Planetary Science

Planetary Biology and Terraforming

by Keli Rae

Keli McMillen & P.J. Boston, honorable mention end of paper.

Planetary biology can be considered in terms of four
components: (1) planetary protection, (2) the search for... more Planetary biology can be considered in terms of four
components: (1) planetary protection, (2) the search for life, (3)
human life support and (4) ecopoiesis and terraforming.
Initially, contamination of a planet with Earth life is to be
minimized in order to facilitate a search for planetary life.
Meanwhile, humans, if present, must be sustained.
Subsequently, large-scale modifications of a planetary
environment can be considered. “Ecopoiesis” is a term
introduced by McKay and Haynes to describe the initiation of a
living, self-sustaining ecosystem in a planetary (Mars)
environment. “Ecosynthesis” refers to the development of an
ecosystem that includes succession (ecosystem maturation by
the replacement of organisms). “Terraforming” refers to
creating an Earth-like world and includes planetary engineering.
A considerable amount of debate, discussion and publication has
been devoted to these subjects, but, at least in the case of
ecopoiesis, there has been very little, if any, experimental
research. The speakers in this session address, in order, issues
of planetary environments and habitability with reference to
Earth analogues, the role of extremophiles as pioneer organisms
in ecopoiesis, and the concept of succession

Diffusion of aluminium in MgO from first principles

by Michael Ammann

Chlorate salts and solutions on Mars

by Jennifer Hanley

published in Geophysical Research Letters, April 2012

Chlorate (ClO3−) is an intermediate oxidation species between chloride (Cl−) and perchlorate (ClO4−), both of which... more Chlorate (ClO3−) is an intermediate oxidation species between chloride (Cl−) and perchlorate (ClO4−), both of which were found at the Phoenix landing site by the Wet Chemistry Lab (WCL). The chlorate ion is almost as stable as perchlorate, and appears to be associated with perchlorate in most terrestrial reservoirs (e.g. Atacama and Antarctica). It is possible that chlorate contributed to the ion sensor response on the WCL, yet was masked by the strong perchlorate signal. However, very little is known about chlorate salts and their effect on the stability of water. We performed evaporation rate experiments in our Mars simulation chamber, which enabled us to determine the activity of water for various concentrations. From this we constructed solubility diagrams for NaClO3, KClO3, Mg(ClO3)2 and Ca(ClO3)2, and determined the Pitzer parameters for each salt. Chlorate salt eutectic temperatures range from 270 K (KClO3) to 204 K (Mg(ClO3)2). Modeling the addition of chlorate to the initial WCL solutions shows that it precipitates in concentrations comparable to other common salts, such as gypsum and epsomite, and implies that chlorates may play an important role in the wet chemistry on Mars.

A stationary bow shock model for plasmas: the spherical blunt obstacle problem

by Pedro Corona-Romero

Co-authored with J.A. Gonzalez-Esparza. In revision in Advances in Space Research.

We present an analytic model of stationary bow shock which describes the interaction between a supermagnetosonic... more We present an analytic model of stationary bow shock which describes the interaction between a supermagnetosonic ambient wind and an obstacle with spherical-like frontal shape. We develop expressions for the bow shocks geometry and the physical properties of the plasma sheath as functions of the upstream conditions. The model allows to use any value of the upstream Mach number and the polytropic index. The solution is limited to axisymmetric magnetic fields. The model points out the influence of the politropic index for the magnetosheath compression and the sbow shock shape. If the Mach number is small the upstream magnetic field orientation can affect the bow shock shape. We compare our results with other models and with in-situ data. By comparing our solution with observational data point we find a reasonable qualitative agreement; however, it seems that our model underestimates the magnetosheath size.

Accretion Outbursts in Circumplanetary Disks

by Rebecca G. Martin

S. H. Lubow, R. G. Martin, 2012, ApJL, accepted

We describe a model for the long term evolution of a circumplanetary disk that is fed mass from a circumstellar disk... more We describe a model for the long term evolution of a circumplanetary disk that is fed mass from a circumstellar disk and contains regions of low turbulence (dead zones). We show that such disks can be subject to accretion driven outbursts, analogous to outbursts previously modeled in the context of circumstellar disks to explain FU Ori phenomena. Circumplanetary disks around a proto-Jupiter can undergo outbursts for infall accretion rates onto the disks in the range ~10^{-9} to 10^{-7} M_sun/yr, typical of accretion rates in the T Tauri phase. During outbursts, the accretion rate and disk luminosity increases by several orders of magnitude. Most of the planet mass growth during planetary gas accretion may occur via disk outbursts involving gas that is considerably hotter than predicted by steady state models. For low infall accretion rates less than ~10^{-10} M_sun/yr that occur in late stages of disk accretion, disk outbursts are unlikely to occur, even if dead zones are present. Such conditions are favorable for the formation of icy satellites.

