ESA’s Cheops begins science mission

Cheops image of star HD 88111. Credit: ESA.

The Cheops telescope, a project of the European Space Agency (ESA), has now joined other similar spacecraft that examine stars in the hunt for exoplanets.

This week ESA announced that the Cheops telescope had begun its science mission.

The CHaracterising ExOPlanet Satellite, or Cheops, “is the first mission dedicated to studying bright, nearby stars that are already known to host exoplanets, in order to make high-precision observations of the planet’s size as it passes in front of its host star. It will focus on planets in the super-Earth to Neptune size range, with its data enabling the bulk density of the planets to be derived – a first-step characterization towards understanding these alien worlds.”

Earlier this year Cheops took its first picture, a star known as HD 88111. The image was taken its in-orbit commissioning. According to ESA, “the star is located in the Hydra constellation, some 175 light years away from Earth, and it is not known to host any orbiting planets. To demonstrate the stability of the satellite and instrument, Cheops took an image of this star every 30 seconds for 47 consecutive hours.”

Watch the ESA feature on Cheops science mission

“The images taken by Cheops are intentionally blurred: this deliberate defocusing is at the core of the mission’s observing strategy, which improves the measurement precision by spreading the light coming from distant stars over many pixels of its detector.”

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

Now that the science mission is underway the Cheops team published its first result, an observation of the transit of KELT-11b in front of its host star HD93396.

In this graphic, the Sun is shown as a comparison, along with the diameter of Earth and Jupiter (calculated from the mean volumetric radius).
In this graphic, the Sun is shown as a comparison, along with the diameter of Earth and Jupiter (calculated from the mean volumetric radius). Credit: ESA.

“HD 93396 is a subgiant yellow star located 320 light-years away, slightly cooler and three times larger than our Sun. It hosts a puffy gaseous planet, KELT-11b, about 30% larger in size than Jupiter, in an orbit that is much closer to the star than Mercury is to the Sun.”

“The light curve of this star shows a clear dip caused by the eight hour-long transit of KELT-11b, which enabled scientists to determine very precisely the diameter of the planet: 181,600 km – with an uncertainty just under 4300 km. The measurements made by Cheops are five times more accurate than those from Earth, providing a taster for the science to come from the Cheops mission.”

About Marc Boucher

Boucher is an entrepreneur, writer, editor & publisher. He is the founder of SpaceQ Media Inc. and CEO and co-founder of SpaceRef Interactive LLC. Boucher has 20+ years working in various roles in the space industry and a total of 30 years as a technology entrepreneur including creating Maple Square, Canada's first internet directory and search engine.

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