Consumer gadgets, such as cameras and computers, tend to advance in quality even as their price comes down. Unfortunately for space scientists, rockets aren't like that. The launch vehicles used for today's spacecraft are fundamentally little different from the glorified guided missiles that delivered the first Sputniks into orbit almost half a century ago. And they are still fantastically expensive, forcing NASA and other space agencies to spend billions of dollars each year on launch fees.

Worse, rockets still fail with disturbing regularity — just ask the scientists working on the European Space Agency's Rosetta comet mission, who are now rearranging their professional lives and scratching around for further funding because a glitch in the Ariane 5 'heavy lifter' has grounded the spacecraft (see page 301).

If scientific instruments are to land on a comet, there is no choice but to rely on today's imperfect rocket science. But for astronomers who merely need to loft their telescopes above the distorting effects of the Earth's atmosphere, a new capability called ultra-long-duration ballooning offers a cheap alternative. While not quite offering a ride into space, a new generation of balloons could allow telescopes to soar above 99% of the atmosphere for more than 100 days at a time — and for a fraction of the cost of launching a space telescope.

The technology has an important qualifying test this month (see page 308). But even though they stand on the brink of an exciting new era, enthusiasts for balloon-based astronomy have nagging worries about NASA's commitment to their cause. They are frustrated, for instance, by the fact that the space agency has never opened up a dedicated line of funding for balloon-based astronomy. And they now fear that, if the ultra-long-duration programme suffers a failure or two, NASA's managers will swiftly bail out.

In part, NASA's limited enthusiasm for ballooning is a reflection of the political environment in which the agency operates: the small firms that manufacture scientific balloons lack the lobbying clout of aerospace giants such as Boeing and Lockheed Martin. But in the current harsh economic climate, NASA should place a high premium on the potential cost-effectiveness of balloon-based astronomy, and remember that rockets are still far from perfect after all these years.