Comet 67/P CAKED in LIFE-GIVING RUBBLE, say astroboffins

Science papers from Philae lander's brief burst of work appear for first time

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When the Philae lander failed to touch down cleanly on Comet 67P/Churyumov­-Gerasimenko, the mission looked like a mess. But the probe's four bounces across the comet's surface turn out to have been a blessing in disguise because they've given us more close-ups of 67P than expected.

The results have now appeared in a special issue of Science containing no less than nine papers about the comet.

At the first touchdown site, known as Agilkia, it has been revealed that:

  • The imaging instrument ROLIS found “metre-size blocks of diverse shapes, coarse regolith with grain sizes of 10–50 cm, and granules less than 10 cm across” but no dust.
  • The gas-sniffing instruments Ptolemy and COSAC found “a suite of 16 organic compounds comprising numerous carbon and nitrogen-rich compounds, including four compounds – methyl isocyanate, acetone, propionaldehyde and acetamide – that have never before been detected in comets.”
  • The sniffers also found “water vapour, carbon monoxide and carbon dioxide, along with smaller amounts of carbon-bearing organic compounds, including formaldehyde.

The finds listed above has excited boffins because the compounds are understood to be “prebiotics” that made it possible for key ingredients of life to form.

The ESA has made a colossal .GIF of the Agilkia region, and of Philae descending towards it. At 7.6MB it's against Reg policy to include it in a story, but you can see it over at the space agency's site by clicking here.

At the so-called Abydos spot where Philae came to rest the probe was able to use the higher-resolution Comet Infrared and Visible Analyser (CIVA) camera array and the MUPUS thermal mapper and penetrator. Having pored over the results, boffins concluded the following about Abydos:

  • CIVA shots show “dark agglomerates, perhaps comprising organic-rich grains. Brighter spots likely represent differences in mineral composition, and may even point to ice-rich materials.”
  • MUPIUS reveals what's thought to be “a thin layer of dust less than 3 cm thick overlying a much harder compacted mixture of dust and ice”.
  • CONSERT, “which passed radio waves through the nucleus between the lander and the orbiter” suggests that “the small lobe of the comet is consistent with a very loosely compacted (porosity 75 to 85 per cent) mixture of dust and ice (dust-to-ice ratio 0.4 to 2.6 by volume) that is fairly homogeneous on the scale of tens of metres.”
 fractured cliff face imaged by CIVA camera 4 reveals brightness variations in the comet’s surface properties down to centimetre and millimetre scales.

Fractured cliff face imaged by CIVA camera 4 reveals brightness variations in the comet’s surface properties down to centimetre and millimetre scales
Image credit: ESA/Rosetta/Philae/CIVA

CONSERT also let Philae boffins figure out where the stricken lander ended up, as illustrated below.

Philae best fit search ellipse

Here lies Philae. Image credit: ESA/Rosetta/Philae/CONSERT

The European Space Agency hopes that humanity hasn't heard the last of Philae as we've just about literally only scratched the surface of the worldlet on which it rests. ®


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