Next week, Europe's space ministers will meet in Brussels to decide on the next generation of projects for the European Space Agency. They will seek to build on a remarkable record of success and very few failures. Set up as a tiny counterpart to the United States and Soviet space programmes, Esa has produced such triumphs as the Giotto spacecraft that visited Halley's Comet in 1986. And without Esa, Europe's space industry - including Arianespace, the world's biggest commercial rocket launcher company - would not exist.
The ministers will consider many possible projects and some possible bear-traps. Given its mission to support European science, it is hard to fault Esa's decision - likely to be confirmed - in favour of Mars Express, which may find life on Mars. Nearer home, new Earth-observation programmes would build on European strengths and provide data to inform policy on issues such as global warming.
More problematic is Esa's involvement in the International Space Station, where Esa risks a walk-on part in a US and Russian affair. Britain's approach of taking part in ISS experiments opportunistically contrasts with the Italian decision to have national equipment on ISS. Time will tell who is right, but the British method at least allows the costs to be known.
The politicians should be glad that Esa, as a comparatively neutral body, can say no to projects on technical grounds. It can also cut its losses, as when it abandoned plans for Ariane to be uprated for crewed space flight. Esa is a free-standing body doing for space what Cern does for particle physics. If the European Commission were in charge, it would have more of an eye for the political and prestige consequences of its decisions. Transport commissioner Neil Kinnock has many virtues, but rocket science may not be his strength.