Tuesday, August 9, 2011

Post-Meeting Results (Mars Mission)

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).

Tuesday, August 2, 2011

What Should the Government’s Manned Space Exploration Strategy Be?

Going beyond the moon requires fundamental changes in the way we approach spacecraft and mission design. Mars makes an excellent target for starting this new process.

Inner Solar System

The key is going back to fundamentals to figure what we really want out of exploration, then looking at required technologies, given that crew survival, safety, and self rescue are THE paramount design requirement for every single phase. You do that for the most challenging mission (Mars) FIRST, and force every single piece of hardware to be totally reusable.

Exploration and the Greater Scheme of Things

This produces one set of "tinkertoys" that takes you anywhere within range: Mars, Venus, NEO's, and Mercury (the entire inner solar system). Plus, you don't have to keep launching components, just propellants and supplies.

This is my Mars mission paper to be presented to the Mars Society convention in Dallas, August 4-7. A shorter version is posted at http://exrocketman.blogspot.com, dated 25 July, 2011.

Inner Solar System Hardware Designed Around a Mars Mission

Main Asteroid Belt

To go further soonest, we simply upgrade the inner solar system “tinkertoys” with knowledge obtained between now and then. Add a provision for artificial gravity, and either solve the food preservation problem, or add frozen food (which is bigger and heavier). That should make two-or three year trips feasible, most likely limited by the accumulation of cosmic ray exposure. It puts the main belt asteroids and some comets within reach.

The Artificial Gravity Problem As We Know It Now

Giant Planets and Outer Solar System

If a better way to shield against radiation can be devised, and even faster “hot rod propulsion” developed, the giant planets and outer solar system become reachable. It would help greatly to know how to build closed-ecology life support by this time.

At this point, we have to repeat the design process from scratch, because upgrades to the inner solar system “tinkertoys” are no longer feasible. We will know more about what to do when that time comes. The target for design should be the Kuiper Belt, where Pluto is.

I suggest some version of the old Project Orion nuclear pulse propulsion. One must build much larger ships for this: it has the odd characteristic of working more efficiently, the larger the mass to be moved.

Nuclear Pulse Propulsion from 1959-1965 USAF "Project Orion"

A Place To Do the Supporting Work

The kinds of “hot rod propulsion” that we will need to explore these places are very dangerous to develop and test on Earth, because the energy sources for the drives are all nuclear. We need a safe place to test, but it has to be dynamically stable (you cannot test a rocket engine in zero gravity where every test is a flight test).

I suggest the airless, waterless, uninhabited moon. Pick a smaller crater with high ring walls, plant a base adjacent to it, and put the test stands down inside the crater. It’s reachable from Earth without any exotic propulsion at all, and the mildest of the “hot rod propulsion” techniques just makes it less expensive. Perfect!

End of an Era Need Not Be End of a Capability

This one appeared as a guest column in the Waco Tribune-Herald newspaper of Waco, Texas. It is not about exploration, but about useful and necessary infrastructure in Earth orbit.

The last shuttle flight is complete, the orbiters are headed for museums, and thousands are being laid off at Cape Canaveral and Mission Control. There is going to be a hiatus in America’s ability to launch its own astronauts that may continue for a few years.

Actually, I do believe the private companies like SpaceX will fill that void sooner rather than later. I also believe there will be a second, privately-owned, space station up there, very soon.

But, these private ventures, which build upon 50 years’ expertise, will require smaller teams on the ground at the Cape and in Mission Control. Except for local employment prospects, that’s a good thing, because it means spaceflight will become less expensive.

I predict that more than one commercial spacecraft will be flying soon, and that some of our familiar launch rockets will be updated and man-rated to launch them. That’s what NASA’s commercial spaceflight initiative was supposed to achieve, and it looks to me as if it is succeeding.

Here is what we will have: space capsules as taxis to orbit, space stations conducting research and business, and NASA looking outward beyond orbit with men for the first time in 40 years. But, something is missing from that picture!

Oh, yes, the “space repair truck” function of the space shuttle will be missing. Remember it?

It was the self-maneuvering shuttle with the adaptable human crew, that enormous cargo bay as a work area, and that manipulator arm, which repaired so many important satellites, most notably the Hubble Space Telescope.

In hindsight, having to launch that capability in every mission makes less sense than having two or three vehicles like that up there all the time. When you need one, send the crew and some thruster fuel up with one of the new space capsules: same results, far less expense.

All we need is a crew cabin, a space frame about the size of the shuttle cargo bay, that manipulator arm, some thrusters, and thruster fuel tanks.

These could be assembled in place by docking-together modules small enough to be launched by the rockets we already have. This is not a gigantic project, there is no new technology here, just a planned series of launches to regain a capability that we lost with Atlantis’s final landing.

It makes sense to have one in the highly-inclined orbit near or docked to the ISS, one in the more standard orbit eastward from the cape (the kind of orbit Hubble is in), and one in polar orbit to service those satellites. This may not be exploration, but it would certainly be helpful to what we are already doing in space.

There will always be satellites needing repair, and we already have one space station to repair, maintain, and upgrade. We might even use this capability to help build the new exploration vehicles.

I recommend this idea to NASA as something worthwhile and necessary. Maybe some of those laid-off workers could be re-hired to carry it out.