US president Barack Obama’s chief science advisor says the Earth is “vulnerable” to a potentially catastrophic asteroid strike.
At a briefing this morning, John Holdren, director of the White House’s Office of Science and Technology Policy, said we’re getting better at finding asteroids, then gave some more detail about how NASA plans to train for the possibility of an extinction threat.
Specifically, the space agency’s incredible plan to visit an asteroid, take a boulder off it and put it into orbit around the Earth’s moon. On the way, the NASA probe ARM (Asteroid Redirect Mission) will experiment with a deflection strategy known as the “enhanced gravity tractor”.
Obviously, it will cost a small fortune. Current estimates range around $US1.25 billion.
But it only takes a small asteroid to cause a lot of damage. The meteor which shook Chelyabinsk Oblast in 2013 damaged 7,200 buildings and caused injuries to more than 1500 people was just 20m across. Damage estimates were north of $US33 million.
And just over 100 years ago, a rock estimated to be twice that size levelled 2070 square kilometres of forest in what has become known as the Tunguska event:
Holdren said while those were 1 in a 100 and 1 in 1000-year events respectively, they also both hit without warning.
“If we are going to be as capable a civilization as our technology allows, we need to be prepared for even those rare events, because they could do a lot of damage to the Earth,” he said.
“This is a hazard that, 65 million years ago, the dinosaurs succumbed to. We have to be smarter than the dinosaurs.”
NASA says an asteroid would have to be at least 1km wide to pose an extinction threat, and claims to have found “90 per cent” of those which it could classify as “near-Earth”. None pose a threat, it says.
But that doesn’t mean we shouldn’t be prepared.
This morning’s discussion at NASA’s Goddard Space Flight Center elaborated on the 2021 mission targeting the 400m wide asteroid 2008 EV5.
The ARM probe will first pull a 6m rock off its surface:
That 6m rock has another purpose later.
Then, riding alongside the 400m asteroid, ARM will attempt to use a “gravity tractor” technique:
ARM and its boulder will create a gravitational force large enough to nudge 2008 EV slightly out of orbit.
ARM will then return to Earth.
One of the other technologies it will be testing will be solar electric propulsion:
After 53 months, the probe will return to an orbit around Earth’s moon.
A team of astronauts will crew Orion, launched by NASA’s Space Launch System, and rendevous with ARM:
They’ll take samples from the boulder it collected off 2008 EV:
The boulder samples, according to NASA, will hopefully provide invaluable insight into whether space rocks contain construction materials for space missions and refuelling stations.
It will be the furthest distance from Earth anyone has ever worked, Holdren says, which is an important step in rehearsing techniques and technologies it needs for any manned missions to Mars.
Holdren says a lunar orbit is a logical place to begin such missions.
“You don’t have to lift stuff off the moon,” he says. “You do it from a jumping-off point in stable orbit around the moon.”
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