Tag: failure

Midnight Run

The phone rang just as I was going to bed.

This phone call had a number I knew all too well, even without the caller ID showing the name… K1 Remote Operations. A this time of night it would be a problem, a serious problem. This particular problem would have me on the road back to the summit an hour later.

Keck at Night
Looking towards the Keck 2 dome on a moonlit night

Midnight runs to the summit are not common, but they do occur in my life. Usually we can work remotely, the night attendant serving as our remote eyes and hands. Just press the right button, flip the correct switch, done. Not this time. We tried, for over an hour we tried.

I really did not want to head back up. I had just gotten down a few hours ago, having spent the day on the summit working on the usual long list of things that need to get done. Days on the summit, in the thin air of nearly 14,000ft elevation are physically draining.

The irony of this malfunction is that I had seen it before. The dome had tripped out inexplicably on previous occasions. The problem would occur then disappear. Once it vanished you could not troubleshoot it. Unlike most of our other systems there are no logs from the shutter drive, nothing records what was going wrong.

The Friday before this it had happened to me again. But this time was different, I had a maintenance computer attached to the PLC serial port. This time I saw the error, something in the code labeled speed mismatch. No idea what this was, or how it worked. Again the error disappeared, and I could not troubleshoot further as the weather was getting worse. No opening the shutters again.

I needed a chance to figure out what this fault was… Later that day I read through the code, figured out this feature was a speed check to insure that both sides of the shutter are driven evenly. A check to compare the right and left sides of the shutter and to fault if the difference is too large. Two words of memory were compared, if the difference was too large it faulted the shutter drive.

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Kepler Mission in Jeopardy Due to Mechanical Failure

Bad news today, the Kepler Spacecraft has suffered a mechanical failure. As feared, one more of the reaction wheels that keep the spacecraft stabilized has failed. Of the set of four reaction wheels two have now failed, at least three are required to continue the mission.

Kepler
Artist’s rendition of the Kepler Spacecraft in orbit around the Sun peering at a distant solar system, press release image from the NASA Kepler website
Keck and Kepler have been a potent team in finding and confirming hundreds of exoplanets. Kepler detects alien world through the transit technique, the very slight dimming of a star as a planet passes in front. Data from an instrument such as Keck’s HIRES spectrograph is required to confirm the find through the use of radial velocity data. Using the technique Kepler has discovered 130 extrasolar planets that are now confirmed. An amazing 2,700 possible planets are awaiting confirmation. Besides the discovery of exoplanets the Kepler data set has been a bonanza to astronomers looking for other phenomena. Magnitude data on more than 100,000 stars with unprecedented precision has allowed the discovery and study of a wide range of stellar phenomena.

Engineers will continue to see if the reaction wheel can be nursed back to some level of function in an effort to salvage the mission. The prognosis is not good, it is likely the Kepler mission has ended. In any case it will take astronomers years to learn what the massive haul of Kepler data can teach us and to work through the backlog of candidate planets. In a few years the spectacular success of Kepler will be followed up by TESS, the Transiting Exoplanet Survey Satellite, due for launch in 2017.