The DART mission is about to collide with an asteroid

The Double Asteroid Redirection Test, or DART, mission aims to see if this type of kinetic impact can help deflect an asteroid that poses a threat to Earth.

“We’re moving an asteroid,” said Tom Statler, NASA’s program scientist for the DART mission. “We are changing the movement of a natural celestial body in space. Humanity has never done this before.”

Here’s what you need to know about this mission.

The DART spacecraft is the size of a school bus. It has traveled to reach its asteroid target since launch in November 2021. The spacecraft will arrive at the asteroid system on September 26. The impact is expected at 7:14 pm ET.

Where are you going?

The spacecraft is heading towards a dual asteroid system, where a tiny “lunar” asteroid, called Dimorphos, orbits a larger asteroid, Didymos.

didimo. which means “twin” in Greek, is approximately 2,560 feet (780 meters) in diameter. Meanwhile, Dimorphos measures 525 feet (160 meters) in diameter and his name means “two forms”.

Upon impact, Didymos and Dimorphos will be relatively close to Earth, within 6.8 million miles (11 million kilometers).

Neither Dimorphos nor Didymos are at risk of collision with the Earth, before or after the collision.

What will DART do?

DART is plunging into a blaze of glory. He will set his sights on Dimorphos, accelerate to 13,421 miles per hour (21,600 kilometers per hour) and crash almost head-on to the moon.

The spacecraft is about 100 times smaller than Dimorphos, so it won’t wipe out the asteroid.

Instead, DART will try to change the speed and path of the asteroid in space. The mission team likened this collision to a golf cart crashing into one of the Great Pyramids – enough energy to leave an impact crater.

The impact will change Dimorphos’ speed by 1% as it orbits Didymos. It doesn’t seem like much, but doing so will change the orbital period of the moon.

The thrust will shift Dimorphos slightly and make it more gravitationally bound to Didymos, so the collision will not change the path of the binary system around Earth or increase its chances of becoming a threat to our planet.

What will we see?

The spacecraft will share its vision of the double asteroid system through an instrument known as the Didymos Reconnaissance and Asteroid Camera for Optical Navigation, or DRACO.

This imager, which acts as DART’s eyes, will allow the spacecraft to identify the double asteroid system and distinguish which space object it should strike.

This tool is also a high-resolution camera that aims to capture images of the two asteroids to be streamed to Earth at the rate of one image per second in what will look almost like video. You can watch the live stream on the NASA website, starting at 6:00 PM ET Monday.

Didymos and Dimorphos will appear as dots of light about an hour before impact, gradually becoming larger and more detailed in the frame.

Dimorphos has never been observed before, so scientists can finally take its shape and surface appearance into consideration.

We should be able to see Dimorphos in exquisite detail before DART crashes into it. Given the time it takes for the images to return to Earth, they will be visible for eight seconds before a signal loss occurs and the DART mission ends if successful.

Even the spaceship he has his photojournalist with him for the trip.

A satellite the size of an Italian Space Agency briefcase hitchhiked the DART into space. Called Light Italian CubeSat for Imaging of Asteroids, or LICIACube, it detached from the spacecraft on September 11th. The satellite is traveling behind DART to record what’s going on from a safe perspective.

Three minutes after the impact, LICIACube will fly close to Dimorphos to capture images and video of the impact plume and maybe even spy on the impact crater. The CubeSat will turn to keep its cameras pointed at Dimorphos as it flies.

The images and video, although not immediately available, will be retransmitted to Earth in the days and weeks following the collision.

How will we know if the mission it has been successful?

The LICIACube will not be the only observer to watch. The James Webb Space Telescope, the Hubble Space Telescope and NASA’s Lucy Mission will observe the impact. The Didymos system could light up when its dust and debris are ejected into space, said Statler, the NASA program scientist.

But ground-based telescopes will be critical in determining whether DART has successfully modified Dimorphos’ motion.

The Didymos system was discovered in 1996, so astronomers have many observations of the system. After the impact, observers around the world will observe Dimorphos passing through and moving behind Didymos.

Dimorphos takes 11 hours and 55 minutes to complete an orbit of Didymos. If DART is successful, that time could decrease by 73 seconds, “but we actually think we’re going to 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 a measurement of the period change came in less than a few days, but even more if it took more than three weeks.

What if DART is missing and doesn’t hit the asteroid?

“I am very confident that we would have hit on Monday and it will be a complete success,” said Lindley Johnson, NASA’s planetary defense officer.

But if DART loses its proverbial dartboard, the team will be ready to ensure the spacecraft is safe and all its information is downloaded to figure out why it didn’t hit Dimorphos.

The Mission Operations Center of the Applied Physics Laboratory will intervene if necessary, even if DART will have operated independently for the last four hours of its journey.

It takes 38 seconds for a command to travel from Earth to the spacecraft, so the team can react quickly. The DART team has 21 contingency plans they’ve tried, said Elena Adams, a DART mission systems engineer at the Applied Physics Lab.

Why do we have to test it and why on this asteroid?

Dimorphos was chosen for this mission because its size is comparable to that of asteroids that could pose a threat to Earth. An asteroid the size of Dimorphos could cause “regional devastation” if it hits Earth.

The asteroid system is “the perfect natural laboratory” for testing, Statler said.

The mission will allow scientists to have a better understanding of the size and mass of each asteroid, which is critical for understanding objects close to Earth.

Near-Earth objects are asteroids and comets with an orbit that places them within 30 million miles (48.3 million kilometers) of Earth. Detecting the threat of near-Earth objects that could cause severe damage is a primary goal of NASA and other space organizations around the world.

No asteroids are currently on a direct impact course with Earth, but there are more than 27,000 near-Earth asteroids of all shapes and sizes.

Valuable data collected by DART will contribute to planetary defense strategies, particularly understanding what kind of force can move the orbit of an asteroid close to Earth that could collide with our planet.

Why don’t we blow up the asteroid, like in “Armageddon”?

Movie making asteroid combat approaches seem like a rushed race to protect the planet, but “This is not the way to do planetary defense,” Johnson said. Blowing up an asteroid could be more dangerous because its pieces could be on a collision course with Earth.

But NASA is considering other ways to change the motion of asteroids.

The DART spacecraft is considered a kinetic simulation device that could change the speed and path of Dimorphos. If DART is successful, it could be a tool for deflecting asteroids.

Another option is a gravity tractor, which relies on the mutual gravitational pull between a spacecraft and an asteroid to pull space rock out of its impact trajectory into a more benign one, Johnson said.

Another technique is the deflection of the ion beam or firing an ion engine at an asteroid for long periods of time until the ions change the speed and orbit of the asteroid.

But they both take time.

“Any technique you can imagine that changes the orbital velocity of the asteroid in orbit is a viable technique,” Johnson said.

An international forum called the Space Planning Commission brought together 18 national space agencies to assess what might be best to deflect an asteroid, depending on its size and path.

Finding dangerous asteroid populations and determining their size are priorities for NASA and its international partners, Johnson said. The project for a space telescope called the Near-Earth Object Surveyor mission is currently under review.

Will any other spacecraft fly to Dimorphos in the future?

The Didymos system won’t be alone for too long. To examine the consequences of the impact, the European Space Agency’s Hera mission will be launched in 2024. The spacecraft, along with two CubeSats, will arrive at the asteroid system two years later.

Hera will study both asteroids, measure Dimorphos’ physical properties, and examine the DART impact crater and orbit of the moon, with the aim of establishing an effective planetary defense strategy.


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