NASA plans to launch a new mission in 2016 to find potentially hazardous asteroids and predict their impact threat to Earth.

NASA’s OSIRIS-REx asteroid sample return mission will arrive at RQ36 in 2018 and orbit the asteroid until 2021. By communicating continuously with a spacecraft in orbit around RQ36, the team will get a much better idea of the asteroid’s orbit.

“We expect OSIRIS-REx will enable us to make an estimate of the Yarkovsky force on RQ36 at least twice as precise as what’s available now,” says Jason Dworkin, OSIRIS-REx project scientist at NASA’s Goddard Space Flight Center in Greenbelt.

The Yarkovsky effect happens simply because it takes time for things to heat up and cool down. Objects tend to be coldest just before dawn and warmest at mid-afternoon, after hours of illumination by the high Sun.

The team will use what it learns about the Yarkovsky effect on RQ36 to help estimate the effects on other asteroids, NASA said in a statement.

The key to all these strategies is to discover the asteroid well in advance of its impact date and attempt to deflect it early, according to Edward Beshore of the University of Arizona, Tucson, deputy principal investigator for OSIRIS-REx asteroid sample return mission.

One of the first things that would be done if an asteroid appeared to be on a collision course with Earth is to send a probe to the asteroid that might look very much like OSIRIS-REx, said Beshore.

OSIRIS-REx will determine if RQ36 is actually a rubble pile by orbiting it and revealing the subtle effects on the orbit from the gravity of any large and dense lumps within the asteroid.

A probe like OSIRIS-REx could map the internal structure of an asteroid this way, providing valuable information on where to target the deflection mechanism.

OSIRIS-REx will also determine the composition of RQ36 using remote measurements from both visible light and infrared spectrometers, and by collecting a sample of material from the asteroid’s surface and returning it to Earth for study.

Since the Yarkovsky effect may vary depending on the type of material and its distribution, a probe with OSIRIS-REx’s capability to map the surface composition will enable a more precise estimate of the effect on the asteroid’s orbit.

The mission will also provide critical experience navigating around asteroids.

According to NASA’s Near-Earth Object (NEO) programme, there are more than 1,300 “Potentially Hazardous Asteroids” (PHAs) — objects at least 150 yards across with a very small chance of impacting us someday because their orbital paths take them close to Earth’s orbit.

(This article was published on February 8, 2013)
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