[meteorite-list] Did Philae Drill The Comet?

[Ron Baalke]

http://blogs.esa.int/rosetta/2014/11/19/did-philae-drill-the-comet/

Did Philae drill the comet?
European Space Agency
November 19, 2014
 			
Philae's Sampling, Drilling and Distribution (SD2) subsystem was activated 
towards the end of the surface operations that Philae performed on Comet 
67P/Churyumov-Gerasimenko last week, despite fears  that it might alter 
the lander's precarious position following its third touchdown. Here we 
present the latest update from the SD2 team.

SD2's goal was to drill into the comet surface in order to collect and 
deliver samples to the COSAC and Ptolemy instruments inside the lander 
(Click here for our introductory post on SD2). It was the last of the 
lander's ten instruments to be operated.

@Philae2014 tweeted that the drill was activated as planned

SD2 principal investigator Amalia Finzi has reported that the drill was 
deployed as planned, extending 46.9 cm below the balcony of the lander 
and 56.0 cm from its reference point.

"It was then retracted to the reference position, the carousel turned 
in a way that the sampling tube was in front of the right oven, the discharge 
operation from the sampling tube to the oven was completed, and the carousel 
rotated in a way that that oven was positioned at COSAC's location," she 
said.

Although the ovens worked correctly, the scientists do not yet know how 
much - if any - material was actually delivered to the ovens by SD2, or 
whether the instruments sampled dust or gas that entered the chamber during 
the touchdown.

Because Philae was not anchored to the comet surface, it is also possible 
that, if the drill touched a particularly hard surface material, it moved 
the lander instead of drilling into the surface. Furthermore, the SD2 
instrument lacks dedicated sensors to determine whether or not the surface 
has been reached, whether a sample was then collected in the sample tube, 
or if it was then discharged into the oven.

But other instruments on board Philae can help understand what actually 
happened. For example, the downward-looking ROLIS camera obtained two 
images of the surface under the balcony, one before and one after the 
lander's main body was lifted and rotated. Because of those movements, 
the SD2 "footprint' may be included in those images and thus may be able 
to provide visual evidence that the drill interacted with the surface. 
We hope to be able to provide an update on this soon.

As for whether COSAC received a sample from the drill, the analysis is 
on-going.

"As far as we can see at the moment, SD2 and COSAC telemetry cannot reliably 
discern between lack of sample and insufficient gas generation from it,"
says Amalia. "A CIVA-MV/MI image would have been needed for  this purpose, 
which was not available for the first sample."

Meanwhile, COSAC's analyses on the data acquired from its surface measurements 
are on-going. But it is apparent that COSAC already "sniffed' the comet's 
atmosphere during the first touchdown, detecting organic molecules. The 
Ptolemy instrument is also reported to have successfully collected the 
ambient gases of the comet. Analysis of the spectra and identification 
of the molecules detected by both instruments are continuing.

Mario Salatti, Philae Program Manager for ASI adds: "We are all hoping 
that Philae wakes up and we can perform many more measurements on the 
surface of the comet, including the chance to drill again with SD2. The 
final site where Philae landed does not enjoy long exposure to sunlight, 
but on the other hand, it opens new perspectives. As the lander appears 
to be currently shielded by walls, the local temperature may be lower 
than it would have been at the chosen landing site. So if Philae wakes 
up, it might remain operative much longer than expected, possibly until 
perihelion, which is extremely exciting."

The SD2 (Sample Drilling & Distribution) instrument was conceived by technologists 
at the Italian Space Agency, designed and developed by the SELEX ES in 
Milan, under the scientific responsibility of the Principal Investigator 
Prof. Amalia Ercoli Finzi from Politecnico di Milano: for more than 10 
years, SD2 team has been planning SD2 operation sequences and validated 
them with the unit spare available at their institution's laboratories.

COSAC Principal Investigator: Fred Goesmann, Max-Planck-Institut fur 
Sonnensystemforschung, Katlenburg-Lindau, Germany

Ptolemy Principal Investigator: Ian Wright, Open University, Milton Keynes, 
UK.