Rosetta's Philea space probe recently re-established radio contact with Earth from its distant comet 67P and sent a stream of science data just before low battery power dropped it into standby mode.
The robot has now been shadowed by a cliff and cannot get enough light on to its solar panels to recharge its systems. So the engineers fear this contact may have been its last, certainly for a while, the BBC reported.
It was suggested that as much as 80 per cent of the primary science objectives had been achieved before the latest downlink.
In the latest tranche of data are the results from the drilling attempt made earlier in the day. Getting into the surface layers and bringing up a sample to analyse onboard was seen as central to the core mission of Philae.
Philae also took another picture of the surface with its downward-looking Rolis camera.
It also exercised its Consert instrument, which was an experiment that sees Philae and Rosetta send radiowaves through the comet to try to discern its internal structure.
Philae was launched from Earth, piggybacked to the Rosetta satellite, in 2004. The pair covered 6.4 billion km to reach Comet 67P out near the orbit of Jupiter.
Whatever happens to Philae, Rosetta will continue to make its remote observations of 67P.
