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Double Asteroid Redirection Test (DART)

NSSDCA/COSPAR ID: 2021-110A

Description

The Double Asteroid Redirection Test (DART) mission is designed to evaluate the kinetic impact technique by striking an asteroid with a spacecraft at high relative velocity and observing the resulting change in orbit. The test involves flying the DART spacecraft at high relative velocity into the smaller of two asteroids that are co-orbiting in a binary pair, and using Earth-based observations before and after the impact to study the effects on the orbit. It will also carry the LICIA Cube CubeSat, which will be released prior to the encounter to image the impact and its result. DART along with the ESA Hera mission make up the international Asteroid Impact and Deflection Assessment (AIDA) collaboration.

The primary objective is to assess kinetic impact as a method for redirection of any future asteroids found to be on a trajectory to impact Earth, with the primary goals: (1) perform a full-scale demonstration of the spacecraft kinetic impact technique for deflection of an asteroid; (2) measure the resulting asteroid deflection, by targeting the secondary member of a binary NEO and measuring the resulting changes of the binary orbit; and (3) study hypervelocity collision effects on an asteroid, validating models for momentum transfer in asteroid impacts.

Spacecraft and Subsystems

The spacecraft is a box-shaped main bus with two large solar panel wings and a total mass at launch of approximately 610 kg. The spacecraft is 18 meters across its two solar panel wings and the main bus box is 1.14 x 1.24 x 1.32 meters. The bus is 2.6 meters high with the thruster and equipment mounted on the top and bottom, and structures on the sides extend to a width and depth of 1.8 x 1.9 meters. Propulsion will be provided by the NASA Evolutionary Xenon Thruster (NEXT-C) ion engine.

It will carry a single instrument, the Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO), which will provide images for the Small-body Maneuvering Autonomous Real-Time Navigation (SMARTNav) algorithm to be used for guidance, navigation, and control operations in targeting the asteroid, assisted by a star tracker and 5 Sun sensors. Orientation and propulsion are provided by 12 hydrazine thrusters. Communications are provided by a gimbaled high-gain radial-line-slot array antenna and two low-gain antennas. DRACO uses a 20.8 cm aperture, F/12.6 telescope with a field of view of 0.29 degrees providing images at a resolution of about 0.5 arcsec/pixel. The two Roll Out Solar Arrays (ROSA) extend from opposite sides of the bus, have a total area of 22 square meters, and are designed to produce 6.6 kilowatts with battery storage.

Mission Profile

DART launched on a Falcon 9 from Vandenberg Air Force Base on 24 November 2021 at 6:21:02 UT (1:21:02 a.m. EST). It will head to the binary S-type asteroid system 65803 Didymos, consisting of a primary, Didymos (formerly Didymos A), roughly 780 meters in diameter, and a secondary, Dimorphos (formerly Didymos B), approximately 163 meters across. En route to the system it may fly by the 578 meter diameter asteroid 2001 CB21 on about 6 March 2022.

It will reach the Didymos system in late September 2022, taking images during approach to constrain the size and shape of Didymos and Dimorphos. Impact is planned for sometime in a window from 26 September to 1 October, 2022. The LICIA Cube will be released about two days before impact. In the last 4 hours before impact, DART will employ the DRACO and SMARTNav systems to target the asteroid. During this time it will also be returning detailed images of the surface (better than 20 cm/pixel at impact) of Dimorphos to pinpoint the exact impact site within one meter and to determine the local surface geology for later impact modelling.

The spacecraft will fly into Dimorphos at approximately 6.58 km/sec with an impact mass of 560 kg. The final images returned 2 seconds before impact will have a resolution of 3 cm/pixel. The LICIACube will fly by about 3 minutes after impact, recording details of the impact plume and surfaces at resolutions up to 2 meters per pixel. After impact, Earth-based observations will continue in order to characterize the resulting change in orbit of Dimorphos induced by the impact. The distance to Earth at impact will be approximately 11.2 million km. (The ESA Hera mission is planned to fly by Didymos in 2026 for followup observations.)

The mass of the Didymos system is estimated at 528 billion kg, with Dimorphos at 4.8 billion kg. The impact will target the center of figure of Dimorphos and should decrease the orbital period of Dimorphos around Didymos, currently 11.92 hours, by roughly 10 minutes. Details of the surface structure, impact, and changes in the orbit recorded by ground-based observatories and the DART and LICIA Cube images will be used to determine the efficiency of impact kinetic energy transfer.

LICIACube

The LICIACube is a 6U CubeSat provided by the Italian Space Agency. It will be carried along with DART to Didymos and released approximately 2 days before the DART impact. LICIACube will perform a separation maneuver to follow behind DART and return images of the impact, the ejecta plume, and the resultant crater as it flies by. It will also image the opposite hemisphere from the impact. LICIACube is 3-axis stabilized and has a propulsion capability of 56 m/s. The onboard imager has a 7.6 cm aperture, F/5.2 telescope, and an IFOV of 2.9 arcsec/pixel.

For more information on the AIDA follow-up mission to Didymos, Hera, see:

https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=HERA

Image credit: NASA/Johns Hopkins Applied Physics Lab/Steve Gribben

Alternate Names

  • DoubleAsteroidRedirectionTest(DART)
  • DART
  • Asteroid Impact and Deflection Assessment (AIDA)
  • urn:nasa:pds:context:instrument_host:spacecraft.dart
  • 49497

Facts in Brief

Launch Date: 2021-11-24
Launch Vehicle: Falcon 9
Launch Site: Vandenberg AFB, United States
Mass: 670 kg
Nominal Power: 6600 W

Funding Agency

  • National Aeronautics and Space Administration (United States)

Discipline

  • Planetary Science

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams

 

Personnel

NameRoleOriginal AffiliationE-mail
Dr. Cheryl ReedProject ManagerApplied Physics Laboratoryheryl.reed@jhuapl.edu
Dr. Andrew F. ChengProject ScientistApplied Physics Laboratoryandrew.cheng@jhuapl.edu
Dr. Andy RivkinProject ScientistApplied Physics LaboratoryAndy.Rivkin@jhuapl.edu
Dr. Tom StatlerProgram ScientistNASA Headquartersthomas.s.statler@nasa.gov
Dr. Scott BellamyMission ManagerNASA Marshall Space Flight Centerkelly.scott.bellamy@nasa.gov

Selected References

  • Cheng, A. F., et al., AIDA DART Asteroid Deflection Test: Planetary Defense and Science Objectives, Planet. Space Sci., Vol. 157, 104-115, doi:10.1016/j.pss.2018.02.015, Aug. 2018.
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