Okay, so the President didn't announce the new space nuclear power initiative in the State of the Union address.

He didn't mention space at all, except in the national-security context of missile defense, and even then it was only implied--the word itself wasn't used.

Of course, I covered my bases--I didn't say he would, just that he might. It's not surprising, because having heard the speech, I'm not sure that such an announcement would have fit in politically--there's not a major constituency for such things in the country, and after pleasing some of the environmental community with the hydrogen-car initiative, he probably didn't want to alienate the significant segment of it that's vehemently and irrationally anti-nuclear power in any form.

That doesn't mean that the space nuclear power program isn't happening, of course. It's now expected (and I've got much higher confidence in this prediction than the State of the Union address) that it will be announced on Monday (February 3), if not by the president, then by NASA administrator Sean O'Keefe, with the unveiling of the proposed federal budget.

So what does it mean for our future in space?

I've become famous (or notorious) in the space community for declaring that the Emperor at NASA's Marshall Space Flight Center has no clothes--that we don't need new space technology. To the degree that I proclaim that, it is with regard to earth-to-orbit transportation. I stand by that position, with the proviso that new technology can help, but it's enhancing, not enabling, when it comes to dramatically reducing the costs of getting into space.

But as the late great science fiction writer, Robert Heinlein, famously wrote, once you're in orbit, you're halfway to anywhere. And getting the rest of the distance, sans new technology, is indeed a challenge.

Yes, the Moon is just a few days away with chemical propulsion, and we can similarly get to Mars, and the asteroids by combining oxidizer with fuel, but the scheduled opportunities to get there are driven by the implacable rule of orbital mechanics, and always involve many months, and the outer planets are always years away, for man or machine. To get around these constraints, we do indeed need new technology.

And on most parts of the earth's moon, night is not just a little longer than the duration of a human sleep period. It lasts for over two weeks. Solar power is not an option, unless you can store the energy to get through the long absence of the sun. It can be done, but it in turn involves other technologies, of batteries or capacitors or the pumping of currently non-existent water in non-existent reservoirs, that are even more unattainable than nuclear power, with which we have decades of experience.

Or imagine an asteroid on a course intersecting with the earth--one that could devastate human civilization when it hits in a few years. It is still far away, and too far from the sun to use solar power to do anything useful to change its course.

Space nuclear power can solve all of these problems.

It is compact, it is well understood (by the relevant technologists), it can be employed with safety, and it is more than ample for the requirements. That NASA hasn't been investing in it over the past couple decades was due not to the lack of need for it, but because of politics and bureaucratic fear of objections by the ignorant but noisy purveyors of hysteria.

There are (at least) two types of nuclear power for space applications. One has been used for years, and is the cause of NASA's previous hesitance to advance the technology, due to uninformed protests against it in the past. This is called radioisotope thermal generation (RTG), in which a decaying amount of radioactive material (generally plutonium) emits heat to create a small amount of electricity via a thermocouple. This is the means by which we've powered the electronics of all of our spacecraft to the outer planets (i.e., Jupiter, Saturn, Neptune, Uranus) without which we wouldn't have gathered the spectacular pictures and knowledge over the past three decades, despite the technofantasies of the anti-nuke crowd.

But the limited capabilities of RTGs, while useful to provide electrical power for the electronics of our previous limited space endeavors, will not be adequate for the applications described above. For those, we will need robust, high-power systems: to melt the frigid ice of the Moon and comets into life-giving water: to take that same water and convert it to steam for propulsion and power: to power the plasma ships that will make trips to other planets and planetary bodies a matter of weeks, rather than months or years, at schedules of our choosing; to break the chemical bonds of lunar silicates and stony iron asteroids to build a new industrial age off our home planet.

Such systems mean actual nuclear reactors in space, something that the Russians have had, but we have not. Unfortunately, when the Russians did it, it was as the Soviet Union, a totalitarian dictatorship whose consideration for things like safety was...imperfect.

Even without ignorant anti-nuclear hysteria, actual past entries of working Soviet nuclear reactors into the atmosphere and on the heads of unsuspecting earthly inhabitants hasn't aided the cause of nuclear space systems. Nonetheless, this technology is absolutely necessary, it can be done safely, and NASA's biggest challenge will not be in developing it, or even in developing it safely (though this is obviously essential as well) but in proving to the skeptics (at least the ones that matter) that they can, will and have done so.

Regardless of NASA's frustrating lack of progress on the earth-to-orbit front, this is a critical technology that must be developed in parallel with efforts, both public and private, to make it more affordable to get off the planet where it will be useful. If they start now, perhaps by the time it's ready for use, we'll be ready to use it.

Dual Tragedies

In addition to Tuesday's anniversary of the Challenger disaster seventeen years ago, Monday saw the thirty-sixth anniversary of the loss of the crew of Apollo 1. Take a moment and remember the pioneers who died to expand life into the universe.

