Philae lander makes fresh contact from comet surface (Update)
The lander re-established contact at 2122 GMT Sunday, nearly a day after a solar battery recharge roused it from hibernation, they said.
"We had another contact overnight. It wasn't very long, about five minutes," European Space Agency (ESA) senior science advisor Mark McCaughrean told AFP.
The connection was "pretty short and pretty faint," he said, but "we got some data down."
Philae landed on Comet 67P/Churyumov-Gerasimenko on November 12 after an epic 10-year trek piggybacking on its mothership Rosetta.
But instead of harpooning itself to the iceball's surface, the lander bounced several times before settling at an angle in the dark.
It had enough stored battery power for about 60 hours of experiments, enabling it to send home reams of data before going into standby mode.
The hope was that better light as the comet approaches the Sun would recharge Philae's batteries enough for it to reboot, make contact and ultimately resume scientific work.
The first word came on Saturday night—a two-minute connection with Earth via Rosetta during which Philae sent home about 40 seconds worth of data—some 300 of an estimated 8,000 data packets on board.
The lander is now "completely awake," head of French space agency CNES, Jean-Yves Le Gall, told France 2 television after the second contact.
McCaughrean explained that as the comet rotates every 12.5 hours, scientists had hoped for two contacts in the 24 hours after the first, but had only one.
"We missed one, then you begin to worry... was it just a random event?" he said.
When the signal finally came it was "a bit like when you have a very bad mobile signal and you see you have a signal on your phone but you're really not able to load any webpages, for example," the scientist said.
According to Philippe Gaudon, head of the Rosetta mission for CNES: "This time, Philae sent us less but more recent data."
Comet "67P" is now 215 million kilometres (134 million miles) from the Sun and 305 million km from Earth, racing at a speed of 31.24 km a second.
It is approaching perihelion, the closest point to the Sun in the comet's orbit, on August 13, after which "67P" will head off again into the deeper reaches of space.
The mission seeks to unlock the long-held secrets of comets—primordial clusters of ice and dust that scientists believe may reveal how the Solar System was formed.
Philae is equipped with 10 instruments with which to probe the enigma on the ground, and Rosetta, in orbit above, has a remote-sensing payload of 11.
McCaughrean said there were two possible reasons for the weak signal—Philae could be in a gully without a straight line of communication to Rosetta, but also the fact that the mothership has had to move away from the comet to avoid gas and dust blasting from its head.
© 2015 AFP