New operational area for observing the southern sky
Originally, the Stratospheric Observatory for Infrared Astronomy (SOFIA) would have observed the night sky of the southern hemisphere from New Zealand as is usually the case. "Due to the travel restrictions caused by COVID-19, we were not able to deploy the Observatory from Christchurch as normal. We therefore decided to switch to Tahiti," says Heinz Hammes, SOFIA Project Manager for the German Space Agency at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). "The observations from the southern hemisphere have great scientific importance. This is why we are very grateful to the government of French Polynesia for hosting us and providing a great service to the scientific community. All of the staff on board are vaccinated, so we expect the campaign to run smoothly and look forward to getting some exciting results." SOFIA landed at Fa'a'ā International Airport in French Polynesia on 19 July 2021 at 13:42 local time (20 July 2021 01:42 CEST). After this campaign, SOFIA will return to California, where it will complete its annual routine check before the airborne observatory sets off again to perform more observations.
From French Polynesia, SOFIA will conduct scientific flights for about eight weeks to observe astronomical sources that are not visible from the northern hemisphere. During this stay, astronomers will use two of the airborne observatory's scientific instruments – the German Receiver for Astronomy at Terahertz Frequencies (GREAT) for high-resolution spectroscopy, and the US High-resolution Airborne Wideband Camera (HAWC+) to measure magnetic fields.
Tracking down the causes of climate change with SOFIA
"The planned projects with the GREAT instrument include new measurements of atomic oxygen in Earth's upper atmosphere. These will help us to better understand climate change," explains Alessandra Roy, SOFIA Project Scientist for the German Space Agency at DLR. Climate models predict that rising greenhouse gas concentrations will increase temperatures in the lower atmosphere, while temperatures in the upper atmosphere (mesosphere) will decrease. "These atomic oxygen measurements are important for estimating temperatures in the upper part of the atmosphere and can confirm the theories describing the exchange of solar energy between Earth’s surface and space," Roy emphasises.
Solving mysteries in the interstellar medium with SOFIA
GREAT will also set its sights on southern targets for two major projects – the Legacy Projects – that were already observed during SOFIA's stay at Cologne Bonn Airport. 'HyGAL' investigates how chemical reactions in the interstellar medium are influenced by high-energy particles – also referred to as cosmic rays – flowing through the galaxy. 'FEEDBACK' will study massive star-forming regions. In doing so, the researchers want to understand the influence of star-forming activities on the formation of other stars in the area – that is, whether they help or hinder the process of star formation. "These observations from SOFIA will give astronomers new insights into why the star formation process is so inefficient. We see far fewer stars than should be there. This raises the question of whether we fully understand the mechanism of star formation," says Roy.
After the 20 planned flights with GREAT, the observatory's engineers and technicians will replace the receiver and use HAWC+ to begin the Legacy Project Study of Interstellar Magnetic Polarization: a Legacy Investigation of Filaments (SIMPLIFI), among other things. In the process, they will point the SOFIA telescope at very special cosmic structures known as filaments – the long, thin gas formations in which most stars are formed. Thanks to the Legacy programme, the scientists will have gained new insights into the role of magnetic fields in star-forming regions. During these 12 flights with HAWC+, the observatory will also observe the Galactic centre to understand the role of magnetic fields in the regions closest to the central supermassive black hole.