Destination: Mars--This time, a reason for optimism.

TCS ^ | 01/22/2003 | Glenn Harlan Reynolds

[MarketR]

I think the nuclear reactor heats reaction mass to the point of vaporization, after which it gets squirted out the back of the rocket.

Right you are! See here:

VASMIR- the full name is the Variable Specific Impulse Magnoplasma Rocket.

This rocket uses radio waves to heat the fuel to 10 million degrees and because this system lacks electrodes it is less likely to break down. Also, this rocket is unique because it has the best of both worlds, high exhaust speed and high thrust. “VASMIR bridges the gap between high- and low-thrust systems.”(7) This is possible because it uses a magnetic choke to constrict the flow of propellant from the central heating chamber. This allows the pilot to the low gear and possible a booster rocket to escape Earth’s magnetic field and then switch to high gear for intersolar travel.

Thrust: Low Gear: 1,200N High Gear: 40N Exhaust Speed: Low Gear: 10kps High Gear: 300kps

Nuclear reactor is used to heat the plasma.

[MarketR]

VASMIR = VASIMR

[Frank_Discussion]

AAAARGGH!!!! Is this Reynolds guy a syndicated columnist? If so, he's an embarassment! While Nuclear Propulsion is a nice prospect for high-powered rocketry, it is NOT what NASA is focusing on. Nuclear-Powered propulsion is different from Nuclear propulsion, but the latter method is neither as efficient or as safe as the former. This Reynolds thinks the latter is what is being proposed, and it will drive the environuts through the roof to read his misguided info.

Nuclear Propulsion in a Nutshell: Blow exhaust gasses over a very hot nuclear pile or reactor core. Very hot and usually quite radioactive gasses spew out of the system, moving very quickly. Not normally considered an environmentally-friendly way to do things when it is working right, even worse in an explosion or mishap. The advantage of such systems is the ability to launch from the ground, since you've got the immediate power to do so.

Nuclear-Powered propulsion in a Nutshell: Using Radio-Thermal Generators (RTG's) or enclosed reactors to produce electrical energy, which is then used to power plasma or ion engines to produce very clean thrust. The RTG's in particular are very safe and low in radioactivity, and the reactors can be similiarly safe by sending the reactor components for in-space assembly only. The word "nuclear" will still put off the die-hard anti-nukers, but only in an irrational way.

Reynolds didn't even pay attention to what the NASA press releases have said on this issue - he just threw his expectations into the mix and regurgitated what he THOUGHT he read. Shoddy, shoddy reporting!

[Frank_Discussion]

VASIMR uses ELECTRICAL ENERGY to basically microwave the plasma to whatever energy is required. It can be from any source, but nuclear reactors are the most power-rich, with RTG's following next in line. A Nuclear Reactor does NOT heat plasma - It would only provide electricity to power the system.

[Frank_Discussion]

The ion engine has too low of an impulse - it's slow and steady propulsion, but humans aboard would die of boredom before reaching anywhere.

See the VASIMR susbject in this thread. Both Ion and VASIMR-type are slow-acceleration systems, that's certainly true. However, I'd wager that a "chemical-rocket-then-coast-to-Mars" mission would be much more boring, since it would take a lot longer to get there. Another thing that many folks don't realize about the Ion/VASIMR systems is that you have a way to abort pretty much the whole way there. With chemical systems, whatever basic speed you've attained initially is what speed you're going to travel at, and usually you've exhausted the huge bulk of your fuel. Beyond a certain very early point in such missions, you're SOL for an abort.

[MarketR]

A Nuclear Reactor does NOT heat plasma - It would only provide electricity to power the system.

You are right and so am I! The reactor does not heat the plasma directly, but drives the microwave generators which do ! So, in actuality, we are both right.

[Frank_Discussion]

Just trying to clarify, not to argue. The reason I am so persnickety about this issue (as may have gleaned from ny rant above) is that the environuts think all nuclear-powered systems are big green-glowing about-to-go-into-meltdown explosion magnets. This isn't the case, and in the particular case we're discussing, the power source is not directly connected to the thrust chamber or its products. It is actually less contaminating that the Space Shuttle, which is quite clean in itself.

[lyby]

Cna't wait to share this with my 15-year-old son who has said "forever" that he wants to be the "first man on Mars!"(Smile)

[MarketR]

Clarification understood and appreciated. I certainly don't want to help foster the notion of a "great radioactivity spewing rocket"

And, on a re-read of my post, I was falling into it.

Thanks for the edit. :-)

[MarketR]

Now...Can we try to do something about this news released today?

"Senate Recommends $200 Million Cut To NASA's 2003 Budget"

[Frank_Discussion]

Hey, no problem. What I do get worked up about are reporter/columnist persons who buy into the misconception, like this Reynolds guy. For someone who writes for a site called Tech Central Station, he sure missed the "Tech" part of this subject, bigtime!

[Frank_Discussion]

Is it the whole Senate, or primarily one party? Could you post the link?

[Centurion2000]

It's about time .... but go Bush ....

[adx]

Mars ain't bad, but me personally, I'm looking forward to setting up a homestead on some rock orbiting Alpha Centauri. That's the only way to ever escape the reach of any Earth-bound government.

[Centurion2000]

The meek shall inherit the Earth. The stars belong to the bold.

I'm gonna steal that :) .. thanks

[Arthalion]

I wouldn't count on any type of useable artificial gravity for at least a few centuries. "Gravity" is a side-effect of the mass warpage caused by our planet, and a 1G environment would therefore require a planetary mass equal to that of Earth. In spite of what Star Trek would have us believe, this type of thing will never be achievable with "gravity plates".

What may eventually be achievable are "planetary gravity generators". These would essentially be mini-blackhole generators that could be placed in the core of a sub-earthmass planet or planetoid in order to adjust its mass (and therefore its gravity) upwards. Our technology currently isn't even capable of drilling to the core of a planet, much less placing a stable machine there that can generate a controlled black hole...but it's still a viable theory with no known impediments. It's just a matter of researching this stuff out.

[MarketR]

Here is the link. It's part of the omnibus spending package being put together which wasn't done last congress.

Here

This still has to go to commitee with the House bill which has given NASA a raise to $15 + billion. So, it probably won't be this bad, but please!

[weikel]

Oh so you think you can escape the reaches of Weikel the Pitiless, God Emperor of the Galaxy do you. Muhahahahahahahahahahahahaha.

[robertpaulsen]

BLAM!

BLAM!

BLAM!

BLAM!

[weikel]

Hmmm don't wanna screw up with black hole tech... be really bad.