But the real test of this asteroid deflection technique will take place in September 2022, when the spacecraft reaches its destination, to see how it affects the motion of a near-Earth asteroid in space.
Near-Earth objects are asteroids and comets whose orbits lie within 30 million miles (48 million kilometers) of Earth. Threat detection of near-Earth objects, or NEOs, which can potentially cause serious damage, is a primary focus of NASA and other space organizations around the world.
Asteroid Didymos and its moon Dimorphos
In Greek, Didymos means “twin”, which is an indication of how the asteroid – about half a mile (0.8 kilometers) across – forms a binary system with the smaller asteroid, or moon – 525 feet (160 m) across. in diameter – which was discovered two decades ago. Clemenis Cygnis, a planetary scientist at Aristotle University in Thessaloniki and a member of the DART team, suggested that the moon be named Dimorphos, which means “two forms.”
This is the right time for the dart mission to happen. Didymos and Dimorphos will be relatively close to Earth — within 6,835,083 miles (11 million kilometers) — in September 2022. The spacecraft will come at a speed of about 15,000 miles (24,140 kilometers) per hour, targeting Dimorphos, said Nancy Chabot, DART coordinating lead at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
A camera on the spacecraft, called DRACO, and autonomous navigation software will help the spacecraft detect and hit Dimorphos. The acronym for DRACO is Didymos Reconnaissance and Asteroid Camera for OpNav.
According to NASA, the purpose of the mission is to intentionally crash into Dimorphos in order to alter the asteroid’s motion in space. The collision will be recorded by LICIACube, or Light Italian CubeSat for Imaging of Asteroids, a companion Cube satellite provided by the Italian Space Agency. This is the first deep space mission of the Italian Space Agency.
The briefcase-sized CubeSat will travel on Dart and then be deployed before impact to record what happens. Three minutes after impact, the CubeSat will fly by Dimorphos to capture images and video.
Video of the impact will be streamed back to Earth, which should be “quite exciting,” said Elena Adams, a Dart mission systems engineer at the Johns Hopkins Applied Physics Laboratory.
“Astronomers will be able to compare observations from Earth-based telescopes before and after Dart’s kinetic impact to determine how much the orbital period of Dimorphos changed,” Tom Statler, Dart program scientist at NASA Headquarters, said in a statement. Has been.” “That’s the key measurement that will tell us how the asteroid responded to our deflection effort.”
A few years after impact, the European Space Agency’s HERA mission will conduct follow-up investigations of Didymos and Dimorphos.
While the DART mission was developed for the NASA Planetary Defense Coordination Office and managed by the Johns Hopkins University Applied Physics Laboratory, the mission team will work with the HERA mission team as part of an international collaboration called the Asteroid Impact and Deflection Assessment, or AIDA. is known as.
“DART is the first step in methods for testing dangerous asteroid deflections,” Andrea Riley, DART program executive at NASA Headquarters, said in a statement. “Potentially hazardous asteroids are a global concern, and we are excited to work with our Italian and European partners to collect the most accurate data possible from this kinetic impact deflection demonstration.”
Dimorphos was chosen for this mission because its size is relative to asteroids that could pose a threat to Earth, but the double asteroid system itself is not a threat to Earth.
The spacecraft is about 100 times smaller than Dimorphos, so it will not obliterate the asteroid.
“It’s not going to destroy the asteroid, it’s just going to give it a small nudge and deflect its path around the larger asteroid,” Chabot said. This means there is no chance of changing the asteroid’s trajectory to further jeopardize it.
The accelerating effect would only change the speed of Dimorphos as it orbits Didymos by up to 1%, which doesn’t sound like much — but it would change the Moon’s orbital period by more than a minute. That change can be observed and measured on Earth with telescopes on the ground.
Dimorphos completes an orbit of Didymos every 11 hours and 55 minutes. If the impact is successful, it would change that duration to at least 73 seconds, said Andy Cheng, lead of the DART investigation team at the Johns Hopkins Applied Physics Lab.
Measuring the momentum transfer between the spacecraft and the dimorphos would reveal how much is needed to change the asteroid’s course.
“If one day an asteroid is discovered on a collision course with Earth, we’ll know exactly how much speed we need for that asteroid to miss Earth,” Cheng said.
Planet Defense Strategies
While there are currently no asteroids on a direct impact course with Earth, there is a large population of near-Earth asteroids – over 27,000 in all shapes and sizes.
“The key to protecting planets is finding them well before they are threatened by impact,” said Lindley Johnson, planetary defense officer at NASA Headquarters. “The principle with all of them is to only change the asteroid’s orbital speed by only a small amount. Changing that speed in the asteroid’s orbit changes its orbit, so in the future, it won’t be in the same place it was on Earth.” It’s going to impress.”
Three years after the impact, Hera will arrive to study Dimorphos in detail, measure the Moon’s physical properties, study the Dart impact and the Moon’s orbit.
It may seem like a long time to wait between impact and follow-up, but it is based on lessons learned in the past.
In July 2005, NASA’s Deep Impact spacecraft launched an 815-pound (370-kg) copper impactor into a comet, Temple 1. But the spacecraft was not able to see the crater, which resulted in tons of dust and ice being released from the impact. However, in 2011 NASA’s Stardust mission was able to characterize the impact—a 492-foot (150-meter) wound.
Together, the valuable data collected by DART and HERA will contribute to planetary defense strategies, in particular to understand what types of force are needed to shift the orbit of a near-Earth asteroid colliding with our planet. Is.
After analyzing the results of the mission, “this technology will be a part of a toolbox that we are starting to build capabilities for to deflect the asteroid,” Johnson said.