
I had initially pledged 35 parts (minimum) in this series. Number 7 today takes us one fifth of the way. For a list of possible upcoming topics see this recent
entry in
BNL.
Today's topic was chosen in part because NASA plans on returning to space today with the scheduled lift off (barring bad weather or other technical hiccups) of Discovery. The shuttle was an amazing piece of engineering for its day, so all the more perplexing that NASA seems incapable of improving its reliability or launch schedule frequency. Original plans where for the Shuttle fleet to make 15-20 launches per years, and maybe launch cost would have come down dramatically if this had happened. It was a romantic but impractical vision to have astronauts ferrying satellites to and from orbit like solar system truck drivers -- one that probably prevented the far more practical development of a cargo lift only variant of the shuttle, and less massive, safer, easier to maintain passenger version.
It is almost painful to watch the last few missions milked from the shuttle fleet. And now we are committed to returning to the Moon and eventually Mars. All with conventional booster lift technologies, albeit improved, but not dramatically so. Given our squeamishness at 1:50 or 1:100 odds of loosing astronauts in a Shuttle disaster, it is perplexing we are contemplating missions to Mars where the radiation load in transit will statistically almost certainly take astronaut lives after return due to cancer or other degenerative diseases years later.
Cheap access to space isn't really a matter of needing scientific breakthroughs (though they wouldn't hurt). What is really needed instead is a willingness to suspend business as usual and put a new infrastructure in place. Carrying all the propellant you will need to get to orbit with you is wasteful and dangerous. The tanks and rockets must be light and thus thin and fragile compared to the weight of the propellant they carry. Design margins are tight. Single-stage-to-orbit designs exacerbate this problem, trading robustness for total reusability. Of course one stage rockets do away with the risk and waste of stage separations.
My view is that we should build launch catapults for what amounts to a "virtual" first stage for our rockets and spacecraft. Perhaps even the
X-33 design could be retrieved and reworked if married to a maglift catapult. A big enough, strong enough catapult design, whether magnetic in nature or using some other accelerating force, say laser or microwave expansion of a column of air beneath the object to lift it all sidestep the issue of carrying all your (explosive) fuel with you.
Of course launch isn't the only high danger moment in space travel, reentry is equally dangerous (as Columbia proved). The reason for this is that all the energy to reach orbit that has been imparted to the vehicle during lift must be dumped in a similar amount of time coming back. This is accomplished with air-friction and that means tremendous heat. Excluding nuclear reactions energy can neither be created nor destroyed (of course modified by modern physics as mass-energy equivalent can neither be created nor destroyed) so all that excess energy must go somewhere. We choose to throw it away as heat -- dangerous, dangerous heat.
Real pie-in-the-sky-dreamers envision
Space-Elevators made of carbon nano-tubes. This may eventually be realized, but requires scientific breakthroughs that we just can't count on happening anytime soon. While we can make carbon nano-tubes now, this is more than just an engineering challenge of scaling-up. We need efficient means to grow them to unprecedented unbroken flawless lengths and weaving them together in such a way that the macro structure cable has similar strength to theoretical strengths measured on the nano-scale. We have not yet created even one carbon nano-fiber cable of any length that exceeds the strength of other conventional high-tension cables.
Still it is a shame to waste all that reentry energy (which space elevators would recapture). A better bet than space elevators and with virtually all the same advantages are
Rotovators. These structures could be made of obtainable materials, as opposed to space elevators that require "Unobtainium" to build. Rotovators would be large pin-wheels in orbit whose ends dip just down to the edge of the atmosphere. Since the rotovator's rotation is synced with that of the Earth's rotation at the point of closest approach the rotovator's teathers tips appear to come down almost vertically towards the Earth and pause before ascending again. Your craft wouldn't even have to break the speed of sound before latching on and getting a free ride up to orbit. Of course this bleeds energy from the rotovator, but is exactly offset by de-orbiting other craft. Much like the Eiffel Tower's paired elevators where one is always going up when one is going down. Keep in mind we could still use our catapult solution for the first leg of our journey then the rotovator for the last step to and from orbit. See also
Space Fountains for another imaginative to-orbit infrastructure.
So in my ideal world we would scale manned flight back and put our money into a new infrastructure instead of continuing to do things the old costly way. While I had initially been a huge manned flight proponent, it just hasn't panned out for now.
But all of this is really a digression from the main question about the impact of "Cheap Access to Space," so rather than continue with "how", what happens "when?" It seems natural to assume Mars's colonization and Hotels in orbit, but these things wouldn't really have much impact on the billions left on Earth. Not only this, but the radiation hazards of space lead me to believe even with cheap-access these visions will not be realized soon. Oh, there will eventually be a manned landing on Mars and a tin can in orbit for the super wealthy to overnight at and brag about, but not have much impact on Mankind at large.
Still
CATS (hmmm, a new meme or mantra?) would open up resource mining in space. Siderophile (Fe, Ni, Mg) rich asteroids could supply all the raw metals we would ever need without strip mining Earth. Huge solar collectors could be placed in orbit to gather all the energy we need for the foreseeable future. Creating materials in Zero-G has huge potential even though early ISS experiments have not yielded many must-have substances yet. But if access to space is no more expensive than a conventional plane ride, then industry will find ways to utilize this unique environment for fabrication purposes.
CATS implies cheap access to the Moon as well. While not high in Siderophile resources, it has all the lighter elements we needed, primarily aluminum and oxygen. It also presents a unique observation platform, especially on the dark side, which is sheltered from almost all the electromagnetic pollution of the Earth. Second generation fusion reactors on Earth could be run on He3 mined from the regolith of Moon, which has been trapping the He3 that spews out of the Sun in the form of solar wind for eons. Deuterium-Tritium based fusion still creates lots of neutron radiation, and while this generates far fewer long-lived radioactive wastes than fission, there are still some (mostly the containment vessels become radioactive from constant neutron bombardment). Helium 3 fusion produces magnitudes of order less neutrons, and thus has virtually NO radioactive waste. Helium 3 is very rare on Earth, but a plentiful source would pretty much guarantee the economic viability of Fusion Energy.
While most of the work in orbit and the surface of the Moon will likely be done by robots -- both remote-controlled and autonomous -- there will likely be a sizeable human work force on the Moon, or more accurately In-The-Moon. Moon residents will dwell mostly bellow several meters of Moon rock or regolith (Moon soil) to stay safe from cosmic rays and solar radiation. They will be needed as caretakers for the machinery and robots, making sure everything continues to work smoothly. Entropy is always in need of fighting.
Like many other advance pondered in
Brink these advances require only modest advances in science, and require more political vision than scientific vision to be realized. While lowering cost will most likely come along incrementally, it like other technologies probably has a tipping point where utilization takes off. I would put the tipping point at about $1,000 per pound (current prices range $4,000-$10,000) at which point it may decrease even more quickly to the abusurdly low price of say 50-100 dollars per pound. This is when the true explosion of space exploitation will occur. In general technologies follow this rule: Cost/N -> Utilization^N
32 minutes until the launch of STS-121 as I finish writing this. While I disagree with how we are setting our space priorities, I wish this mission well and hope it gets back on track in space, even it isn't the fast track for now.
[Addendum: no go today, scrubbed at T-6 minutes due to weather]
Here is how I would place the odds of $1000 per pound launch cost (2006 dollars)
10 Years 5%
20 Years 30%
50 Years 70%
100 Years 95%
Here is how I would place the odds of $100 per pound launch cost (2006 dollars)
10 Years 0%
20 Years 5%
50 Years 50%
100 Years 80%
Current News Space Launch Cost