Robotic Lake Lander Test Bed for Autonomous Surface and Subsurface Exploration of Titan Lakes

by Ramaprasad Kulkarni

"Co-authored with Wolfgang Fink, Markus Tuller, Alexander Jacobs, Mark Tarbell, R Furfaro, V R Baker","published in 'IEEE Aerospace Proceedings',2012"

We introduce a robotic lake lander test bed that can be operated either stand-alone or as part of a Tier-Scalable... more We introduce a robotic lake lander test bed that can be operated either stand-alone or as part of a Tier-Scalable Reconnaissance mission architecture to study and field test an integrated hardware and software framework for fully autonomous surface and subsurface exploration and navigation of liquid bodies. The lake lander is equipped with both surface and subsurface sensor technologies. Our particular focus is on Saturn's moon Titan with its hydrocarbon lakes with respect to future missions involving lake landers (e.g., Titan Mare Explorer (TiME) mission), potentially in conjunction with balloons/airships and orbiter-support overhead. This test bed serves as an analog to a Titan unpiloted surface vessel equipped with its own onboard realtime navigation and hazard avoidance system, surface and subsurface exploration sensor suite, and autonomous science investigation software system. As such the test bed helps map out a technical path toward true autonomy for the robotic exploration of the Solar System.

Quo Vadis, Modern Man?

by Dario Abram

Searching for Pedogenic Phyllosilicates in Ancient Soils on Mars

by Briony Horgan

Presented at the 2011 AGU Fall Meeting

On Earth, vast deposits rich in phyllosilicates are commonly created during soil formation, or pedogenesis. When soils... more On Earth, vast deposits rich in phyllosilicates are commonly created during soil formation, or pedogenesis. When soils are preserved in the stratigraphic record as paleosols, they become valuable resources for terrestrial geologists because paleosol isotopes, mineralogy, and chemical weathering profiles can be used to reconstruct ancient surface environments and to provide quantitative constraints on regional paleo-climate. Thus, paleosol sequences developed in sedimentary settings can record millions of years of surface and climatic evolution. Ancient paleosols on Earth also have excellent organic and biosignature preservation potential, and therefore harbor some of the oldest known (2-3 Ga) non-marine organics, biosignatures, and fossils.

On Mars, pedogenesis in the ancient past may be responsible for some of the phyllosilicate-bearing units observed today, especially for regionally extensive deposits and those in clear sedimentary settings (e.g., Arabia Terra/Mawrth Vallis, Gale Crater, Noctis Labyrinthus). Many of these possibly pedogenic deposits exhibit compositional layering (e.g., interbedded kaolinites, smectites, and sulfates), which may have formed due to episodic sediment deposition under changing environmental conditions. Such deposits represent excellent targets for in situ investigation, as finding and characterizing paleosols on Mars would allow us to place constraints on the extent and duration of past surface and near-surface habitability, and may even provide preserved samples of ancient martian organics.

We are currently investigating a broad range of methods for identifying and characterizing paleosols on Mars from orbit and in situ with Mars Science Laboratory, based on analysis of phyllosilicate-rich (30-95 wt.%) Eocene-Oligocene paleosols in the Painted Hills of the John Day Fossil Beds National Monument in Eastern Oregon. These paleosols were formed under a wide range of environmental conditions, and include highly weathered soils rich in well-crystalline oxides and kaolinites, moderately weathered soils rich in smectites, and minimally weathered soils rich in poorly-crystalline allophanes and ferrihydrite.

Here we present (1) an overview of the climatic regimes that lead to the pedogenesis of specific phyllosilicate minerals, (2) the near and mid-infrared spectral properties and interpreted mineral assemblages of these terrestrial paleosols, and (3) an evaluation of a pedogenic origin for phyllosilicates at several sites on Mars, including those listed above. Preliminary results from near-infrared spectral analysis of our terrestrial paleosols indicate that paleo-environment can be constrained based on mineral assemblages interpreted from spectral properties, including phyllosilicate composition (constrains water availability), the presence of allophane and ferrihydrite (indicating a cool climate), and the strength of oxide absorptions (constrains soil maturity). Mineral assemblages can also be used to detect burial diagenesis by the presence of diagenetic minerals, including celadonite, illite, and hematite (in the presence of phyllosilicates indicating less mature soils). Our results also indicate that poorly crystalline minerals (allophane and ferrihydrite) can be spectrally dominant in these soils even after burial and diagenesis.

