Reinhard Roll

The landing(s) of Philae and inferences about comet surface mechanical properties

The Philae lander, part of the Rosetta mission to investigate comet 67P/Churyumov-Gerasimenko, was delivered to the cometary surface in November 2014. Here we report the precise circumstances of the multiple landings of Philae, including the bouncing trajectory and rebound parameters, based on engineering data in conjunction with operational instrument data. These data also provide information on the mechanical properties (strength and layering) of the comet surface. The first touchdown site, Agilkia, appears to have a granular soft surface (with a compressive strength of 1 kilopascal) at least ~20 cm thick, possibly on top of a more rigid layer. The final landing site, Abydos, has a hard surface.

Organic compounds on comet 67P/Churyumov-Gerasimenko revealed by COSAC mass spectrometry

Comets harbor the most pristine material in our solar system in the form of ice, dust, silicates, and refractory organic material with some interstellar heritage. The evolved gas analyzer Cometary Sampling and Composition (COSAC) experiment aboard Rosetta’s Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-Gerasimenko. Twenty-five minutes after Philae’s initial comet touchdown, the COSAC mass spectrometer took a spectrum in sniffing mode, which displayed a suite of 16 organic compounds, including many nitrogen-bearing species but no sulfur-bearing species, and four compounds—methyl isocyanate, acetone, propionaldehyde, and acetamide—that had not previously been reported in comets.

The COSAC experiment on the lander of the ROSETTA mission

Abstract The COSAC experiment on the Lander of the ESA mission ROSETTA is aimed at the in situ investigation of matter of a cometary nucleus (P/Wirtanen) with respect to its chemical and isotopic composition. Special emphasis is put on the identification of complex organic molecules including their chirality. The instrument, presently under development, will employ for analysis a multi-column gas-chromatograph and a high-resolution TOF mass spectrometer. These instruments can be controlled from ground and used either separately or in the GC/MS coupling mode. They are suited for analysis of the natural cometary atmosphere or pyrolytically generated gas from surface or near-surface samples.

Construction of a new multi-turn time-of-flight mass spectrometer.

A new type of multi-turn time-of-flight mass spectrometer was constructed, consisting of four cylindrical electric sectors and 28 electric quadrupole lenses, the size of the vacuum chamber being 60 x 70 x 20 cm. It was demonstrated that the mass resolution can be increased according to the number of cycles of the ions through the ion optical system.

Gas chromatography for in situ analysis of a cometary nucleus - IV. Study of capillary column robustness for space application

As part of the development of the European Space Agency Rosetta space mission to investigate a cometary nucleus, the selection of columns dedicated to the gas chromatographic subsystem of the Cometary Sampling and Composition (COSAC) experiment was achieved. Once the space probe launched, these columns will be exposed to the harsh environmental constraints of space missions: vibrations, radiation (by photons or energetic particles), space vacuum, and large temperature range. In order to test the resistance of the flight columns and their stationary phases, the columns were exposed to these rough conditions reproduced in the laboratory. The comparison of the analytical performances of the columns, evaluated prior and after the environmental tests, demonstrated that all the columns withstand space constraints, and that their analytical properties were preserved. Therefore, all the selected capillary columns, even having porous layer or chiral stationary phases, were qualified for space exploration.

A space time-of-flight mass spectrometer for exobiologically-oriented applications

Abstract A new type of multi-turn time-of-flight mass spectrometer was designed and constructed as a laboratory model of the ‘COSAC’ project of the ‘ROSETTA’ mission cometary study. This miniature time-of-flight mass spectrometer (TOF/MS) comprises of four electric sectors and eight electric quadrupole lenses, and it was demonstrated that mass resolution can increase according to the number of cycles of the ions through the ion optical system.

Experimental Investigations of the Comet Lander Philae Touchdown Dynamics

The comet lander Philae (as part of Europe’s Rosetta mission) is en route to its target, 67/P Churyumov-Gerasimenko. With landing operations coming up at the end of 2014, a partial retesting of the Philae lander’s touchdown system was carried out in spring of 2013. Intensive testing was performed as part of Philae’s design and verification program approximately 10 years ago. However, the new test series specifically addresses touchdown conditions that have been out of capability of the pendulum test facility used at those times. Thus, the follow-up tests focus on touchdown conditions such as asymmetric loads, effects from terrain undulation, and the effect of granular soil mechanics, which could not be studied sufficiently in the original tests. This paper provides insight into the touchdown system of the Philae lander, the characteristics of the used test facility, its weight offloading operating mode, and the specific application to a small-body landing test. The results of the study are presented and d...

The first mass spectrometry measurements of COSAC after touchdown on comet 67P/Churyumov-Gerasimenko

Comets harbor the most pristine material in our solar system in the form of ice, dust, silicates, and refractory organic material with some interstellar heritage. The evolved gas analyzer Cometary Sampling and Composition (COSAC) experiment aboard Rosetta’s Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-Gerasimenko. Twenty-five minutes after Philae’s initial comet touchdown, the COSAC mass spectrometer took a spectrum in sniffing mode, which displayed a suite of 16 organic compounds, including many nitrogen-bearing species but no sulfur-bearing species, and four compounds—methyl isocyanate, acetone, propionaldehyde, and acetamide—that had not previously been reported in comets.