SOFIA starts science flights in New Zealand

The Stratospheric Observatory for Infrared Astronomy (SOFIA), a joint project between the US space agency NASA and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), started the first observation flight of this year's New Zealand campaign on 19 June 2015 at 09:20 CEST (19:20 local time). Over the coming five weeks, SOFIA will conduct 14 research flights using the US Faint Object Infrared Camera for the SOFIA telescope (FORCAST) and the German Receiver for Astronomy at Terahertz Frequencies (GREAT), a far-infrared spectrometer. The scientists will focus mainly on star-forming regions in the Large and Small Magellanic Clouds and the Milky Way. Together with two other instruments and one of the camera viewfinders of the telescope, a stellar occultation by the dwarf planet Pluto will also be observed.

The airborne observatory departed from its home base in Palmdale, California, on 12 June, heading for Hawaii, where the aircraft made a four-hour stopover to refuel and switch the flight crew. The scientists on board made good use of the seven-hour night flight, employing the FORCAST instrument to observe gas and dust clouds in the galactic centre – at the heart of the Milky Way. The flight from Honolulu to Christchurch took another 10 hours. On arrival, a group of excited plane spotters had already gathered to welcome SOFIA. An over 100-strong team, including scientists, pilots, a maintenance crew and telescope operators, will be responsible for conducting the measurement campaign, which is scheduled to run until 20 July.

SOFIA and the New Horizons spacecraft on the track of Pluto

To ensure that this SOFIA mission proves as successful as its predecessors, it has received some 'help from above'. A representative from the Māori Ngāi Tahu tribe brought a blessing from New Zealand's indigenous population for a successful outcome of this year’s campaign. This year's operations will be particularly exciting; in the early morning of 29 June, at around 05:00 local time, a stellar occultation by the dwarf planet Pluto will be observed. The First Light Infrared TEst CAMera (FLITECAM), the High Speed Imaging Photometer for Occultations (HIPO) and one of the telescope's acquisition/guidance/tracking cameras (the Focal Plane Imager [FPI]) will observe how the light from a background star is diminished as the occultation occurs and then increases again. This will allow the scientists to draw conclusions about the atmosphere of Pluto. However, for this purpose, excellent timing is required, because the shadow of Pluto will only be approximately 2000 kilometres across and will be moving across the South Pacific at 80,000 kilometres per hour.

The fact that the NASA New Horizons spacecraft will pass Pluto at a distance of approximately 12,000 kilometres just two weeks later, on 14 July, adds a particular touch of interest to observing this phenomenon New Horizons will employ a number of instruments to inspect Pluto close-up for the first time. These rather short observations of the dwarf planet will be included in the long-term research into Pluto’s atmosphere, along with the data that will be acquired by SOFIA.

Following the exciting Pluto occultation, SOFIA will initially continue its astronomical observations with FORCAST. Afterwards, the team will use the final two weeks of the mission to deploy the GREAT spectrometer developed by scientists at the Presse release University of Cologne and MPI about publication in Bonn. Here, as in its July 2013 mission, SOFIA will exploit the long winter nights in New Zealand and the low concentration of atmospheric water vapour found at this time of the year to conduct its observations. Even the tiniest quantities of airborne water vapour absorb a portion of the infrared radiation entering the atmosphere from space. This is also the reason why the analyses are conducted from an aircraft travelling at an altitude of around 14 kilometres, where the atmospheric water vapour content above it is substantially lower than on the ground.

During the research flights, the scientists will place particular focus on the Large and Small Magellanic Clouds. These two 'dwarf galaxies' – immediate neighbours of the Milky Way – can only be observed from the southern hemisphere. The star-forming regions are located approximately 200,000 light years from Earth. The scientists can use their infrared instruments to observe the entire cycle of stellar birth at this distance. Their aim is to add to the data they collected during the first New Zealand mission in 2013 and to analyse further celestial regions. The mission is being supported by the US National Science Foundation (NSF), which bases its Antarctic Research Programme at Christchurch Airport and has generously allowed SOFIA to make use of its infrastructure. SOFIA is scheduled to return to Palmdale on 24 July, following another stopover in Hawaii.