Finding Hazardous Asteroids Using Infrared and Visible Wavelength Telescopes (2019) / Chapter Skim
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2 The Components of Planetary Defense
2 The Components of Planetary Defense
Pages 14-19
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From page 14... ...
Once a newly detected asteroid moves away from Earth, it quickly becomes dimmer and eventually undetectable until it makes another close pass, perhaps as many as several years or even decades later. In addition to initially detecting an NEO, there are other variables needed to determine the possibility of an asteroid impact and its potential severity.
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From page 15... ...
Astrometric observations measure the course of an asteroid across the sky in order to refine its orbit. Without astrometric observations, the positional uncertainties from insufficiently constrained orbits will quickly grow, impeding future targeted observations and the accurate assessment of impact probabilities.
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From page 16... ...
The population of NEOs has a wide variation in how reflective their surfaces are, which leads to uncertainty in this size-measurement technique. However, the uncertainties are much smaller when the measurements are done using emitted infrared light rather than reflected visible light (the reason for this improved accuracy is that albedo has only a weak effect on the emitted thermal flux)
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From page 17... ...
The measurement of asteroid shapes and rotational properties through brightness variations due to their irregular shapes and rotations also requires a large amount of highly accurate photometric observations over many apparitions. Both properties, combined with accurate thermal-infrared observations, can significantly improve the physical characterization of asteroids and are able to improve bulk density estimates.
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From page 18... ...
Radar observations provide an opportunity to obtain highly accurate astrometric data and shape and rotational information for a small sample of asteroids that come close enough to Earth to be observed with this technique. While this limitation prevents its broader use for asteroid characterization in a large-scale survey, it can be used to understand the range of properties in the overall asteroid population by characterizing individual objects.
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From page 19... ...
The most successful campaign to protect Earth from the consequences of a large impact will involve strong contributions both from scientific study of the solar system and engineering approaches to asteroid discovery and deflection. Pure science will inevitably profit from a robust asteroid detection and defense program, while the proper design of deflection strategies must be informed by the latest scientific discoveries about the nature of asteroids and comets.
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