Monday, October 5, 2009

Space Travel Feasibility Round-Up


In gathering articles for the main ORBITAL VECTOR site, I try to stay clear of favoritism for any particular idea. I DO try to make clear a particular technology's real-world feasibility, whether its hard science or soft science, how advanced society likely needs to be to produce it, etc.

However, that doesn't mean I think that all technologies I write about are equally probable. There are other factors besides just purely technological to overcome. Economics, politics, circumstance, location, culture, are as likely to determine if a technology becomes widely used or if it just sits on the shelves of history as a curiosity. The Segway is a perfect example. As a technology, it exceeded expectations, and fulfills its utility niche almost perfectly. However, it was cultural and economic factors--basically the fear of lawsuits--that killed its wide-spread use.

With all that in mind, I thought I'd give my own personal views of the likelihood of various Space Travel technologies I've written about so far on the main site. Just keep in mind these represent my own personal views of what will likely be developed or not based on political, economic, cultural, and other factors in the real world. Believe me, I would love to see a huge flowering of advanced space technology within the next decade, but I try to be as realistically constrained with the predictions as I could, while still assuming the world community in general continues to slowly develop space capabilities. Also, the needs and attitudes of various space-faring nations/companies/groups may change over time, so what seems likely now may also change in the future.

Each technology discussed is linked to an article explaining how it works.

CHEMICAL ROCKETS: Will probably remain the main means of obtaining orbit and maneuvering in space for at least the next half-century, if not longer. Its just too reliable and well proven a technology, and with so much infrastructure already in place to manufacture rocket components they will likely remain the cheapest option for some time to come. In the second half of the century I think they'll start slowly being replaced by other technology, but even so they will still linger for many decades.

SPACE PLANES: Also a well-proven technology, from the old X-series rocket planes to Virgin Galactic's SpaceShipOne. As Virgin Galactic gears up and actually begins running tourist flights, imitators will likely blossom from every corner, and I think the rocket/space plane will have a serious renaissance in the 2020s and beyond.

ION DRIVES: Now a proven technology, ion drives are very fuel efficient and will likely begin to slowly supplant chemical rockets as the main thrusters on deep space robes. Will likely be a routine technology by mid-century, used mostly for unmanned scientific and (hopefully) industrial payloads.

PLASMA ROCKETS: I do think old-style chemical rockets will begin turning over to these within a few decades, starting in the 2030s or 2040s; they have many of the same characteristics s chemical rockets but with much greater power. By the end of the century they will likely be the dominant space propulsion technology.

FISSION ROCKETS: Toxic radioactive exhaust will make sure this technology is never seriously used, despite its near-term feasibility and other advantages.

NUCLEAR PULSE DRIVES: Despite being actually much more dangerous than fission rockets, nuclear pulse drives have much more support among the space and scientific communities. Plus they also deliver phenomenal amounts of thrust compared to most other drives to compensate. Will likely be used for large deep-space missions in the second half of the century and beyond, perhaps even for the first interstellar probes.

SOLAR BOILER ROCKETS: Nominally a very cheap form of deep space rocket, these only become economically feasible if enough infrastructure in space exists to easily refuel them with water, which probably won't happen until the next century. But when that does happen, they will likely become the cheap transport workhorses of any emerging space culture.

SOLAR/MAGNETIC SAILS: A little too far out-there as a concept to gain a lot of real popular or political support, plus in order to turn them into decent-performance vehicles, you need to build powerful laser or particle beam facilities that could too easily be interpreted as weapons, making them a political sticking point. I foresee them being used only occasionally for certain scientific missions into the foreseeable future.

FUSION ROCKETS: Fusion has always one of the big "ifs" of science. They've been promising the big breakthrough for cheap, sustainable fusion power for half a century now, but if that will actually happen anytime soon is up for speculation. IF it comes within the next few decades, fusion rocket spacecraft may begin plying deep space sometime in the last half of the century, I'd guess. However, like with fission rockets, its radioactive exhaust will make its use infrequent at first, but as humanity moves further out into the solar system its superior power will become a premium. That likely won't happen until well into the next century, however.

ANTIMATTER DRIVES: The ultimate rockets, but the problems, technical and economic (and probably political, as antimatter can easily be turned into a weapon), involved in producing and storing antimatter means these probably won' be used in any significant way until well into the next century.

LAUNCH TOWERS: Feasible, but would probably only be seriously pursued if a space elevator proves definitively unobtainable. Even so they probably wouldn't be constructed until late in the century, after any space elevator projects fail.

SPACE ELEVATORS: With the development of carbon nanotubes, these seem definitively feasible, and there is currently a large populist push within the space and scientific community to develop one. It still unfortunately remains a little too far-out-there as an idea to get any significant funding politically, which probably won't really change for at least few decades yet. However, by the 2030s or 2040s I can see space elevator technology being seriously pursued, and the first commercial one may open in the second half of the century.

I'd love to hear other peoples' opinions. I may do another feasibility round-up of space technology (focusing on space stations and planetary exploration and such) some time in the future.

1 comment:

King of the Snow said...

I have done too much research into the requirements for a space elevator. I must say that this approach to orbit is by far the most unlikely to happen. As soon as carbon nanotubes become available in commercial quantities, every other product requiring the strength of the material will have priority. From car bumpers and seat belts, to ballistic military clothing, all will be more economically appealing to a nascent, "buckey-tube" manufacturing industry.

A launch tower has some promise, but even the weight of hydrogen creates tremendous pressure at the base of such a structure. The need to make an inflatable structure rigid enough to lift any sizable package means that one has to compact the gas. Large airships employ a rigid frame, to support bags that are only filled - not inflated - with an inert lifting gas. Twelve miles high is ridiculously optimistic. Hydrogen has one fifth more "lift" than helium - at sea level. The higher in the atmosphere we measure the lift, the less there is.

How about a giant, toroidal dirigible, lifting a concentrically located, chemical rocket launch platform to a height of around 5-7 miles? Weather ceases to be a major factor of a launch. Other complications of a fixed tower are also mitigated.