The Gaia mission: one year after the launch

<i>Gaia</i> launch, one year ago. Photo: ESA
Gaia launch, one year ago. Photo: ESA
Research
(18/12/2014)

On 19 December, we celebrate the 1st anniversary of Gaia mission launch. The satellite of the European Space Agency (ESA) aims at creating the most complete 3D map of the Milky Way ever done. For five years, the satellite will chart positions, distances and movements of a billion stars and it will study their physical properties, for instance age and chemical composition. The final catalogue will contain 10,000 times more stars than present catalogues and measures will be even 200 times more accurate.

 

Assessment of missionʼs first year

During its first year of operation, Gaia has already proved its abilities, for example it has discovered of several supernovas. In October 2014, the satellite had already observed around 12 billion transient sources, that is ten thousand gigabytes of data. In a year, Gaiaʼs radial velocity spectrograph has obtained an amount of spectrums than is larger than the total got throughout the history of astronomy.

Moreover, it is important to highlight that instrumentsʼ good results have enabled to observe stars which are fainter than it was thought. It was believed that Gaia will detect and measure the positions of all objects down to magnitude 20, but it will reach magnitude 21.

Data are analysed every day in search of possible science alerts such as supernovas, variable stars or new objects of the Solar System. All systems are operating at full capacity and they have already given the first results, for instance the discovery of seven supernovas.

 

Gaiaʼs unexpected anomalies

The commissioning phase uncovered some unexpected anomalies. One problem is associated with ʻstray lightʼ reaching Gaiaʼs focal plane at a level higher than predicted before launch. This appears to be a mixture of light from the Sun finding its way past Gaiaʼs 10 m-diameter sunshield and light from other astronomical objects, both making their way to the focal plane as a diffuse background.

Another problem detected early in the commissioning was associated with water freezing on some parts of the optics, causing a temporary reduction in transmission of the telescopes. This water was likely trapped in the spacecraft before launch and emerged once it was in a vacuum. Heating the affected optics to remove the ice has now largely solved this problem, but it is likely that one or two more ʻdecontaminationʼ cycles will be required during the mission to keep it in check.

In spite of observed anomalies, Gaia is in good shape to fulfil its promise: to study one billion stars in order to create the most accurate map yet of the Milky Way.

 

Data analysis

From its launch to July 2014, commissioning activities took place. In July, the board members of the mission in-orbit commissioning review confirmed the readiness of the space and ground segments to start routine operations.

Gaia data processing and analysis is a long and complex process that will lead to the creation of a final catalogue with a volume of more than one Petabyte (one million gigabytes). The first release of the catalogue will take place in summer 2016 and the final version will be published in 2022.

 

UB participation in the mission

Gaia UB Group is composed by researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), the Institute of Space Studies of Catalonia (IEEC) and the Department of Astronomy and Meteorology of the UB. Gaia UB Group (ICCUB/IEEC) has been involved in Gaia mission since the very early phases. It has played a major role in the scientific and technological design of the instrumentation, database prototypes and data simulation. It has also developed a calibration algorithm of photometric data, and the system that will enable to daily process satelliteʼs data and store them in a database to later extract the first scientific results.

Furthermore, the group is developing tools for scientific exploitation, by means of data got from the Earth in order to complement those provided by Gaia. It leads the development of the catalogues of the mission, the intermediate ones and the final one. The Data Processing Center of Barcelona, which includes CESCA and Barcelona Supercomputer Center, provides resources to carry out some operations throughout the mission and has been a necessary tool to carry out simulations in order to test the instrument.

 

<i>Gaia</i> launch, one year ago. Photo: ESA
Gaia launch, one year ago. Photo: ESA
Research
18/12/2014

On 19 December, we celebrate the 1st anniversary of Gaia mission launch. The satellite of the European Space Agency (ESA) aims at creating the most complete 3D map of the Milky Way ever done. For five years, the satellite will chart positions, distances and movements of a billion stars and it will study their physical properties, for instance age and chemical composition. The final catalogue will contain 10,000 times more stars than present catalogues and measures will be even 200 times more accurate.

 

Assessment of missionʼs first year

During its first year of operation, Gaia has already proved its abilities, for example it has discovered of several supernovas. In October 2014, the satellite had already observed around 12 billion transient sources, that is ten thousand gigabytes of data. In a year, Gaiaʼs radial velocity spectrograph has obtained an amount of spectrums than is larger than the total got throughout the history of astronomy.

Moreover, it is important to highlight that instrumentsʼ good results have enabled to observe stars which are fainter than it was thought. It was believed that Gaia will detect and measure the positions of all objects down to magnitude 20, but it will reach magnitude 21.

Data are analysed every day in search of possible science alerts such as supernovas, variable stars or new objects of the Solar System. All systems are operating at full capacity and they have already given the first results, for instance the discovery of seven supernovas.

 

Gaiaʼs unexpected anomalies

The commissioning phase uncovered some unexpected anomalies. One problem is associated with ʻstray lightʼ reaching Gaiaʼs focal plane at a level higher than predicted before launch. This appears to be a mixture of light from the Sun finding its way past Gaiaʼs 10 m-diameter sunshield and light from other astronomical objects, both making their way to the focal plane as a diffuse background.

Another problem detected early in the commissioning was associated with water freezing on some parts of the optics, causing a temporary reduction in transmission of the telescopes. This water was likely trapped in the spacecraft before launch and emerged once it was in a vacuum. Heating the affected optics to remove the ice has now largely solved this problem, but it is likely that one or two more ʻdecontaminationʼ cycles will be required during the mission to keep it in check.

In spite of observed anomalies, Gaia is in good shape to fulfil its promise: to study one billion stars in order to create the most accurate map yet of the Milky Way.

 

Data analysis

From its launch to July 2014, commissioning activities took place. In July, the board members of the mission in-orbit commissioning review confirmed the readiness of the space and ground segments to start routine operations.

Gaia data processing and analysis is a long and complex process that will lead to the creation of a final catalogue with a volume of more than one Petabyte (one million gigabytes). The first release of the catalogue will take place in summer 2016 and the final version will be published in 2022.

 

UB participation in the mission

Gaia UB Group is composed by researchers from the Institute of Cosmos Sciences of the University of Barcelona (ICCUB), the Institute of Space Studies of Catalonia (IEEC) and the Department of Astronomy and Meteorology of the UB. Gaia UB Group (ICCUB/IEEC) has been involved in Gaia mission since the very early phases. It has played a major role in the scientific and technological design of the instrumentation, database prototypes and data simulation. It has also developed a calibration algorithm of photometric data, and the system that will enable to daily process satelliteʼs data and store them in a database to later extract the first scientific results.

Furthermore, the group is developing tools for scientific exploitation, by means of data got from the Earth in order to complement those provided by Gaia. It leads the development of the catalogues of the mission, the intermediate ones and the final one. The Data Processing Center of Barcelona, which includes CESCA and Barcelona Supercomputer Center, provides resources to carry out some operations throughout the mission and has been a necessary tool to carry out simulations in order to test the instrument.