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Debris From NASA Asteroid Collision May Hit Mars – Newsweek

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A NASA experiment that sent a spacecraft slamming into the side of an asteroid may have sent debris flying into space, possibly into the path of Mars.

The asteroid, named Dimorphos, was hit by NASA's Double Asteroid Redirection Test (DART) in September 2022 as part of an experiment to investigate how the asteroid's path would be deflected.

In the months since, scientists have found that not only was the asteroid's orbit around its larger companion Didymos altered by 32 minutes, but its shape was totally changed by the collision.

Now, according to a pre-print paper by researchers from Johns Hopkins Applied Physics Laboratory and the DART teamyet to be published in a peer-reviewed journalsome of the boulders flung off during the impact may be on a collision course with Mars.

Dimorphos is 525 feet in diameter, and orbits a larger, 2,560-foot asteroid known as Didymos. The DART mission was designed to test how slamming a spacecraft into the side of an asteroid would impact how it travels through space, and therefore if doing so could successfully deflect a space rock from a collision with Earth.

A paper in the journal Nature Astronomy from earlier this year revealed that the DART impact resulted in "more than 1.32.2107kg" being flung out into space from the collision, which was equivalent to around 0.3 to 0.5 percent of the mass of the entire asteroid. This caused 8 percent of Dimorphos' mass to be displaced around the asteroid, causing the rock to entirely change shape.

Now, the new pre-print says that the ejecta thrown out into the solar system consisted of 37 boulders, some of which measured up to 22 feet across.

"We did not expect that many boulders that were that big to be blown off," Andy Rivkin, an astronomer at the Johns Hopkins Applied Physics Laboratory and a member of the DART team, told National Geographic.

According to the paper, none of the boulders will threaten the Earth, with the closest passing at a distance of around 1.9 million miles in about 2,500 years.

"On the contrary, the Mars MOID [minimum orbit intersection distance] will be very small in four instances, two near 6 kyr [thousand years] and the other two near 15 kyr. Therefore, there may be a chance for them to impact Mars in the future," the researchers wrote in the paper.

So the asteroid's ejecta might collide with our Red Planet neighbor, but not for several thousand years.

In the rare occurrence of these rocks hitting Mars, they may burn up in the planet's thin atmosphere, or alternatively, collide with its surface, creating a large impact crater.

"Given the rarefaction of the Martian atmosphere, we expect the boulders to arrive intact on the ground and excavate a small impact crater," the researchers wrote.

This could pose an issue for a future Mars-based civilization.

"The issue that a possible human settlement will be facing on Mars linked to meteor showers will be not far from the challenges that a human settlement on the moon will face in case of an incoming object hitting the ground," Stefania Soldini, an associate professor in space engineering at the University of Liverpool in the U.K., told Newsweek. "I think the mitigation strategies that are going to be developed to guarantee the safety of a human settlement on the moon could be applied for Mars."

Soldini pointed out that Mars' atmosphere could offer protection from smaller objects whereas the moon has no atmosphere. Current efforts by NASA, the European Space Agency and Japan's space agency to protect Earth from potential dangers originating in space will also be of value for future human settlements on Mars, she said.

The latest study is important for the implications of the DART experiment, as it means any ejecta from the surface of asteroids caused by the impact of spacecraft sent up to deflect them must be monitored, as this too could end up posing a threat to the Earth one day.

"The results presented here provide a further indication that some meteorites found on Earth originated in collisions of around 100 m [328 feet] near-Earth asteroids with projectiles of around 1 m [3 feet] in size," the researchers wrote.

Thankfully, none of the 33,000 near-Earth asteroids being tracked by NASA are heading towards our home planet any time soon.

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Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

Newsweek is committed to challenging conventional wisdom and finding connections in the search for common ground.

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Debris From NASA Asteroid Collision May Hit Mars - Newsweek

A Nasa mission that collided with an asteroid didn’t just leave a dent it reshaped the space rock – theconversation.com

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A frequent idea in sci-fi and apocalyptic films is that of an asteroid striking Earth and causing global devastation. While the probabilities of this kind of mass extinction occurring on our planet are incredibly small, they are not zero.

