Stephen Hawking observed that one of the major factors in the possible scarcity of advanced intelligent life in our galaxy is the high probability of an asteroid or comet colliding with inhabited planets.
With Hawking’s observation in mind, a team of scientists, astronomers and engineers are meeting weekly at the Johns Hopkins University Applied Physics Laboratory research campus to discuss plans to save the world with DART, the Double Asteroid Redirection Test, their plan to avert catastrophe from an asteroid impact similar to the one that sealed the fate of the dinosaurs.
It’s also, reports the Washington Post, NASA’s first mission not to explore space, but to defend against it. The plan is simple: The research team at the Johns Hopkins University Applied Physics Laboratory in Laurel plans to launch a spacecraft, speed it up really fast and smash it into an asteroid.
“Kind of like a big missile,” said Elena Adams, the mission’s lead engineer. “It’s very exciting. You are actually doing something for the fate of humanity.”
An estimated 100 tons of space debris -mostly dust and sand-at the Johns Hopkins University Applied Physics Laboratory falls to Earth every day say scientists with NASA’s Jet Propulsion Laboratory at the California Institute of Technology. Occasionally according to our planet’s geological record, “space sends something bigger.”
In August of 2018 NASA confirmed it will provide US$3.8 million over the next 4 years to support the construction and operation of two asteroid-hunting observatories south of the Equator. Researchers, reports Nature, plan to build one facility in South Africa, but are still deciding on a location for the second outpost. The observatories will join two existing telescopes on the islands of Maui and Hawaii as part of the Asteroid Terrestrial-impact Last Alert System (ATLAS), which is run by the University of Hawaii.
Three Northern Hemisphere observatories, including ATLAS, spotted more than 95% of the 2,057 near-Earth asteroids discovered in 2017. But these northern surveys are blind to roughly 30% of the southern sky — and to any asteroids in that region that could hit Earth.
A southern presence for ATLAS is also alluring to astronomers because the southern sky is rich in interesting objects. “If you want to look at the Galactic Center, that’s where you want to be,” says Matthew Holman, director of the Minor Planet Center in Cambridge, Massachusetts. The forthcoming telescopes could yield data across the whole range of astrophysics, he says.
The southern ATLAS units’ primary purpose, however, will be to spot relatively small asteroids that bigger telescopes miss. The asteroid that scientists believe wiped out the dinosaurs was 9 kilometers in diameter, but much smaller space rocks can also inflict serious damage. The mid-air explosion of a 20-meter asteroid in 2013 resulted in burns, cuts and broken bones for people in the Chelyabinsk region of Russia. And researchers think that a 50-meter asteroid devastated thousands of square kilometers of Russian forest in the 1908 Tunguska event.
Large telescopes such as those that are part of the Catalina Sky Survey in Tucson, Arizona, excel at finding asteroids in the far reaches of the Solar System like our recent first interstellar visitor, the asteroid Oumuamua. But the current ATLAS telescopes shine at picking out small objects that are much closer to Earth — within 7.5 million kilometers of the planet. They do so by conducting relatively rapid scans of the entire sky, which gives researchers more opportunities to detect diminutive asteroids as soon as the objects are visible from the ground.
ATLAS also has software optimized to detect fast-moving objects. As a result, the network can spot asteroids roughly the size of the Chelyabinsk and Tunguska rocks a few days to a week before impact, says John Tonry, the founder and principal investigator of ATLAS, who is based at the University of Hawaii at Mānoa. in Honolulu.
In early June, 2018 the system proved its mettle by providing data on the trajectory of a 1.8-meter asteroid called 2018 LA that swept over Africa. Researchers were subsequently able to find fragments of this space rock in Botswana. Since it started making observations in 2015, ATLAS has discovered 171 asteroids whose path brings them close to Earth’s orbit.
Establishing relatively inexpensive ATLAS systems in the south will enable astronomers “to cover the entire night sky every day or two to provide as much warning as we can”, says Lindley Johnson, planetary defense officer for NASA in Washington DC.
After the southern ATLAS observatories come online, “we’ll have close to round-the-clock coverage of the night sky”, says Larry Denneau, an ATLAS co-principal investigator at the University of Hawaii. “The more eyes you have looking, the better.”
NASA has considered nuking an asteroid with warheads, reports the Washington Post, but that risks turning a single incoming rock into a shower of debris as happened in “Deep Impact.” Another plan calls for flying a spacecraft beside the asteroid and gradually drawing it off course like a gravity tractor. DART offers a third strategy, and will be the first to be given a live test. “It’s the simplest and most effective,” NASA’s Paul Chodas said.
The team at the Hopkins laboratory has begun the final design and construction of the DART spacecraft. It will be about the size of a Honda Civic, scheduled for launch in summer 2021 for a journey will take more than one year.
The deflection test target is the tiny moon of an asteroid, collectively named Didymos, or Greek for “twin” that orbit the sun between Earth and the Asteroid Belt. The moon is not much bigger than the Washington Monument — minuscule in the scale of space. “This is by far the smallest object anyone has ever flown a spacecraft into,” said Andy Cheng, the mission’s co-lead and chief scientist in APL’s space department. DART will reach speeds as fast as 15,000 miles per hour. The crash in October 2022 will fling debris from the asteroid moon. A small satellite will accompany the DART spacecraft to measure the effect.
“We don’t see the moon of the asteroid until we’re just an hour away,” said Adams, the engineer. “That last hour is going to be really thrilling.”
“We’re just going to give it a love tap,” said Andy Rivkin, the mission’s other co-lead and planetary astronomer at APL.