Sunday, 29 August 2010

Afternoon Three of our Jupiter observations, Mauna Kea Observatory

I'm now sitting in the IRTF office at Hale Pohaku (HP), the 3,000-metre level dormitory complex where we sleep after observing. There is more oxygen down here, so it makes for (somewhat) clearer thinking. Last night's images have already been put into movie form, fairly crudely, so there is a lot of image processing to do.

The spectra take longer to analyse. But spectroscopy, which tells you about temperatures and densities of the molecules you are looking at, contains the real physics. I'm one of these people who don't believe the pretty pictures until I can see the spectra.

Being actually present at the telescope when you are observing gives you so much more insight into what a complex operation modern astronomy is. If you pick up a scientific paper in Astrophysical Journal, Monthly Notices, Nature or Science, you never get the real picture of just how much goes into getting the data upon which all science is supposed to be based. Too many theoreticians think it drops like manna from heaven.

Because I'm currently working on the NASA IRTF, I'll use that as an example. Starting at the "top" - in terms of altitude, not necessarily seniority - you have the telescope operators. They are the guys who actually run the telescope: if you thought NASA would allow some ham-fisted amateur like me to play with their telescope and maybe run it into the dome or commit some other mortal sin with it, you have to be joking.

Seated alongside us for this run, we have Dave Griep and Bill Golisch. They are some of the most experienced TOs on the mountain. They have literally worked on Mauna Kea for decades, from the days in the late '70s and early '80s when the Mauna Kea Observatory was establishing itself as the world's premier site for astronomy, particularly in the infrared wavelengths. Dave has enabled us to observe when the winds were literally shaking the dome; Bill's inventiveness for work-arounds when what we want to do is not quite standard is legendary. I have also worked many times with the the two TOs, Paul Sears and Eric Volquardsen, both top-rate TOs whose love of the telescope makes for effective and efficient observing.

Coming up to help out, too, are the various support astronomers. Last night we were lucky that Bobby Bus from the Hilo branch for the Institute for Astronomy was at the telescope when we arrived just before midnight. He stayed on for a couple of hours beyond his shift to help us with guiding the telescope on Jupiter, and came up with a novel technique of using Jupiter - which spans an impressive 49 seconds of arc across the sky at the moment - as if it were a mere pinpoint of light. Even he was impressed by how well it worked.

While the astronomers and TOs are sleeping through the day, the telescope is in the hands of the day crew. They fix and upgrade and generally ensure that these multi-million dollar science factories perform to ever more demanding standards. At IRTF the Observatory Superintendent George Keonig leads a team who work at 4,200 metres in (almost) all weathers to see to it that astronomers get their data. George is backed up by his foreman Lars Bergknut, whose favourite phrase seems to be "are you sure you want to that?" before he gets the engineering and software team to work out a way to enable awkward astronomers to do things with the telescope that would make you blush. "Can do" gets things done!

Telescopes are no good unless they have instruments. In the rush to build ever-bigger light buckets, this is often forgotten. One of the saddest outcomes of the UK's Science and Technology Facilities Council's drive to save money is that its flagship infrared telescope, the United Kingdom Infrared Telescope (UKIRT) - itself one of the original 1970s "big three" on Mauna Kea - is now restricted to imaging survey work. A unique set of instruments, including one that enables astronomers to take spectra in polarised light, are now gathering dust. Britain should be ashamed, very ashamed.

IRTF has its teams of instrument builders. John Rayner, an ex-pat Brit who fell in love with Honolulu (and who wouldn't?) a quarter of a century ago, is currently putting together a new spectrometer for the telescope that will more than double the spectral resolution - the ability of the telescope to discriminate between individual wavelengths - of IRTF, and keep it competitive even in the age of telescopes up to ten times larger than its 3-metre mirror.

This high-resolution spectroscopy is important because, as well as measuring gas temperatures and densities, we can work out how fast the gas is going. On Jupiter, we regularly measure winds in the polar regions, where the aurorae are formed, of between 1 and 2 kilometres per second. These generate huge amounts of energy: the winds themselves and electric currents that go with them heat Jupiter's upper atmosphere more than 100 times more effectively than sunlight alone. John's new instrument should be available for IRTF to work alongside a space mission to Jupiter called JUNO, which, unfortunately, does not have a high-resolution infrared spectrometer on board (despite my arguing for one).

No run-down of IRTF is complete (and this one leaves out many, many of the telescope's key players) without a mention of its current director Alan Tokunaga. Based in Honolulu, but regularly visiting his beloved telescope, Alan himself knows all the dififculties of building top-quality instruments. His CSHELL spectrometer, now nearly 20 years old, still delivers great science, a testimony to his design skills and ability to see complex projects through. It costs about $10,000 a night to run IRTF, and it's Alan's job to ensure that NASA supports the IRTF financially so that it can support NASA's much-more-costly space missions.

And on a personal note, I cannot leave this blog entry without a mention of Alan's predecessor as IRTF director. Bob Joseph took over as director in 1989. I had met him for the first time earlier that year, where I talked about the discovery (as it then was) of the H3+ molecular ion on Jupiter. Bob was a "merging galaxy" person, looking at what happens when galaxies crash into one another, releasing huge amounts of energy and triggering massive star formation events. But IRTF was (and still is) 50% dedicated to planetary science.

So Bob asked me if I wanted to work with him on a project to exploit this new discovery of H3+. Of course, I agreed. His idea was that he would make the observations using his "director's time" in Hawaii while I did the calculations back at University College London. Fat chance!

The opportunity to come to Hawaii was not to be missed, the privilege to work at Mauna Kea Observatory an irresistible temptation. Bob taught me infrared astronomical observing in March 1990, and introduced me to Ken's House of Pancakes in Hilo. The rest, as they say, is history.

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