H. Lämmer

Space Research Institute

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Author Order

Document Type

Co-Authors

P. Wurz

University of Bern

115

Herbert Lichtenegger

Space Research Institute

108

M. L. Khodachenko

Austrian Academy of Sciences

107

НВ

Н. В. Еркаев

Institute of Computational Modeling

P. Odert

University of Graz

K. G. Kislyakova

University of Vienna

C. P. Johnstone

University of Vienna

Manuel Scherf

Space Research Institute

M. Güdel

Max Planck Institute for Astronomy

L. Fossati

Austrian Academy of Sciences

Cooperative Institutions

Centre National de la Recherche Scientifique

255

Austrian Academy of Sciences

153

Space Research Institute

146

Max Planck Society

117

Nanjing Library

Vatican Secret Archives

Sorbonne Université

Southwest Research Institute

Max Planck Institute for Astronomy

Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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Experimental Insights Into Space Weathering of Phobos: Laboratory Investigation of Sputtering by Atomic and Molecular Planetary Ions

Journal of Geophysical Research Planets (2020)

Paul Stefan Szabo Herbert Biber Noah Jäggi Markus Wappl Reinhard Stadlmayr

Abstract Investigating the space weathering of the Martian moon Phobos represents an important step toward understanding the development from its origin to its present‐day appearance. Depending on Phobos’ orbital position, its surface is continuously sputtered by the solar wind and planetary ions that originate in the Martian atmosphere. Based on Mars Atmosphere and Volatile Evolution measurements, it has been proposed that sputtering by planetary O + and O 2 + ions dominates in the Martian tail region, where the planet mostly shadows Phobos from the solar wind. In these models, uncertainties for sputtering yield inputs still exist due to the lack of sufficient analog experiments. Therefore, sputtering measurements with O + , O 2 + , C + , and CO 2 + ions between 1 and 5 keV were performed using augite samples as Phobos analogs. The experimental results for O + irradiations show smaller mass changes than predicted by SDTrimSP simulations, which probably can be attributed to O implantation enabled by the Fe content of the target. Sputtering with O 2 + and CO 2 + in the low keV range shows no deviations in the sputtering yields attributable to molecular effects. Therefore, CO 2 + ions will most likely be negligible for the sputtering of Phobos according to the current understanding of ion fluxes on the Martian moon. Ultimately, our experiments suggest that the sputtering contribution on Phobos by O ions is about 50% smaller than previously assumed. This does not change the qualitative outcome from previous modeling stating that planetary O ions are by far the dominant sputtering contribution on Phobos in the Martian tail region.

Space weathering

Regolith

10.1029/2020je006583

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Citations (16)

Cosmic Ray Impact on Extrasolar Earth-Like Planets in Close-in Habitable Zones

Astrobiology (2005)

J.-M. Grieβmeier A. Stadelmann U. Motschmann Н. К. Белишева H. Lämmer

Because of their different origins, cosmic rays can be subdivided into galactic cosmic rays and solar/stellar cosmic rays. The flux of cosmic rays to planetary surfaces is mainly determined by two planetary parameters: the atmospheric density and the strength of the internal magnetic moment. If a planet exhibits an extended magnetosphere, its surface will be protected from high-energy cosmic ray particles. We show that close-in extrasolar planets in the habitable zone of M stars are synchronously rotating with their host star because of the tidal interaction. For gravitationally locked planets the rotation period is equal to the orbital period, which is much longer than the rotation period expected for planets not subject to tidal locking. This results in a relatively small magnetic moment. We found that an Earth-like extrasolar planet, tidally locked in an orbit of 0.2 AU around an M star of 0.5 solar masses, has a rotation rate of 2% of that of the Earth. This results in a magnetic moment of less than 15% of the Earth’s current magnetic moment. Therefore, close-in extrasolar planets seem not to be protected by extended Earth-like magnetospheres, and cosmic rays can reach almost the whole surface area of the upper atmosphere. Primary cosmic ray particles that interact with the atmosphere generate secondary energetic particles, a so-called cosmic ray shower. Some of the secondary particles can reach the surface of terrestrial planets when the surface pressure of the atmosphere is on the order of 1 bar or less. We propose that, depending on atmospheric pressure, biological systems on the surface of Earth-like extrasolar planets at close-in orbital distances can be strongly influenced by secondary cosmic rays. Astrobiology 5, 587–603.

