Posted in MiARD
The dates are fixed, and invitations have been sent out, for the workshop to be held from 15th-19th January by the International Space Science Institute (ISSI) in Bern, Switzerland in conjunction with the MiARD project. The preliminary programme and futher details can be found at http://www.issibern.ch/workshops/post67p/
According to ISSI, the aims of the workshop are:
- To review the progress made on multi-instrument data analysis after Rosetta Mission. This shall include
- Current status of the development of an integrated 3D shape model,
- Current status of the mapping of properties/measurements to surface facets of the 3D model,
- Current status and results from gas dynamics modelling including activity distributions using multiple data sets,
- Current status of dust emission and brightness modelling,
- Current status of analysis of surface physical structure and thermal balance,
- Current understanding of the coma and surface chemical composition,
- Placing the results in the context of other observations of comets.
- To assess and possibly revise current models of nucleus activity (including potential evidence for different mechanisms) and evolution.
- To assess our current understanding of risk from comets (through perturbation of nuclei by non-gravitational forces and particle impact on interplanetary spacecraft) including link to ground-based observations.
- To re-assess the (extensive) study work performed on possible comet nucleus sample return studies and provide guidelines as to how this work should be updated in the light of Rosetta’s results.
A number of papers arising from the workshop (and thus the MiARD project) will be published by Springer in the Space Sciences Series of ISSI, both in journal format and as a hard-cover book. We currently expect publication to take place in early 2019.
Unfortunately, a nearly-full moon will hamper observations of the Perseid meteor shower this year (close to 12th August) and the weather in north-west Europe is also not ideal. If you don’t see any Perseids this year, then you may wish to take a look at the International Meteor Organization’s calendar which lists all expected meteor shows for 2017 with comments as to the likely viewing conditions.
Meteor shows are in general due to dust particles shed by comets as they approached the sun on previous orbits. The Perseids are associated with comet Swift-Tuttle, a 27 km large body which last passed near Earth in 1992 and is not expected again until 2126. We see ‘shooting stars’ because the dust particles are traveling at about 60 km/s relative to the Earth, and this is fast enough that air friction heats the tiny dust particles to white heat in the upper atmosphere, about 90 km above us.
Space.com has posted a video showing early Perseids from this years shower, photographed by a NASA all-sky camera.
Don’t miss MiARD researcher Nicholas Attree from the Laboratoire d’Astrophysique de Marseille on the astrotweeps Twitter channel this week:
Nick works in the MiARD project on determining the physical and mechanical properties of comet 67P. In particular, he uses OSIRIS camera images from the Rosetta mission to analyse surface features, such as overhanging cliffs and fractures, to estimate the mechanical strength of the nucleus material. He also uses navigational and position data to measure the effects of outgassing on the comet’s orbit (an example of ‘non-gravitational forces’ affecting the comet’s orbit). The MiARD project seeks to develop a better model for ‘non-gravitational forces’ in order to be able to make better predictions of comets’ trajectories in future.
Within the MiARD project, the team members at Heriot-Watt University on Scotland are using terrestrial rocks as analogues for the porous material expected at the cometary surface when they carry out numerical simulations of gas flow through such porous material.
The link below is to a file from an X-ray computer tomography or ‘CT’ scan of a porous rock. (On some platforms the file will be viewable in your browser, on others you will have to download the file and use a viewer for .stl files, such as ‘Preview’ on Macintoshes or ‘Meshlab’ on Macintosh, Windows or Linux platforms.). The image is taken from the same file, and shows the extremely high porosity of this rock sample. Estimates of the porosity of the cometary surface vary, but it may be as high as 75%.