PARIS: A fridge-sized robot lab hurtling through the Solar System aboard a European probe is about to wake from hibernation and prepare for the first landing by a spacecraft on a comet.
The delicate operation, starting Friday, marks the next phase in the European Space Agency’s billion-dollar mission to explore one of these ancient wanderers of our star system.
Sent to sleep in 2011 to save energy, the lander will start a weekslong process of progressively waking up and updating its systems ahead of its historic rendezvous with Comet 67P/Churyumov-Gerasimenko.
Dubbed Philae, the 100-kilogram lander carried by the Rosetta spacecraft is the scientific star in a mission that has already taken 10 years and a seven-billion-kilometer trek around the inner Solar System.
Comets follow elliptical orbits around the Sun, spewing spectacular tails of gas and dust as close brushes with the hot star cause surface ice to evaporate.
They are sometimes called “dirty snowballs” – but cosmologists say comets’ primeval mix of ice and dust are time capsules, offering insights into how the Solar System formed 4.5 billion years ago.
Some scientists believe comets may have brought much of the water in today’s oceans and possibly complex molecules that kick-started life on Earth.
This is where Philae comes in: it is stuffed with 10 instruments designed to probe and analyze the comet’s surface, teasing out the secrets of its composition and organic chemistry.
Philippe Gaudon of France’s CNES space agency said Philae’s 33-month slumber was almost exactly “like an animal in hibernation,” for only its temperature was monitored during this time to check if it remained alive in the chill of deep space.
The wake-up, he added: “will be like switching on a computer that’s been off for three years.”
“By the beginning of July, Rosetta will be about 50,000 kilometers from the comet, by the beginning of August no more than 150 kilometers,” Gaudon said.
In August, the satellite will be inserted into an orbit 25 kilometers above Comet “C-G,” which travels at speeds up to 135,000 kilometers per hour, in order to start scanning the surface for a suitable landing site for Philae.
On Nov. 11, Rosetta will inch its way to within 2 to 3 kilometers of the comet’s surface in order to put down its precious load in a “delicate, difficult” operation, Gaudon added.
The box-shaped lander will touch down on its three legs, fire two harpoons into the surface to provide anchorage and then further secure itself with ice screws before starting its work.
Cameras will send back images of the surface, and microscopes and spectrometers will analyze the soil from samples taken from as deep as 24 centimeters.
Over the last quarter-century, 11 unmanned spacecraft have been sent on missions to comets, but none has ever landed.
The U.S. Stardust probe brought home dusty grains snatched from a comet’s wake, while Europe’s Giotto ventured to within 200 kilometers of a comet’s surface.
If the landing goes well, Philae’s mission will last four to six months, enough to explore the comet “from all angles,” Gaudon said.
But if it fails to wake up or trips up on landing, the mission will continue with observations by Rosetta itself as it accompanies the comet in its loop around the sun for a total 17 months.