Double Asteroid Redirection Test

Double Asteroid Redirection Test
Name	Double Asteroid Redirection Test
Mission type	Planetary defense technology demonstration
Operator	NASA / Johns Hopkins Applied Physics Laboratory
Spacecraft	DART
Manufacturer	Johns Hopkins Applied Physics Laboratory
Launch date	24 November 2021
Launch rocket	Falcon 9
Launch site	Vandenberg Space Force Base
Deployed from	SpaceX
Impact date	26 September 2022
Target	Dimorphos (moon of Didymos)
Programme	NASA's Planetary Defense Coordination Office
Previous mission	None
Next mission	Hera (spacecraft)

Double Asteroid Redirection Test was a groundbreaking NASA mission designed to test a method of deflecting an asteroid by kinetic impact. Conducted by the Johns Hopkins Applied Physics Laboratory under the direction of NASA's Planetary Defense Coordination Office, it was humanity's first full-scale planetary defense experiment. The mission successfully impacted the small moon Dimorphos, which orbits the larger asteroid Didymos, altering its orbit and demonstrating the viability of the kinetic impactor technique.

Mission overview

The primary objective was to assess the feasibility of deflecting a potentially hazardous near-Earth object by deliberately crashing a spacecraft into it at high speed. This concept, known as a kinetic impactor, was a key strategy considered by planetary defense experts. The mission targeted the binary asteroid system 65803 Didymos, specifically its moonlet Dimorphos, as a safe and observable test subject. International partners, including the Italian Space Agency which contributed the LICIACube cubesat, supported the effort to gather critical data.

Spacecraft design

The DART spacecraft was a relatively simple, box-shaped vehicle with a mass of approximately 610 kilograms at impact. Its sole instrument for autonomous navigation was the Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO), a high-resolution camera derived from the New Horizons spacecraft's LORRI imager. Propulsion was provided by the innovative NASA Evolutionary Xenon Thruster–Commercial (NEXT-C) ion thruster, and it deployed two Roll-Out Solar Arrays (ROSA) for power, technology previously tested on the International Space Station. A key technological achievement was the Small-body Maneuvering Autonomous Real Time Navigation (SMART Nav) system, which guided the spacecraft to its final impact point without human intervention.

Target asteroid system

The mission's target was the near-Earth asteroid 65803 Didymos, a member of the Amor asteroid group. Didymos is a roughly 780-meter-diameter asteroid orbited by a 160-meter moonlet, Dimorphos. This binary system was an ideal natural laboratory because the orbit of Dimorphos around Didymos could be precisely measured from Earth using ground-based telescopes like those at the Lowell Observatory and the Las Cumbres Observatory. Prior to impact, extensive observation campaigns were conducted by facilities worldwide, including the Very Large Telescope in Chile and the Hubble Space Telescope.

Impact and results

On 26 September 2022, the DART spacecraft collided with Dimorphos at approximately 6.1 kilometers per second. The impact was observed by LICIACube, which flew by three minutes later, and by numerous telescopes such as Hubble and the James Webb Space Telescope. Data confirmed the impact shortened Dimorphos's orbital period around Didymos by 33 minutes, far exceeding the pre-defined success threshold of 73 seconds. The event created a vast debris plume, effectively turning Dimorphos into an active asteroid, and significantly increased the moonlet's orbital eccentricity.

Scientific and planetary defense implications

The mission proved that a spacecraft's kinetic energy can substantially alter an asteroid's trajectory, validating a core planetary defense technique. The large momentum transfer, enhanced by ejecta from the impact, was measured by follow-up observations from the Atacama Large Millimeter Array and the Southern Astrophysical Research Telescope. These findings are crucial for agencies like the European Space Agency, which is developing the follow-up Hera (spacecraft) mission to perform a detailed post-impact survey. The success informs future strategies for mitigating threats from objects like Bennu, studied by the OSIRIS-REx mission.

Mission timeline

Development was authorized by NASA in 2017, with the Johns Hopkins Applied Physics Laboratory leading the build. The spacecraft launched on a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California on 24 November 2021. After a ten-month cruise, it performed its final maneuver and impacted Dimorphos on 26 September 2022. The European Space Agency's Hera (spacecraft) mission is scheduled to arrive at the Didymos system in 2026 to conduct a detailed forensic analysis of the impact effects.

Category:NASA spacecraft Category:Asteroids Category:2021 in spaceflight Category:Planetary defense