The current edition of The Economist (July 2nd, 2011) has a provocative cover story. With the retirement of the last space shuttle this month, and the de-orbiting of the International Space Station in 2020, The Economist believes ‘the game will be up’ for manned spaceflight: there will be no more of it. And with all the planets already visited by robot craft, even unmanned space exploration will soon be sputtering out.

The tag line for the article is: ‘Inner space is useful. Outer space is history’. The Economist sees much future activity in the economically-valuable torus bounded by low-Earth and geosynchronous orbits, a volume destined to become a ‘tamed wilderness’. But beyond that: nothing.

Space exploration has always been driven by earthly goals, often power politics, rather than scientific research or utopian ideas of humanity’s manifest destiny amongst the stars. The Moon and planets are arid, inhospitable environments and no formal business case for visiting them has ever really worked. This applies equally whether you’re China, Japan, Russia, Europe or the US. Does this mean that short of a few vanity-tourist or national-prestige projects, the final frontier has been abandoned for ever?

The business case for interplanetary and interstellar missions is structured into revenues and costs. In pure energy terms it ought not to be too expensive to launch missions but current technologies (basically giant rockets) are shockingly cost-inefficient and fly too infrequently to recover their enormous upfront overheads. Payload costs, by comparison, benefit from endlessly-cheaper computing power and off-the-shelf sensors & effectors and are less of a limiting factor.

Costs aside, it’s harder to see where future deep-space revenues might come from. A species which has so far dismally failed to colonise the poles and the ocean floor is not about to plant colonies on the Moon or other planets. Nor do deep-space material resources appear to have any significant premium over things we can obtain here on earth with far less effort.

Absent a breakthrough in propulsion technologies, it’s hard to disagree with The Economist’s conclusions in the short term, say the next few decades. In the longer term the costs will come down, space is not going anywhere, and we surely will be back … won’t we?