Landing on a comet – a first

By May 2014, Rosetta was just 934,000 kilometres from the comet 67P/Churyumov-Gerasimenko. It then spent several weeks conducting a rendezvous manoeuvre. In August 2014, a mere 100 kilometres from the comet, the orbiter bagin mapping its target to locate a suitable landing site for Philae. The actual touchdown point was defined in October 2014: landing site 'J' on the comet head. Philae is scheduled to land on the comet 12 November 2014 – a first in the history of space flight.

Philae will anchor itself to the comet

Comets are relatively small objects with small gravitational fields. So the problem is not that it will crash as it lands – even though it weighs 100 kilograms on Earth, this is only equivalent to a few grams on the four-kilometre-wide comet. The difficulty lies in ensuring that the Philae landing craft does not simply bounce back off the comet's surface. As soon as the landing craft makes contact with the comet, it will fire two harpoons that will anchor it to the surface. Philae has been designed in such a way that in the event of any breakdown in almost all important functions, one or more redundant solutions exist. So Philae has two harpoons and a small thruster that is ignited upon landing to counteract any possible rebound.

It is very probable that the comet will already be active upon touchdown, and that it will emit gas and dust, further complicating the situation. The landing will be entirely automatic, as Earth-based control is not possible due to the immense distance and the consequent time delay of around 30 minutes it takes for the signals to travel at the speed of light.

Last modified: 23/10/2014 14:27:26

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Dr.rer.nat. Ekkehard Kührt
German Aerospace Center (DLR)

Institute of Planetary Research, Asteroids and Comets

Tel.: +49 30 67055-514

Fax: +49 30 67055-340
Dr Stephan Ulamec
German Aerospace Center (DLR)

Microgravity User Support Center (MUSC), Space Operations and Astronaut Training

Tel.: +49 2203 601-4567
Elke Heinemann
Deutsches Zentrum für Luft- und Raumfahrt (DLR) - German Aerospace Center

Tel.: +49 2203 601-2867

Fax: +49 2203 601-3249

Course of the landing on Comet 67P/Churyumov-Gerasimenko


The German Aerospace Center (DLR) Lander Control Center (LCC) is responsible for the operation and commanding the Philae lander.

Landing of Philae on the comet

Landung von Philae auf dem Kometen

In mid-November 2014, the Philae lander will descend onto the target comet, 67P/Churyumov-Gerasimenko. (Frame from 'Chasing A Comet – The Rosetta Mission'.)

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