by In recent years there have been a series of close encounters and collisions with various asteroids. Interestingly, the composition of asteroid debris has been surprising in several cases.
Asteroid probes from several nations have found not solid objects, but rather countless pieces of gravel and boulders loosely held together by the object’s small gravity field.
Ultimately, it was NASA’s OSIRIS-REx mission that left bite marks on asteroid Bennu, snagging and bagging pieces of that debris pile, and then parachuting those collectibles to Utah last September. Similarly, Japan’s two Hayabusa missions transported specimens from the debris piles, asteroid Itokawa (2010) and asteroid Ryugu (2020), to Earth.
This revelation is circulating among the planetary defense community. How do we deal with incoming space rocks that are a double problem: bad for Earth, but also difficult to handle because of their composition?
Related: Debris-accumulating asteroids are ‘giant space cushions’ that live forever
Reference technique
The resounding success of NASA’s Double Asteroid Redirection Test, or DART, allowed humanity to conduct its first mission to intentionally move a celestial object. After ten months of travel, DART’s precise, kinetic impact of asteroid Dimorphos occurred in September 2022, altering the asteroid’s orbit period around its small celestial companion, asteroid Didymos.
“Pre-impact projections estimated a range of possible deviations, and post-impact observations revealed a significant deviation of the target asteroid at the high end of pre-impact models,” NASA reports, citing the DART result as “a promising result”. result to apply the technique in the future if necessary.
The kinetic impact method introduced by DART has been the “technique of choice” if trying to deflect an asteroid heading toward Earth, said John Brophy, an engineering fellow at the Jet Propulsion Laboratory.
“They hit it very close to the center of mass. It was a good shot,” Brophy told Space.com.
On the other hand, piles of asteroid debris apparently give rise to Forrest Gump’s axiom that life is like a box of chocolates: “You never know what you’re going to get.”
“If you hit it hard enough to deflect it, in a single impact, you’re very likely to destabilize it. And destabilize it means shatter it,” Brophy said. What happens next is “a chaotic process with uncertain outcomes,” he said.
Controlled process
Having kinetic impactors repeatedly hit a target in a kinder, gentler way is one idea, but that approach also presents challenges.
Brophy was a leader in the study of a new planetary defense idea known as ion beam deflection. “You direct the ion beam to hit the asteroid, along its velocity vector. By deflecting the ion beam you spread that power over months or maybe even a year or two,” he said.
Using this ion beam concept has several benefits, Brophy added. On the one hand, it is a very controlled process. It also works on piles of debris and doesn’t care what the object’s strength is, its composition, or how the space rock spins.
Ion beam deflection “is a potentially attractive approach that can help mitigate the problems of deflecting debris piles,” Brophy said. Then, of course, he noted, there is the use of a nuclear device for diversion purposes, but many see it as a technique of last resort.
Read more: 8 Ways to Stop an Asteroid: Nuclear Weapons, Paint and Bruce Willis
Big dog
Ed Lu is executive director of the Asteroid Institute, which is a program of the B612 Foundation. As a NASA astronaut, he flew on three space missions, logging 206 days in Earth orbit, to help build and live aboard the International Space Station.
Lu is also co-inventor of the Gravity Tractor, a controllable means of deflecting asteroids, using only the gravitational field of a spacecraft to transmit the required thrust. The possibility of testing the concept in space on an experimental basis is being studied, he said.
From a planetary defense standpoint, Lu has long said that diversion is not the difficult issue. “It’s never been the hard part. It’s always been finding, tracking and getting a complete catalog and knowing when something is going to happen,” he told Space.com.
The big asteroid news, Lu said, is the Vera C. Rubin Observatory, currently under construction on Cerro Pachón in Chile. It is expected to excel in detecting new asteroids, as the facility will monitor large areas of the sky every night and can detect very faint moving objects.
“It’s really the big dog and can make most of those discoveries in the next few years. The first few years of its operation are the most prolific. That’s when everything is easy,” Lu said.
Governance issues
A recent public survey said monitoring the trajectories of asteroids that hit Earth should be NASA’s top priority.
“Monitoring asteroids that could potentially impact Earth is at the top of the public’s list of priorities for NASA. Monitoring the planet’s climate system also ranks high as a priority for NASA. But relatively Few Americans say it should be a top priority to send human astronauts to the Moon or Mars,” reported a July 20 Pew Research Center “data tank” finding.
Dealing technologically with piles of debris is one thing, but more work also seems necessary to debate the political and sociological aspects of defending against asteroids targeting Earth.
Nikola Schmidt works as a senior researcher and heads the Center for Governance of Emerging Technologies at the Institute of International Relations in Prague. He authored a recent look at 30 years of planetary defense governance.
“The problem is that we don’t know what’s beneath the surface of the debris piles,” Schmidt told Space.com. “There could be gaps inside or the spaces between larger rocks could be completely filled with regolith. This is something we don’t know and can cause significantly different effects. So yes, the structure is an issue and about 70-80% of the asteroid population are believed to be piles of debris,” he said.
Security regimes
In Schmidt’s article appearing in the January issue of the journal Acta Astronautica, he observes that today we are not in a situation where the Earth can defend itself without problems.
“This does not mean that United Nations agencies, expert entities and the entire planetary defense scientific community are not communicating or sharing information.” They are, Schmidt quickly adds, but the fact that States want to keep decision-making in their own hands goes against being prepared at a planetary level and avoiding unnecessary international debates in the event of an imminent threat.
“That is why states have developed international cooperation in the form of multilateral security regimes,” Schmidt said. “They establish decision-making procedures that will not change due to elections in particular states and can provide security guarantees to all for an unequal contribution, which is crucial for the security of small states and the legitimacy of action for states powerful; each can contribute what he can, but all enjoy the same security of cooperation.”
Cosmopolitan responsibility
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Schmidt told Space.com that he has been arguing for years that planetary defense is about cosmopolitan responsibility, “which is constituted by the continuous production of new scientific knowledge about asteroids and their orbits. The knowledge changes our perception of the world that surrounds us and that crosses them. “The borders of nation-states and their power to do anything about them. “Therefore, states must find a way to cooperate or they will fail in their primary reason for existence: to provide security to citizens.”
Cosmopolitan is also not the kind of language that should be sold to the public, Schmidt concludes, “but planetary defense is rearticulating the social contract like anything else in an ever-transforming society.”
