Earth lives in the middle of a shooting gallery. We are surrounded by thousands of asteroids that whiz close to our planet. While we don’t know of an imminent threat to humanity as of now, history shows that eventually, something big will hit us. Just ask the dinosaurs.
By Elizabeth Howell | MOTHERBOARD
On September 8, if all goes according to plan, an SUV-sized spacecraft will blast off on its mission to a potentially hazardous nearby asteroid called Bennu. One important goal of OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is to help scientists better predict the path of these small, rocky bodies as they careen through the solar system.
The NASA-led mission, which includes participation from the Canadian Space Agency, will stay at Bennu for two years, mapping its shape and size, and scooping a sample from the surface to return to Earth in 2023. For asteroid defense purposes, scientists will watch how solar heating affects the asteroid’s movements through a phenomenon called the Yarkovsky effect. “The asteroid absorbs the heat and it re-radiates that heat, which gives a subtle push to its orbit,” said Lindley Johnson, NASA’s planetary defense officer, in an interview with Motherboard. “Over time, especially for smaller asteroids, it changes the orbit subtly.”
Scientists have tracked Bennu’s Yarkovsky effect since 1999, when the Arecibo Observatory in Puerto Rico took measurements using radio wavelengths. Those measurements were repeated in 2005 and 2011, said mission principal investigator Dante Lauretta at a televised NASA press conference Aug. 17.