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10:23

Mote Prime > Science

The Case for Space

Getting to space is expensive and dangerous at present. Wouldn't we be better off not bothering at all?

"Earth is the cradle of humanity, but one cannot stay in the cradle forever."
- Tsiolkovsky.

The Case for Space

Future generations may well ask why it took us so long to get our act together and get into space.

One of my favourite pieces of science fiction dialogue sums this viewpoint up quite nicely, from At the Bottom of a Hole, by Larry Niven. In it Lit Schaeffer, First Speaker for the Belt Political Section, is in conversation with Luke Garner, head of the UN Technological Police Force and one of the first men to live to be 160 years old. Garner asks why we went into space in the first place, if not for abstract knowledge. Schaeffer replies:

"There's everything in space. Monopoles. Metal. Vacuum for the vacuum industries. A place to build cheap without all kinds of bracing girders. Free fall for people with weak hearts. Room to test things that might blow up. A place to learn physics where you can watch it happen. Controlled environments--"

"Was it all that obvious before we got here?"

"Of course it was!" Lit glared at his visitor. The glare took in Garner's withered legs, his drooping, mottled, hairless skin, the decades that showed in his eyes - and Lit remembered his visitor's age. "...Wasn't it?"

As we edge into the new millenium, it seems that it isn't obvious. So let's go over the reasons for going.

Abstract Knowledge

Garner was right. We did go into space first for abstract knowledge. But abstract knowledge has a disturbing knack of turning out to be useful somewhere down the line. This was Niven's point in the story.

Here are just a few examples. Fullerenes, a new form of carbon, were discovered after analysing the properties of interstellar dust clouds. This one discovery has revolutionised whole areas of materials science - close relatives of fullerenes, the "buckytubes" may be the strongest materials known, and fullerenes doped with iodine are superconductors, able to conduct electricity without loss.

The probes to the other planets - from the Ranger moon impacts of the early 1960s to Voyager, Galileo and the Mars Surveyor now on its way to the red planet - have shown us that the points of the light in the sky are real worlds. Each has its own diverse landscapes, composition and gology. By understanding how they formed, we have a better idea of how our own planet came to be the way it is.

Sometimes a cautionary lesson is learned. Venus swelters under an envelope of carbon dioxide, with a surface hot enough to melt lead, a fact confirmed by the early Mariner spacecraft. Although it is unlikely that global warming will lead to a runaway effect of this magnitude on Earth, it is still a haunting reminder that the greenhouse effect is not a force to be trifled with.

Profit can come directly from knowledge. Weather services already sell predictions based on satellite data, communications companies can now offer calls to anywhere in the world via geostationary communications satellites, and prospecting companies use remote sensing to refine the probable locations of mineral deposits.

Profit

Well, why not? Profit is a motive that drives almost everything we do. As soon as we get launches cheap enough, some things will be cheaper to do in space than on the ground. Crystals for the electronics and pharmaceutical industries can be grown in microgravity to purities which far surpass those available in the constant 1-G acceleration at the surface of the Earth.

And quite apart from the hard-nosed, practical applications, what about tourism? Some people are predicting that space tourism will be what drives the early commercialisation of manned spaceflight. How many people are rich enough to spend a week in free-fall? Not many, but the supply of seats would be so low to start with that they would still be fighting for places.

Resources

Profit will, of course, drive the search for resources in space. Platinum is an extremely expensive metal, and unlike gold, which has limited industrial use, it is very important as a catalyst in many chemical reactions. The catalytic converter on a car requires platinum to work correctly. Other elements are just as useful, and many of them can be found in asteroids.

We know this because meteorites commonly contain large amounts of platinum and its close cousins. An asteroid 10km across would weigh in excess of a trillion tonnes, and with a substantial portion of that as useful metals, its worth as a mining resource would be enormous.

Not only have you raw materials in space, but you also have power, too. Uninterrupted, unfiltered, solar power. Twenty-four hours a day, 365 days a year. Solar panels or simple heat engines can be used to extract this power and use it. Ultra-thin aluminised plastic sheets can be joined and inflated to provide concave mirrors a kilometre across, gathering as much energy as a large power station on Earth, or simply focussing it as a source of heat. All free, all low maintenance, all the time.

