But what if we did have advance notice? What then? Inertia is a mighty enemy. In the void of space, those heavy rocks are moving very, very fast along the same gravitational grooves they’ve followed for billions of years. They’re hard to stop. Plans for handling such an impending crisis have taken on an added urgency as our ability has increased to identify near-Earth objects, or NEOs.
Now in its 20th year, NASA’s NEO Observations Program has gained support under both Obama and Trump (though it is not part of the proposed Space Force). Funding is expected to increase sharply to $150 million for 2019, up from $60 million.
An earlier NASA mission, NEOWISE, greatly expanded the current bank of knowledge about asteroids. Right now, NASA and the Japanese Space Agency JAXA have probes visiting asteroids, for the purpose of studying them, collecting samples and returning to Earth. NASA’s OSIRIS-Rex mission arrived at asteroid Bennu in December. JAXA’s Hayabusa2 landed French-German robots on the asteroid Ryugu in September.
This year, for the first time ever, the White House publicly unveiled a 23-page “Near-Earth Object Preparedness Strategy and Action Plan,” which outlines steps NASA plans to take to increase advance detection and preparedness to deal with them. Of necessity, the plan is still heavy on preparedness, light on action to derail a danger once it’s detected.
Data from NASA-funded telescopes, plus those of outside governments, science institutes and private citizens around the world, is continuously fed to the NASA-funded Minor Planet Center and the Planetary Defense Office at NASA headquarters. Sightings of near-Earth objects and impacts are compiled by the Minor Planet Center into reports that land on Mr. Johnson’s desk.
“There is a protocol” in the event of an immediate threat, Mr. Johnson says. “We provide the information up through our management to the administrator and to the White House through the Office of Science and Technology Policy, alerting them of a potential impact – how big an object is and how near we are to impact – and our assessment of what the effect might be.”
That message spreads not only through a network of US agencies, such as the Federal Emergency Management Agency, or FEMA, but also to any other nations that may be affected, via the State Department and the UN-sanctioned International Asteroid Warning Network, which informs the UN Office of Outer Space Affairs. If the impact were large and headed toward a densely populated area, a mass evacuation might be recommended, with the decision and handling left to that area’s government.
Meteor strikes historically have not cooperated with this plan: They arrive unannounced. But on June 2, an astronomer working with the NASA-funded Catalina Sky Survey spotted a two-meter wide object headed for Earth, only the third such advance detection in history, a feat even more remarkable because of this asteroid’s puniness. With that data, Jet Propulsion Laboratory scientists were able to predict where it would impact. Eight hours later, the spectacular fireball streaked across the night sky in Botswana, lighting up the rural landscape like a giant flash bulb. No one was hurt.
Eight hours would have been enough time to issue a warning that could have saved lives had the asteroid been larger and targeting a major city – but not long enough for a full evacuation.
Dr. Tim Spahr, the former Director of the Minor Planet Center and a founder of the Catalina Sky Survey, is now CEO of his own private consulting firm NEO Sciences. He says confidently that the bigger the threat, the greater the chance we might see it advance.
“Let’s say instead of two meters, it was 40 meters,” Dr. Spahr says. “We would have discovered it weeks ahead of time, not eight hours. And that’s enough time to go, ‘Hello! People in Botswana! You just need to get 30 kilometers away and you’ll all be fine.’”
But even a few weeks is not nearly enough to mount any kind of deflection or intervention against the asteroid itself. Even if we had something to deflect it with. At the moment, an effective mission would require a warning of about 20 years. “They’re trying to reduce that,” Dr. Spahr adds. “The idea that you could do something on a decadal time scale [10 years instead of 20] is not out of the question.”
In its five numbered goals, the NASA “Strategy and Action Plan” lists “Develop Technologies for NEO Deflection and Disruption Missions” as Goal No. 3. Another way of saying that: Those technologies, as a complete package, are not yet developed. We have the ability to launch missions to asteroids – but those take decades of work prior to launch. Existing machinery, in theory, could be adapted to thwart an impact once we get there – but we haven’t tested it.
Still, sending a defense is feasible, building on technology developed on previous space missions. One idea would be to move the asteroid’s orbit slightly so it doesn’t hit Earth. Various theories for how to do that have been floated.
Among what NASA calls “the most mature in-space concepts”: slamming a device into the asteroid’s surface, known as a “kinetic impactor”; parking a man-made object nearby and letting its gravitational pull tug the asteroid off course, a so-called “gravity tractor” (an idea first proposed by a team that included B612’s Dr. Lu); and last, exploding a hydrogen bomb near the surface, which should slow the asteroid’s momentum, allowing it to miss Earth.
These remain untested. NASA has scheduled a kinetic impactor attempt in 2022, Mr. Johnson says, when a spacecraft will hit the smaller member of a twin asteroid system, Didymos, to slightly alter its path. For the immediate future though, safety plans in the face of threatening asteroids rest on early detection, warning protocols and public awareness.