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Written by Sarah Kellett

Earlier this week, the Rosetta spacecraft released a lander called Philae (FEE-lay) to land onto a comet’s icy surface. This European Space Agency mission is the first ever to orbit and land on a comet.

The Rosetta spacecraft has just completed a high-speed chase to catch comet 67P/Churyumov-Gerasimenko. Rosetta was launched ten years ago from Earth. Since then, it has travelled over six billion kilometres, going around the Sun five times before meeting the comet halfway between the orbits of Jupiter and Mars.

A tricky landing

It’s been a tricky trip to the comet. Over the last few months, Rosetta has made many manoeuvres to make sure it is going the right way. It had to change its speed to match how fast the comet was moving. If it didn’t do that, it would fly right past it.

This will be the most detailed study of a comet ever. Rosetta carries the gear for 11 science experiments, including tools to measure the gas and dust around the comet. It has already found out that the comet is releasing water vapour, and loses two small glasses worth of water each second.

The lander Philae detached from Rosetta successfully and arrived softly on the comet, but it seems its harpoons didn’t fire. The harpoons were supposed to tether the lander to the comet, and Philae might have landed in a tricky spot.

The mission ahead

As people figure out more details about the landing, Philae is getting started on its primary mission. It carries a multi-purpose sensor to study the comet’s surface. The lander also has tools to drill into the comet, take samples and analyse them.

Comets are like pieces of history frozen in time. They haven’t changed much since the solar system formed over four billion years ago. Rosetta and Philae may well find out new details about the start of our solar system.