spaceSpace and Physics

Planet-Hunter Cheops Spots Its First Exoplanets And Is Now Ready For The Science


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockApr 17 2020, 15:49 UTC

Artist's impression of Cheops, ESA's Characterising Exoplanet Satellite, in orbit above Earth. ESA / ATG medialab

The European Space Agency’s Cheops mission is a brand new planet-hunting orbital observatory launched in late December 2019. After three months in orbit, where it was tested over and over again, the satellite is now ready to start its scientific mission in earnest, and has even spotted its first exoplanets.

“The in-orbit commissioning phase was an exciting period, and we are pleased we were able to meet all requirements,” Nicola Rando, Cheops project manager at ESA, said in a statement. “The satellite platform and instrument performed remarkably, and both the Mission and Science Operation Centres supported operations impeccably.”


The team tested how well the satellite was responding to actually being in space by having Cheops looking at well-known stable stars. Thanks to those, the mission's scientists and engineers were able to see if there were any issues with the instruments. Luckily, none was found. Cheops work perfectly and can observe stars for hours while moving in its orbit, which is crucial for its scientific mission.

Cheops is the Greek name of the Egyptian pharaoh Khufu, but for the spacecraft, it stands for CHaracterising ExOPlanets Satellite (the backronym was truly reaching here) and in the last two weeks of tests, it showed that it is very good at it. Cheops observed two exoplanet-hosting stars, catching them as the planets were transiting (passing) in front of their star, blocking a fraction of the starlight and causing the tell-tale blip. 

Cheops observations of KELT-11b. ESA/Airbus/CHEOPS Mission Consortium

The mission is designed to measure planet sizes with great accuracy. For one of the targets observed, low-density planet KELT-11b, Cheops estimated its diameter as 181,600 kilometers (112,840 miles) with an uncertainty of just 4,300 kilometers (2,671 miles). That’s five times more precise than what ground-based observatories can measure. Reaching such high precision for a planet 320 light-years away from Earth is an amazing achievement.


“That gives us a foretaste for what we can achieve with Cheops over the months and years to come,” said Willy Benz, Principal Investigator of the Cheops mission consortium, and professor of astrophysics at the University of Bern.

The primary mission duration is planned for 3.5 years and it will focus on measuring the properties of known transiting planets orbiting bright and nearby stars, providing new information and crucial insights for further investigation in the future from larger telescopes.

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