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The Philae lander reveals low-strength primitive ice inside cometary boulders
Laurence O'Rourke1, Philip Heinisch2, Jürgen Blum2
1European Space Agency (ESA), European Space Astronomy Centre (ESAC), Madrid, Spain. lorourke@esa.int.
Nature
|October 29, 2020
Summary
Philae lander's second touchdown on comet 67P/Churyumov-Gerasimenko exposed ancient water ice. This primitive ice, mixed with organic material, has low compressive strength and high porosity, offering insights for future cometary missions.
Area of Science:
- * Planetary Science
- * Astrobiology
- * Cometary Science
Background:
- * The Philae lander mission to comet 67P/Churyumov-Gerasimenko aimed to study cometary nucleus properties.
- * Previous data provided initial insights into the comet's surface.
- * The exact location and nature of Philae's secondary landing sites were not fully understood.
Purpose of the Study:
- * To investigate the previously undiscovered site of Philae's second touchdown on comet 67P.
- * To analyze the properties of exposed primitive water ice and associated materials.
- * To determine the physical characteristics of the cometary nucleus, including compressive strength and porosity.
Main Methods:
- * Analysis of data from Philae's instruments during its second touchdown and subsequent surface interactions.
- * Multi-instrument observations conducted 19 months after the landing.
- * In situ measurements of ice compressive strength and porosity.
Main Results:
- * Philae's second touchdown site revealed primitive water ice within cometary boulders.
- * The exposed ice is mixed with dark organic-rich material, with a specific dust/ice mass ratio.
- * In situ measurements indicated very low compressive strength ( < 12 Pa) and high porosity (75 ± 7%) for the primitive ice.
Conclusions:
- * The physical properties of the cometary nucleus, particularly its icy interiors, have been constrained.
- * The findings provide crucial data for understanding cometary composition and evolution.
- * Results offer valuable insights for designing future landers targeting volatile-rich ice samples on comets.
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