Author
Stephan Ulamec
Bio: Stephan Ulamec is an academic researcher from German Aerospace Center. The author has contributed to research in topics: Comet & Asteroid. The author has an hindex of 22, co-authored 104 publications receiving 2001 citations.
Topics: Comet, Asteroid, Sample return mission, Comet nucleus, Near-Earth object
Papers published on a yearly basis
Papers
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Max Planck Society1, University of Bremen2, Centre national de la recherche scientifique3, George Washington University4, Goddard Space Flight Center5, University of Bern6, University of Houston–Clear Lake7, Maynooth University8, Instituto Nacional de Técnica Aeroespacial9, Paris Diderot University10, Carnegie Institution for Science11, German Aerospace Center12
TL;DR: The evolved gas analyzer Cometary Sampling and Composition experiment aboard Rosetta’s Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-Gerasimenko, and displayed a suite of 16 organic compounds that had not previously been reported in comets.
Abstract: 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.
394 citations
TL;DR: The precise circumstances of the multiple landings of Philae, including the bouncing trajectory and rebound parameters, are reported, based on engineering data in conjunction with operational instrument data, which provide information on the mechanical properties of the comet surface.
Abstract: 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.
250 citations
Max Planck Society1, Johns Hopkins University Applied Physics Laboratory2, European Space Research and Technology Centre3, Aalto University4, Academy of Sciences of the Czech Republic5, Finnish Geodetic Institute6, VTT Technical Research Centre of Finland7, Spacelabs Healthcare8, Institut supérieur de l'aéronautique et de l'espace9, Aristotle University of Thessaloniki10, German Aerospace Center11, Royal Observatory of Belgium12
TL;DR: Hera will investigate the smallest asteroid visited so far, providing a unique opportunity to shed light on the role cohesion and Van der Waals forces may play in the formation and resulting internal structure of such small bodies.
134 citations
TL;DR: This paper focuses on the science return of AIM, the current knowledge of its target from ground-based observations, and the instrumentation planned to get the necessary data.
110 citations
TL;DR: The Asteroid Impact and Deflection Assessment (AIDA) mission as mentioned in this paper is the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor to deflect an asteroid.
106 citations
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01 Jan 2005
TL;DR: The Monthly Notices as mentioned in this paper is one of the three largest general primary astronomical research publications in the world, published by the Royal Astronomical Society (RAE), and it is the most widely cited journal in astronomy.
Abstract: Monthly Notices is one of the three largest general primary astronomical research publications. It is an international journal, published by the Royal Astronomical Society. This article 1 describes its publication policy and practice.
2,091 citations
TL;DR: The asteroids in the main asteroid belt have been discovered to be more compositionally diverse with size and distance from the Sun than had previously been known, implying substantial mixing through processes such as planetary migration and the subsequent dynamical processes.
Abstract: Advances in the discovery and characterization of asteroids over the past decade have revealed an unanticipated underlying structure that points to a dramatic early history of the inner Solar System. The asteroids in the main asteroid belt have been discovered to be more compositionally diverse with size and distance from the Sun than had previously been known. This implies substantial mixing through processes such as planetary migration and the subsequent dynamical processes.
419 citations
University of Bern1, Tel Aviv University2, Versailles Saint-Quentin-en-Yvelines University3, University of Michigan4, University of Orléans5, Paris Diderot University6, Belgian Institute for Space Aeronomy7, Braunschweig University of Technology8, Southwest Research Institute9, Max Planck Society10, University of Lorraine11, Aix-Marseille University12, University of Hawaii13, University of Toulouse14, Hoffmann-La Roche15
TL;DR: The presence of volatile glycine accompanied by methylamine and ethylamines in the coma of 67P/Churyumov-Gerasimenko measured by the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer demonstrates that comets could have played a crucial role in the emergence of life on Earth.
Abstract: The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it is generally believed that these are formed by aqueous alterations. In the collector aerogel and foil samples of the Stardust mission after the flyby at comet Wild 2, the simplest form of amino acids, glycine, has been found together with precursor molecules methylamine and ethylamine. Because of contamination issues of the samples, a cometary origin was deduced from the 13C isotopic signature. We report the presence of volatile glycine accompanied by methylamine and ethylamine in the coma of 67P/Churyumov-Gerasimenko measured by the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer, confirming the Stardust results. Together with the detection of phosphorus and a multitude of organic molecules, this result demonstrates that comets could have played a crucial role in the emergence of life on Earth.
403 citations
Max Planck Society1, University of Bremen2, Centre national de la recherche scientifique3, George Washington University4, Goddard Space Flight Center5, University of Bern6, University of Houston–Clear Lake7, Maynooth University8, Instituto Nacional de Técnica Aeroespacial9, Paris Diderot University10, Carnegie Institution for Science11, German Aerospace Center12
TL;DR: The evolved gas analyzer Cometary Sampling and Composition experiment aboard Rosetta’s Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-Gerasimenko, and displayed a suite of 16 organic compounds that had not previously been reported in comets.
Abstract: 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.
394 citations
01 Dec 2012
TL;DR: Computer simulations show that a giant impact on early Earth could lead to a Moon with a composition similar to Earth’s, and simulate impacts involving larger impactors than previously considered that can produce a disk with the same composition as the planet's mantle, consistent with Earth-Moon compositional similarities.
Abstract: In the giant impact theory, the Moon formed from debris ejected into an Earth-orbiting disk by the collision of a large planet with the early Earth. Prior impact simulations predict that much of the disk material originates from the colliding planet. However, Earth and the Moon have essentially identical oxygen isotope compositions. This has been a challenge for the impact theory, because the impactor’s composition would have likely differed from that of Earth. We simulated impacts involving larger impactors than previously considered. We show that these can produce a disk with the same composition as the planet’s mantle, consistent with Earth-Moon compositional similarities. Such impacts require subsequent removal of angular momentum from the Earth-Moon system through a resonance with the Sun as recently proposed.
378 citations