The U.S. government released a new report detailing some of the efforts underway to prepare for and respond to a catastrophe caused by a “near-Earth object” (NEO), an asteroid or comet that impacts the Earth. Included in the report are several strategies the government could take to avert such a collision, which has the potential for immense widespread destruction.
Such an impact is highly unlikely, given the vastness of space and the relatively tiny size of the NEOs in our solar system. “Fortunately, this type of destructive event is extremely rare,” White House official Aaron Miles told Bloomberg.
The report breaks the NEOs into five general categories by the potential of impact devastation, ranging from “none” (the shooting stars we see in the sky all the time) to “global” (the event that led to the end of the dinosaurs).
Even relatively small objects can cause extensive devastation because they’re traveling at such high speeds. In 1908, for example, an object about 150 feet across exploded over Tunguska, Russia, leveling more than 800 square miles of forest. The report estimates that such an event over New York City would result in millions of casualties.
Luckily, we’re getting a lot better at tracking the most dangerous objects. In conjunction with the International Asteroid Warning Network and the United Nations, NASA has documented 96 percent of the largest “planet-killers,” according to Lindley Johnson, a planetary defense officer for NASA. The agency is currently tracking some 18,310 NEOs, with 8,000 of those in the “global” category.
On the other hand, there is a chance that a rogue object could suddenly appear from interstellar space, giving us mere months to prepare. That was the case with ‘Oumuamua,’ a strange cigar-shaped asteroid that was apparently just a visitor that cruised quickly into our solar system, slingshotted around the sun at 196,000 miles per hour, and departed.
The report encourages preliminary planning and designs for three different “NEO deflection” missions:
- Kinetic impact: Just smashing a spacecraft into the asteroid may be enough to sufficiently deflect its trajectory, especially if the object was years away from impact.
- Gravity tractor: Landing and attaching a heavy spacecraft on the object would have a similar effect to a barnacle on a ship’s hull, altering the path due to the increased mass.
- Nuclear explosion: While obviously the tactic Bruce Willis would approve of, the reality is more nuanced. A nuclear blast would reduce the mass of the object, allowing its trajectory to be altered more easily by other methods. The report emphasizes that no nuclear explosive tests in space are planned or necessary, and such a scenario would only be undertaken for a large object that is more than a decade from impact.
In the short term, the administration wants to increase funding for missions like the NASA Double Asteroid Redirection Test (DART), which will test some of these theories by crashing a spacecraft into the orbiting moonlet of a dual asteroid.