“We didn’t see this thing coming?”
“Well, our object collision budget’s a million dollars, that allows us to track about 3% of the sky, and beg’n your pardon sir, but it’s a big-ass sky.”
– Armageddon, 1998
In the 1998 film Armageddon, a massive asteroid threatens to obliterate life on Earth, and NASA determines the only way to cancel doomsday is to send a up a team to drill into the asteroid’s surface and detonate a nuclear bomb. While this approach has its basis in the Hollywood studio rather than the NASA laboratory, asteroids and other Near-Earth Objects (NEO’s) pose a very real threat to life on our planet.
Back in February of 2013, a 19 meter-wide meteor exploded over Russia with the force of 40 Hiroshima-type atom bombs. The resulting shock wave shattered thousands of windows and injured more than 1,600 people. Its brilliant flash temporarily blinded 70 Russian citizens and caused dozens of severe sunburns. [1] At 11,000 tons, this meteorite was the largest object to impact Earth since 1908. And the truly scary part is the fact that nobody saw it coming.
In 1994 the comet Shoemaker-Levy unexpectedly broke apart and sent fragments as large as 2 kilometers crashing into Jupiter. [2] This was the first direct observation of a collision between objects in our Solar System, and it prompted Congress to direct NASA to begin compiling a catalogue of all the NEO’s that could pose a threat to Earth.
Even with a number of programs in place to track NEO’s, we cannot anticipate every extraterrestrial threat. In the best case scenario, relatively small space rocks like the one that exploded over Russia can be identified two days before impact. But even the new ATLAS telescope array in Hawaii will only be able to identify 1/3 of these smaller objects. [3] Ground-based space surveys can only identify objects in the night-time part of the sky, and as the Russian incident demonstrated an asteroid doesn’t care at what time it’s arriving to our planet.
While small meteors can be difficult to detect, NASA is confident that over 90% of the asteroids that are over 1 kilometer wide have been identified. [4] NASA has released a map of over 1,400 Potentially Hazardous Asteroids (PHA’s) thats shows the orbital paths of space rocks that tend to come uncomfortably close to Earth. According to officials at NASA, none of the (identified) threats pose a danger within the next century.
But what if we do identify an asteroid zooming toward our beloved planet? NASA and the U.S. government are entertaining a number of potential strategies to prevent disaster. [5] Some seem rather straightforward: using nuclear detonations to deflect the incoming rock, or nudging it off course with a “kinetic interceptor” spacecraft. Others are more innovative: ‘painting’ part of the asteroid so that solar radiation slowly pushes it off course, or heating the rock’s surface with mirrors, forcing it to spew vapors and change its course. If none of these work, we can always fall back on the Armaggeddon model and send up Bruce Willis with a nuke.
“The dinosaurs became extinct because they didn’t have a space program. And if we become extinct because we don’t have a space program, it’ll serve us right!”
– Larry Niven, science-fiction author
[1] http://www.cbc.ca/news/technology/dangerous-meteors-hit-earth-way-more-often-than-thought-1.2417013
[2] http://pan-starrs.ifa.hawaii.edu/public/asteroid-threat/asteroid_threat.html
[3] http://www.newscientist.com/article/dn25080-earth-is-prepared-enough-for-the-next-asteroid-strike.html#.VRCqyvnF8rk
[4] http://www.space.com/22369-nasa-asteroid-threat-map.html
[5] http://news.discovery.com/space/asteroids-meteors-meteorites/top-10-asteroid-deflection-130130.htm