The Double Asteroid Redirection Test mission, or DART, aims to see if this 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 motion of a natural celestial body in space. Humanity has never done anything like this before.”
Here’s what you need to know about this mission.
The DART spacecraft is about 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. Impact is expected at 19:14.
where is he going
The spacecraft is headed for a double asteroid system, where a small “moon” asteroid, called Dimorphos, orbits a larger asteroid, Didymos.
Didymos meaning “twin” in Greek, it is approximately 2,560 feet (780 meters). in diameter Dimorphos, meanwhile, measures 525 feet (160 meters) across, and its name means “two forms.”
At the time of impact, Didymos and Dimorphos will be relatively close to Earth, within 6.8 million miles (11 million kilometers).
Neither Dimorphos nor Didymos At risk of impact with Earth — before or after impact.
What will DART do?
DART is going down in a blaze of glory. It will set its sights on Dimorphos, accelerate to 13,421 miles per hour (21,600 kilometers per hour) and crash almost head-on into the moon.
The spacecraft is 100 times smaller than Dimorphos, so it won’t obliterate the asteroid.
Instead, DART will try to change the speed and path of the asteroid in space. The mission team compared this collision to a golf cart crashing into one of the Great Pyramids, with enough energy to leave an impact crater.
The impact will change Dimorphos speed by 1% as he orbits Didymos. It doesn’t seem like much, but doing so will change the moon’s orbital period.
The thrust will slightly change Dimorphos and more gravitationally bind Didymos; therefore, the collision will not change the binary system’s path around Earth or increase the chances of it becoming a threat to our planet.
What will we see?
The spacecraft will share its view of the double asteroid system through an instrument called the Didymos Reconnaissance and Asteroid Camera for Optical Navigation, or DRACO.
This imager, which serves as DART’s eye, will allow the spacecraft to identify the double asteroid system and distinguish which space object to hit.
Didymos and Dimorphos will appear as pinholes an hour before impact, gradually getting larger and more detailed in the frame.
Dimorphos has never been observed before, so scientists can finally understand its shape and surface appearance.
We should be able to see Dimorphos in great 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 until signal loss occurs and the end of DART’s mission, if successful.
Even the spaceship he has his own photojournalist along for the ride.
A briefcase-sized satellite from the Italian Space Agency carried it into space with DART. Called the Light Italian CubeSat for Imaging of Asteroids, or LICIACube, it was released from the spacecraft on September 11. The satellite follows DART to record what happens from a safe vantage point.
Three minutes after impact, LICIACube will fly past 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.
Images and video, while not immediately available, will be sent back to Earth in the days and weeks following the collision.
How will we know the mission? was it successful?
LICIACube will not be the only observer. The James Webb Space Telescope, the Hubble Space Telescope and NASA’s Lucy mission will observe the impact. The Didymos system may light up as its dust and debris are ejected into space, said NASA program scientist Statler.
But ground-based telescopes will be key to determining whether DART has successfully altered Dimorphos’ motion.
The Didymos system was discovered in 1996, so astronomers have many observations of the system. After the impact, observatories around the world will see them cross in front of Dimorphos and go behind Didymos.
It takes Dimorphos 11 hours and 55 minutes to complete one orbit of Didymos. If DART is successful, that time could be reduced to 73 seconds, “but we really think we’ll change it to about 10 minutes,” said Edward Reynolds, DART project manager at Johns Hopkins University’s Applied Physics Laboratory.
Statler said he would be surprised if the period change measurement came in a few days, but even more so if it took more than three weeks.
What if DART misses the asteroid and doesn’t hit?
“I’m very confident that we’re going to hit it on Monday, and it’s going to be a complete success,” said Lindley Johnson, NASA’s planetary defense officer.
But if DART loses its all-important dart board, the team will be ready to make sure the spacecraft is safe and download all its information to find out why it didn’t hit Dimorphos.
The Applied Physics Laboratory’s Mission Operations Center will intervene if necessary, although DART will operate autonomously for the last four hours of its journey.
It takes 38 seconds for a commando to travel from Earth to the spacecraft, so the team can react quickly. The DART team has 21 contingency plans that have been rehearsed, said Elena Adams, DART mission systems engineer at the Applied Physics Lab.
Why should we try this, and why on this asteroid?
Dimorphos was chosen for this mission because its size is comparable to asteroids that could pose a threat to Earth. An asteroid the size of Dimorphos could cause a “regional catastrophe” if it hit Earth.
The asteroid system is a “perfect natural laboratory” for the test, Statler said.
The mission will allow scientists to better understand the size and mass of each asteroid, which is critical to understanding near-Earth objects.
Near-Earth objects are asteroids and comets, with orbits that place them within 30 million miles (48.3 million kilometers) of Earth. Detecting the threat of near-Earth objects that could cause serious damage is the main focus of NASA and other space agencies around the world.
There are currently no asteroids directly impacting Earth, but there are over 27,000 near-Earth asteroids of all shapes and sizes.
The valuable data collected by DART will help in planetary defense strategies, especially in understanding what forces might change the orbit of a near-Earth asteroid that could collide with our planet.
Why don’t we blow up the asteroid, like in ‘Armageddon’?
the movies Approaching asteroids seems like a hasty battle to protect the planet, though “That’s no way to defend the planet,” Johnson said. Exploding an asteroid could be more dangerous because then its pieces could be on a collision course with Earth.
But NASA is exploring other methods of altering the motion of asteroids.
The DART spacecraft is considered a kinetic impactor that can change the speed and path of Dimorphos. If DART is successful, it could be a tool to deflect asteroids.
Another option is a gravity tractor, which relies on the mutual gravitational attraction between a spacecraft and an asteroid to pull the space rock out of its impact path to a more benign one, Johnson said.
Another technique is ion beam deflection, or firing an ion engine at an asteroid for a long time until the ions change the asteroid’s speed and orbit.
But these two take time.
“Any technique that changes the orbital speed of an orbiting asteroid is viable,” Johnson said.
An international forum called the Space Planning Commission has brought together 18 national space agencies to assess how best to deflect an asteroid, based on its size and trajectory.
Will any other spacecraft fly by Dimorphos in the future?
The Didymos system will not be alone for long. To study the effects 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 the two asteroids, measure the physical properties of Dimorphos, and study the DART impact crater and the moon’s orbit, with the goal of establishing an effective planetary defense strategy.