On the morning of February 15, 2013, people in western Russia were dazzled by an incredibly
bright meteor blazing a fiery contrail across the sky.
A few minutes later a shockwave struck, shaking the buildings and blowing out windows.
1,500 people went to the hospital with injuries from shattered glass.
This was the Chelyabinsk meteor, a chunk of rock that struck the atmosphere going almost
19 kilometers per second.
Astronomers estimate that it was 15-20 meters across and weighed around 12,000 metric tonnes.
Here's the crazy part.
It was the largest known object to strike the atmosphere since the Tunguska explosion
in 1908.
Catastrophic impacts have shaped the evolution of life on Earth.
Once every 65 million years or so, there's an impact so destructive, it wipes out almost
all life on Earth.
The bad news is the Chelyabinsk event was a surprise.
The asteroid came out of nowhere.
We need to find all the potential killer asteroids, and understand what risks we face.
I'm Ned Wright...
That's Dr. Ned Wright.
He's a professor of physics and astronomy at UCLA, and the Primary Investigator for
the Wide-field Infrared Survey Explorer mission; a space telescope that looks for low temperature
objects in the infrared spectrum.
I think the best way to protect the Earth from asteroids is to get out and look very
assiduously to find all the hazardous asteroids.
Although astronomers have been finding and cataloging asteroids for decades, we still
only have a fraction of the dangerous asteroids tracked.
The large continent destroyers have mostly been found, but there's a whole class of smaller,
city killers out there, and they're almost entirely unknown.
There are...
... these dark asteroids that may not be the most dominant part of the population but they
certainly can be a very hazardous subset, it's important to do the observations in the
infrared.
So you actually, instead of looking for the ones that reflect the most light, you look
for the ones that have the biggest area and therefore the ones that are the heaviest and
can do the most damage.
And so, I think that an infrared survey is the way to go.
In the infrared wavelengths, we can find these objects because they're large, not because
they're bright.
And to really do this right, we need a space-based infrared observatory capable of surveying
vast areas of the sky, searching for anything moving.
The WISE mission has been offline for a few years, but...
... WISE is actually being reactivated right now to look for more Near Earth Objects, so
we're currently cooled down to 93 K, and when we get to 73 K, which is where we were when
we turned off in 2011 we'll probably be able to go out and find more Near Earth Objects.
But to really find the vast majority of dangerous asteroids, you need a specialized mission.
One proposal is the Near Earth Asteroid Camera, or NEOCam because...
... it'd be much better to have a telescope that was slightly colder than the 73 K WISE
is with coolant, and you can do that by getting away from the Earth.
and so the NEOcam telescope is designed to go a million and a half kilometers from the
Earth and therefore it would be quite cold, about 35 K and at that temperature, it can
operate longer into the infrared and do a very sensitive survey for asteroids.
NEOCam is just one idea.
There's...
... also the Sentinel proposal from B612 Foundation.
It's also an infrared survey and it would go into an orbit like Venus' orbit, so it
would be hundreds of millions of km away from Earth, but not orbiting around Venus, because
that would be too hot as well and then with an infrared telescope, it would survey for
asteroids.
NEOCam and Sentinel would operate for years, scanning the sky in the infrared to find all
of the really hazardous asteroids...
... You wouldn't be able to necessarily find the ones the size of the one that hit Chelyabinsk,
and so that broke some windows, but it didn't kill people, didn't knock buildings down.
So that's definitely a hazard, but not the city destroying hazard that a 100 meter diameter
asteroid would be.
We live in a cosmic shooting gallery.
Rocks from space impact the Earth all the time, our next dangerous asteroid is out there,
somewhere.
Let's build a space-based infrared survey mission so we can find it, before it finds
us.