Our planet has just enjoyed a weekend of rare company. The “wolf Moon”, as it is known to native Americans, has hung huge and full at its nearest point to Earth. Mars, meanwhile, has made its closest approach in six years, its red glow almost as bright as any star. Yet at this moment of tantalising proximity to our celestial neighbours, Barack Obama stands accused of pushing them farther away.
The Nasa budget that he presented yesterday cancels the new rockets that might return astronauts to the Moon and the plans for a manned lunar base as a stepping-stone to Mars. But it also closes a chapter in the history of human spaceflight: the US Government is getting out of the business of building craft to send people into orbit and beyond.
The decision has been condemned as a failure of imagination, the antithesis of audacity and hope. It should more properly be seen as a long overdue triumph of realism. By scaling back manned spaceflight, America will in no way betray its pioneer spirit. It will remain a proud spacefaring nation. It is just that its spacefaring will increasingly be done not by people but by the true pioneers of our age — robots. Astronauts do precious little exploring. Human beings are poorly designed for the job. They need food, water and oxygen, they must be shielded against radiation and they generally want to come home. That makes every launch prohibitively expensive, and limits where they can go.
Mechanical probes have none of these shortcomings. They can fly farther and faster, to destinations such as Venus and Jupiter to which no man, however bold, could go. They can roll around planets for years: the Spirit and Opportunity rovers have been prospecting Mars since 2004.
Their scientific returns dwarf those of manned missions for a fraction of the outlay. The Kepler planet- hunting probe cost $600 million — the equivalent of one and a half shuttle flights — while the next Mars rover, Curiosity, will cost less than the proposed Moon rockets would have consumed every year. And when robots go wrong, nobody dies.
Even astronauts’ vaunted ability to inspire is more than matched by machines. Do feats such as fixing the space station’s toilet really fire the imagination more than Cassini’s close-ups of Saturn?
Manned spaceflight may have a future in the private sector, as the Obama plan acknowledges. If it has value, the market will surely find it. But as robots can accomplish so much more than crewed spacecraft, so much more cheaply, it is essential to ask if the latter are a luxury that US taxpayers can afford. The President is right to say “no we can’t”.
Mark Henderson, science editor.