Other things are more futuristic, but may be just as important. The first reactors using nuclear fusion may be up and running soon into the next century. Research suggests that the rare isotope, helium-3, would be a better fuel than radioactive tritium, and lead to more recoverable energy and less radiation risk. Helium-3 is very rare on Earth, but is found more abundantly in the atmospheres of Jupiter and Saturn, and closer to home on the surface of the moon. Helium-3 would be a high-value, low mass cargo which would be ideal for return to Earth, and would cetainly be safer than beaming power back to Earth from solar power stations in orbit.

Safety

Safety? Space is hard vacuum, radiation sleets through everything, extremes of cold and heat exist that are unknown on Earth. Hardly safe, but as Heinlein said "The Earth is too small and fragile a basket for humanity to keep all its eggs in."

Recently, a lot has been talked about catastrophic events that could wipe out mankind. Meteor strikes are the current favourite doomsday prediction. By spreading ourselves out, we gain safety precisely by not having all our eggs in one basket. Self-sustaining colonies off Earth are an expensive dream, but they should certainly be one of the long term goals for space exploration.

So How Do We Get There?

The key to all this is cheap launches. Once you are in orbit you are half way to anywhere in the solar system, energy wise. The most difficult step is hauling yourself off the surface off the planet. Several companies are looking at ways of doing this. Rocket fuel is really relatively cheap, and using liquid hydrogen and oxygen means that virtually the only exhaust product is water. The trouble is that the engines we use to burn it need to be serviced after every flight. Imagine what it would be like to own a car where, after every hundred mile trip, the engine needed to removed, taken apart, cleaned, parts replaced, reassembled and rigorously tested before you could go again. Even aircraft, which have a stringent maintenance schedule, have progressed past this point.

Several concepts have been advanced to get round this problem, most of them falling into two camps. The first is the descendant of the old Saturn rockets that got a dozen men to the moon. It may still be cheaper to build and fly "big dumb boosters" than to design small, serviceable craft. If it costs $100 per flight to service an advanced engine, but only $80 to build a "dumb" engine, use it and throw it away, then the dumb engine is still the way to go. A similar approach is the "small dumb booster", essentially a modified missile, which is airlaunched from a conventional aircraft which carries it above the thick parts of the atmosphere. The Pegasus launcher is a small dumb booster, and has already placed several small payloads into orbit.

The second main camp is to build a more expensive, smaller, but completely reusable craft that can be flown like an aircraft. Take it to orbit and back, wipe it down, fill it up with fuel and off we go again. This is what NASA's original design for the space shuttle entailed, but budget cutbacks and other factors turned it into the spectacular but expensive DC-9-strapped-to-three-sticks-of-dynamite configuration we are all familar with. To be fair, NASA is now working on the technology demonstrator for a reusable single-stage-to-orbit system called the X-33. Rotary Rocket are working on a single-stage-to-orbit manned satellite launcher, Kistler aerospace are working on a two-stage fully recoverable booster, and the Pioneer rocket plane is a strange one-stop concept that fills up with oxidiser from an airborne tanker before continuing to orbit.

Other, even cheaper ways of getting into space are known, but will need a large infrastructure already in space to do so. Orbital rotors, Clarke towers and other advanced mechanisms are typically very large, and have to be very strong, and most importantly have to be manufactured in orbit. This implies that there is already a manufacturing base in orbit placed there by conventional launch technology. We have to walk before we can run.

See Also

Abstract knowledge - The current crop of planetary probes includes Galileo, NEAR, Cassini, Mars Exploration Rovers, and many more.

Profit + Resources - Apart from the low Earth orbit communications satellite constellations, the NEAP is a privately funded prospecting mission to an asteroid.

So how do we get there? - My favorite for a while was the Rotary Rocket Company, now sadly defunct. As for advanced, non-rocket based methods of getting out there, check out LiftPort Group who are funding research into strong materials for use in space elevators.