WHAT is the biggest question in science? The origin of consciousness? How to combine quantum mechanics with general relativity? These are big, but arguably there's a bigger one: is there anyone out there?

Understanding exactly what life is, how it began and whether it exists beyond our planet is, I believe, the greatest challenge of our time. Finding alien life would be the most important discovery in history, and the search for it is more likely than anything else to maintain public support for space research. Given this, you'd think space agencies would be devoting pretty much all their resources to it. Oddly, they are not.

NASA and the European Space Agency both have planned missions to Mars to look for conditions favourable to life, but neither will be equipped to look directly for living organisms, which should be the priority. And even these missions are not getting the funding they deserve. Furthermore, NASA often appears so worried about being seen to be looking for aliens that it seems coy about the whole enterprise.

This is daft. What's needed is a direct, no-holds-barred approach to the search for life. Science needs to shed its ET hang-up. NASA's annual budget is $20 billion, yet it won't spend a significant sum on what should be a flagship mission to Mars to look for existing life. Similarly, it is bizarre that no public funds are available for even a modest search for alien radio transmissions.

It is time to refocus public space programmes on answering the biggest question of all. That means funding big, expensive, ambitious exploration projects on Mars, Titan, Europa and any other promising places, and flying telescope arrays to spot extrasolar Earths. Cancel everything else, if necessary.

It sometimes seems that for the past 30 years NASA and other agencies have gone out of their way to make space exploration seem as dull as possible. It should take the opportunity to turn the tables while it still has a budget.

Michael Hanlon is science editor of the London Daily Mail. His latest book, Eternity: Our next billion years, is published by Macmillan