Kate Becker: Sunrise, sunset on NASA’s science fleet

It’s easy to forget that spacecraft are mortal.

NASA’s space telescopes and robotic rovers are built to last, and engineers have gotten so good at wringing extra years and extra science out of them that they seem practically indestructible.

Take Opportunity, one of the twin Mars rovers that was still exploring the surface of the Red Planet this year, having begun its mission in 2004. 2004! In 2004, “Friends” was still on the air. Britney Spears got married, twice. Flip phones were at the top of their game. In short, 2004 was a long time ago.

It wasn’t Opportunity’s sheer longevity that was remarkable, though: It was how dramatically it exceeded NASA’s expectations. Opportunity’s primary mission was only supposed to last three months, but 90 Martian sunrises came and went, and Opportunity kept rolling. Opportunity has outlived its planned lifetime so extravagantly that it seemed like it would go on roving forever.

But now, we may finally have said our last goodbyes. There’s been no word from Opportunity since June, when a dust storm (a “planet-encircling dust event,” to be more specific) sent it into hibernation mode. The storm is over, but Opportunity still hasn’t phoned home. Yet there are Opportunity lovers who think the old-timer rover still has a few miles left on her. They even have their own hashtag (#SaveOppy) and NASA has promised to keep listening for Opportunity at least into 2019.

Then there’s the Kepler Space Telescope. Things didn’t go quite as smoothly for Kepler. After just four years in space, a mechanical failure brought Kepler’s main mission to a halt. (Still, the telescope had already exceeded its “nominal” three-year assignment.) But that wasn’t the end of Kepler’s planet-hunting. Engineers figured out a way to keep the telescope stable enough to run a series of shorter observation campaigns. Kepler has now discovered thousands of exoplanets and transformed our thinking about worlds beyond Earth. Thanks in large part to Kepler, we now know that warm, Earth-sized planets probably number in the billions. In fact, sometimes it’s hard to remember that there was a time when we didn’t know this.

Even after low-fuel warnings dropped Kepler into safe mode over the summer, Kepler researchers kept eking more and more science out of the telescope. Finally, late last month, the telescope was powered down for good. Kepler’s goodbye wasn’t a surprise. Still, after all those saves-from-the-brink, I had to read the “NASA Retires Kepler” headline twice. Surely they meant, “NASA Retries Kepler.”

As if that weren’t enough trouble, earlier in October, the Hubble and Chandra space telescopes were sidelined within just days of each other, both by ailing gyroscopes. Luckily, their stories have happier endings. Chandra, the x-ray observatory launched back in 1999 (Y2K panic! Backstreet Boys!), is resting its glitchy gyro and has activated a different one instead. Hubble, which was having problems with a back-up gyro, had to “perform numerous maneuvers” to clear a “blockage between components,” according to a NASA statement: a sort of hokey-pokey in space. As Hubble Operations Project Manager Patrick Crouse told The Washington Post, “If people want to call it jiggling around, I suppose they can.”

What else would you expect from the comeback kid of telescopes? Though Hubble is quickly closing in on its thirtieth anniversary, boasting a resumé of discovery that’s light-years long, the telescope faced serious mirror defects from the start. In 1993, a team of astronauts fit it with “glasses” to correct its vision, the first of five servicing missions that have brought Hubble new instruments, replacement parts, and upgraded computers, extending Hubble’s life long beyond the fifteen years in its original mission plan.

Eventually, Hubble will use up its last comeback and it will come back down to Earth, one way or another. It’s maudlin, sure, but it also makes it possible to plan for future missions. (The James Webb Space Telescope is set to launch in 2021, around the time Hubble’s current mission extension runs out.) Still, I know I will find myself wishing for one more view through those eyes: flawed from the get-go, the eyes of an aging, mortal machine.

Kate Becker is a science writer living in Boston. Contact her at spacecrafty.com, or connect via facebook.com/katembecker or twitter.com/kmbecker.