Don't Panic, Asteroid Bennu Won't Destroy the Earth

Tuesday, 02 August 2016 - 10:10AM
Astrophysics
NASA
Tuesday, 02 August 2016 - 10:10AM
Don't Panic, Asteroid Bennu Won't Destroy the Earth
In September, NASA will launch their OSIRIS-REx mission, which will see NASA send a space probe to asteroid 101955 Bennu, take a sample, and bring it back to Earth for study for the first time ever. There are several mission objectives that will hopefully be accomplished in this mission, but according to the lead researchers, saving Earth from a literal Armageddon isn't one of them.

Bennu is a large asteroid, and there is a chance that it will collide with Earth sometime in the 22nd century. But any reports that it could potentially destroy the world, wipe out the human race, or any other hyperbolic disaster language is completely overblown.
Opening quote
"We're not talking about an asteroid that could destroy the Earth," OSIRIS-REx principal investigator Dante Lauretta told Space.com. "We're not anywhere near that kind of energy for an impact."
Closing quote

According to NASA, the danger posed to Earth by any particular asteroid can be measured using the Torino scale, which is somewhat comparable to a Richter scale for earthquakes. Tellingly, Bennu is a zero (or virtually zero) on the Torino scale, so while a devastating impact can't be ruled out, it's unlikely. And even if it did, the results would be far from the catastrophic impacts we see in movies, because it simply isn't big enough. For comparison, Bennu is half a kilometer wide, while the asteroid that killed the dinosaurs is thought to be approximately ten kilometers in size.

Opening quote
"It would certainly cause devastation on large scale if it was to impact down," NASA's Glen Nagel told The ABC. "It's about a half a kilometre in size. Certainly not the dinosaur killer that we tend to think of, or destroying the planet as they show in a lot of Hollywood movies."
Closing quote

The OSIRIS-REx mission will, in fact, tell us the probability of an impact from Bennu, although it isn't quite as urgent as some were thinking:

Opening quote
"Our uncertainties will shrink, so that will allow us to recalculate the impact probability," Lauretta said. "We don't know which direction it'll go. It could go down, because we just eliminated a bunch of possible keyholes that Bennu may hit. Or it may go up, because in the area that's left we have a higher concentration of keyholes compared to the overall area of the uncertainty plane."
Closing quote

But even if it's not saving the world exactly, the OSIRIS-REx mission will do something that's arguably just as exciting: tell us where we came from. Many scientists have theorized that life on Earth was seeded by an extraterrestrial body such as an asteroid, and since the asteroid would have retained most of its composition from the early Solar System, this direct sampling could settle that question once and for all. 

Opening quote
"Did these kinds of bodies deliver organic material and water, in the form of hydrated minerals like clays, to the surface of our planet that created the habitability and the environments that may have led to the origin of life? That's the prime mission," Lauretta said.
Closing quote
Science
Space
Astrophysics
NASA