The DART mission, or NASA’s Double Asteroid Redirection Test, takes off at 22.20 PT on 23 November aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California.
Following its launch in November, NASA will test its asteroid deflection technology in September 2022 to see how it affects the motion of a near-Earth asteroid in space.
The target of this asteroid deflection technology is Dimorphos, a small moon orbiting the asteroid Didymos near Earth. This will be the Agency’s first full – scale demonstration of this type of technology on behalf of planetary defense.
Near-Earth objects are asteroids and comets whose orbits place them within 30 million miles of Earth. It is a primary focus of NASA and other space organizations around the world to detect the threat from near-Earth objects or NEOs that could potentially cause serious damage.
Didymos and Dimorphos
Two decades ago, it turned out that a binary system involving an asteroid near Earth had a moon orbiting it, called Didymos. In Greek, Didymos means “twin”, which was used to describe how the larger asteroid, which is almost half a kilometer across, is orbited by a smaller moon that is 525 feet in diameter. At that time, the moon was known as Didymos b.
Kleomenis Tsiganis, a planetary scientist at Aristotle University of Thessaloniki and a member of the DART team, suggested that the moon be named Dimorphos.
“Dimorphos, which means ‘two forms’, reflects the status of this object as the first celestial body to have the ‘form’ of its orbit significantly altered by humanity – in this case by the DART impact,” Tsiganis said. “As such, it will be the first object known to humans of two, very different forms, one seen by DART before impact and the other seen by the European Space Agency’s Hera, a few years later.”
By September 2022, Didymos and Dimorphos will be relatively close to Earth and within 11 million kilometers of our planet. This is the perfect time for the DART mission to take place.
DART will deliberately crash into Dimorphos to change the asteroid’s motion in space, according to NASA. This collision will be detected by LICIACube, a companion CubeSat or cube satellite provided by the Italian space agency. CubeSat will travel on the DART and then be deployed from it before impact so it can record what is happening.
“Astronomers will be able to compare observations from terrestrial telescopes before and after DART’s kinetic impact to determine how much dimorphos’ orbital period changed,” said Tom Statler, DART program scientist at NASA headquarters, in a statement. “It’s the most important measurement that will tell us how the asteroid reacted to our deflection effort.”
A few years after the impact, the European Space Agency’s Hera mission will conduct a follow – up study on Didymos and Dimorphos.
While the DART mission was developed for the NASA Planetary Defense Coordination Office and led by the Johns Hopkins University Applied Physics Laboratory, the mission team will work with the Hera mission team under an international collaboration known as the Asteroid Impact & Deflection Assessment, or AIDA.
“DART is a first step in testing methods for dangerous asteroid bending,” said Andrea Riley, DART Program Manager at NASA Headquarters, in a statement. “Potentially dangerous asteroids are a global concern and we are pleased to work with our Italian and European counterparts to gather the most accurate data from this demonstration of kinetic impact.”
A mission of the former
Dimorphos was chosen for this mission because its size is relative to asteroids that could pose a threat to Earth.
The DART will crash into Dimorphos at a speed of 14,763.8 miles per hour. A camera on DART, called DRACO, and autonomous navigation software will help the spacecraft detect and collide with Dimorphos.
This rapid influence will only change Dimorpho’s speed, as it orbits Didymos by 1%, which does not sound like much – but it will change the moon’s orbital time by several minutes. This change can be observed and measured from ground-based telescopes on Earth. It will also be the first time humans have altered the dynamics of a solar system body in a measurable way, according to the European Space Agency.
Three years after the impact, Hera will study Dimorphos in detail, measure the physical properties of the moon, study the DART impact, and study its orbit.
It may sound like a long time to wait between the effect and the follow-up, but it is based on previous experience.
In July 2005, NASA’s Deep Impact spacecraft launched an 815-pound copper impact into a comet, Temple 1. But the spacecraft could not see the crater that resulted because the impact released tons of dust and ice. However, NASA’s Stardust mission in 2011 was able to characterize the impact — a 492-foot gash.
Together, the valuable data collected by DART and Hero will contribute to planetary defense strategies, especially understanding the kind of force needed to move the orbit of a near-Earth asteroid that could collide with our planet.
This article updates a story that was first published in June 2020.