Hubble has put several billion miles on its odometer, and, as with any high-mileage vehicle, things go wrong. An onboard computer froze in October of last year, briefly shutting down the whole telescope. But today, it's running smoothly. And that's good news, says Jennifer Wiseman, Hubble's senior scientist.

"We're doing everything from looking at objects in the Solar System — trying to understand, for example, Jupiter — to looking at things far beyond our solar system," Wiseman says. "We're even studying some of the most distant galaxies ever detected."

The telescope is in more popular than ever, Wiseman says. This year, astronomers have written more than a thousand proposals for how to use Hubble. That demand is partly because of upgrades done by astronauts like Massimino. But the main appeal is its location.

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