NASA's DART Spacecraft Crashes Into Asteroid In First Planetary Defense Test

Keneci Channel

The Double Asteroid Redirection Test (DART) spacecraft slammed into a small asteroid, Dimorphos at about 2314 UTC, Sept. 26. Scientists at the National Aeronautics and Space Administration hope the Spacecraft, which was obliterated on impact, will alter the moonlet's orbit by a fraction of a percent, and prove that humans have the ability to deflect any such incoming hazardous space rock.

Though Dimorphos poses no threat, the risk of a catastrophic asteroid impact on Earth is remote but real, according to NASA scientists. The space agency has found about 40% of the large asteroids as wide as 500 feet (140 meters) that could pose a threat to the Earth and regularly scans the sky for more.

The DART mission was designed to test a method of deflecting an asteroid for planetary defense, using the "kinetic impactor" technique. The spacecraft's target was the binary asteroid system Didymos, which means "twin" in Greek. The system consists of a near-Earth asteroid Didymos measuring 0.48 miles (780 meters) across and its moonlet Dimorphos measuring 525 feet (160 meters) across.

According to NASA, DART deliberately impacted the moonlet Dimorphos at speeds of 4.1 miles per second (6.6 km/s or 23,760 kph). An impact at this speed should cause the moonlet's orbital speed to change by a fraction of a percent and this shift should be enough to change its orbital period by several minutes. The change in Dimorphos' orbit around Didymos will be observed and measured by telescopes on Earth, to see whether the mission has succeeded.

The DART spacecraft is a box-shaped main vehicle measured roughly 3.9 x 4.3 x 4.3 feet (1.2 x 1.3 x 1.3 meters) — about the size of a refrigerator. Each of the two large solar arrays was 27.9 feet (8.5 meters) long when fully deployed. The DART spacecraft contained just one instrument — Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO).

The DART mission was launched at 0620 UTC Nov. 24, atop a SpaceX Falcon 9 rocket from the Space Launch Complex 4 at the Vandenberg Space Force Base in California.

Once launched, the DART spacecraft deployed its Roll-Out Solar Arrays (ROSA) to power itself for the journey to Didymos. According to NASA, scientists tested the ROSA arrays onboard the International Space Station in June 2017 and were deemed suitable to provide the power required to support DART's electric propulsion system. NASA had added larger versions of the ROSA arrays to the space station's power grid.

The DART spacecraft also used the next-generation, fuel-efficient NASA Evolutional Xenon Thruster-Commercial (NEXT-C) solar electric propulsion system as part of its in-space propulsion.

The DART mission is managed by the John Hopkins University Applied Physics Laboratory (JHUAPL), with contribution from scientists and engineers from around the world.

According to Ellen Howell, a senior research scientist at the University of Arizona Lunar and Planetary Laboratory and a co-investigator for DART, "We've worked really closely with our European colleagues and colleagues all over the world." She said such level of international cooperation would be essential if a real hazardous asteroid is about to hit the Earth.

Early detection of near-Earth asteroids is the first step in planetary defense. Approximately 30 new discoveries of near-Earth asteroids are made each week, and at the start of 2019, there were more than 19,000 discovered near-Earth asteroids according to NASA.

WATCH the moment DART spacecraft impacted Dimorphos.