This week brought the news that things are looking pretty grim for the Hitomi satellite, a Japanese X-ray astronomy mission. Through a chain of software errors, the spacecraft found itself spinning so fast that pieces of it apparently broke off. All hope is not yet lost, but my guess is that the mission is unlikely to produce much science. Around the same time, the Kepler spacecraft had gone into emergency mode, but is now up and running again. Whew.
Hitomi is not the only astronomy satellite to fail, not by a long shot. An earlier Japanese X-ray mission, Astro-E was lost in a launch failure. The Wide-Field Infrared Explorer, or WIRE, lost all of its cryogen and didn’t complete any of its original mission although the spacecraft was repurposed to do different science. The Hubble Space Telescope looked like a failure when it was discovered that its main mirror had been made incorrectly; this problem was overcome by building corrective lenses into new cameras installed by astronauts. Popular Science’s list of NASA mission failures contains many more planetary probes and Earth-observation satellites, and reminds me of what space commentator (and X-ray astronomer) Jonathan McDowell said:
Repeat after me: Space is hard. Space is hard. Space is hard. Space is hard ...... :-(— Jonathan McDowell (@planet4589) March 27, 2016
Why is space hard? Lots of reasons. Compared to Earth, the space environment is unforgiving: low pressures, extremes of temperature, higher radiation levels. Things in orbit are moving very fast: there’s not always a lot of time to react. Spacecraft built for science missions have lots of complex subsystems which have to work together perfectly. They are usually one-offs, built uniquely for a given mission—the replacement of Astro-E with Astro-E2 (Suzaku) was pretty unusual—and often use new technologies. Space missions go through lots and lots of testing before they launch (the joke is that when the stack of paperwork is as high as the rocket, you can launch) but it’s not really possible to exactly simulate the space environment on the ground.
I worked on Spitzer starting a couple of years before it launched, and that really opened my eyes to how complicated a space science mission is. There were endless rounds of testing of the hardware and software, integration tests, reversion tests, design reviews, readiness reviews, and much more. (George Rieke’s book gives many of the details and also some of the politics behind the mission.) But you still never know what’s going to happen at launch, and I was pretty nervous on August 25, 2003. Would the project I had spent the last 2 years on succeed? If it blew up on the launch pad, (how) would I get another job in astronomy? Of course, the mission was a success, and nearly 13 years later is still going. There is a group of “Spitzer babies” now nearing 12 years old, born after their parents were fairly sure they’d have jobs for a few years.
The scientists and engineers who work on Hitomi are in a really tough place: not quite sure that the mission is gone and having to work very hard to see if they can recover it, but possibly losing hope. Many have spent years working on the mission—hard work with long hours and no immediate payoff—and the long-term rewards may not ever come. If the mission isn’t recovered, some may well be looking for new jobs or new careers. So, yeah, space is exciting. But it is hard, and Hitomi reminds us that it doesn’t always go easily.