Jun 19, 2019 | Updated: 09:31 AM EDT

Defending the Earth from Asteroids

Apr 17, 2019 09:19 AM EDT

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Defending the Earth from Asteroids
(Photo : NASA)

In February 2013, the Chelyabinsk meteor, a mere 17-20 meters across, caused extensive ground damage and several injuries when it exploded on impact with the atmosphere of the Earth.

In a bid to avert such impact, Amy Mainzer and colleagues utilized an ingenious yet straightforward way to spot these tiny near-Earth objects (NEOs) as they hurtle toward the planet. As the principal investigator of NASA's asteroid-hunting mission at the Jet Propulsion Laboratory in Pasadena, California, Amy will make a presentation to outline the work of NASA's Planetary Defense Coordination Office this week at the American Physical Society in Denver. Also, she will talk about her team's recognition technique of NEO and how it will help the efforts to prevent future Earth impacts.

Mainzer said that if she finds an object only a few days from impact, it considerably limits their choices. In their search efforts, they have focused on finding NEOs when they are further away from Earth, granting the maximum amount of time and opening up a more extensive range of mitigation possibilities.

She explained further that it is a difficult task, typical of spotting a lump of coal in the night's sky. NEOs are intrinsically faint because they are mostly small and far away from us in space. In addition to this fact is that some of them are as dark as printer toner, and trying to spot them against the black space is quite hard.

Against the use of visible light to spot incoming objects, Mainzer's team at JPL/Caltech has leveraged a unique signature of NEOs which is their heat. The sun heats comets and asteroids, and they shine brilliantly at infrared, thermal wavelengths, making them easier to spot with the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope.

She said further that with the NEOWISE mission, they would have the capability of spotting objects regardless of their surface color and use it to measure their sizes and other surface properties.

When Mainzer and colleagues discovered NEO surface properties, they had the provision of having an insight into how big the objects are and what they are made of in terms of both significant points to mount a defensive policy against an Earth-threatening NEO.

The example of one defensive strategy is through a physical 'nudge' of a NEO from an Earth impact trajectory. But to calculate the energy needed for that nudge, details of NEO mass, and therefore size and composition, are all necessary.

Mainzer is now eager to leverage advances in camera technology to aid in the search for NEOs. She added that they are proposing to NASA a new telescope, the Near-Earth Camera (NEOCam), to do a much more thorough job of mapping asteroids and measuring their sizes.

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