The new stone is a comet identified as 67P/Churyumov-Gerasimenko
- It was first observed in 1969 and named after its Russian discoverers
- The comet is in an elliptical 6.45-year orbit that takes it from beyond Jupiter at its furthest point, to between the orbits of Mars and Earth at its closest to the Sun.
- It is approximately 3.5 x 4 km in size, has a rotational period of 12.7 hours and a mass of 3.14±0.21×1012 kg
- The surface temperature appears to be around -70ºC, which is warmer than expected
- It is currently about 405 million km from earth (about 22.5 light-minutes) and moving at 55,000 km/hr
The European Space Agency’s Rosetta craft has now arrived at 67P/Churyumov-Gerasimenko after a 10 year, 6.4 billion km long journey and has entered orbit around its new stone
Rosetta is a cornerstone mission to chase, go into orbit around, and land on a comet. It will study the Jupiter-family comet 67P/Churyumov-Gerasimenko with a combination of remote sensing and in situ measurements. The spacecraft will orbit the comet and release the Philae lander, which carries a suite of instruments for imaging and sampling the comet nucleus. The mission will track the comet through perihelion, examining its behaviour before, during and after.
The spacecraft was launched from Kourou aboard an Ariane 5G+ on 2 March 2004. It required four gravity assists for its journey, one by Mars and three by Earth. Rosetta had already flown by the asteroids 2867 Steins (in 2008) and 21 Lutetia (in 2010), before entering deep space hibernation in June 2011.
Rosetta’s main goals will be reached in 2014. Following a planned exit from hibernation on 20 January, the spacecraft’s instruments were checked as it continued on its journey to 67P/Churyumov-Gerasimenko. The spacecraft arrives at the comet in August 2014, and deploys the lander in November 2014.
Rosetta is just 100 km from the comet’s surface, but it will edge closer still. Over the next six weeks, it will describe two triangular-shaped trajectories in front of the comet, first at a distance of 100 km and then at 50 km.
At the same time, more of the suite of instruments will provide a detailed scientific study of the comet, scrutinising the surface for a target site for the Philae lander.