Constraints on the location of a putative distant massive body in the Solar System from recent planetary data

by Lorenzo Iorio

L. Iorio, Constraints on the location of a putative distant massive body in the Solar System from recent planetary data, Celestial Mechanics and Dynamical Astronomy, vol. 112, no. 2, pp. 117-130, 2012.

We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a very distant,... more We analytically work out the long-term variations caused on the motion of a planet orbiting a star by a very distant, pointlike massive object X. Apart from the semi-major axis a, all the other Keplerian osculating orbital elements experience long-term variations which are complicated functions of the orbital configurations of both the planet itself and of X. We infer constraints on the minimum distance d X at which X may exist by comparing our prediction of the long-term variation of the longitude of the perihelion to the latest empirical determinations of the corrections to the standard Newtonian/Einsteinian secular precessions of several solar system planets recently estimated by independent teams of astronomers. We obtain the following approximate lower bounds on d X for the assumed masses of X quoted in brackets: 150–200 au (Mars), 250–450 au (07m), 3500–4500 au (4 m Jup).

Analysis and Survival of Amino Acids In Martian Regolith Analogs

by Inge Loes ten Kate

VAPoR–Volatile Analysis by Pyrolysis of Regolith–an instrument for< i> in situ</i> detection of water, noble gases, and organics on the Moon

by Inge Loes ten Kate

Organics on Mars?

by Inge Loes ten Kate

Development of an evolved gas-time-of-flight mass spectrometer for the Volatile Analysis by Pyrolysis of Regolith (VAPoR) instrument

by Inge Loes ten Kate

The geometry of volcano flank terraces on Mars

by Paul Byrne

A volcanotectonic survey of Ascraeus Mons, Mars

by Paul Byrne

Search for eternally sunlit areas at the lunar South Pole from recent data: new indications found

by Michiel Kruijff

This paper details the identification of the exact location of the Peaks of Eternal Light on the Lunar South Pole, in the late 90s following the Clementine mission.

IAF-98-Q.4.07
Jeroen F. de Weerd, Michiel Kruijff, Wubbo J. Ockels.

Recent lunar missions have revealed areas near the lunar South Pole that are lit for a very large fraction of time.... more Recent lunar missions have revealed areas near the lunar South Pole that are lit for a very large fraction of time. These Peaks of Eternal Light (PEL) were found to be close to permanently shaded craters containing large quantities of water ice. The combination of these features makes the lunar South Pole a primary option for an early lunar base, a benign place, where the abundance of solar energy can convert the ice into valuable fuel for the trip back to Earth or further out into the solar system. However, one encounters practical problems when planning a mission to such an oasis in the cold: the PEL is still hypothetical, its location and size are not precisely known. As a consequence, the practical feasibility of a PEL pinpoint landing is not yet quantified.
The objective of this paper is to pinpoint the Peak of Eternal Light (PEL) on the lunar South Pole and to understand its surroundings. Three techniques were developed by which conclusions can be drawn from relatively little photographic data:
1. The development of a Digital Elevation Map (DEM) from shadow simulation on wax clay, plus the S/W that can be used for assessment of lighting and communication conditions during
orbital, landing and roving activities.
2. The use of Monthly Illumination Spectra (MIS) to identify and characterise the PEL and its surroundings.
3. Landing simulation for mission engineering purpose, based on shadow and reflection simulation on a fractal enhanced DEM model.
The results of the work reported in this paper can be applied to future precursor missions to a human lunar outpost. It was performed in the framework of ESA’s LEDA and Euromoon 2000 studies.
Processing of all relevant Clementine satellite images as well as a detailed radar picture from the Arecibo telescope resulted in the identification of two 'mountain tops' that most likely habitat a 'Peak of Eternal Light'. One 'mountain top' is located at the
crossing of the western rim of crater Shackleton and a small 3 km diameter crater. The second 'mountain top' is located about 8 kilometres west of the rim of Shackleton.
Consistency is shown with the expected characteristics of a PEL. Implications for engineering are discussed.

Spuren einer kosmischen Katastrophe - Ein Einschlag vor 200 Millionen Jahren in Westeuropa

by Martin Schmieder

Sterne und Weltraum 01/2012, supplementary 'Plus' article. Co-authored with Elmar Buchner, Mario Trieloff, Winfried Schwarz, and Tilmann Althaus.

