Heidelberg Astronomers Develop Software for the Gaia Satellite

Graphic: Astrium Toulouse und ESA

Artistic rendering of the Gaia satellite, solar panels unfurled, against the backdrop of the Milky Way. It measures approximately 10 metres across.

Heidelberg scientists have developed highly complex software for the Gaia astrometry satellite. Daily for five years, the software will track in detail the correct functioning of all on-board systems as well as the quality of the raw scientific data. Experts from the Astronomisches Rechen-Institut at the Centre for Astronomy of Heidelberg University developed the software. The launch of Gaia is planned for late November from the spaceport at Kourou in French Guiana. From a distance of 1.5 million kilometres from Earth, the satellite will map the stars of our Milky Way with unprecedented precision.

"Astronomers hope to learn more about the formation and evolution of our home galaxy, the Milky Way, from the data Gaia will send back to Earth," says Prof. Dr. Eva Grebel. The scientist is director at the Astronomisches Rechen-Institut (ARI) and spokesperson of the university's "The Milky Way System" Collaborative Research Centre, which is studying the Milky Way and its cosmic environment. "Gaia will be in a position to map the locations of a billion stars with incredible precision, similar to measuring – from Earth – the diameter of a coin located on the moon," explains Dr. Ulrich Bastian, who heads a European working group of Gaia scientists and software engineers at the ARI. According to the scientists, the Gaia satellite of the European Space Agency (ESA) is finally ready to begin its journey after a total of 19 years of preliminary work and eight years of construction.

The software for the so-called "First Look", which was developed in Heidelberg, comprises approx. 350,000 lines of Java code, written for the most part by the Gaia group at the ARI. Every day for five years, the software will prepare a 2,000 page report on the status of the systems on board as well as the technical integrity and scientific quality of the data. "Of course no one person is capable of reading and working through 2,000 pages of documentation a day," says Dr. Michael Biermann, head of the Heidelberg First Look team. "Instead, our software looks for and flags any deviations in the numbers, tables and diagrams of the report. This will allow the First Look team member on duty to very quickly and systematically investigate any connection to other data and look for possible solutions to problems and suggest workarounds," explains Dr. Biermann. This should prevent the loss of valuable scientific measurements or the degradation of measurement accuracy.