Rosetta Spacecraft Makes Contact After 31 Dormant Months

It was a fairy-tale ending to a tense chapter in the story of the Rosetta space mission this evening as ESA heard from its distant spacecraft for the first time in 31 months. Rosetta is chasing down Comet 67P/Churyumov-Gerasimenko, where it will become the first space mission to rendezvous with a comet, the first to attempt a landing on a comet’s surface, and the first to follow a comet as it swings around the Sun.

Since its launch in 2004, Rosetta has made three flybys of Earth and one of Mars to help it on course to its rendezvous with 67P/Churyumov-Gerasimenko, encountering asteroids Steins and Lutetia along the way. Operating on solar energy alone, Rosetta was placed into a deep space slumber in June 2011 as it cruised out to a distance of nearly 800 million km from the warmth of the Sun, beyond the orbit of Jupiter.

Now, as Rosetta’s orbit has brought it back to within ‘only’ 673 million km from the Sun, there is enough solar energy to power the spacecraft fully again.
 
While, still about 5.5 million miles from the comet, Rosetta’s pre-programmed internal ‘alarm clock’ woke up the spacecraft. After warming up its key navigation instruments, coming out of a stabilizing spin, and aiming its main radio antenna at Earth, Rosetta sent a signal to let mission operators know it had survived the most distant part of its journey. The signal was received by NASA’s Goldstone ground station in California at 1818 GMT during the first window of opportunity the spacecraft had to communicate with Earth. It was immediately confirmed in ESA’s space operations center in Darmstadt and the successful wake-up announced via the @ESA_Rosetta twitter account, which tweeted: “Hello, World!”
 
“We have our comet-chaser back,” says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration. “With Rosetta, we will take comet exploration to a new level. This incredible mission continues our history of ‘firsts’ at comets, building on the technological and scientific achievements of our first deep space mission Giotto, which returned the first close-up images of a comet nucleus as it flew past Halley in 1986.”
 
“This was one alarm clock not to hit snooze on, and after a tense day we are absolutely delighted to have our spacecraft awake and back online,” adds Fred Jansen, ESA’s Rosetta mission manager.

“All other comet missions have been flybys, capturing fleeting moments in the life of these icy treasure chests,” says Matt Taylor, ESA’s Rosetta project scientist. “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 behavior and ultimately helping us to decipher their role in the formation of the Solar System.”

But first, essential health checks on the spacecraft must be completed. Then the eleven instruments on the orbiter and ten on the lander will be turned on and prepared for studying Comet 67P/Churyumov-Gerasimenko. “We have a busy few months ahead preparing the spacecraft and its instruments for the operational challenges demanded by a lengthy, close-up study of a comet that, until we get there, we know very little about,” says Andrea Accomazzo, ESA’s Rosetta operations manager. Rosetta’s first images of 67P/Churyumov-Gerasimenko are expected in May, when the spacecraft is still 1.2 million miles from its target. Towards the end of May, the spacecraft will execute a major maneuver to line up for its critical rendezvous with the comet in August.
 
After rendezvous, Rosetta will start with two months of extensive mapping of the comet’s surface, and will also make important measurements of the comet’s gravity, mass and shape, and assess its gaseous, dust-laden atmosphere, or coma. The orbiter will also probe the plasma environment and analyze how it interacts with the Sun’s outer atmosphere, the solar wind. Using these data, scientists will choose a landing site for the mission’s Philae probe. The landing is currently scheduled for November 11 and will be the first time that a landing on a comet has ever been attempted.
 
In fact, given the almost negligible gravity of the comet’s 2.5 mile-wide nucleus, Philae will have to use ice screws and harpoons to stop it from rebounding back into space after touchdown.

(Images provide by ESA)

FMI: www.esa.int