -1/+9NASA = the only worthwhile ***** thing the federal government is doing.
- bmorris, on 08/08/2008, -8/+16Boring. Call me when they make a plasma rifle.
- muniak, on 08/08/2008, -2/+7Well I buried that story, maybe the bury to digg ratio on that silly drama picture is a lot higher than it is on this interesting article WITH pictures. Not everything is a conspiracy, you could probably take off your tinfoil hat now.
- carnivore0311, on 08/08/2008, -0/+5Hell yes!
- Frozo, on 08/08/2008, -1/+6It's not the slow acceleration that's keeping it from being used at launch. If you fully read the article, you would see that this was designed to only work in the vacuum of space.
- pathouston22, on 08/08/2008, -0/+5"Now Ad Astra is in negations with the U.S. government to mount its rocket engine to the space station for testing"
Wait. We're going to test a rocket engine by mounting it to a multi-billion dollar space station? - muhadeeb, on 08/08/2008, -0/+4Aye, Scotty would be proud. (StarTrek).Next I want to see warp drive.
- prometheanspark, on 08/08/2008, -0/+3It's similar. The difference between ion engines and VASIMR though is that VASIMR has a variable impulse.
The problem with high ISP electric engines is that E=1/2mv^2 and ISP (fuel efficiency) is proportional to v. Thus a doubling in efficiency requires 4x the energy consumption. Some maneuvers require more immediate impulse than other, and when flying astronauts about naturally you don't want to twiddle your thumbs for two years waiting for them to spiral out of orbit. VASIMR allows considerable tradeoff between thrust and fuel efficiency, so that when you need to goose it, you can, and the rest of the time it can operate at high efficiency. This would be great for a manned craft (or perishable supplies) that carries people/stuff one way and returns empty, for instance.
Despite having 'high-thrust' for an electric engine, it is still far from even unity thrust-to weight, making it impractical for spacelaunch from earth (typical booster engines have T/W around 80), but there are many applications in space for such thrusters.
These haven't had a whole lot of priority because a large craft would require nuclear power to use a large VASIMR engine, and we aren't conducting missions that require the flexibility the engine provides. With the return to the moon coming up, and Mars missions on the horizon, VASIMR or something like it will gain more interest. - earthforce1, on 08/08/2008, -0/+3Your two statements are contradictory;
If it takes only a few (call it f) years to approach c, (speed of light) and the alpha centauri triple star system is about is 4.3 l.y. distant, http://en.wikipedia.org/wiki/Alpha_Centauri, then the time required to reach the system is slightly more than f + 4.3, or 2f + 4.3 if we actually want to slow down for a visit instead of blowing by at near light speed.
The advantage of plasma drive is that the fuel is much more efficiently used than a chemical rocket. Every atom of fuel in a plasma drive engine can be pushed out the back at near light speed, giving a lot of push for a tiny amount of fuel. The byproduct of chemical reactions in rocket engines cannot deliver anywhere near that amount of per atom thrust; ergo rockets burn tremendous amounts of fuel. The plasma drive's thrust seems unimpressive by comparison, but it can deliver its gentle push for a year or more without expending much fuel which really adds up over time. A chemical rocket delivers a huge thrust, but runs out of fuel in a matter of minutes.
Think of it like the tortise vs. the hare. Except the tortise accelerates just a little bit faster with each passing step. - RogerStrong, on 08/08/2008, -0/+2Alas, even if you had a reactionless drive, even a reactor powering it would need to be refueled long before it gets near the speed of light. Pushing the spacecraft plus the reactor, that's a whole lot of power needed, for a long time.
- MadOgre, on 08/09/2008, -0/+2Weight of the fuel is a huge factor. Mercury is heavy. And toxic. Your idea is stupid.
- ShadowofAres, on 08/09/2008, -0/+2explain
- Derrekito, on 08/09/2008, -0/+2Really?!!! You seriously don't think the war on Iraq and the War on drugs is the best ***** thing ever?
- ShadowofAres, on 08/09/2008, -0/+2What do you think would happen if 8 people died on a privately owned spacecraft?
- bbqsalad, on 08/08/2008, -0/+2backpedal
- RogerStrong, on 08/08/2008, -0/+2>> All of NASA and space exploration should be privatized,
No. Most of what NASA does, private industry won't do. They don't have a business case to make a profit off it. Alas, that even included the aviation safety stuff that NASA does.
And private industry has a poor track record in space research - even when commercially applicable:
NASA tested ion drive on the ground in the 1960s. Private industry knew all about it (it even got mentioned in the original Star Trek series) and knew that it would be a far better alternative than chemical rockets for communications satellite station-keeping.
But the commercial satellite industry is conservative as all hell. They wouldn't use ion drive because, well, no-one had used ion-drive. Once NASA used it on a space probe in the late 90s, private industry started using it. - RogerStrong, on 08/08/2008, -0/+2>> ISS is nearing the end of it's slated shelf life
No, it isn't.
Much is made of the one module, Zarya, being half-way through its 15 years life-span. Zarya provided electrical power, storage, propulsion, and guidance to the ISS during the ***INITIAL*** stage of assembly. As other modules with more specialized functionality were added, the Zarya's role primarily becomes storage, both inside the pressurized section and in the externally mounted fuel tanks.
In any case, Zarya incorporates a lot of the lessons learned from Mir. ISS has a lot more redundency. It has a whole lot more spare parts being prepositioned on the outside of the station. Zarya has already had substantial refurbishment that was hard or impossible on Mir (a Soyuz or Progress can only carry so much) - new batteries, fire extinguishers, smoke detectors, etc. - Velocity14, on 08/08/2008, -0/+1It's okay. Eric would be proud of you.
