![]() The agency’s Planetary Defense Coordination Office, established in 2016 and led by Johnson, has brought together efforts dating back to the 1990s to make early detections of potentially hazardous space rocks. Protecting the planet is a task that Congress has increasingly asked of NASA. ![]() DART would also be equipped with the Roll Out Solar Array that was tested in June at the International Space Station. Designers have ideas about how to scale up the concept for kilometer-class objects too, should that ever be necessary.Įditor’s note: In the illustration at the top of this page, A solar electric propulsion engine glows in the rendering of the proposed Double Asteroid Redirection Test, or DART, spacecraft. The DART technique could in theory be applied on smaller objects, but the trick would be to spot those far enough away and get enough lead time, something that can’t reliably be done now because of the dimness of these objects at considerable distances. If DART makes it off the drawing board and works as planned, NASA will have demonstrated a technique for protecting us from what is the most likely risk from space: a collision with a Didymoon-size asteroid that could gouge out a crater at least a kilometer wide and hurl searing heat and debris for tens of kilometers. The behemoth that wiped out the dinosaurs and 75 percent of Earth’s species measured an estimated 10 km across. The 1908 asteroid or comet that leveled a forest near the Podkamennaya Tunguska River in Siberia was probably just twice Chelyabinsk’s size. For a sense of scale, the asteroid that blazed into the atmosphere as a meteor over Chelyabinsk, Russia, in 2013 measured only about 20 meters across, NASA estimates. For Lindley Johnson, NASA’s planetary defense officer and a DART leader, the “mission is deeply exciting” because it would demonstrate autonomous navigation software for a guided-missile-like strike, show off a next-generation thruster powered by sunlight and electricity, not to mention how NASA might someday “‘save the world,’ so to speak,” as Johnson puts it.ĭidymoon’s name might be amusing, but an asteroid of its size, 160 meters across, could do enormous damage, although short of endangering the entire world. DART would be “the first demonstration of a kinetic impactor and we want to know that it works if we ever have a realistic threat,” says Cheryl Reed, the DART project manager at the Johns Hopkins University Applied Physics Laboratory in Maryland. There is no shortage of enthusiasm in some quarters to get this mission done. Over a span of millions of kilometers, the cumulative trajectory change would turn a collision with a genuinely Earth-bound asteroid or comet into a safe, albeit nerve-wracking, close shave. Didymoon is no threat to Earth, but this kind of slight momentum transfer might well save us from catastrophe from other objects. The punch of the sacrificial spacecraft should alter the moonlet’s orbit around its host asteroid by a tiny, yet measurable amount. The rendezvous would be short-lived, though, for DART’s goal is to intentionally plow right into Didymoon. This spacecraft would cruise toward the asteroid Didymos, arriving in its vicinity in October 2022 when the object and its moonlet, nicknamed Didymoon, make a near but harmless sweep past Earth. DART received the agency’s go-ahead in June to enter a preliminary design phase. NASA is preparing the kinetic impactor portion of the mission, a proposed spacecraft dubbed DART, the Double Asteroid Redirection Test. The mission would consist of two spacecraft, one to strike a small asteroid and hopefully nudge it onto a slightly new course, and the other to watch and characterize the collision up close. Planners of a proposed 2020 mission called AIDA (pronounced “eye-EE-duh”), the Asteroid Impact and Deflection Assessment, are proceeding on that planetary defense front. Knowing about a threat is one thing mitigating it is another. The house-sized space rock, designated 2012 TC4, will miss Earth by 50,000 kilometers - a mere fifth of the moon’s remove. 12, 2017, a hefty asteroid will give our planet a shot across the bow. Managers of proposed mission hope to protect Earth from giant space rocks Course corrector By Adam Hadhazy | October 2017
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