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SO THE icon of NASA’s space science programme is to be allowed to fade away. Next year’s planned shuttle mission to Hubble, due to install two new instruments and replace ailing gyros and ageing batteries, has been cancelled, prompting astronomy fans all the way up to the Maryland senator Barbara Mikulski to inundate NASA with requests to reconsider.

Their dismay is hardly surprising. Thanks to an impressive back catalogue of discoveries – and NASA’s formidable PR machine – this is a telescope that has captivated a whole generation. Hubble images are now the subject of art exhibitions. Even pictures whose scientific purpose is unclear are often breathtakingly beautiful.

But how far should we let Hubble’s glorious past colour our judgement of its future? Suspicions abound among astronomers that Hubble is being axed to save money for Bush’s vision of piloted missions to the moon and Mars. NASA insists that astronaut safety, not money, is the reason for cancelling next year’s service mission.

There can be no doubt that without an effective shuttle programme Hubble is a lost cause. Early service missions spectacularly restored Hubble’s defective vision, and subsequent missions have installed ever more sophisticated instruments. But plainly the shuttle is now in trouble. After decades of macho management, NASA has been obliged to accede to the recommendations of the Columbia accident investigators.

Three of these recommendations are key to the Hubble debate. On any future shuttle mission, the accident board has stipulated, there must be the ability to inspect the vehicle’s outer shell, and, if required, to carry out certain types of in-orbit repair. There must also be a safe haven for the astronauts or the ability to bring them down. These requirements can be met on missions to the International Space Station but not on a one-off mission to Hubble.

NASA has reacted cannily to the pressure by agreeing to review its decision and by appointing Admiral Harold Gehman, who chaired the Columbia accident board, to the job. It seems highly unlikely that Gehman will dilute the recommendations of his own board by giving Hubble a waiver.

Hubble has certainly done great science. Its maps of the universe, the deepest ever made, have given us glimpses of galaxies no more than a few billion years old. Its images of distant supernovae led to the spectacular conclusion that the expansion of the universe is accelerating under the apparent influence of some mysterious repulsive force.

If the service mission could go ahead, Hubble would continue to generate new images and do excellent science. Having twice served on the Hubble Time Allocation Committee, I can attest to the very high quality of the proposals. But the baton may now have passed to other telescopes. Since Hubble was launched 14 years ago, a new generation of large ground-based telescopes has been built whose images will rival Hubble’s in clarity. In space, meanwhile, the Chandra observatory continues to do great work in X-rays, the Spitzer infrared telescope will soon be producing impressive results, and in a few years we will have Herschel and Planck observing in the sub-millimetre part of the spectrum.

What troubles astronomers is that these telescopes mostly view the heavens at different wavelengths from the optical and ultraviolet bands that Hubble works in. If Gehman gives a thumbs-down to repairing Hubble, the right reaction from NASA might be to develop a relatively cheap robotic space telescope specialising in the same wavelengths as Hubble.

It is worth keeping Hubble working as long as possible. But this should not involve risking the lives of astronauts. Astronomy is a wonderful subject but it is not more important than life itself.