Image Credit: NASA / Johns Hopkins APL / Steve Gribben
Nuclear bombs. This is the right solution for upcoming space objects like asteroids and comets, as far as Hollywood is concerned. movies like deep effect And the disaster Rely on nuclear weapons to save the world and deliver drama.
But in fact, planetary defense experts say, if astronomers detect a dangerous incoming space rock, the safest and best answer might be something more precise, such as pushing it off course simply by ramming it with a small spacecraft.
That’s exactly what NASA is preparing to experience, with a spacecraft scheduled to smash into an asteroid at 7:14 p.m. ET on Monday.
The impact will be the culmination of NASA’s Double Asteroid Redirection Test (DART), a more than $300 million effort that launched a spacecraft in November of 2021 to conduct humanity’s first-ever test of planetary defense technology.
The planned collision is just a push along the lines of “running a golf cart at the Great Pyramid,” says Nancy Chabot, DART coordination lead at Johns Hopkins University’s Applied Physics Laboratory.
Tweaking the orbit of a space rock
The target asteroid, called Demorphos, is located about 7 million miles away and poses no threat to Earth. It is about 525 feet wide and orbits another, larger asteroid.
NASA officials stress that there is no way their testing could turn any of these space rocks into danger.
“There is no scenario in which one body or the other could become a threat to Earth,” says Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “It’s not scientifically possible, just because of conservation of momentum and other things.”
Instead, the impact should shorten just a little bit the time it takes Dimorphos to orbit the larger asteroid. At the moment, the full cycle takes 11 hours and 55 minutes. The DART effect should alter Dimorphos’ trajectory so that it gets closer to the large asteroid and takes less time to navigate, possibly once every 11 hours and 45 minutes.
These two asteroids are so far away that telescopes see them as a single point of light that dims and lights up as Demorphos orbits. Images from the DART spacecraft’s camera will be the first opportunity for scientists to see the asteroid they were working on colliding.
In fact, the spacecraft’s navigation systems will initially target the larger and left-handed asteroid specifically, turning their attention only to Dimorphos in the final hour of the mission.
The space agency will broadcast images from the doomed spacecraft in real time on its website. Dimorphos will loom larger and larger as the spacecraft hurtles toward it at around 14,000 miles per hour. At the moment of impact, the images will suddenly stop.
But a smaller spacecraft nearby will be watching, and will send the images back to Earth in the following days. Telescopes on all seven continents, as well as space telescopes such as James Webb, will also watch the collision and its aftermath for weeks, allowing astronomers to accurately measure how the asteroid’s path has changed.
Moreover, within two years, the European Space Agency will send a mission called Hera to this double asteroid system, allowing scientists to gather more information about the impacts of the collision.
All of this should reveal just how the asteroid reacts to a deliberate thrust, and scientists can take this information to help them make contingency plans to prepare for future threats.
“Bottom line, it’s great,” says Ed Low, who serves as executive director of the Asteroid Institute, a program run by a nonprofit organization dedicated to planetary defense. “One day, we’ll find an asteroid with a high probability of hitting Earth, and we’ll want to craft it.”
When that happens, Low says, “we have to have, beforehand, some experience to know that this will work.”
Not many asteroids found and tracked
However, people working on the DART task seem to understand that their project may seem far-fetched.
“We’re moving an asteroid. We’re changing the motion of a natural celestial body in space. Humanity has never done this before,” says Tom Statler, NASA’s DART program scientist. “These are things from science fiction books and really cliched episodes of Star Trek when I was a kid, and now they are real. And it’s kind of amazing that we’re already doing this, and what heralds the future of what we can do.”
NASA tracks a lot of space rocks, especially large ones that can cause extinction-level events. Fortunately, nothing is currently threatening the Earth. But many asteroids the size of Demorphos have yet to be discovered, and would likely wipe out a city if they crashed.
That’s why NASA’s Planetary Defense Coordination Office wants to launch the NEO Surveyor asteroid-hunting space telescope, which could go up in 2026 or 2028, depending on how much money Congress appropriates.
“It’s something we need to do so we know what’s out there, we know what’s coming, and we have time to prepare for it,” says Lindley Johnson, NASA’s Planetary Defense Officer.
Such a telescope, he says, could give Earthlings years, decades, or even centuries of warning about space rocks on an alarming trajectory — plenty of time for a solution, whether it’s a “kinetic collider” like DART or perhaps another type of spacecraft that will It flies past a disturbing asteroid and uses gravity to gently pull it away.
This is all very different from the usual way in which Hollywood portrays saving the planet, Johnson points out.
“They have to make it exciting,” he says, “you know, we find the asteroid just 18 days before it hits it, and everyone’s running around with their hair on fire.” “This is not the way to do planetary defense.”
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