This area will cover relevant news of the threat to the planet from Near Earth Objects (NEOs) including concepts and designs for mitigation. All opinions are those of the author.
18 August 2011
From the MIT Technology Review article of a new paper from Wolters, et al called "Measurement requirements for a near-Earth asteroid impact mitigation demonstration mission"...
In 2002, the European Space Agency began a program called Don Quijote to find out how best to perform such a deflection. Don Quijote involves sending two spacecraft to a near Earth asteroid; one to smash into it and the other to watch while in orbit above the impact crater. The goal is to change the asteroid's semimajor axis by more than 100 metres and to measure the change with an accuracy greater than 1 per cent. But the question is how best to monitor what's going on in a way that is relevant to other asteroids. After all, the ultimate plan is to use the information from this mission to move some other asteroid with our name on it. Now, Stephen Wolters at the Open University in the UK and a few friends have published a new analysis of the mission saying that measuring the change in orbit is not enough. Instead, the spacecraft needs to characterise the impact in detail, determining the density of the material near the asteroid's surface, the size of the surface grains as well as the mass and speed distribution of the impact ejecta. Only with this information will it be possible to work out exactly how the momentum from the impactor was transferred to the asteroid. That significantly changes the mission. In addition to an on-board radio transmitter that will allow space scientists back on Earth to work out its distance exactly, the spacecraft will need a sophisticated imaging suite capable of photographing the damage and carrying out infrared spectroscopy to determine the asteroid's mineral content.
Measurement requirements for a near-Earth asteroid impact mitigation demonstration mission
Authors: Stephen D. Wolters, Andrew J. Ball, Nigel Wells, Christopher Saunders, Neil McBride (Submitted on 21 Jul 2011)
Abstract: A concept for an Impact Mitigation Preparation Mission, called Don Quijote, is to send two spacecraft to a Near-Earth Asteroid (NEA): an Orbiter and an Impactor. The Impactor collides with the asteroid while the Orbiter measures the resulting change in the asteroid's orbit, by means of a Radio Science Experiment (RSE) carried out before and after impact. Three parallel Phase A studies on Don Quijote were carried out for the European Space Agency: the research presented here reflects outcomes of the study by QinetiQ. We discuss the mission objectives with regards to the prioritisation of payload instruments, with emphasis on the interpretation of the impact. The Radio Science Experiment is described and it is examined how solar radiation pressure may increase the uncertainty in measuring the orbit of the target asteroid. It is determined that to measure the change in orbit accurately a thermal IR spectrometer is mandatory, to measure the Yarkovsky effect. The advantages of having a laser altimeter are discussed. The advantages of a dedicated wide-angle impact camera are discussed and the field-of-view is initially sized through a simple model of the impact.
Cite as: arXiv:1107.4229v1 [astro-ph.IM]
Link: MIT Technology Review Article
Link: Paper (PDF format)
Posted by A.C. Charania at 01:48
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