philae first photo
Philae sends first photo after successful comet landing.ESA/Rosetta/Philae/CIVA

It is D-Day for Philae after landing on comet 67P, with great concerns the battery will be dead within hours.

Earlier this week, the ESA made history by landing a probe on a comet half a billion kilometres from Earth – the culmination of the decade-long Rosetta mission.

However, Philae did not land in the area chosen by scientists, having bounced 1km into the air after first reaching the surface of the comet.

Scientists do not know exactly where the lander is, but it is believed it is sitting in the shadow of a cliff, meaning it is not getting the solar energy needed to power its rechargeable battery. This means the mission will likely come to an end over the next few hours, instead of lasting until next year – as scientists had hoped.

As a result, experts working on Philae have told the BBC it is "time to take more risks" with the probe in order to get as much information and data from the comet before Philae dies.

The ESA will today upload commands to deploy its drill – the second step in its scientific mission. The lander will drill down just over 20cm in the surface of the comet to gather samples to analyse on Philae's onboard laboratory.

However, the procedure is extremely risky as Philae is not completely stable – it is sitting on the surface with two feet on the ground and the other in open space.

Despite the setback, Paolo Ferri, the head of the mission operations, said he is confident the engineers will find a way to solve the battery problems.

Further details of the mission will be announced later today.