Andy Rivkin remembers going to the arcade in the early 1980s to play the iconic video game “Asteroids.” Later this month, the team he leads is scheduled to launch a satellite aimed at an asteroid 7 million miles away to prove that Earthlings can save themselves from an asteroid impact by shooting first, Atari-style.
The launch window for NASA’s Double Asteroid Redirection Test (DART) mission opens next week. DART is an experiment to see if by crashing a spacecraft directly into an asteroid, the asteroid can be nudged off its trajectory. If intercepted and struck far enough away, even a slight alteration in the path of an asteroid could cause it to miss Earth, avoiding a potentially catastrophic impact.
“We know of no asteroids that are coming in to hit the Earth,” Rivkin emphasizes. DART, he says, is part of a multi-pronged effort to examine the asteroid collision problem. “Asteroid impacts are really the only natural disaster that humanity can see coming years or decades in advance and do anything about.”
NASA calls DART its “First Planetary Defense Test Mission.” Rivkin is the DART investigation team lead at Johns Hopkins University’s Applied Physics Laboratory, which is running the experiment for NASA.
In tandem with taking a hit-and-deflect approach to inbound asteroids, NASA is pursuing active asteroid monitoring via telescope and other means through its Center for Near-Earth Object Studies at its California-based Jet Propulsion Laboratory.
While asteroid monitoring represents a hurricane warning-like Civil Defense response to incoming space rocks, DART will test our ability to be proactive without resorting to proposed use of a space-borne nuclear device to detonate near a threatening object to partly vaporize and deflect it via a shock wave.
DART could be likened to the high speed “Hit-To-Kill” kinetic missile interceptors developed by the U.S. over the last couple of decades, including Lockheed Martin’s PAC-3 Missile Segment Enhancement interceptor, which successfully engaged tactical ballistic missiles in testing for the Army’s Integrated Air and Missile Defense Battle Command System earlier this month.
Like missile interceptor tests, the DART mission involves targets. Two little-known asteroids — Didymos and Dimorphos — are co-orbiting the Sun in a binary pair about seven million miles away from Earth. The pair is not on a collision course with Earth but they make for good test targets.
The larger asteroid, Didymos, is 0.48 miles in diameter while Dimorphos, the smaller asteroid which orbits it in moon-like fashion, is 525 feet in diameter. The DART spacecraft will be targeting Dimorphos. If all goes well, the spacecraft will impact Dimorphos nearly head-on, shortening the time it takes the small asteroid moonlet to orbit Didymos by several minutes.