Rosetta’s one year at the Comet 67P/Churyumov–Gerasimenko

With comet 67P’s closest approach to the Sun less than one week away, ESA’s unmanned spacecraft Rosetta celebrated one year at the comet on August 6, 2015.

After a 10-year chase spanning more than 6.4 billion km (4 billion miles) across the Solar System, the European Space Agency's spacecraft got up close and personal with the Comet 67P/Churyumov-Gerasimenko somewhere between the orbits of Mars and Jupiter on August 6, 2014. Rosetta was the first probe to orbit a comet and also to soft land a probe – Philae – on a comet.

Key moments in Rosetta’s first year at Comet 67P/Churyumov–Gerasimenko. Image credit: ESA/ATG medialab.

Since it’s launch in the year 2004, Rosetta has had a long and exciting journey. The journey featured Earth, Mars and two asteroid flybys. After arriving at a distance of 100 km (62 miles) from the double-lobed comet, Rosetta has spent an intense year analyzing the properties of this intriguing body – the interior, surface and surrounding dust, gas and plasma. While ground-based observations can monitor the development of the coma and tail from afar, Rosetta has a ringside seat for studying the source of this activity directly from the nucleus. One important aspect of Rosetta’s long-term study is watching how the activity waxes and wanes along the comet’s orbit.

The journey wasn’t totally smooth. The mission teams had to learn to fly in different environments, especially inhospitable ones. In spite of all that, the spacecraft has been rendering a great service to the scientists. It continues to bring back new images and insights about the behavior and composition of the rubber duck shaped comet. The spacecraft has returned a wealth of outstanding scientific data from this intriguing comet, spanning its interior, the dramatic surface and the surrounding cloud of dust, gas and plasma.

“This mission is about scientific discovery and every day there is something new to wonder at and try to understand,” said Nicolas Altobelli, acting Rosetta project scientist. “A year of observations near to the comet has provided us with a wealth of information about it, and we’re looking forward to another year of exploration.”

Celebrating Rosetta’s first year at Comet 67P/Churyumov–Gerasimenko. Credit: ESA.

Discoveries made with Rosetta include the fact that the comet’s water vapor has a different flavor to our oceans. The first detection of molecular nitrogen in a comet provided important clues about the temperature environment in which the comet was ‘born’. Nitrogen was more common when the Solar System first formed. Rosetta’s measurements indicate that comets originate from the cold and distant Kuiper Belt.

With data collected by Rosetta and Philae, scientists came to learn that the comet’s nucleus was non-magnetized, at least on large scales. This conflicts with the theory of large building blocks playing any potential role in moving small and magnetized dust grains when the solar system was infant.

The orbit of Comet 67P/Churyumov–Gerasimenko and its approximate location around perihelion, the closest the comet gets to the Sun. The positions of the planets are correct for August 13, 2015.

Now, both Rosetta and the comet are awaiting perihelion, the point on its 6.5-year orbit that takes it closest to the Sun. On August 13, they will be 186 million kilometers (115 million miles) from the Sun, about a third of the distance at rendezvous last August.

Featured image:The European Space Agency is celebrating the one year anniversary of Rosetta arriving at Comet 67P. Credit: ESA.