Looking Back – The New Horizons Jupiter Encounter (2007)

Six years ago, I was in the final year of work on my PhD in Oxford and was awarded funding by the UK’s Particle Physics and Astronomy Research Council (PPARC) to participate in another giant planet observing run at NASA’s IRTF.  Before leaving, I dredged up my notes on that last trip to remind myself of some of the technical details, and it brought back a whole host of memories.  New Horizons, still hurtling towards Pluto for its close encounter, was at that point approaching Jupiter, and we’d secured time on both the IRTF and Subaru to provide contextual infrared observations of Jupiter during the flyby.  Unlike this flight, that time (February 25^th 2007) I had a window seat all the way, and watched the plane’s vapour trail shadow over the pristine snow of Iceland, as well as some daunting and towering clouds over the summit of Mauna Kea as we looped to the north of the Big Island.  Apparently it had been raining on the island for days.  Water poured off the flanks of Mauna Kea as we drove along the Saddle Road to Hale Pohaku, the astronomers quarters at 10’000 feet.

As soon as I arrived I started to hear dire reports about the snowed-in summit.  Chains were required on the wheels, and when I rose at midnight on February 28^th, we were told that our Subaru time was cancelled – the technicians had heard the sound of ice cracking as they opened the telescope dome, so had cautiously cancelled all the observations.  We finally headed up to the summit at 5am for some pre-dawn observations from the IRTF, but of the three usual instruments we use, one was too warm, one was too cold, and the other wasn’t exactly ideal for the science we wanted to achieve during the flyby.  However, the images at 5 microns were eventually used by Baines et al. (2007) (DOI: 10.1126/science.1147912) in a study of Jupiter’s cloud variability, and we also caught glimpses of Jupiter’s Oval BA from the Very Large Telescope via some remote observations, which later formed a part of a detailed New Horizons study by Cheng et al. 2008 (doi:10.1088/0004-6256/135/6/2446). 

To our disappointment, our second night of observing was also cancelled due to high humidity and fog at the summit, but the following night yielded some more nice results from the MIRSI infrared instrument that were also used in later publications.  Tom Stallard and Mackenzie Lystrup were also on Mauna Kea to use another instrument, CSHELL, so I spent an additional night with them learning the ropes and observing jovian aurora at high spectral resolution.  My last full night, March 3^rd, was devoted to infrared observations of Saturn, and we were all really excited to see the return of cold 5-µm structures in Saturn’s deep cloud decks.  So despite a catalogue of errors at the start of the 5-night run, by the end we’d got a valuable dataset to support the New Horizons flyby, and some new Saturn data to support Cassini’s ongoing exploration, so I left Mauna Kea happy.

Unlike in 2013, back in 2007 I had time to explore Hawaii for a week afterwards, accompanied by an old uni friend of mine.  We visited the volcano park, and hiked some of the way out to where erupting Kileuaea was spewing lava into the sea.  We headed for the solidified lava lake of Kileuau Iki, and hiked down through the rainforest and onto the solidified lava floor, stopping to see the steam vents and visiting the Thurston lava tube on our way back out of the crater.  We kayaked on Kealakeua Bay, where Captain Cook had first ‘discovered’ Hawaii in 1778, and sailed across to the monument that stands where the locals ultimately killed Cook.  We flew on to Maui, and spent a great day snorkeling near Lahaina, took a trip to see humpback whales during their breeding season; then wine tasting on the slopes of Haleakala before driving to the summit to look back across to the bulks of Mauna Kea and Mauna Loa to the southeast.  Finally we flew on to Oahu for a final night out in Waikiki before the end of a superb trip.  The Hawaiian islands are truly beautiful places, I hope I get to take my family someday.  But there’ll be none of that on this trip.  This time, it’s all about the observing run.  So, from a bar in LAX at midnight (my time), onwards to Hilo....