Rosetta Spots Its Comet

The European Space Agency’s comet-chasing spacecraft has imaged its destination for the first time since waking up from 957 days of hibernation.

Rosetta's been chasing that dot for a decade.

Comet 67P/Churymov-Gerasimenko in the constellation Ophiuchus. This image was taken on 21 March by the OSIRIS Narrow Angle Camera. The comet is indicated by the small circle next to the bright globular star cluster M107. The image was taken from a distance of about 5 million kilometres to the comet.

See that little circle around a white dot? That dot is the comet that Rosetta’s been chasing around the solar system for 10 years.

In this narrow-angle view, Comet 67P/Churyumov-Gerasimenko looks like one more bright dot in a field of stars, but that’s because Rosetta is still months away from reaching it. This is the first image take since Rosetta woke up from electronic hibernation back in January 2014.

This image was taken on March 21st by the spacecraft’s OSIRIS narrow-angle camera. OSIRIS’s wide- and narrow-angle cameras are designed to obtain hi-res images of Comet 67P/Churyumov-Gerasimenko’s nucleus once the spacecraft rendezvouses with the comet. OSIRIS will be the eyes that scout out a landing site for Rosetta’s robotic cargo: a lander named Philae (FEE-lay).


Wide-angle view of Comet 67P/Churyumov-Gerasimenko

Comet 67P/Churymov-Gerasimenko in the constellation of Ophiuchus. This image was taken with the OSIRIS Wide Angle Camera on 20 March and shows a wide field 25 times larger than the diameter of the full moon. The colour composite shows a background of hydrogen gas and dust clouds in the constellation Ophiuchus.

Rosetta and Philae are expected to arrive at their destination in August, but between now and then, they have a very busy schedule. Part of that will be scouting out a landing site for Philae, because scientists have no image of the comet’s surface and therefore could not pick one out beforehand. Rosetta’s approach in these next few months will allow it render the 4-kilometer-wide (2.5-mile-wide) ice ball to an image over 2,000 pixels across, resolving surface features.

The landing site itself has to be chosen in a matter of weeks. This means observing the comet’s orientation, spin, landmarks, and other basic characteristics in order to map its surface well enough to identify a safe place for Philae touchdown. Philae will then anchor itself down (the comet has extremely low gravity) to do some in-situ measurements on the icy surface.

Should everything go according to plan, Philae’s deployment sometime in August will make history. It will be the first man-made object ever to land softly on a comet’s nucleus. After dropping its payload, Rosetta will escort the comet on its long journey towards the Sun, observing firsthand how a chunk of ice and rock makes the transition from a quiet space boulder to a bright, tailed comet.

All comments must follow the Sky & Telescope Terms of Use and will be moderated prior to posting. Please be civil in your comments. Sky & Telescope reserves the right to use the comments we receive, in whole or in part, and to use the commenter’s username, in any medium. See also the Terms of Use and Privacy Policy.