Working from a super-low-level understanding here...

1) "frigid ice of the Moon"?? Do you mean "frigid ice of Mars"?

2) My very simplistic impression was that the ratio of shielding needed per unit power (to meet our safety specs) made nuclear power prohibitively heavy (too much weight for the amount of power, to run it safely).

At least for to-orbit, which was probably your point - nuclear power works much better once you're already out in space. You still have to move the mass, though - would you be talking move about a series of controlled impulses rather than a long thrust (which, again from limited understanding, would be difficult to control with fission)?

Discussions of how to use nuclear power for space propulsion are "thick on the ground" in science-fiction literature -- at least the old-fashioned, no-unicorns-and-elves kind.

In response to the points above:

1) Nope, he probably means the Moon. The Clementine mission detected ice-like signatures near the South Lunar Pole in 1999, so there's at least as much evidence for water on the Moon as there is for water on Mars.

2) Nuclear plants would require quite a bit of mass, even for unmanned missions. (Ionizing raditation and computers don't mix) However, IIRC Prometheus is talking about nuclear electric propulsion rather than a NERVA type rocket- so basically, we're talking about an ion drive, but with a nuclear plant supplying the requisite energy. Ion drives have high enough Isp that they'll be able to move pretty much whatever reactor mass you want- maybe not at high acceleration, but they'll move it.

Actually, it may be a plasma rocket (i.e., Variable Specific Impulse Magnetoplasma Rocket (VASIMIR)).

Nuclear space drives, hydrogen fuel economy, missle defense, what are the implications?

A hyrdrogen fuel economy requires a lot of power, really, the only way to support it is with nuclear power plants, lots and lots of nuclear power plants, OR, space based solar power, or both.

SDI requires access to space. Period.

If Bush gets his way, we are going, finally.

The Prometheus project is very encouraging. The earlier we get going the better. I would have announced it during the SOTA but the president is not such a fool as I. For me, the biggest surprise was the hydrogen car initiative. I don't see it making economic sense, where Prometheus certainly does... My take is it was designed as a political foil, to blunt criticism and leave opponents guessing.

Using more energy to produce and contain hydrogen than we get back doesn't make much sense and certainly wouldn't lessen our energy needs. The numbers don't seem to add up?

Getting nuclear power back into space will also reduce the costs of acquired scientific data, and by a huge factor. Mars Pathfinder relied on solar energy, and therefore had a lifespan measured in weeks (due to dust degradation of the solar panels, and to diurnal thermal cycling). Using RTGs would add a bit to the initial price (but probably save weight), to yield a lifetime of months if not years.

I worked on Pathfinder, and it was painful to watch a working probe die for no good reason. This idea is justifiable on costs alone.

(to Ken Anthony: that one puzzled me, too -- but then it occurred to me that in our process toward such a goal, the necessary power generation would have to be built... and the economics of the final notion thoroughly investigated. Maybe we'd end up with the first step -- SPS or nuclear -- and then prudently stop?)

I expect that Pres. Bush didn't mention space nuclear power in his speech because nukes are hard to sell to the general public -- and the general public does tend to round off "nuclear powered devices for space exploration" to "nukes, nukes, nukes." I'm all for such nukes, myself, but the topic is tricky to sell to the public.

This is the point I was trying to make earlier with the Louisiana Space Society guy.

...

As for electrical power plants in orbit that will send electricity down to earth: please tell me what electromagnetic frequency you plan to use to convey the power. What frequency is there that won't heat up the atmosphere somewhat, if the transmitter wattage is really significant?

[Of course, I covered my bases--I didn't say he would, just that he might. It's not surprising, because having heard the speech, I'm not sure that such an announcement would have fit in politically--there's not a major constituency for such things in the country, and after pleasing some of the environmental community with the hydrogen-car initiative, he probably didn't want to alienate the significant segment of it that's vehemently and irrationally anti-nuclear power in any form.]

[ Using more energy to produce and contain hydrogen than we get back doesn't make much sense and certainly wouldn't lessen our energy needs. The numbers don't seem to add up? ]

It makes plenty of sense if fission, fusion, or solar power is used to separate H2 from O.

The argument for using more energy for generating hydrogen than we get back is if the convenience of the hydrogen in a transportable form is worth the energy cost. To put it crudely, it may be worth the extra cost to have the energy in a form that can run an automobile, rather than in a form that can't be transported except by powerlines. Personally I'm not sure it makes economic sense yet, although I have always thought that inventing a really good way of storing electricity is the most "green" thing somebody could do, so I am always amused that so few environmentalists are studying physics and engineering.

So, is Prometheus an ion drive powered by an RTG? Forgive my ignorance. "Nuclear Drive" could mean a lot of things.

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