Hubble Reaches Drinking Age, and Prepares to Die

Hubble’s only turning 21 this weekend, but it’s been through more than you know. It started as a punchline, its mirror tragically flawed from the get-go by a 2 micron mistake. It’s needed five elaborate service missions by the space shuttle, endeavors that added new parts each time to turn the observatory into a kind of a Frankenstein monster (not unlike the 30-year-old shuttle itself). The resulting discoveries it’s made have made it the most productive and well known scientific instrument in history.

But just as the telescope is taking the best pictures of its career and consistently wowing us, like some well-traveled wunderkind sending back fantastic postcards from the wild places it’s seen, NASA itself is entering austerity mode. The agency’s cutting two major astronomy missions, and preparing for the retirement of the Space Shuttle, without which Hubble wouldn’t still be taking amazing photos of the universe, and without which the telescope can’t be brought back home.

Signs of Hubble’s real demise began in earnest in 2005, when the NASA administrator nixed the final planned fix-it mission to Hubble – meant to repair gyroscopes and sensors, depleted batteries, and some of its instruments – because it meant the shuttle would not be able to also dock at the space station, a prospect deemed too risky after the Space Shuttle Columbia disaster.

It was only after public outcry, largely from astronomers and various Hubble nerd constituencies, that NASA finally launched a daring bid to repair and enhance the massively complex machine in 2008. It was a task that involved astronauts climbing all over the thing in a well-rehearsed – and at one crucial moment, nail-bitingly improvised – extra-vehicular activity. Imagine trying to bring a crashed Internet server back online back to life while floating around it in bulky suits. It’s no walk in the park. That is why they call it a space walk.

It’s a good thing the Hubble has been repaired and enhanced over the years; indeed, some have argued that these five missions alone justified the entire space shuttle program. The machine, which has cost the space agency over $6 billion, is able to make photographs that no ground-based observatory could. It’s true that existing Earth-bound telescopes, including various proposed Extremely Large Telescopes, have much larger mirrors, and so exceed the HST in terms of sheer light-gathering power.

Even with Earth telescopes’ adaptive optics technology (AO), which allows observatories like Lucky Cam, for example, to produce very crisp images, Hubble’s cameras produce photos at a much higher resolution. Hubble can also study the heavens across the entire electromagnetic spectrum, most of which is blocked by Earth’s atmosphere. And space is just a better place from which to observe, considering it doesn’t have the “airglow” that comes from Earth’s atmosphere absorbing solar energy during the day and releasing it at night.

In terms of viewing location and optics however, Hubble may pale in comparison to its successor, the James Webb Space Telescope, which is still scheduled to launch in 2014, right around the time Hubble’s machinery is expected to reach its end. While Hubble was kept close to Earth so that it could be serviced by the shuttle, Webb will peer at the farthest objects in the known universe from a perch some 930,000 miles from our planet. The telescope will be equipped only with infrared cameras, meaning a better idea of what’s happening at the far reaches of space, but no more of those dramatic photographs that Hubble can capture with its visible light camera.

When it was launched in 1990, the expectation was that someday Hubble would come back to Earth aboard a shuttle and end up on display in the Smithsonian, where it would presumably awe children for ages. With the shuttle entering retirement, that’s no longer possible. During the last repair mission, astronauts attached something called the Soft Capture and Rendezvous System (SCRS), a ring-like device that will allow a future manned or robotic mission to capture and safely dispose of the machine.

If that mission doesn’t happen, Hubble will come down on its own. Well after its scientific life is over, drag in the upper atmosphere will eventually pull the telescope down, sometime between 2019 and 2032, a date that depends largely upon the sun’s activity. Much of the telescope would burn up on re-entry, but not all. Engineers expect that some parts of the main mirror and its support structure would probably survive. They’ve estimated the chances that one of these pieces could land on a human: 1 in 700. Considering how much that mirror has done for humanity, getting flattened by it might be an honor.