Phobos mass determination from the very close flyby of Mars Express in 2010

Pätzold, M.; Andert, T. P.; Tyler, G. L.; Asmar, S. W.; Häusler, B.; Tellmann, S.

doi:10.1016/j.icarus.2013.10.021

Cited by 41 publications

(46 citation statements)

References 16 publications

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“…The knowledge of the gravity field when combined with other bulk parameters, such as shape, volume, bulk density, porosity, and water ice content are key information for models of internal mass distribution, structure, composition, and Deimos/Phobos origins. Using data from X-band radio tracking during recent spacecraft flybys, especially by Mars Express (Andert et al, 2010;Pätzold et al, 2014b;Rosenblatt et al, 2008), the mass of Phobos has been estimated as 1.065 ± 0.016 10 16 kg (Pätzold et al, 2014a). The higher degree and order terms of the gravity fields (e.g., the C 20 and the C 22 terms) of Phobos suffer from large uncertainties (Pätzold et al, 2014b), due to the faint gravity signatures, the high spacecraft flyby speeds and the large flyby distances.…”

Section: Mass and Gravity Fieldmentioning

confidence: 99%

“…Using data from X-band radio tracking during recent spacecraft flybys, especially by Mars Express (Andert et al, 2010;Pätzold et al, 2014b;Rosenblatt et al, 2008), the mass of Phobos has been estimated as 1.065 ± 0.016 10 16 kg (Pätzold et al, 2014a). The higher degree and order terms of the gravity fields (e.g., the C 20 and the C 22 terms) of Phobos suffer from large uncertainties (Pätzold et al, 2014b), due to the faint gravity signatures, the high spacecraft flyby speeds and the large flyby distances. Besides, even though the Phobos ephemeris has improved over the years (Lainey et al, 2007;Jacobson, 2010;Lainey et al, 2016), the Phobos positions relative to the spacecraft during the flybys were poorly known.…”

Section: Mass and Gravity Fieldmentioning

confidence: 99%

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DePhine – The Deimos and Phobos Interior Explorer

Oberst

Wickhusen

Willner

et al. 2018

Advances in Space Research

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DePhine -Deimos and Phobos Interior Explorer -is a mission proposed in the context of ESA's Cosmic Vision program, for launch in 2030. The mission will explore the origin and the evolution of the two Martian satellites, by focusing on their interior structures and diversity, by addressing the following open questions: Are Phobos and Deimos true siblings, originating from the same source and sharing the same formation scenario? Are the satellites rubble piles or solid bodies? Do they possess hidden deposits of water ice in their interiors? The DePhine spacecraft will be inserted into Mars transfer and will initially enter a Deimos quasi-satellite orbit to carry out a comprehensive global mapping. The goal is to obtain physical parameters and remote sensing data for Deimos comparable to data expected to be available for Phobos at the time of the DePhine mission for comparative studies. As a highlight of the mission, close flybys will be performed at low velocities, which will increase data integration times, enhance the signal strength and data resolution. 10 -20 flyby sequences, including polar passes, will result in a dense global grid of observation tracks. The spacecraft orbit will then be changed into a Phobos resonance orbit to carry out multiple close flybys and to perform similar remote sensing as for Deimos. The spacecraft will carry a suite of remote sensing instruments, including a camera system, a radio science experiment, a high-frequency radar, a magnetometer, and a Gamma Ray / Neutron Detector. A steerable antenna will allow simultaneous radio tracking and remote sensing observations (which is technically not possible for Mars Express). Additional instrumentation, e.g. a dust detector and a solar wind sensor, will address ---further science goals of the mission. If Ariane 6-2 and higher lift performance are available for launch (the baseline mission assumes a launch on a Soyuz Fregat), we expect to have greater spacecraft mobility and possibly added payloads.