Rotation period

Planetary surface

Tidal locking

Planetary habitability

10.1089/ast.2005.5.587

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Citations (149)

Effects of Low Energetic Neutral Atoms on Martian and Venusian Dayside Exospheric Temperature Estimations

Space Science Reviews (2006)

Herbert Lichtenegger H. Lämmer Yuri N. Kulikov Shahin Kazeminejad Gregorio H. Molina-Cuberos

Exosphere

Airglow

Orbiter

Atmosphere of Venus

Atmosphere of Mars

Solar maximum

10.1007/s11214-006-9082-1

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Citations (42)

The Ionosphere as a Plasma

Physics of earth and space environments (2004)

S. J. Bauer H. Lämmer

10.1007/978-3-662-09362-7_6

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Citations (0)

Comparative analysis of Venus and Mars magnetotails

Planetary and Space Science (2008)

A. Fedorov C. Ferrier J. A. Sauvaud S. Barabash Tielong Zhang

Magnetosheath

Current sheet

Plasma sheet

Jupiter (rocket family)

10.1016/j.pss.2007.12.012

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Citations (56)

Martian Atmospheric Evolution: Implications of an Ancient Intrinsic Magnetic Field

Astrobiology (2002)

H. Lämmer W. Stumptner Gregorio J. Molina‐Cuberos

The Magnetometer / Electron Reflectometer (MAG/ER) experiment on board of Mars Global Surveyor (MGS) has detected surface Magnetic anomalies of up to 1500 nT during its low aerobreaking passes, resulting from remnant crustal magnetism. These magnetic anomalies strongly indicate the existence of a strong ancient intrinsic Martian magnetic moment, which corresponded to a magnetic field strength of 10% - 100% of present Earth's.

Magnetism

10.1007/978-3-642-59381-9_14

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Citations (6)

Astrobiological instrumentation for Mars – the only way is down

International Journal of Astrobiology (2002)

Alex Ellery C. Kolb H. Lämmer John Parnell Howell G. M. Edwards

In this paper, in this edition of the Journal commemorating the life and work of David Wynn-Williams, we consider approaches to the astrobiological investigation of Mars. We provide a brief account of the scientific rationale behind the approach presented here. In particular, we outline the capabilities of the Raman spectrometer for the detection of biomarkers. David Wynn-Williams was an active champion of this instrument who was keen to field-qualify a version in Antarctica with a view to flying a Raman instrument onboard a Mars-bound space mission. We examine a scenario for the deployment of such an instrument in conjunction with other instrumentation and argue that subsurface deployment of scientific instruments is essential if we are to succeed in detecting any evidence that may exist for former life on Mars. We outline a mission scenario – Vanguard – which represents a novel but low-risk, low-cost approach to Mars exploration that was conceived and developed jointly by one of the authors (Ellery) and the late David Wynn-Williams.

Scientific instrument

Instrumentation

Wynn

Champion

10.1017/s1473550403001204

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Citations (27)

The sodium exosphere of Mercury: Comparison between observations during Mercury's transit and model results

Icarus (2008)

A. Mura P. Wurz Herbert Lichtenegger H. Schleicher H. Lämmer

Exosphere

10.1016/j.icarus.2008.11.014

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Citations (85)

Magnetic moment and plasma environment of HD 209458b as determined from Lyα observations

Science (2014)

K. G. Kislyakova Mats Holmström H. Lämmer P. Odert M. L. Khodachenko

Transit observations of HD 209458b in the stellar Lyman-α(Lyα) line revealed strong absorption in both blue and red wings of the line interpreted as hydrogen atoms escaping from the planet's exosphere at high velocities. The following sources for the absorption were suggested: acceleration by the stellar radiation pressure, natural spectral line broadening, or charge exchange with the stellar wind. We reproduced the observation by means of modeling that includes all aforementioned processes. Our results support a stellar wind with a velocity of ≈400 kilometers per second at the time of the observation and a planetary magnetic moment of ≈1.6 × 10(26) amperes per square meter.

Exosphere

Line (geometry)

Outflow

Radiation Pressure

10.1126/science.1257829

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Citations (138)

Effects of Low Energetic Neutral Atoms on Martian and Venusian Dayside Exospheric Temperature Estimations

Springer eBooks (2007)

Herbert Lichtenegger H. Lämmer Yuri N. Kulikov Shahin Kazeminejad Gregorio H. Molina-Cuberos

Exosphere

10.1007/978-0-387-70943-7_21

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Citations (1)