Im Westen Frankreichs in der Umgebung des Städtchens Rochechouart befindet sich eine ungewöhnliche geologische... more Im Westen Frankreichs in der Umgebung des Städtchens Rochechouart befindet sich eine ungewöhnliche geologische Struktur – ein rund 50 Kilometer großer Einschlagkrater, der sich nur noch an seinen besonderen Gesteinen erkennen lässt. Einem Forscherteam gelang nun eine neue Datierung des Einschlagzeitpunkts.

THE PEAKS OF ETERNAL LIGHT ON THE LUNAR SOUTH POLE, How they were found and what they look like

by Michiel Kruijff

6-page summary of full IAF paper, for ESA/ESTEC.

This paper summarizes the search for the Peaks of Eternal Light (PELs) on the lunar South Pole. Already predicted in... more This paper summarizes the search for the Peaks of Eternal Light (PELs) on the lunar South Pole. Already predicted in the 19th century, the question of existence of such peaks has revived after the Clementine and Lunar Prospector missions and detailed ground based radar imagery. These peaks can be considered primary targets for future robotic or manned missions. For the first time now, a detailed analysis has been made of the existence, whereabouts and characteristics of these peaks. Also
tools have been developed to analyse the surface and slopes of the polar areas at pixel-level based on orbital imagery. Mission planners of the arising multitude of (commercial) lunar or Mercury missions can use this information and these tools to derive engineering implications.

Circumplanetary Discs: Truncation and Outbursts

by Rebecca G. Martin

Martin R. G., Lubow S. H., 2011
Poster at "Extreme Solar Systems II", Jackson Hole, WY, USA, September 2011

After a planet with a mass greater than that of Nepture forms it opens a gap in the circumstellar disc. Material... more After a planet with a mass greater than that of Nepture forms it opens a gap in the circumstellar disc. Material continues to flow on to the planet and a circumplanetary disc forms. We model circumplanetary discs as accretion discs subject to the tidal forces of the central star. The tidal torques remove the disc angular momentum near the disc outer edge and permit the accreting disc gas to lose angular momentum at the rate appropriate for steady accretion. Circumplanetary discs are truncated near the radius where periodic ballistic orbits cross, where tidal forces on the disc are strong. This radius occurs at approximately 0.4 times the planet Hill radius. During the T Tauri stage of disc accretion, the disc is fairly thick with aspect ratio H/r>0.2. We model the disc structure using one-dimensional time-dependent and steady-state models and also two-dimensional SPH simulations. The circumplanetary disc structure depends on the variation of the disc turbulent viscosity with radius and is insensitive to the angular distribution of the accreting gas. If the disc is turbulent throughout, the predicted disc structure near the location of the regular Jovian and Saturnian satellites is smooth with no obvious feature that would favor formation at their current locations. Dead zones form in accretion discs where the temperature is too low for the disc to be fully thermally ionised. They are even more favorable in circumplanetary discs than in circumstellar discs because the surface densities are high while the temperature remains low enough to avoid thermal ionisation. We consider the conditions under which dead zones form and the resulting unsteady accretion on to the planet. Outbursts in the accretion rate on to the planet have observational implications for planet detection.

Truncation of Circumplanetary Discs by Tidal Torques

by Rebecca G. Martin

Martin R. G, & Lubow S. H
Poster at 217th AAS Meeting, Seattle, January 2011

We model circumplanetary discs as accretion discs subject to the tidal forces of the central star. The tidal torques... more We model circumplanetary discs as accretion discs subject to the tidal forces of the central star. The tidal torques remove the disc angular momentum near the disc outer edge and permit the accreting disc gas to lose angular momentum at the rate appropriate for steady accretion. Circumplanetary discs are truncated near the radius where periodic ballistic orbits cross, where tidal forces on the disc are strong. This radius occurs at approximately 0.4 times the planet Hill radius. During the T Tauri stage of disc accretion, the disc is fairly thick with aspect ratio H/r>0.2. We model the disc structure using one-dimensional time-dependent and steady-state models and also two-dimensional SPH simulations. The circumplanetary disc structure depends on the variation of the disc turbulent viscosity with radius and is insensitive to the angular distribution of the accreting gas. If the disc is turbulent throughout, the predicted disc structure near the location of the regular Jovian and Saturnian satellites is smooth with no obvious feature that would favor formation at their current locations.