Wake-up call for Rosetta

An internal "alarm clock" aboard the Rosetta spacecraft was scheduled to go off at 1000 UTC on Monday, waking it up from nearly three years of slumber. But given the six hours Rosetta would need to power up its system, plus the time needed for its signal to traverse the 807 million kilometers (501 million miles) to Earth, the European Space Agency (ESA) said it wasn't expecting to hear anything until the early evening.

The signal is to be heard first by NASA's deep space tracking dish in Goldstone, California, then by eastern Australia's station in Canberra, and finally, by the ESA's station in Western Australia.

The ESA launched Rosetta into space in 2004 with the goal of carrying out tests on the comet 67/Churyumov-Gerasimenko. If all goes well on Monday, the spacecraft will fly towards the comet in the coming months (depicted above), enter into its orbit and eventually land on its surface. Scientists hope to gather samples from the rock with its 220-pound (100 kg) lander Philae, which could reveal more about the make-up of the solar system at its earliest stages.

In the time since it was thrust into space, the comet-chaser has been gathering speed to put it on the right trajectory toward comet 67/Churyumov-Gerasimenko. It has travelled past Earth three times and Mars once.

In mid-2011, ESA scientists shut down all of its operating systems except for its computer and several heaters. Rosetta has been running on solar power since that time on its journey toward Jupiter's orbit.

The ESA has provided a link to its live broadcast as it awaits signs of life from Rosetta:ESA live transmission

kms/pfd (AP, Reuters)