NASA Will Map An Asteroid With X-Rays

The OSIRIS-REx spacecraft from NASA is all ready to be launched in September 2016 and make a journey to the asteroid Bennu near Earth, where it will take a sample of the surface and return with it to Earth for further observation. However, even before a sample site on the asteroid is selected for harvest prospects, scientists will be able to know the elemental make-up of Bennu. The feat will be made possible by an instrument onboard the spacecraft that will pinpoint the elements found on the asteroid and in what quantity.

Called, Rexis or The Regolith X-ray Imaging Spectrometer, the instrument can reportedly capture X-ray emission from Bennu and create an elemental abundance map of the asteroid's surface. "REXIS is different from the other imaging instruments on OSIRIS-REx because we're going to determine what Bennu is made of at the level of individual atomic elements," said Richard Binzel, principal investigator of REXIS. "We're sniffing the atoms on the surface of Bennu".

The REXIS will get the added assistance of the sun to make its mission successful. The surface atoms on Bennu absorb the X-rays coming in from the sun that are emitted along with the solar wind. The process makes the atomic electrons shift to a higher energy level, however for a short duration as the electrons are in an excited state and henceforth unstable, therefore they fall back to their original level of energy and give out their own X-ray. The whole procedure is called fluorescence, and it makes the surface of Bennu glow, which in turn will help researchers decode which elements are present on the asteroid.

Incidentally, REXIS has a coded aperture mask which will help in mapping the emitted X-rays by creating a shadow design on REXIS' detector. To explain in simpler terms, if a car passes by when you are sitting in your bedroom, there will be a pattern formed with the light and shadows of the headlight on your wall. Moreover, the shadows and their associated patterns will move when the car makes a movement. Similarly, REXIS will move over Bennu's surface and the change in the shadow patterns will help the researching team to point out the bright spots of the asteroids which could indicate its abundance of certain elements.