- OBKenobi, on 08/09/2008, -1/+2When the oil companies stop holding the world hostage.
- ASSASSYN360, on 08/09/2008, -0/+1I want my plasma (light) saber!
- rheaume, on 08/09/2008, -0/+12015 in the timeline ending right now, doubt they will kill it.
Hopefully in a long time it will be a museum connected to a giant ***** station. - OBKenobi, on 08/09/2008, -0/+1You are wrong.
- muniak, on 08/08/2008, -1/+2I really don't think we should give any more power to corporations let them start their own space divisions, maybe let them sponsor missions created by NASA engineers for the purpose of space exploration rather than created by corporate executives with the purpose of spreading a brand name.
- dafragsta, on 08/08/2008, -1/+2I think you mistake "run out of uses" for "having no contingency plan." Do you think we know everything we need to know about life in space that can't be learned from the ISS yet, seriously? ISS is nearing the end of it's slated shelf life, but the truth is it would be considerably cheaper to renovate it and replace seals and other parts that wear down over time due to the exposure of space and large amounts of radiation than it would be to put up another space station.
- rowlodge, on 08/08/2008, -0/+1details, details...
- jamaph, on 08/19/2008, -0/+1Dude... Don't vote. You'll probably circle McCain because he's "fiscally responsible"
- rowlodge, on 08/08/2008, -1/+2what if it explodes?
- S1ngular1ty1, on 08/10/2008, -0/+1I wrote a technical paper on this type of propulsion back in college several years ago. It is very promising and even more promising when connected to a nuclear power source.
- Enlefo, on 08/08/2008, -1/+2No one is awesome enough to get the reference from the mega man cartoon show.... sad.
- jamaph, on 08/19/2008, -0/+1Ok start thinking champ.
- RogerStrong, on 08/08/2008, -0/+1Yes, I understand the concept behind "low thrust but for a long time". I stand by what I said.
From http://www.nasa.gov/centers/glenn/technology/warp/ ...
"Our third big challenge is energy. Even if we had a nonrocket space drive that could convert energy directly into motion without propellant, it would still require a lot of energy. Sending a Shuttle-sized vehicle on a 50 year one-way trip to visit our nearest neighboring star (subrelativistic speed) would take over 7 x 10^19 Joules of energy. This is roughly the same amount of energy that the Space Shuttle’s engines would use if they ran continuously for the same duration of 50 years. "
So.... To get to the nearest star in 50 years, you need *high* thrust for the whole time. A lighter spacecraft probably isn't in the cards - a tiny reactor won't do it.
You'd need to refuel two or three times in that time, and you can't just bring the fuel with you: Your spare fuel has the same half-life - it'll be decaying from start of the mission too. You need it freshly refined.
And that's with a reactionless drive. The VASIMR still needs reaction mass to provide thrust. From the link above:
"Even if we look at the best conceivable performance that we could engineer based on today’s knowledge, say an Ion engine or an antimatter rocket whose performance was 100 times better that the shuttle engines, we would need about ten railway tanker sized propellant tanks."
Of course with that much propellant, your spacecraft is a whole lot bigger than the shuttle. Your energy requirements are now a whole lot more.
And that's for the accelleration. Multiply this by thousands of times it you want to slow down at the other star. (Since now you need more fuel to accellerate the fuel needed to slow down.) And again, more energy is needed.
VASIMR is good for motoring around the solar system. It's still not good enough for interstellar travel. (Other than giving a probe a shove to let it fly past another star in a few centuries, rather than a few millenia.) - RogerStrong, on 08/09/2008, -0/+1So you've shown that NASA is efficient compared to other government agencies. How does this mean that we should privatize it?
You could easily make the case that NASA should get out of the launch business - buying only from private industry. But what about everything else?
I've yet to see a business case on how to show a profit even for the "sexy" space missions - like the Mars rovers. You could make *some* money on advertising, but nowhere near enough to pay for the mission. You certainly wouldn't pay for the vast majority of missions, that people who aren't space buffs never hear about. And you can't begin to make a profit off the proposed moon landings.
Heck, look at all the aviation safety and new aviation technologies stuff that NASA does. Nothing stops private industry from doing it *now* - other than a lack of profit in it.
To borrow your own words, if you want to add something constructive to the discourse please learn something about how private industry operates. - marx2k, on 08/09/2008, -0/+1No wonder they pay me to donate plasma!!
- thcobbs, on 08/08/2008, -0/+1Well, all you have to do is mount the rocket on a 3-axis table and there ya go.
- ASSASSYN360, on 08/09/2008, -0/+1"NASA plans to return astronauts to the moon by 2020." I detect another space race this time for the moon. The Chinese plan to launch to the moon in 2024.
- jamaph, on 08/19/2008, -0/+1Not only did we win, we have 50 years of rocketry under our belt. How many probes do we have on Mars? How many does anyone else have?
Moon is no problem - razorsedge555, on 08/09/2008, -0/+1Fantastic, now I will be able to buy that heavy plasma gun from Warhammer 40K....register that, washington d.c.!
- ShadowofAres, on 08/09/2008, -0/+1Just hitch a ride on the Tachyon Train
- earthforce1, on 08/09/2008, -0/+1From the article:
> Even if we look at the best conceivable performance that we could engineer based on today’s knowledge, say an Ion engine or an
> antimatter rocket whose performance was 100 times better that the shuttle engines, we would need about ten railway tanker sized
> propellant tanks.
That is a lot less than the shuttle burns climbing to orbit and like a conventional rocket, spent fuel tanks can be discarded to reduce the mass. That being said, there is still a lot of work to do before even unmanned interstellar missions become practical. -
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