ÐÓ°ÉÔ­´´

AS ANY farmer knows, relying on a monoculture is a risky business. It only
takes a single pest to knock out an entire harvest. For similar reasons, being
wedded to a single idea can also be dangerous.

Since 1996, when scientists found traces of what looked like fossilised
bacteria in Martian meteorite ALH84001, NASA has championed the search for life
in the Universe. No bad thing, you may say. The agency fired the public’s
imagination at a time when it faced a hostile US Congress. But is NASA now
relying too much on this search?

Take the surface of Mars, which is covered with what look like river valleys
and flood plains. If there was ever water here, the reasoning goes, life may not
be far below. A few weeks ago, NASA reacted with great enthusiasm to a
photograph that seems to show gullies that have been freshly cut by water
(New ÐÓ°ÉÔ­´´, 1 July, p 6).

Yet this week comes the suggestion from Australia that the Martian channels
were made by carbon dioxide, not water. If true, it greatly reduces the
prospects for life on the planet
(see p 6).
Separately, Aron Vecht and Terry
Ireland from the University of Greenwich, London, announced an experiment which
shows how a chemical process can make the carbonate patterns that were taken to
be signs of life in ALH84001.

There are many good reasons to explore Mars and our other neighbours—to
help us understand the Earth and the Solar System, to push technology to its
limits and add to the richness of human culture. But relying on a single raison
d’être is a dangerous game. NASA needs to broaden its aims and find other
ways to capture the imagination. If it doesn’t, it risks getting lost in space.