Topic of the Moment – the Rosetta comet mission

In August, the European Space Agency’s probe Rosetta made its final approach to Comet Churyumov–Gerasimenko, entering the last stage of a mission a decade in the making that aims to be the first to land a spacecraft on a comet.

Topic of the Moment – the Rosetta comet mission

In 1969, Kiev-based astronomers Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko discovered the comet now being orbited by the Rosetta spacecraft.

The rock that bears their name is a body about two and a half miles across that orbits the Sun once every 6.5 years on a highly elliptical path that sees it approach as close as 186 million km and retreat as far as 850 million km.

The Rosetta probe, one of ESA’s ‘cornerstone’ missions, was launched to study it in March 2004, after a failure of one of the agency’s Ariane 5 rockets nixed plans to rendezvous with Comet Wirtanen.

Building up the speed required to intercept Churyumov–Gerasimenko required Rosetta to undertake several gravity assist manoeuvres in the inner solar system, using the mass of Mars and the Earth to accelerate the probe. The journey took more than ten years, and the spacecraft eventually reached its destination on 6 August 2014.

Currently circling the comet under its rocket power, Rosetta will enter a proper orbit during September and, after identifying a suitable touchdown site, deploy its lander, Philae, in November. If successful, it’ll be the first ever landing on a comet.

The instruments on board Philae are intended to be used to study the makeup of the comet’s nucleus, what chemicals are present, and how the structure of the comet changes as it approaches the Sun – it will make its closest approach in August 2015.

In particular, the lander will search for organic compounds – potentially helping to answer the question of whether comets could have seeded life on Earth.