ESA Rosetta Mission: Sneak peek at Comet 67/P's "underside" - Cheops

ESA Rosetta NavCam captures a four-image mosaic of 67P/Churyumov-Gerasimenko on Jan. 16, 2015. 

Credit: ESA/Rosetta /NAVCAM – CC BY-SA IGO 3.0

A particularly dramatic view of comet 67P/C-G due to the angle of solar illumination, this is a mosaic made from four images acquired by ESA Rosetta's NavCam on January 16, 2015, from a distance of 28.4 km (17.6 miles).

The assembled image shows the larger "bottom" lobe of comet 67/P, with a flat region called Imhotep along the left side and, on the lower right, the transition area stretching up to the comet's smaller "head" lobe.

Outgassing jets can be seen as faint streaks at the upper right, and ejected dust grains show up as bright specks above its surface.

Also in this view is one of 67P's larger boulders, a somewhat pyramid-shaped rock dubbed "Cheops."

Position of the Cheops boulder on 67P 

Credit: ESA /Rosetta /Navcam

One in a cluster of boulders on 67P's "underside," Cheops is about 45 meters wide and 25 meters high (148 x 82 feet).

When it was first observed in Rosetta images Cheops and the nearby cluster reminded scientists of the pyramids at Giza in Egypt, and so it was named for the largest of those pyramids, the Great Pyramid, a tomb for the pharaoh Cheops (the Hellenised name for Khufu) built around 2,550 BCE.

Scientists are still working to determine the nature of 67P's boulders. It's not yet known what they are made of or how they came to be where they are observed today.

Did they fall into their current positions? Or were they exposed upwards from below as a result of the comet's activity? And why do they have alternating rough and smooth areas on their surfaces?

"It almost looks as if loose dust covering the surface of the comet has settled in the boulder's cracks, but, of course, it is much too early to be sure," said OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research (MPS) in Germany.

As comet 67P approaches perihelion over the course of the next six months we will get to see firsthand via Rosetta what sorts of changes occur to its surface features, including office-building-sized boulders like Cheops.

OSIRIS image of Cheops acquired on Sept. 19, 2014. 

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

ESA CHEOPS: SSTL to design Exoplanet satellite mission

CHEOPS was selected from 25 missions proposed in response to ESA Call for Small Missions in 2012, which was targeting innovative small science missions that offer high value at low cost (cheapest option wins).

Surrey Satellite Technology (SSTL) has been selected by the European Space Agency (ESA) for the competitive design phase of CHEOPS science satellite, which will improve mankind's understanding of exoplanets - planets orbiting distant stars outside our solar system.

The contractor selection for the implementation phase is planned by mid-2014 and the launch is scheduled late 2017.

The CHaracterising ExOPlanets Satellite (CHEOPS) will finely characterise known exoplanets and their parent stars with an unprecedented accuracy.

The satellite will measure the orbit and radius of those exoplanets, enabling the scientists to assess their potential habitability.

The mission will also act as a "scout" performing preliminary observations on targets for the future European Extremely Large Telescope (ESO ELT) and James Webb Space Telescope (JWST) that will be capable of more detailed analysis.

CHEOPS was selected from 25 missions proposed in response to ESA Call for Small Missions in 2012, which was targeting innovative small science missions that offer high value at low cost.

CHEOPS is jointly developed by ESA and a consortium of Member States led by Switzerland.

The Swiss-built instrument using a Ritchey-Chretien optical telescope will observe the stars and their orbiting planets, while ESA is responsible for the provision of the satellite platform and the launch.

Over the next 10 months SSTL will design the satellite platform, which will host the telescope payload.

To provide the mission within a short schedule and at low cost, ESA asked that any solution be based on an existing, flight-proven, satellite platform.

SSTL's solution is based on a variant of the highly successful SSTL-150 platform, which has seen recent service in Canada's Sapphire space surveillance mission and the 5-satellite RapidEye Earth observation constellation.