The results of Nasas Dart mission to the asteroid Dimorphos have now been published. They contain fascinating details about the composition of this asteroid and whether we can defend Earth against incoming space rocks.

The Double Asteroid Redirection Test (Dart) was a spacecraft mission that launched in November 2021. It was sent to an asteroid called Dimorphos and commanded to collide with it, head on, in September 2022.

Dimorphos posed and poses no threat to Earth in the near future. But the mission was designed to see if deflecting an asteroid away from a collision course with Earth was possible through kinetic means in other words, a direct impact of a human-made object on its surface.

Asteroid missions are never easy. The relatively small size of these objects (compared to planets and moons) means there is no appreciable gravity to enable spacecraft to land and collect a sample.

Space agencies have launched a number of spacecraft to asteroids in recent times. For example, the Japanese space agencys (Jaxa) Hayabusa-2 mission reached the asteroid Ryugu in 2018, the same year Nasas Osiris-Rex mission rendezvoused with the asteroid Bennu.

The Japanese Hayabusa missions (1 and 2) fired a small projectile at the surface as they approached it. They would then collect the debris as it flew by.

However, the Dart mission was special in that it was not sent to deliver samples of asteroid material to labs on Earth. Instead, it was to fly at high speed into the space rock and be destroyed in the process.

A high-speed collision with an asteroid needs incredible precision. Darts target of Dimorphos was actually part of a double asteroid system, known as a binary because the smaller object orbits the larger one. This binary contained both Didymus the larger of the two objects and Dimorphos, which behaves effectively as a moon.

The simulations of what has happened to Dimorphos show that while we might expect to see a very large crater on the asteroid from Darts impact, it is more likely that it has, in fact, changed the shape of the asteroid instead.

The collision was of a mass of 580kg hitting an asteroid of roughly 5 billion kg. For comparison, this is equivalent to an ant hitting two buses. But the spacecraft is also travelling around 6 kilometres per second.

The simulation results based on observations of the asteroid Dimorphos have shown that the asteroid now orbits around its larger companion, Didymus, 33 minutes slower than before. Its orbit has gone from 11 hours, 55 minutes to 11 hours, 22 minutes.

The momentum change to the core of Dimorphos is also higher than one would predict from the direct impact, which may seem impossible at first. However, the asteroid is quite weakly constructed, consisting of loose rubble held together by gravity. The impact caused a lot of material to be blown off of Dimorphos.

This material is now travelling in the opposite direction to the impact. This acts like a recoil, slowing down the asteroid.

Observations of all the highly reflective material that has been shed from Dimorphos allows scientists to estimate how much of it has been lost from the asteroid. Their result is roughly 20 million kilograms equivalent to about six of the Apollo-era Saturn V rockets fully loaded with fuel.

Combining all the parameters together (mass, speed, angle and amount of material lost) and simulating the impact has allowed the researchers to be fairly confident about the answer. Confident not only regarding the grain size of the material coming from Dimorphos, but also that the asteroid has limited cohesion and the surface must be constantly altered, or reshaped, by minor impacts.

But what does this tell us about protecting ourselves from an asteroid impact? Significant recent impacts on Earth have included the meteor which broke up in the sky over the city of Chelyabinsk, Russia, in 2013, and the infamous Tunguska impact over a remote part of Siberia in 1908.

While these were not the kinds of events that are able to cause mass extinctions like the 10km object that wiped out the dinosaurs when it struck our planet 66 million years ago the potential for damage and loss of life with smaller objects such as those at Chelyabinsk and Tunguska is very high.

The Dart mission cost US$324 million (255 million), which is low for a space mission, and with its development phase completed, a similar mission to go and deflect an asteroid heading our way could be launched more cheaply.

The big variable here is how much warning we will have, because a change in orbit of 30 minutes as was observed when Dart struck Dimorphos will make little difference if the asteroid is already very close to Earth. However, if we can predict the object path from further out preferably outside the Solar System and make small changes, this could be enough to divert the path of an asteroid away from our planet.

We can expect to see more of these missions in the future, not only because of interest in the science surrounding asteroids, but because the ease of removing material from them means that private companies might want to step up their ideas of mining these space rocks for precious metals.

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A Nasa mission that collided with an asteroid didn't just leave a dent it reshaped the space rock - theconversation.com