Nuclear Rocketry, Anyone?

One of the deal-breakers with fission-based rocketry was the need to cool the reactor with the propellant fluid, which, first, made the whole scheme subject to the fundamental Carnot limitations of heat engines and, second, put huge stresses on the reactor itself, since it has to withstand the vibration generated by the working fluid flowing through it.

This approach is an attempt to build a "dusty plasma" reactor, where the fission products themselves can either become the reaction mass for the rocket, or can be decelerated in an electric field to directly generate electricity for some kind of ion propulsion. Using the fission products as reaction mass could yield a specific impulse of about 1,000,000 seconds (that's about a factor of 100 better than the best ion engines, BTW).

On the downside, this rocket works by emitting nuclear waste at 3-4% of the speed of light. This qualifies it as the second-dirtiest rocket ever envisioned. (Don't forget Project Orion!)

Eat Your Heart Out, Jules Verne

A cannon for shooting supplies into space:

John Hunter wants to shoot stuff into space with a 3,600-foot gun. And he’s dead serious—he’s done the math. Making deliveries to an orbital outpost on a rocket costs $5,000 per pound, but using a space gun would cost just $250 per pound.

Building colossal guns has been Hunter’s pet project since 1992, when, while a physicist at Lawrence Livermore National Laboratory, he first fired a 425-foot gun he built to test-launch hypersonic engines. Its methane-driven piston compressed hydrogen gas, which then expanded up the barrel to shoot a projectile. Mechanical firing can fail, however, so when Hunter’s company, Quicklaunch, released its plans last fall, it swapped the piston for a combustor that burns natural gas. Heat the hydrogen in a confined space and it should build up enough pressure to send a half-ton payload into the sky at 13,000 mph.

Hunter wants to operate the gun, the “Quicklauncher,” in the ocean near the equator, where the Earth’s fast rotation will help slingshot objects into space. A floating cannon—dipping 1,600 feet below sea level and steadied by a ballast system—would let operators swivel it for different orbits. Next month, Hunter will test a functional, 10-foot prototype in a water tank.

You certainly couldn't launch people this way--they'd turn into goo at the kinds of jerk and acceleration needed--but it'd work great for consumables. I don't know if you could launch modules with complex machinery and electronics through such a system, but air, water, food, and propellants are going to make up the bulk of any large-scale suborbital or interplanetary presence, and a massive reduction in launch costs might just be the enabling technology that we need.

Progress

January 7, 1610:



January 7, 2010:



I want to live forever, because I want to see what happens next.

Earth, Say Hi to Fomalhaut B

The first images of an extraterrestrial planet have been obtained.

The achievement, the result of years of effort on improved observational techniques and better data analysis, presages more such discoveries, the experts said, and will open the door to new investigations and discoveries of what planets are and how they came to be formed.

This is a big deal.

When you can image a planet, you can get its spectrum. One day, not too far in the future, we will obtain the spectrum of a planet and there will be free oxygen lines in it. How different will the world be when we know that there is life on another planet, circling another star? Will we feel compelled to send probes there, irrespective of the cost? Or will this just become yet another datum in the panoply of wonders that is our modern world.

The economy sucks. We're embroiled in a low-intensity world war. Our politics is about to undergo the biggest upheaval since 1981, maybe since 1932. But we can still do... this.

A Plane That Can Stay Up For Five Years

DARPA is looking for something that can stay up for five years, fly at 60,000 to 90,000 feet, and carry a payload of 450 kg.

Rain On Our Parade, Why Don't You, Nick?

Nick Bostrom takes the occaision of the successful touchdown of the Phoenix lander on Mars and turns it into--well, a real downer. Technology Review registration (free) required.

Space-Based Fresnel Telescopes

Here's a proposal for a very light, very large space telescope with a Fresnel imager. We're talking possibly a 30-meter objective Fresnel plate with a focus spacecraft flying in tandem several kilometers away. Great angular resolution, very high contrast; in other words, it would be a terrific terrestrial planet finder. But two spacecraft working in tandem would obviously be a big problem.

It's Too Late to Shut Up Now

If we wanted to keep alien civilizations from learning of our existence, we're probably out of luck:

For 40 years, astronomers have fired microwaves off objects to chart near-Earth space and track the movement of close asteroids - and these signals are traceable back to us. By comparison, Zaitsev says, dedicated transmissions - often described as "shouting into an unknown jungle" - are a mere whisper. He calculates the astronomy signals have filled an area of the sky 2000 times greater than dedicated broadcasts have managed to date

Maybe when they show up they'll merely want to serve man.

Surprisingly enough, communicaiton with extraterrestrial intelligence has recently become a topic of serious debate. (See David Brin's cogent argument against such communication.) It would be foolish to assume that all alien species are nicer and higher-minded than we. While it might not be possible for aliens to colonize Earth, there's a considerably lower barrier to launching self-replicating weapons at us. Before you scoff, think about the debate that we humans would have if we discovered a high-tech civilization nearby, along with evidence that it was at least moderately aggressive.

