National Aeronautics and Space Administration

N A S A’ S F I R S T P L A N E TA R Y
DEFENSE TEST MISSION

The Double Asteroid
Redirection Test (DART)Developed and led for NASA by the Johns Hopkins
Applied Physics Laboratory (APL) in Laurel, Maryland, DART
demonstrated the planetary defense technique known as kinetic
impact on September 26, 2022. The DART spacecraft, which
launched on November 24, 2021, slammed into an asteroid andshifted its orbit, taking a critical step in demonstrating one way
to protect our planet from a potentially hazardous impact.
DART’s target was a binary asteroid system including Didymos(Greek for “twin”), about a half-mile across, and its smaller
companion called Dimorphos (Greek for “two forms”), about
530 feet across. DART relied on an autonomous targetingsystem to aim itself at Dimorphos. The spacecraft, roughly thesize of a vending machine, struck the smaller body at about
14,000 miles per hour. A ride-along CubeSat named LICIACube,
built by the Italian Space Agency, separated from DART before
impact to observe the collision. Telescopes on Earth and inspace observed the asteroid system and measured the change
in Dimorphos’ orbit around Didymos. DART’s impact alteredDimorphos’ orbit around Didymos by 32 minutes, shortening theorbit to 11 hours and 23 minutes.

Planetary Defense
On February 15, 2013, a meteor exploded over
Chelyabinsk, Russia, creating an airburst andshockwave that struck six cities across thecountry — and sending a stark reminder that
dangerous objects can enter Earth’s atmosphereat any time. Astronomers estimate there are tensof thousands of near-Earth asteroids close to500 feet wide and larger, big enough to cause
regional devastation if they actually hit Earth. The
Chelyabinsk object was just about 60 feet wide,
demonstrating that even small asteroids canbe of concern — and making real-world tests ofspace-based planetary defense systems all themore important.

The Impact
APL built the DART spacecraft and its single instrument, the Didymos
Reconnaissance and Asteroid Camera for Optical navigation. Known as
DRACO, the camera not only captured images of Didymos and Dimorphos,
but also supported DART’s onboard, APL-developed autonomous navigation
capability, the Small-body Maneuvering Autonomous Real Time Navigation(SMART Nav) algorithms, to direct the spacecraft toward its target.
The flawless operation of those systems positioned DART to unleash a streamof important data. The last close-up images of Dimorphos’ surface offer
critical insight into the asteroid’s structure and composition. The investigationteam continues to use data from ground- and space-based observatories toanalyze the “ejecta,” or the tons of rock displaced and launched into space by
the impact.
The recoil from the blast of debris substantially enhanced DART’s pushagainst Dimorphos — a little like a jet of air streaming out of a balloon sends
the balloon in the opposite direction. And as new information comes in eachday, astronomers can better assess whether, and how, a mission like DART
could be used to help protect Earth from a collision with an asteroid if we everdiscover one headed our way.

The last complete image of asteroid moonlet
Dimorphos, taken by the DRACO imager on NASA’sDART spacecraft approximately 7 miles (12 kilometers)from the asteroid and 2 seconds before impact. Theimage shows a patch of the asteroid that is 100 feet(31 meters) across. Dimorphos’ north is toward the topof the image.
Credit: NASA/Johns Hopkins APLThe Team
Planetary defense is an international concern; that’s why the DART teamis drawing on expertise from around the world to evaluate the mission’s
results and enable planning for future planetary defense efforts.
NASA’s Planetary Defense Coordination Office supervises NASA-sponsored projects to find andcharacterize asteroids and comets that pass near Earth’s orbit and coordinates development oftechniques and technologies to respond to an identified impact threat. In addition to managing
the mission and building and operating the DART spacecraft, APL is also coordinating theinvestigation team.
U.S. partner institutions include NASA Goddard Space Flight Center, Johnson Space Center,Langley Research Center, Glenn Research Center, Marshall Space Flight Center, Kennedy Space
Center, and Launch Services Program; Jet Propulsion Laboratory; SpaceX; Aerojet Rocketdyne;
Lawrence Livermore National Laboratory; Auburn University; Carnegie Science Las Campanas
Observatory; University of Colorado; Las Cumbres Observatory; Lowell Observatory; Universityof Maryland; New Mexico Tech with Magdalena Ridge Observatory; Northern Arizona University;
Planetary Science Institute; and U.S. Naval Academy.

For more information about DART, visit:

Imagery from NASA’s Hubble Space Telescope from Oct. 8,2022, shows the debris blasted from the surface of Dimorphos
285 hours after the asteroid was intentionally impacted by NASA’s
DART spacecraft on Sept. 26. The shape of that tail has changed
over time. Scientists are continuing to study this material and how
it moves in space in order to better understand the asteroid.
Credits: NASA/ESA/STScI/Hubble

nasa.gov/planetarydefense/dart

dart.jhuapl.edu

JHUAPL_22-05061_11.21.22