This week I experienced three days at -70C and zero humidity while measuring stardust and witnessing the southern lights all within one 10-hour flight. This was on-board Nasa's modified Boeing 747SP Sofia aircraft - the Stratospheric Observatory for Infrared Astronomy is the world's largest flying observatory and usually based in California.
Light is made up of different wavelengths; ultraviolet (UV) has a shorter wavelength than visible light which is shorter than infrared light (IR). Telescopes like the Hubble measure optical and ultraviolet light, while Sofia concentrates on infrared light. IR light is given off by low energy processes including warm clouds of gas which give birth to new stars and winds that are created when a new star is born. Because far-infrared light can pass through clouds of gas and dust, Sofia is able to see inside objects that look opaque to the Hubble telescope. Sofia also has interchangeable instruments which can be mounted on the telescope between flights - much easier and cheaper than Hubble, which has to be serviced in space by astronauts.
Sofia's cabin is a large, open space filled with computers which sit in front of a 2.5m wide, 17-tonne telescope. Once the plane reaches the second major layer of Earth's atmosphere, the stratosphere, a huge door opens allowing the telescope to start collecting information. As 99 per cent of the Earth's infrared-blocking water vapour layer sits below the stratosphere, traditional land-based telescopes struggle to see what becomes very clear up at 44,000ft. Although only based out of the US Antarctic Programme Centre by Christchurch Airport for 8 weeks, Sofia flies from New Zealand to study celestial objects best observed from southern latitudes.
The first thing we focused the telescope on was Arcturus, one of the brightest stars in the sky. Nicknamed Alpha Boo, this star is a very strong infrared source used to calibrate the telescope before it collects the scientific data for this trip. During our overnight flight, which involved passing through the International Date Line twice, we had three meticulously planned research projects.
