Nicholas Attree

Nicholas Attree
Technische Universität Braunschweig · Institute for Geophysics and Extraterrestrial Physics

PhD

About

30
Publications
2,507
Reads
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270
Citations
Citations since 2017
24 Research Items
246 Citations
2017201820192020202120222023010203040506070
2017201820192020202120222023010203040506070
2017201820192020202120222023010203040506070
2017201820192020202120222023010203040506070
Additional affiliations
June 2010 - September 2010
University of Leicester
Position
  • Summer Research Project

Publications

Publications (30)
Preprint
Full-text available
Aims. Understanding the activity is vital for deciphering the structure, formation, and evolution of comets. We investigate models of cometary activity by comparing them to the dynamics of 67P/Churyumov-Gerasimenko. Methods. We matched simple thermal models of water activity to the combined Rosetta datasets by fitting to the total outgassing rate a...
Article
Full-text available
We use the Martian surface temperature response to Phobos transits observed next to the InSight lander in Elysium Planitia to constrain the thermal properties of the uppermost layer of regolith. Modeled transit lightcurves validated by solar panel current measurements are used to modify the boundary conditions of a 1D heat conduction model. We test...
Article
Full-text available
Martian araneiform terrain, located in the Southern polar regions, consists of features with central pits and radial troughs which are thought to be associated with the solid state greenhouse effect under a CO2 ice sheet. Sublimation at the base of this ice leads to gas buildup, fracturing of the ice and the flow of gas and entrained regolith out o...
Preprint
Full-text available
Martian araneiform terrain, located in the Southern polar regions, consists of features with central pits and radial troughs which are thought to be associated with the solid state greenhouse effect under a CO$_{2}$ ice sheet. Sublimation at the base of this ice leads to gas buildup, fracturing of the ice and the flow of gas and entrained regolith...
Article
Full-text available
Although ice fracturing and deformation is key to understanding some of the landforms encountered in the high‐latitude regions on Mars and on other icy bodies in the solar system, little is known about the mechanical characteristics of CO 2 ice. We have measured the hardness of solid CO 2 ice directly in the laboratory with a Leeb hardness tester a...
Article
Full-text available
Nongravitational forces induced by sublimation of volatiles affect the rotational and orbital dynamics of comets. In addition to contributing to the improvement of ephemerides and of rotational models, nongravitational effects can help constrain the regional distribution and temporal evolution of cometary activity, which in turn provides input for...
Conference Paper
Full-text available
Mars surface temperature response to insolation variations constrains soil properties and indicates layering consistent with cementation at depth.
Preprint
Heat flow is an important constraint on planetary formation and evolution. It has been suggested that Martian obliquity cycles might cause periodic collapses in atmospheric pressure, leading to corresponding decreases in regolith thermal conductivity (which is controlled by gas in the pore spaces). Geothermal heat would then build up in the subsurf...
Article
Full-text available
Heat flow is an important constraint on planetary formation and evolution. It has been suggested that Martian obliquity cycles might cause periodic collapses in atmospheric pressure, leading to corresponding decreases in regolith thermal conductivity (which is controlled by gas in the pore spaces). Geothermal heat would then build up in the subsurf...
Article
Full-text available
Correction to: Space Sci. Rev. (2019) 215: 2910.1007/s11214-019-0594-x The article The Thermal, Mechanical, Structural, and Dielectric Properties of Cometary Nuclei After Rosetta, written by Groussin et al., was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 2 May 2019 without open access. With th...
Article
Full-text available
The physical properties of cometary nuclei observed today relate to their complex history and help to constrain their formation and evolution. In this article, we review some of the main physical properties of cometary nuclei and focus in particular on the thermal, mechanical, structural and dielectric properties, emphasising the progress made duri...
Article
Full-text available
Short: The shape and internal structure of bilobate comet 67P is controlled by shear deformation inducing mechanically driven erosion along shear fracture networks, according to a 3D analysis of images from the Rosetta mission. Long: Bilobate comets—small icy bodies with two distinct lobes—are a common configuration among comets, but the factors s...
Article
Full-text available
Aims. We investigate the influence of three basic factors on water production rate as a function of heliocentric distance: nucleus shape, the spin axis orientation, and the distribution of activity on a comet’s surface. Methods. We used a basic water sublimation model driven by solar insolation to derive total production rates for different nuclei...
Article
Aims. We use four observational data sets, mainly from the Rosetta mission, to constrain the activity pattern of the nucleus of comet 67P/Churyumov-Gerasimenko (67P). Methods. We developed a numerical model that computes the production rate and non-gravitational acceleration of the nucleus of comet 67P as a function of time, taking into account its...
Preprint
Aims. We use four observational data sets, mainly from the Rosetta mission, to constrain the activity pattern of the nucleus of comet 67P/Churyumov-Gerasimenko. Methods. We develop a numerical model that computes the production rate and non-gravitational acceleration of the nucleus of comet 67P as a function of time, taking into account its complex...
Article
Full-text available
12 pages, 17 figures. Accepted for publication in forthcoming Rosetta issue of Astronomy and Astrophysics
Article
Full-text available
We directly measure twenty overhanging cliffs on the surface of comet 67P/Churyumov-Gerasimenko extracted from the latest shape model and estimate the minimum tensile strengths needed to support them against collapse under the comet's gravity. We find extremely low strengths of around one Pa or less (one to five Pa, when scaled to a metre length)....
Article
Full-text available
We simulate the stresses induced by temperature changes in a putative hard layer near the surface of comet 67P/Churyumov--Gerasimenko with a thermo-viscoelastic model. Such a layer could be formed by the recondensation or sintering of water ice (and dust grains), as suggested by laboratory experiments and computer simulations, and would explain the...
Article
Small (~50km scale), irregular features seen in Cassini images to be emanating from Saturn's F ring have been termed mini-jets by Attree et al. (2012). One particular mini-jet was tracked over half an orbital period, revealing its evolution with time and suggesting a collision with a local moonlet as its origin. In addition to these data we present...
Article
Full-text available
Jets of material extending several hundred kilometers from Saturn's F ring are thought to be caused by collisions at speeds of several tens of ms–1 between ~10 km diameter objects such as S/2004 S 6 and the core of the ring. The subsequent effects of Keplerian shear give rise to the multi-stranded nature of the F ring. Observations of the ring by t...
Article
The unusual nature of Saturn's F ring can be understood by considering the combined effects of gravity and collisional encounters. Gravitational perturbations from Prometheus and Pandora orbiting on either side of the ring produce the regular, streamer-channel phenomenon and also trigger the formation of clumps in the ring. There is also evidence f...
Article
In stark contrast to the ordered regularity of the planet's main rings, Cassini images of Saturn's F ring show a diversity of structures on a variety of scales. The ring is located ~3000km beyond the edge of the A ring and Cassini ISS images reveal a core (radial width ~50km) with localised radial distortions (~50km), as well as occasional spiral s...

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Projects

Project (1)
Project
An H2020 research project to make use of the data from the completed ROSETTA mission to comet 67P/Churyumov-Gerasimenko, in particular to better understand the history, activity and composition of the comet. See http://www.miard.eu