The Mars Society convention was a lot of fun and very informative. My paper was presented in the advanced technology track on Saturday afternoon. It was well received: I had several people come up to me afterwards and tell me so.
Most of the other mission designs included some sort of Mars base assets with the first manned mission. This is quite different from what I assumed regarding the nature of exploration versus subsequent activities. So, I pitched my paper as less of a “real” mission plan, and more of a “mine” for different and potentially useful ideas. In part, that’s why it was so well received.
Changes to My Paper (see the 7-25-11 posting not far below)
I did learn some very interesting things, two in particular. One has to do with my alternate for the manned ship’s “hot rod propulsion”. It seems VASIMR is not really an improvement on electric propulsion, just another way of doing it. Its weakness is indeed what I thought: the mass of the nuclear electric power plant required. Its thrust per unit power supplied is just a lot worse than I thought it was when I did the calculations. It’s just not suitable for really fast missions.
The other interesting thing is the notion of a light gas gun for launching hardened payloads into orbit very inexpensively. It should be possible to launch large quantities of propellants and tough hardware for something on the order of $300/pound, if they can be hardened to withstand 3200 gees. This is based on a smaller gun already launching small experimental scramjet payloads for the Air Force at Mach 9. Refueling of my reusable manned ship looks really good in such a situation. Once there is a water mine and propellant station on Mars, the same thing is true for refueling the lander assets left in Mars orbit.
In any event, about the only change I might make in my paper is to replace the VASIMR alternate with a solid core nuclear thermal version, and include artificial gravity and frozen food in the habitat configuration. Its one-way trip time would be 6 to 8 months, and the stay at Mars a little longer than the baseline 16 weeks. The technology development, to be run in parallel with the baseline gas core nuclear thermal rocket effort, would be the artificial gravity habitat. I think a pair of rigid arms out to inflatable living spaces, and spinning the entire T-shaped ship, might work well enough.
Another Interesting Idea
A third very interesting idea is to store and ship hydrogen as frozen water. In this form, it is very strong and so is proof against accidents or mishap. You thaw and electrolyze what you need as you go, which does require power, although solar thermal thawing offers a big help. The oxygen liberated by electrolysis can be used for a lot of things. It takes very little pressure to prevent sublimation of the ice, and a simple sunshade keeps it very cold.
This would apply to chemical as well as nuclear propulsion. Nuclear uses only hydrogen. Chemical uses both hydrogen and oxygen at a mass ratio of 1:6. The ratio in the water is 1:8, so that leaves excess oxygen left over for other uses, even with chemical systems. There is just more available in a nuclear scenario.
A Very Serious Near-Term Problem
Consider: 100% of the humans who ever walked on the moon were Americans, sent there by NASA in its human spaceflight program. 100% of the so-far successful landers on Mars were (and are) American, sent there by NASA in its robotic exploration program. Almost 100% of the probes sent to other celestial bodies are American, sent there by NASA in its robotic exploration program.
The human and robotic programs began together in the late 1950’s; they are synergistic. You cannot successfully do one without the other. Regardless of your opinion of NASA and its effectiveness today, it is the premier entity for the exploration of space, and therefore it is irreplaceable.
Here is the problem: there has been no human exploration target since Apollo ended in 1973. Manned operations in Earth orbit, while essential and even inspiring, are not exploration. We have had men and machines in Earth orbit, beginning with Sputnik in 1957. Going back to the moon is not exploration in the public’s eyes, because “we’ve already been there”. This perception is quite real, even though we didn’t really explore the moon (in the sense of my paper) during Apollo.
The public supports exploration: that is why the probes, the Mars landers, and the Hubble pictures are so popular. Of all the probes and landers, it is the Mars probes that hold the public’s fascination best. This is because Mars has fascinated people for centuries. It is not just the best target for human exploration, it is the only one. Those other near-Earth targets are at best but steps along the way to Mars. (The next destination after Mars is the stars, with the outer solar system destinations but steps along the way.) Reality has nothing to do with perception, and experience says you cannot fight perception.
We have a budgetary and political tsunami about to sweep America, with a great likelihood of doing massive damage to all aspects of all of our lives. One’s politics and outlook on this do not matter, discretionary spending is about to be drastically cut or eliminated, no matter how useful or necessary, for the sake of election politics. That means NASA, among many other things. And NASA has had no viable target or plan for manned exploration since Apollo. A vague “give us X-billion dollars for the next 20-40 years and we might reach Mars” is not a manned exploration program. If the manned spaceflight program is cancelled, the robotic program will eventually fall, as well.
Folks, this cannot be allowed to happen.
It is feasible to send men to Mars right now, with the technologies and hardware we have right now or within the next very few years. We don’t even have to have giant launch rockets. We can do this for under $50 billion, not the trillions everybody out there seems to think it will take. But we cannot do this with the “business as usual” techniques of the last 4 decades, and that includes the way NASA works. Massive management change is required, and that is the hardest part, not the actual flying to Mars.
If you are a space exploration enthusiast, then help get the word out. Technologically we are ready to send men to Mars. And we can do it for a few billions, not multiple trillions, of dollars. The real change required is managerial (and political, not surprisingly).