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

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

[SJackson]

NASA

Recent reports from the Los Angeles Times and Space.com indicate that President Bush may announce a spectacular new Mars initiative, aimed at putting humans on Mars by 2010. Having been through this with a previous President Bush, who announced similar plans only to see them shot down, interestingly enough, by the maneuverings of NASA bureaucrats, I confess to a bit of skepticism. But there's reason to think that this time it could work.

One reason for optimism is that this time around cost, and technology, have gotten a lot more thought. Nuclear propulsion is at the forefront this time - back then, it was a political non-starter. It's possible to go to Mars using chemical rockets alone, but just barely. Using nuclear space propulsion - where a reactor heats gases to form high-speed exhaust rather than using chemical explosions to do so - cuts travel times from six months to two, and, because of better specific impulse (efficiency), allows for higher payloads. (There are no plans, as far as I know, to use Orion-style nuclear-explosive propulsion, of the sort I've written about href=http://techcentralstation.com/1051/defensewrapper.jsp?PID=1051-350&CID=1051-091102C>here, and here. Should I turn out to be wrong about this, it will probably be a sign that somebody somewhere is very worried about something.)

The United States experimented with nuclear propulsion as part of the Kiwi and Nerva projects in the 1960s and early 1970s. The results were extraordinarily promising, but the projects died because, with the United States already abandoning the Moon and giving up on Mars, there was no plausible application for the technology. Nuclear propulsion is mostly useful beyond low-earth orbit, and we were in the process of abandoning everything beyond low-earth orbit.

That appears to be changing, and it's a good thing. It has certainly won praise from the Mars Society, whose President, Robert Zubrin, calls the Bush decision a "tremendously positive step. It will greatly enhance the prospects for human exploration and settlement of the Solar System." He's right about that, and like him, I think that the "settlement" part is as important as the "exploration" part. And while exploration is possible based on chemical rockets alone, settlement without using nuclear power will be much more difficult.

Of course, as this article by Ken Silber notes, nuclear space propulsion has had its critics and opponents for years, though weirdly their opposition stems largely from fears that it will lead to "nuclear powered space battle stations." This isn't quite as weird as Rep. Dennis Kucinich's legislation to ban satellite-based "mind control devices," but it seems pretty far down the list of things we should be concerned about. With worries about earthbound nuclear weapons in the hands of Iraq, North Korea, and perhaps assorted terrorist groups, it's hard to take seriously claims that possible American military activity in space, spun off from civilian Mars missions, might be our biggest problem. Indeed, the whole concern about "space battle stations" has a faintly musty air about it, redolent of circa-1984 "nuclear freeze" propaganda. Who would we fight in space today? Aliens? And if we needed to do that, wouldn't nuclear-powered space battle stations be a good thing?

Nor are environmental concerns significant. Space nuclear reactors would be launched in a "cold" (and thus safe) state, and not powered up until they were safely in orbit. And again, compared with the environmental threat caused by rogue nuclear weapons, their dangers seem minuscule.

We also have to weigh the dangers of not acting. Earth, as we have seen, is an increasingly dangerous place. Some years ago I attended a small workshop on high-technology terrorism, focusing on such future threats as bioterror, abuse of nanotechnology, and so on. As we left the room after one session, another participant remarked "I think I just became a fan of space colonies."

She was right. Many of the threats posed by advanced technologies are, for the most part, manageable. But in the aggregate, they are significant. And the increasingly small Earth is, as I have written here before, too tiny and too fragile a basket for all our humanity's eggs.

The administration's Mars proposal is at least a step in the right direction, and its adoption of nuclear space propulsion indicates more realism than the flags-and-footprints approach favored by the previous Bush administrations. What's more, the use of nuclear propulsion, which makes interplanetary travel both cheaper and faster, greatly increases the likelihood of going beyond flags and footprints to true space settlement. It's about time.

[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.