Comet-chasing space probe Rosetta phones home

Space scientists are celebrating tonight after a sleeping spacecraft “phoned home” to show it had woken up and was ready to chase a comet.

How ESA’s space probe Rosetta will look as it flies alongside the comet later this year. Credit: Astrium

Europe’s Rosetta robotic probe was put into hibernation in July 2011, more than seven years after it was launched, as it headed through the cold depths of the Solar System, 500 million miles from Earth.

It was due to come back to life at 10am today before recharging its batteries and sending a signal back to Earth to say all was well. Giant radio telescope dishes in the US and Australia listened in for the message from the probe, 420 million miles away.

Mission controllers at the European Space Agency’s operations centre at Darmstadt, in Germany, spent many anxious minutes waiting for the signal to appear as a spike on a screen of data during a window of opportunity from 5.30 to 6.30pm UK time.

Then the tension was broken at 6.18pm when both radio telescopes picked up the call home showing that Rosetta’s “alarm clock” had gone off. Whoops and cheers filled the ESA control room as scientists, engineers and others showed their joy and relief.

The spike is visible in data from the two radio telescopes. Credit: ESA

ESA had run a fun “Wake up Rosetta” campaign over recent weeks with space fans all over the world recording videos of themselves spurring on the distant probe. The contest finished today and the ten videos judged the best will be beamed out to Rosetta by one of ESA’s deep-space tracking stations. Two winners will be invited to Darmstadt for the landing in November.

The next few months will be spent checking out the health of the spacecraft and its instruments. Then observations of the comet will begin as it begins to study a ball of ice and rock called Comet 67P/Churyumov-Gerasimenko heading in to zip around the Sun. And in a daring climax to the mission in November, Rosetta will attempt to land a smaller probe called Philae on the surface of the comet itself.

Mission scientist Matt Taylor lifted his arms in delight when the call from Rosetta arrived to show it was alive. He said: “We will face many challenges this year as we explore the unknown territory of Comet Churyumov-Gerasimenko and I’m sure there will be plenty of surprises, but today we are just extremely happy to be back on speaking terms with our spacecraft.”

Comets interest scientists because they are leftovers from the material that built the planets and which may have seeded the Earth with the ingredients that gave it life. First pictures of the comet are expected in May. Rosetta is still nearly six million miles away from it.

Matt added: “All other comet missions have been flybys, capturing fleeting moments in the life of these icy treasure chests,. With Rosetta, we will track the evolution of a comet on a daily basis and for over a year, giving us a unique insight into a comet’s behaviour and ultimately helping us to decipher their role in the formation of the Solar System.”

Since its launch in 2004, Rosetta has made three flybys of Earth and one of Mars to help it build speed on its mission. It has already encountered and studied two asteroids, Steins and Lutetia, along the way.

On one of its approaches to Earth, it was mistaken briefly for a dangerous incoming asteroid.

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