More on the US Manned Space Plans…

It’s not often I agree with what Mike Griffith, the former NASA administrator, has to say; but I find myself in total agreement with his statement during a recent interview that the Senate’s plan for a heavy lift vehicle is sizing the vehicle too small.  The Senate plan for a vehicle that will lift only 75 tons is only slightly larger than what the shuttle can lift today and is too small to support lunar or interplanetary manned programs.  This would be a “make-do” heavy lift vehicle that would be able to support ISS or most Low Earth Orbit needs but would be too small to support any other missions without multiple launches.  Griffith thought the lift capability ought to be along the lines of a Saturn V, about 120 tons, and I agree.  I’d target the 130-140 ton range, just to make room for expandability, i.e., the capability to lift more than we ever have before to lunar orbit.

Frankly, the heavy lift concept I’d like to see explored would be a configurable vehicle that could be used to boost payloads in the 70 -140 ton range.  As you needed the bigger payload capability, you simply added more tankage or engines to the basic module.  (Yes, I do know this is the basic idea behind rocket design and jettisonable stages, i.e., mass ratios.).  Once you designed such a beast, it would probably meet your needs for several decades, with upgrades occurring incrementally as materials and engines improved.

The other thing I’d like to discuss is the idea of a manned asteroid mission, and why a direct Earth to asteroid mission is a waste of time and money.  As part of a long term vision, it makes no sense; and I’d rather see our time and money spent on developing orbital infrastructure.

If you’ve followed the symposium that was conducted on this subject, then you know the asteroids they’re talking about targeting are those that wander toward earth and therefore become more accessible than those in the main asteroid belt outside the orbit of Mars.  There are not many of those; one article I saw said there were only two.  For the billions of dollars we’re going to spend and the six months we’re going to put astronaut lives at risk, we’re going to send a crew to a rock that’s not going to be big enough to land on; we’re going to have to “dock” with it instead.   While I am a proponent of manned exploration and do believe humans can often provide insight and information that machines cannot, I have a hard time understanding why this mission needs to be manned. There simply isn’t a huge area to be explored.  The real exploration of the asteroids, and the one I believe will yield more science than a single rendezvous, will come from missions launched from Mars orbit to explore the asteroid belt, ones that will compile data from multiple sources and yield more understanding about the asteroid belt as a whole.  I’d want manned missions there so we could look for differences, i.e., those things we didn’t anticipate or think existed.

Part of the argument for the single rendezvous asteroid mission is that it serves as a “test run” for a Mars mission.  I can understand that from an operational and engineering perspective, and it does fit into that methodology.  But as the only target our manned spaceflight program is moving toward, it leaves too many gaps.  I believe we need to move away from the idea of launching everything from the surface of the earth and need to be building low earth orbit or lunar infrastructure, i.e., a continuous manned presence, instead of focusing exclusively on “single missions” as we tend to do.  I’d like to see us channeling our time and money into turning ISS into a launching point for the moon and beyond, see us return to the moon to investigate “permanent” habitation there and develop its use as a possible platform for outreach to further points in the solar system, rather than simply focusing on a single goal objective, one that will be easily derailed by a shift in the political winds.

Frankly, I have to wonder just how much of the enthusiasm for the single-rendezvous asteroid mission is generated from real scientific zeal or whether it’s real motivator is political pandering to keep some kind of manned mission going, even if it makes little sense.  For now, I’ll assume that the interest and zeal is honestly motivated.

While the current Administration is jumping on the asteroid bandwagon and saying the current Senate plan endorses it, it does not.  What it does do is simply keep the door open for it and, if properly implemented and funded, keeps the door open for a lot more than that.  That really is what we need to do until we can all agree on exactly where it is we want America in space to go and how much we are willing to spend to send it there.

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