Distant hunter of comets to awaken


A fridge-size 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 the 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, checking and updating its systems ahead of its historic rendezvous with Comet 67P/Churyumov-Gerasimenko.

Dubbed Philae, the 100-kilogram (220-pound) lander carried by the Rosetta spacecraft is the star in a mission that has already taken 10 years and a trek around the inner solar system.

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.

Philae is stuffed with 10 instruments designed to probe and analyze the comet’s surface, teasing out the secrets of its composition and organic chemistry.

In August, the satellite will be inserted into an orbit 25 kilometers (15 miles) above Comet “C-G,” which travels at speeds up to 135,000 kilometers per hour (84,000 miles per hour), to start scanning the surface for a suitable landing site for Philae.

On Nov. 11, Rosetta will inch to within 2 to 3 kilometers of the comet surface to put down its precious load.

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 (9½ inches).

Over the last quarter of a century, 11 unmanned spacecraft have been sent on missions to comets, but none has landed. The U.S. Stardust probe brought home 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. But if it fails to wake up or land correctly, the mission will continue with observations by Rosetta itself as it accompanies the comet in its loop around the sun for a total of 17 months.