A bumpy landing reveals a duck-shaped comet's soft-serve heart
Embargoed until:
Publicly released:
2020-10-29 03:00
The lander Philae touched down on the duck-shaped comet 67P/Churyumov–Gerasimenko back in 2014 but it was not a smooth landing, and it bounced twice on touchdown before coming to rest. Although the first and third landing points were identified previously, the location of the second site remained unknown, until now. European researchers have finally found the second touchdown site, which they named ‘skull-top ridge’. The impressions the lander made on the icy boulders at this site also suggest the boulders are extraordinarily soft – fluffier than froth on a cappuccino (or given its cold temperature, perhaps soft-serve). The researchers say understanding that the comet has such a fluffy interior is really valuable information in terms of how to design future landing mechanisms, and also for the mechanical processes that might be needed to retrieve samples.
Journal/conference: Nature
Research: Paper
Organisation/s: European Space Agency (ESA)
Funder: B.G. and J.B. thank Deutsches Zentrum für Luft- und Raumfahrt (DLR) for
continuous support and Deutsche Forschungsgemeinschaft for their support under grant Bl
298/24-2 in the framework of the Research Unit FOR 2285 ‘Debris disks in planetary systems’.
OSIRIS was built by a consortium led by Max-Planck-Institut für Sonnensystemforschung,
Göttingen, Germany, in collaboration with CISAS, University of Padova, Italy, Laboratoire
d’Astrophysique de Marseille, France, Instituto de Astrofisica de Andalucia, CSIC, Granada,
Spain, the Scientific Support Office of the European Space Agency, Noordwijk, The
Netherlands, Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, Universidad
Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala
University, Sweden, and Institut für Datentechnik und Kommunikationsnetze der Technischen
Universität Braunschweig, Germany. The support of the national funding agencies of Germany
(DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical
Directorate is gratefully acknowledged. Those authors who are part of the VIRTIS and GIADA
teams wish to thank the Italian Space Agency (ASI, Italy; contract number I/024/12/2) and
Centre National d’Études Spatiales (CNES, France) for supporting their contribution. The
contribution of the ROMAP and RPC-MAG teams was financially supported by the German
Ministerium für Wirtschaft und Energie and the Deutsches Zentrum für Luft- und Raumfahrt
under contract 50QP1401. This research has made use of the scientific software shapeViewer
(www.comet-toolbox.com). Video rendering was powered by PRo3D, a viewer for the
exploration and analysis of planetary and smaller body surface reconstructions. It was
developed by VRVis Zentrum für Virtual Reality und Visualisierung Forschungs-GmbH in close
collaboration with Joanneum Research and Imperial College London; see http://pro3d.space
for more details. Trajectory and instrumental information relevant to the observations
performed on Rosetta was based on the use of SPICE kernels. We acknowledge the important
role played by the Rosetta Science Ground Segment, the Rosetta Mission Operations Team
and the Philae Lander team(s) in the running of the Rosetta mission and Philae Lander
Operations.
Media release
From: Springer Nature
Planetary science: Philae’s bumpy landing at skull-top ridge yields insights about comets (N&V) *IMAGE & VIDEOS*
The second touchdown site of the Philae lander as it bounced on the surface of comet 67P/Churyumov–Gerasimenko is identified in a study published in Nature. An analysis of the impressions made by Philae on the icy boulders at this site — named ‘skull-top ridge’ — provides insights into the strength of the ice freshly exposed by the landing.
On 12 November 2014, the Philae lander descended towards 67P/Churyumov–Gerasimenko. The lander bounced twice on touchdown before coming to rest under an overhang in the Abydos region of the comet. Although the first and third landing points were identified previously, the location of the second site remained unknown.
On the basis of a new landing trajectory analysis, Laurence O’Rourke and colleagues set out to identify the second touchdown point of the Philae lander. Using a comparative analysis of pre- and post-landing imagery from the Rosetta spacecraft — which was in orbit around 67P/Churyumov–Gerasimenko — the authors observed changes in the features of two adjoining boulders on the surface of a ridge, which could only be explained by Philae’s presence. They determined that the lander spent nearly two minutes at this site, making four distinct surface contacts. In doing so, it exposed water ice in the interior of the boulders. At the third contact point, an approximately 0.25-metre impression made by Philae was observed in the ice. From this, the authors calculated that the strength of the ice in the boulder was very low (less than 12 pascals, softer than freshly fallen light snow). The findings provide insights into the mechanical processes that will be needed to collect ice samples in future comet missions, they conclude.
