The Influence of Reactive Torques on Comet Nucleus Rotation

Reactive torques, due to anisotropic sublimation on a comet nucleus surface, produce slow variations of its rotation. In this paper the secular effects of this sublimation are studied. The general rotational equations of motion are averaged over unperturbed fast rotation around the mass center (Euler-Poinsot motion) and over the orbital comet motion. We discuss the parameters that define typical properties of the rotational evolution and discover different classifications of the rotational evolution. As an example we discuss some possible scenarios of rotational evolution for the nuclei of the comets Halley and Borrelly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42565/1/10569_2004_Article_5114381.pd

A mission control architecture for robotic lunar sample return as field tested in an analogue deployment to the Sudbury impact structure

A Mission Control Architecture is presented for a Robotic Lunar Sample Return Mission which builds upon the experience of the landed missions of the NASA Mars Exploration Program. This architecture consists of four separate processes working in parallel at Mission Control and achieving buy-in for plans sequentially instead of simultaneously from all members of the team. These four processes were: Science Processing, Science Interpretation, Planning and Mission Evaluation. Science Processing was responsible for creating products from data downlinked from the field and is organized by instrument. Science Interpretation was responsible for determining whether or not science goals are being met and what measurements need to be taken to satisfy these goals. The Planning process, responsible for scheduling and sequencing observations, and the Evaluation process that fostered inter-process communications, reporting and documentation assisted these processes. This organization is advantageous for its flexibility as shown by the ability of the structure to produce plans for the rover every two hours, for the rapidity with which Mission Control team members may be trained and for the relatively small size of each individual team. This architecture was tested in an analogue mission to the Sudbury impact structure from June 6-17, 2011. A rover was used which was capable of developing a network of locations that could be revisited using a teach and repeat method. This allowed the science team to process several different outcrops in parallel, downselecting at each stage to ensure that the samples selected for caching were the most representative of the site. Over the course of 10 days, 18 rock samples were collected from 5 different outcrops, 182 individual field activities - such as roving or acquiring an image mosaic or other data product - were completed within 43 command cycles, and the rover travelled over 2,200 m. Data transfer from communications passes were filled to 74%. Sample triage was simulated to allow down-selection to 1kg of material for return to Earth

Data for: Identification of the Apollo 12 Lunar Module Ascent Stage impact site on the Moon

M122353240LC-crop-flip-contrast.png is part of LROC NAC image M122353240LC which has been cropped, flipped in the vertical direction to place north near the top, and contrast-stretched. It has been extended on the western (left) side to create space for part of the mapped data which falls just outside the image.M122353240LC-map-overlay.png is the same image as M122353240LC-crop-flip-contrast.png with an overlay showing dark streaks apparently associated with the Apollo 12 Lunar Module Ascent Stage impact. The streaks were visually identified on a contrast-enhanced version of the image and on versions processed by merging with an image having opposite illumination as described in the text. A small extension of the streak map outside the area of image M122353240LC was added by registering adjacent images to the geometry of M122353240LC, not shown here

Data for: Identification of the Apollo 12 Lunar Module Ascent Stage impact site on the Moon

This image was produced by merging parts of two LROC NAC images, M129431676LC and M122353240RC, which show the linear field of streaks we describe in the paper. The images have approximately opposite illumination (morning and afternoon) so shadows and highlights caused by topography roughly cancel each other and albedo variations are enhanced. The contrast was then greatly enhanced to emphasize the pattern of streaks. The putative impact site is visible at the right edge. North is approximately at the top in this image, which may be compared with Figure 1 for location and orientation. Figure 1C is a crop of a small atrea of this image. The topographic shading does not cancel exactly so craters are still visible, allowing this image to be georeferenced if desired. As presented the image is not georeferenced

Data for: Identification of the Apollo 12 Lunar Module Ascent Stage impact site on the Moon

M122353240LC-crop-flip-contrast.png is part of LROC NAC image M122353240LC which has been cropped, flipped in the vertical direction to place north near the top, and contrast-stretched. It has been extended on the western (left) side to create space for part of the mapped data which falls just outside the image.M122353240LC-map-overlay.png is the same image as M122353240LC-crop-flip-contrast.png with an overlay showing dark streaks apparently associated with the Apollo 12 Lunar Module Ascent Stage impact. The streaks were visually identified on a contrast-enhanced version of the image and on versions processed by merging with an image having opposite illumination as described in the text. A small extension of the streak map outside the area of image M122353240LC was added by registering adjacent images to the geometry of M122353240LC, not shown here.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Data for: Identification of the Apollo 12 Lunar Module Ascent Stage impact site on the Moon

This image was produced by merging parts of two LROC NAC images, M129431676LC and M122353240RC, which show the linear field of streaks we describe in the paper. The images have approximately opposite illumination (morning and afternoon) so shadows and highlights caused by topography roughly cancel each other and albedo variations are enhanced. The contrast was then greatly enhanced to emphasize the pattern of streaks. The putative impact site is visible at the right edge. North is approximately at the top in this image, which may be compared with Figure 1 for location and orientation. Figure 1C is a crop of a small atrea of this image. The topographic shading does not cancel exactly so craters are still visible, allowing this image to be georeferenced if desired. As presented the image is not georeferenced.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2003

Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the north poles of rotation and the prime meridians of the planets, satellites, and asteroids. This report introduces a system of cartographic coordinates for asteroids and comets. A topographic reference surface for Mars is recommended. Tables for the rotational elements of the planets and satellites and size and shape of the planets and satellites are not included, since there were no changes to the values. They are available in the previous report (Celest. Mech. Dyn. Astron., 82, 83–110, 2002), a version of which is also available on a web site