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On Monday, a NASA spacecraft will deliberately collide with an asteroid called Demorphos.
The Double Asteroid Redirection Test mission, or DART, aims to see if this type of kinetic collision could help divert an asteroid posing a threat to Earth.
“We’re moving an asteroid,” said Tom Statler, a NASA program scientist on the DART mission. “We are changing the motion of a natural celestial body in space. Humanity has never done this before.”
Here’s what you need to know about this task.
The DART spacecraft is the size of a school bus. It has been traveling to reach its asteroid target since its launch in November 2021. The spacecraft will arrive at the asteroid system on September 26. An impact is expected at 7:14 PM ET.
The spacecraft is headed to a double asteroid system, where a small “moon” asteroid, called Demorphos, orbits a larger asteroid, Didymos.
Didymus. Which means “twin” in Greek, it’s about 2,560 feet (780 meters) tall. in diameter. Meanwhile, Demorphos is 525 feet (160 meters) wide, and its name means “two shapes.”
At the time of the collision, Didymus and Demorphos would be relatively close to Earth – 6.8 million miles (11 million km) away.
Neither Dimorphos nor Didymus At risk of hitting the ground – before or after the collision.
DART descends in flames of glory. It will set its sights on Demorphos, accelerating to 13,421 miles per hour (21,600 kilometers per hour) and nearly hitting the moon.
The spacecraft is about 100 times smaller than Demorphos, so it won’t wipe out the asteroid.
Instead, DART will attempt to change the asteroid’s speed and path through space. The expedition team compared this collision to a golf cart that crashed into one of the Great Pyramids – enough energy to leave a crash crater.
The effect will change Dimorphos’ speed by 1% as it orbits Didymos. It doesn’t sound like much, but doing so would change the orbital period of the moon.
The boost will shift Dimorphos a bit and make them more gravitationally bound to Didymos – so the collision won’t alter the binary system’s trajectory around Earth or increase its chances of becoming a threat to our planet.
The spacecraft will share its view of the double asteroid system through an instrument known as Didymos for reconnaissance and the Asteroid Camera for Optical Navigation, or Draco.
This imaging, which acts as a DART eye, will allow the spacecraft to identify the double asteroid system and distinguish which space object it is supposed to collide with.
This tool is also a high-resolution camera that aims to capture images of two asteroids that are beamed back to Earth at a rate of one image per second in what will roughly look like video. You can watch the live broadcast on NASA’s website, starting at 6 p.m. ET on Monday.
Didymos and Dimorphos will appear as tingles of light about an hour before impact, gradually getting larger and more detailed in the frame.
Dimorphos have not been observed before, so scientists can finally take on its shape and surface appearance.
We should be able to see the Dimorphos in great detail before DART hits him. Given the time it takes for the images to stream to Earth, they will be visible for eight seconds before signal loss occurs and the DART mission ends – if successful.
spacecraft too Her own photojournalist along the way.
A briefcase-sized satellite from the Italian Space Agency has made a trip with DART into space. Dubbed the Light Italian Asteroid Imaging CubeSat, or LICIACube, it separated from the spacecraft on September 11. The satellite was traveling behind DART to record what was happening from a safe perspective.
Three minutes after the collision, LICIACube will fly close to Dimorphos to capture images and videos of the impact plume. And maybe even spy on the impact crater. The CubeSat will turn to keep its cameras pointed at the Dimorphos as they fly.
Although the images and videos are not immediately available, they will be streamed back to Earth in the days and weeks following the collision.
LICIACube will not be the only observer watching. The James Webb Space Telescope, the Hubble Space Telescope and NASA’s Lucy mission will monitor the impact. Statler, a NASA program scientist, said the Didymos system may light up when dust and debris are expelled into space.
But ground-based telescopes will be key in determining whether DART has succeeded in altering the motion of Dimorphos.
The Didymos system was discovered in 1996, so astronomers have plenty of observations about the system. After the collision, observatories around the world will watch as Demorphos crosses in front of Didymus and moves behind him.
Dimorphos take 11 hours and 55 minutes to complete an orbit around Didymos. If DART was successful, that time could drop by 73 seconds, “but we actually think we’ll change it by about 10 minutes,” said Edward Reynolds, DART project manager at the Johns Hopkins University Applied Physics Laboratory.
Statler said he would be surprised if the measurement of period change came in as little as a few days but more so if it took more than three weeks.
“I’m pretty confident we’ll hit on Monday, and it’s going to be a complete success,” said Lindley Johnson, NASA’s planetary defense officer.
But if DART misses the proverbial dart board, the team will be on hand to make sure the spacecraft is safe and download all of its information to figure out why it didn’t hit the Dimorphos.
The mission operations center of the Applied Physics Laboratory will intervene if necessary, although DART will operate independently during the last four hours of its flight.
It takes 38 seconds to travel from Earth to the spacecraft, so the team can respond quickly. Elena Adams, a DART mission systems engineer at the Applied Physics Laboratory, said the DART team has 21 contingency plans in place.
Dimorphos were chosen for this mission because their size is comparable to asteroids that could pose a threat to Earth. An asteroid the size of Demorphos could cause “regional devastation” if it hit Earth.
Statler said the asteroid system is the “perfect natural laboratory” for testing.
The mission will allow scientists to get a better understanding of the size and mass of each asteroid, which is critical to understanding NEOs.
NEOs are asteroids and comets that orbit within 30 million miles (48.3 million km) of Earth. Detecting the threat of near-Earth objects that can cause significant harm is a primary focus of NASA and other space organizations around the world.
There are no asteroids currently in a direct impact path with Earth, but there are more than 27,000 near-Earth asteroids of all shapes and sizes.
The valuable data collected by DART will contribute to planetary defense strategies, particularly understanding what kind of force could alter the orbit of a near-Earth asteroid that could collide with our planet.
Movies The approach to the asteroid made it seem like a quick scramble to protect the planet, but “This is not the way to planetary defense,” Johnson said. Exploding an asteroid may be more dangerous because its pieces may be on a collision course with Earth.
But NASA is studying other ways to alter the motion of asteroids.
The DART spacecraft is a kinetic collider that can change the speed and trajectory of Dimorphos. If DART succeeds, it could be one tool to deflect asteroids.
Another option, Johnson said, is the gravitational tractor, which relies on the mutual gravity between a spacecraft and an asteroid to pull space rocks from its impact trajectory to a milder one.
Another technique is ion beam deflection, or firing an ion drive at an asteroid for extended periods of time until the ions change the asteroid’s speed and orbit.
But both take time.
“Any technology you can imagine to change the orbital velocity of an asteroid in orbit is a viable technology,” Johnson said.
An international forum called the Space Planning Commission has brought 18 national space agencies together to assess what might be best for an asteroid discharge, depending on its size and trajectory.
Johnson said finding and sizing dangerous asteroid populations is a priority for NASA and its international partners. A space telescope design called the Near-Earth Object Survey mission is currently under review.
Didymos will not be alone for long. To clear the fallout from the collision, the European Space Agency’s Hera mission will launch in 2024. The spacecraft, along with two CubeSats, will arrive at the asteroid system two years later.
Hera will study both asteroids, measure the physical properties of Demorphos, and examine the DART impact crater and the Moon’s orbit, with the goal of creating an effective planetary defense strategy.
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