Something to think about when you've managed to achieve that perfect paranoid mood.

Lunar Nomads

Here's a proposal from JPL for a six-legged robot that would carry NASA's lunar habitat from place to place on its back:

The astronauts' 15-tonne living quarters, or habitat, could be mounted on ATHLETE before sending it to the Moon in a lunar lander. That would solve one major problem for NASA – how to lift the habitat off the lander, whose cargo area may sit up to 6 metres above the ground, and set it down at a desired location.

ATHLETE's wheel-tipped legs are so long, "it just steps right off and carries the payload anywhere you want," says JPL's Brian Wilcox, who heads the ATHLETE project...

The habitat's solar arrays would power the robot, which could also store power in fuel cells. In Wilcox's scenario, the habitat would stay permanently attached to ATHLETE, which could roam from place to place and simply squat down to bring the habitat door close enough to the ground for astronauts to get in and out (watch a video of ATHLETE lowering itself).

ATHLETE would normally drive around the lunar surface, since that is much more energy-efficient than walking. But whenever the robot encountered very bumpy ground, or its wheels got mired in deep soil, it could switch to walking.

"If we get into ankle-deep dust, we'll lock the wheels, use them as feet, and just tiptoe out, effectively," Wilcox told New Scientist. Watch a video of ATHLETE walking and driving.

I'm not sure I'd want to be sitting on top of this thing while it's stepping over rough terrain on a steep slope but I guess you learn to trust your technology or you don't fly it in the first place. It certainly seems silly to drop a base in one place and be restricted from exploring elsewhere. Presumably, you could drive the robot when you wanted to make rapid progress. Maybe you'd give it overnight goals and let it go on its own while the crew slept.

Going Geyser-Diving on Enceladus

This is pretty cool:

NASA's Cassini spacecraft will make an unprecedented "in your face" flyby of Saturn's moon Enceladus on Wed., March 12.
The spacecraft, orchestrating its closest approach to date, will skirt along the edges of huge Old-Faithful-like geysers erupting from giant fractures on the south pole of Enceladus. Cassini will sample scientifically valuable water-ice, dust and gas in the plume.

The source of the geysers is of great interest to scientists who think liquid water, perhaps even an ocean, may exist in the area. While flying through the edge of the plumes, Cassini will be approximately 120 miles from the surface. At closest approach to Enceladus, Cassini will be only 30 miles from the moon.

Return to the Moon? Maybe Not

NASA May Abandon Moon Under Revised Exploration Vision. I'm not sure what to think about this. At one level, this is pure thrashing. In addition, it's just shameful that we haven't been back to the Moon in 25 years.

On the other hand, this vision makes a lot of sense. Certainly, going to the Moon has nothing to do with going to Mars. Of course, neither does going to L5 or to an asteroid.

I think it's probably moot anyway. I expect the Democrats to gut the space program like a fish.

Collaborative Space Exploration

In Aviation Leak, we find a piece on how international collaboration is heating up for deep space exploration. This has long been a pet peeve of mine. Finally, the will seems to be appearing to subsume national pride into a more rational cost-sharing structure.

Manned space exploration still has a way to go, but it's nice to see the Moon and Mars getting the unmanned attention they need.

How 'Bout a Little Rocket Science?

Technology Review has an interview with Franklin Chang Diaz, the founder of Ad Astra Rocket Company. These guys are nearing a static test of a VASIMR propulsion system.

Coincidentally, I've been reading Centauri Dreams, which is an excellent summary of the various wild schemes people have thought up when envisioning an interstellar mission.

It's not a fun time in the United States right now. In addition to the war and the political situation and the sense of fragility that we're all experiencing, it's clear that everything is changing. I'm moderately optimistic that we'll come out the other side of these changes much better off than we went into them, but there are no guarantees. Meanwhile, it's nice to see that the art of dreaming big hasn't gone out of fashion. Serendipity is our friend. When we do hard things, good stuff happens, even if it isn't the good stuff we originally envisioned.

Why Isn't the Space Program International?

I was going to come up with a wonderful manifesto on political philosophy and realted nonsense, but I'm never going to get to it. So, I'll just wade in. Saw this item in the NYT on Chinese efforts to use satellite launching as an instrument of soft power. As usual, they're conducting a much more nuanced foreign policy than the US--which is crazy.

But it begs a more interesting question: Why are international collaborations on space programs so feeble? In a world swimming in cash, you'd think that going trans-national would allow a huge investment in both technologies and missions.

What are the impediments?

• Collaboration on launcher, guidance, and control systems have dual-use military applications. Couldn't we restrict this technology to a pool of countries that already have these technologies?
• There are lots of sensitive technologies from which commercial advantage can be derived. But we've done lots of trans-national technology incubators. Why can't we put the non-controversial bits into a pool?
• International managment is a nightmare. Sounds like an opportunity to develop some procedures to me.
• There are problems with national prestige. We just need to get over this one.