Incoming! Studying and avoiding near-Earth asteroids and comets
On Thursday, February 16, the Planetary Society returned to KPCC In Person’s Crawford Family Forum for another Planetary Radio Live. Host Mat Kaplan and his panel of planetary scientists – or, as Kaplan called them, “defenders of our world” – explored the topic of Near Earth Objects (NEOs). The panel discussed current efforts to find, track and potentially deflect NEOs – objects like asteroids and comets that orbit in relatively close proximity to Earth. They also investigated the impact NEOs – past and future – have made or could make when they land on Earth. Despite the looming threat of Armageddon, the event was lighthearted, exciting and fact packed. The Forum even welcomed a few NEOs at the end of the night; Kaplan rewarded planetary whizzes in the audience with rubber asteroids when they answered trivia questions correctly. Kaplan’s panel of experts answered many questions about NEOs and the scientific efforts around them. Here, we’ll recap just a few.
How many NEOs have we found so far?
Approximately 15,500, according to NASA’s planetary defense officer, Lindley Johnson. Launched in 1998, NASA’s NEO program has found about 500 to 600 objects per year. (Before the program’s launch, about 500 total NEOs were known.) Since larger asteroids are easier to find, the program has identified most asteroids that are 1 kilometer and larger and about half of those between 300 meters and 1 kilometer, Johnson said. Smaller objects, between 130 meters and 300 meters in size, are harder to detect and more abundant; Johnson said NASA has identified about 8 percent.
But advanced technologies are changing that. “The rate at which we’re finding [smaller asteroids] is increasing with our additional capabilities,” Johnson said. In almost 20 years, NASA’s program has found about 73 percent of the projected NEO population, Johnson said. It found 1,884 near-Earth asteroids last year, he said. “We’re finding more and more each year, but we have a ways to go.”
Are NEOs going to bring on Armageddon?
A large enough NEO can cause a catastrophe if it comes crashing into the Earth’s surface. As Mat Kaplan said, “The dinosaurs didn’t have [a space program] and you know what happened to them.” Fortunately, however, we do have a space program. We also have scientists around the world who have made significant progress in locating and tracking NEOs. These scientists convene frequently to discuss potential options for deflecting a threatening NEO. At the Planetary Defense Conference, experts from around the world meet to discuss how the international community will respond when it sees a “rock that has our name on it,” Kaplan said. Johnson explained that at this conference, experts work to find, track and understand NEOs and their orbits. They also determine the threat of potential impacts and what people can do, together, to avoid them.
“We like to say that this is the only preventable large-scale natural disaster,” said Bruce Betts, director of science and technology for the Planetary Society. Amy Mainzer, senior research scientist at the Jet Propulsion Laboratory (JPL) and principal investigator for the asteroid-hunting infrared explorer NEOWISE, was also optimistic. “It is a fairly tractable problem,” she said. “I mean, we can basically go out and look for these objects; we can find them. It is a soluble problem.”
Paul Chodas, manager of the NASA NEO Program Office at JPL, discussed a few potential options for deflecting an Earth-bound NEO. Chodas said that given enough time to respond, scientists can, for example, run a spacecraft into an approaching asteroid at great enough velocity to alter its course - a method called kinetic impaction.
NEOs sound pretty threatening. Do we have any reason to like them?
According to this panel of planetary defenders, absolutely. Pieces of NEOs, recovered after impact or, ideally, sampled in space, are clues to the origins of our solar system. “We like to think of these as time capsules, really,” said Mainzer. “These things are very precious to us because they’re one of the few ways that we have to really understand what it was like at the beginning for our solar system.”
Because of Earth’s weather conditions and the fact that its geological processes constantly turn rocks over, Mainzer said, it’s hard to find rocks on Earth that can tell you nearly as much as an asteroid can.
“The study of asteroids and comets tells us more about our place in the cosmos – our place in space,” said Planetary Society CEO Bill Nye in a pre-recorded video at the start of the event. “We get closer to answering those two deep questions: Where did we all come from? And are we alone in the Universe?”
Mainzer is particularly excited about OSIRUS-REx, the current NASA mission headed to sample near earth asteroids. “It’s always really kind of amazing to me that a… tiny piece of rock that I’m holding in my hand is as old as the solar system.”