Millions of miles away, a space probe has awakened from a 31-month nap. Staff at the European Space Agency (ESA) control centre in Germany sighed with relief: Rosetta, a €1.3bn spacecraft, is on course to make a historic landing on Comet 67P/Churyumov-Gerasimenko, roughly 670 million kilometres from the sun, near the orbit of Jupiter.
Until 20 January, Rosetta had been napping to save energy. It launched almost a decade ago, in March 2004. Since then it has managed three flybys of the earth (and one of Mars) as it has built up speed and adjusted its trajectory, photographing two bodies in the asteroid belt – Lutetia and Steins – along the way. The main attraction, however, is due this year.
The last time we heard from Rosetta was in 2011, when ESA operators put it into hibernation as it entered a region of space where solar panels are ineffective. After heading out 800 million kilometres from the sun, it swung back towards 67P/Churyumov-Gerasimenko. When it gets there, it will steer itself into orbit, scanning the icy rock to find a suitable landing site for Philae, its on-board lander.
The Rosetta mission will be the first to orbit and to land on a comet (Japan’s Hayabusa mission landed and retrieved a sample from the Itokawa asteroid in 2005, returning the sample to Planet Earth in 2010). If the ESA succeeds, its findings could be some of the most valuable on the early history of our solar system.
The closest we’ve got to comets before is brief flybys, such as ESA’s Giotto mission, which sailed through the tail of Halley’s Comet in 1986. That mission confirmed the “dirty snowball” hypothesis, that comets are made up largely of ice, dust and frozen gases such as carbon dioxide and methane.
Rosetta will go much further. For two months it will map the comet’s surface extensively, measure its gravity and observe how it interacts with the solar wind. Then, after harpooning itself to a suitable landing site, it will release its 100-kilogram Philae lander in November. This will be able to transmit the first panoramic photos from the surface of a comet.
It’s a funny thing, waiting ten years to see if something you fired into space is still alive. Twitter didn’t exist when Rosetta launched but when the spacecraft woke up, the ESA dutifully tweeted “Hello, world!” in each of the 20 languages of the organisation’s member states from the official @ESA_Rosetta account.
The wait to see if Rosetta would wake up again became a social media event, with the ESA asking people to submit their “Wake up, Rosetta!” videos by Facebook – which was only two months old when the probe launched.
A social media campaign would not have been in the minds of the scientists who started sketching out the funding proposal for the Rosetta mission in the early 1990s, when the Facebook founder, Mark Zuckerberg, still would have had baby teeth. These missions are, without exaggeration, the life work of the scientists involved.
Maybe by the time one of the next major ESA missions is completed – the ExoMars rover, maybe, due to launch in 2015 and land on Mars in 2018 to search for signs of extraterrestrial life – it will find that the world it has left behind isn’t interested in tweets any more. Maybe we’ll be watching new photos of other worlds come through on our augmented reality headsets, like Google Glass.
Our interaction with the stars will continue to change, even if they don’t.
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