CHEOPS ready for scientific operation

The CHEOPS space telescope has been in orbit since last December. After extensive tests, it was declared ready for scientific operation in March and can now be used by researchers.

CHEOPS was successfully launched on December 18th 2019. Image: ESA

Last December, there was great excitement when the launch of the CHEOPS (Characterising Exoplanet Satellite) space telescope had initially been postponed, but then later cleared to proceed. The satellite reached its observation orbit and sent a first signal to the control centre roughly three hours being launched into space on a Soyuz rocket from the Guiana Space Centre in Kourou (French Guiana). This and other signals in the days to come were used to test communication with the satellite. Since 18 December last year, CHEOPS has been orbiting the Earth at an altitude of 700 kilometres along the day-night boundary at intervals of approximately one and a half hours.

Commissioning of the satellite
Although the launch is the most spectacular and risky stage, there are many more steps that need to be taken in order to ensure smooth operation of the satellite and enable it to carry out its mission: to observe and describe exoplanets. On 8 January, the University of Bern began the process of commissioning, which entailed starting up the computer, conducting various tests and putting all components into operation. All of this went smoothly.

During the commissioning process, CHEOPS delivered several images that were completely black as the telescope lid was still closed. These images were used to calibrate the instrument with the lid closed. Once the lid was opened, the next series of commissioning steps could begin on 29 January. In the two months that followed, various stars with or without planets were targeted to check the precision of the telescope measurements under different conditions. At the same time, all aspects of the ground-based segment were tested.

An image of Star HD 88111 taken by CHEOPS. The star is 175 light years away from Earth and is not known to have any planets orbiting around it.
Image: ESA/Airbus/CHEOPS Mission Consortium

First images
The next step in the commissioning process took place in early February, when CHEOPS took the first images of the sky. Willy Benz, Professor of Astrophysics at the University of Bern and the main person responsible for the CHEOPS mission, explains: ‘The first images were crucial for us to be able to judge whether the telescope optics had survived the rocket launch undamaged.’ When the images of a star field appeared on the screen, it was clear to the scientists involved that the telescope was working. In terms of sharpness, the first images surpassed all expectations.

CHEOPS now fully operational
After several months of tests, some of which were carried out by mission personnel from their homes under coronavirus conditions, the European Space Agency (ESA) declared at the end of March that the telescope was now ready to collect scientific data and carry out its mission. With this announcement, ESA also handed over responsibility for CHEOPS activities to the consortium entrusted with the mission.

Researchers from all over the world will be given access to CHEOPS during observation times through ESA's Guest Observers Programme. The expertise acquired by European players will also be used and further developed with implementation of the ESA's next exoplanet missions, Plato and Ariel.

Further Information

Kamlesh Brocard, SERI
Scientific Advisor, Space Office