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Section: Mass and Gravity Fieldmentioning

confidence: 99%

Section: Mass and Gravity Fieldmentioning

confidence: 99%

DePhine – The Deimos and Phobos Interior Explorer

Oberst

Wickhusen

Willner

et al. 2018

Advances in Space Research

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“…We use a 100 m resolution Digital Terrain Model [ Willner et al , ], which was computed using HRSC image data from 20 flybys applying photogrammetric stereo techniques. The latest bulk density value of 1.862 g cm −3 [ Pätzold et al , ; Willner et al , ] was used. The other two contributions to surface acceleration are connected to the orbital evolution of Phobos.…”

Section: Orbital Evolution and Changes In Dynamical Environmentmentioning

confidence: 99%

“…While the satellite is currently moving in a near‐circular orbit at a distance of only 2.76 Mars radii from Mars center, it is expected to disrupt within timescales of 20–50 Ma [ Burns , ; Bills et al , ; Black and Mittal , ]. With its small dimension of 13.03 × 11.4 × 9.14 km [ Willner et al , ] and low bulk density of 1.862 g cm −3 [ Pätzold et al , ], the self‐gravitation of Phobos is relatively weak. In contrast, its extreme proximity to Mars near the Roche limit and its fast synchronous rotation are associated with considerable tidal and centrifugal forces [ Dobrovolskis and Burns , ; Bills et al , ].…”

Section: Introductionmentioning

confidence: 99%

Mass wasting on Phobos triggered by an evolving tidal environment

Shi

Oberst

Willner

2016

Geophysical Research Letters

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The Martian moon Phobos is experiencing orbital decay, increasing tidal forces, and possible disruption in the near future. We suggest that this changing dynamic tidal environment has contributed to resurfacing of the odd‐shaped small moon. We investigated mass wasting features in craters using high‐resolution images acquired by the Mars Express on board High‐Resolution Stereo Camera. We model the evolving dynamical environment of Phobos by reconstructing dynamic slopes on its surface with Phobos at different distances to Mars. We note that the increase in slope by tidal effect correlates with most of the observed landslides, which is particularly obvious for craters near the sub‐Mars and anti‐Mars points. We suggest that the effect has triggered mass displacements that are responsible for observed asymmetries of some craters. The most recent landslides are likely to be geologically young and occurred within the past few hundred million years.

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“…A similar estimate was made for a disk clump in T Cha, for which Schisano et al (2009) report a clump mass M cl ≈ 4 × 10 20 g. However, their calculation was based on optical extinction (A V ) and an assumed N H to A V relationship. For comparison, the mass of the Martian moon Phobos is 1.06 × 10 19 g (Pätzold et al 2014).…”

Section: Relationship Between Atomic and Optical Extinctionmentioning

confidence: 99%

Evidence for variable, correlated X-ray and optical/IR extinction towards the nearby, pre-main-sequence binary TWA 30

Principe

Sacco

Kastner

et al. 2016

Mon. Not. R. Astron. Soc.

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We present contemporaneous XMM-Newton X-ray and ground-based optical/near-IR spectroscopic observations of the nearby (D ≈ 42 pc), low-mass (mid-M) binary system TWA 30A and 30B. The components of this wide (separation ∼3400 AU) binary are notable for their nearly edge-on disk viewing geometries, high levels of variability, and evidence for collimated stellar outflows. We obtained XMM-Newton X-ray observations of TWA 30A and 30B in 2011 June and July, accompanied (respectively) by IRTF SpeX (near-IR) and VLT XSHOOTER (visible/near-IR) spectroscopy obtained within ∼20 hours of the X-ray observations. TWA 30A was detected in both XMM-Newton observations at relatively faint intrinsic X-ray luminosities (L X ∼8 × 10 27 erg s −1 ) compared to stars of similar mass and age . The intrinsic (0.15-2.0 keV) X-ray luminosities measured in 2011 had decreased by a factor 20-100 relative to a 1990 (ROSAT) X-ray detection. TWA 30B was not detected, and we infer an upper limit of (L X 3.0 × 10 27 erg s −1 ). We measured a large change in visual extinction toward TWA 30A (from A V ≈ 14.9 to A V ≈ 4.7) between the two 2011 observing epochs, and we find evidence for a corresponding significant decrease in X-ray absorbing column (N H ). The apparent correlated change in A V and N H is suggestive of variable obscuration of the stellar photosphere by disk material composed of both gas and dust. However, in both observations, the inferred N H to A V ratio is lower than that typical of the ISM, suggesting that the disk is either depleted of gas or is deficient in metals in the gas phase.

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Phobos mass determination from the very close flyby of Mars Express in 2010

Cited by 41 publications

References 16 publications

DePhine – The Deimos and Phobos Interior Explorer

DePhine – The Deimos and Phobos Interior Explorer

Mass wasting on Phobos triggered by an evolving tidal environment

Evidence for variable, correlated X-ray and optical/IR extinction towards the nearby, pre-main-sequence binary TWA 30

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