On 24 November, NASA’s Double Asteroid Redirection Test (DART) mission got under way with the aim of defending the Earth from possible asteroid attacks. The mission represents just one part of the huge scenario concerning the defense strategies supported by NASA. The mission was developed and led by Johns Hopkins member of the Applied Physics Laboratory (APL) in Maryland. The aim of the mission will be to target the asteroid Dimorphos, the smallest of the Didymos complex, which consists of two asteroids. Dimorphos has a diameter of about 530 feet (160 meters), while Didymos has a diameter of about 2,560 feet (780 meters).

The kinetic impact of DART can be measured much more easily than a change in the orbit of a single asteroid around the Sun. The reason is that Dimorphos orbits Didymos at a much lower relative velocity than the pair orbiting the Sun. This mission will be a test of whether we will be able to save ourselves from a possible asteroid impact on Earth.

The first stages of the mission

The launch vehicle used to launch the mission was SpaceX’s Falcon 9. About an hour after the rocket lifted off from the launch pad, the second stage of the rocket separated. A few minutes later, the mission operators (the Earth station in charge of monitoring the mission) received the first telemetry signals.

The satellite was oriented to reach its optimum position relative to the Sun. This allowed the deployment of the 8.53-metre-wide solar panels. They will power both the spacecraft and the Evolutionary Xenon Thruster, the ion engine developed by NASA. Environmental tests, which took place a year before the launch, verified that the thruster can withstand the vibrations and extreme temperatures of space flight. This is also a new technology that will be tested on this very mission.

What will happen in 11 months?

In less than a year, the DART mission will have to hit its target like a bullet: the asteroid Dimorphos. The kinetic impact between the two bodies in question will serve to change, slightly, the direction of the asteroid. In this way, the Dart mission will demonstrate that a spacecraft is capable of navigating autonomously towards its target. The added value for the spacecraft is the ability to intentionally impact towards a hazard. This test will serve as a guinea pig to collect important data that will allow us to be prepared for a possible defence against a particularly dangerous asteroid. The motion of the asteroid will be measured by the installation of ground-based telescopes on board DART.

Lindley Johnson, Planetary Defense Officer at NASA Headquarters says:

“We have not yet found any significant threat of asteroid impact on Earth. We continue to look for that sizable population that we know is yet to be found. Our goal is to find any possible impact, years or decades in advance, so that it can be deflected.

The impact will occur between 26 September and 1 October 2022 at about 6 km/s. Scientists say the impact will shorten the asteroid’s orbit around its complex. Researchers, however, will validate this theory quantitatively by measuring the deviation of Dimorphos.

Instrumentation used by the DART mission

DRACO Didymos Reconnaissance and Asteroid Camera for Optical navigation is the instrument that will provide the first images of the asteroid. It will be switched on one week before impact. The other system on board is the SMART Nav (Small-body Maneuvering Autonomous Real Time Navigation), a sophisticated guidance system. It will enable the spacecraft to distinguish between the two asteroids, directing it towards Dimorphos. The mission is being monitored and controlled by several ground stations:

• the Jet Propulsion Laboratory in southern California
• the Goddard Space Flight Center in Greenbelt, Maryland
• the Johnson Space Center in Houston
• the Glenn Research Center in Cleveland
• the Langley Research Center in Hampton, Virginia

The launch is managed by NASA’s Launch Services Program, based at the agency’s Kennedy Space Center in Florida.

Italian contribution to the DART mission

The small satellite on board DART: LiciaCube is all Made in Italy. It was built by a Turin-based company Argotec, in collaboration with the Italian Space Agency (Asi), which works in the field of microsatellites. The LiciaCube will have the task of filming the impact to declare the success of the mission. The satellite will go to work about 10 days before impact and once separated from DART, it will travel autonomously to film the impact. It will be equipped with two cameras Leia (Liciacube Explorer Imaging for Asteroid) and Luke (Liciacube Unit Key Explorer). LiciaCube will be the first Italian satellite farthest from Earth and will be operated only by Italians.