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NASA will launch the DART spacecraft that will reach a double asteroid and try to divert its moon from its orbit

The Double Asteroid Redirection Experiment (DART) mission was designed to test the planetary defense capability in the event of a threatened asteroid impact on Earth

Schematic illustration of the DART mission showing the lunar impact of the asteroid (65803) Didymus. Observations after the collision from optical telescopes on Earth and a planetary radar will measure the change in the Moon's orbit around the main body. Figure: NASA
Schematic illustration of the DART mission showing the lunar impact of the asteroid (65803) Didymus. Observations after the collision from optical telescopes on Earth and a planetary radar will measure the change in the Moon's orbit around the main body. Illustration: NASA

The Double Asteroid Redirection Experiment (DART) mission is assigned by NASA to the Applied Physics Laboratory (APL) with support from several NASA centers: the Jet Propulsion Laboratory (JPL), Goddard Space Flight Center (GSFC), Space Center III Venson (JSC), Glenn Research Center (GRC) and Langley Research Center (LRC).

DART is a planetary defense experiment of technologies to prevent the collision of a dangerous asteroid with the Earth. DART will be the first demonstration of the kinetic collider technique to alter the motion of an asteroid in space. The DART mission is in Phase C, led by APL and managed as part of NASA's Solar System Exploration Program at the Marshall Space Flight Center for NASA's Planetary Defense Coordination Office and the Planetary Science Division of the Science Mission Administration at NASA Headquarters in Washington.

Two different views of the DART spacecraft. The DRACO imager is based on New Horizons' LORRI high-resolution imager. The left view also shows the RLSA (Radial Lined Solar Slot Array) antenna with the ROSA (Rotated Solar Arrays) folded away. The view to the right shows a clearer view of the NEXT-C ion engine. Image: NASA
Two different views of the DART spacecraft. The DRACO imager is based on New Horizons' LORRI high-resolution imager. The left view also shows the RLSA (Radial Lined Solar Slot Array) antenna with the ROSA (Rotated Solar Arrays) folded away. The view to the right shows a clearer view of the NEXT-C ion engine. Illustration: NASA

The near-Earth binary asteroid (65803) Didymus is the target of the DART demonstration. Didymus' main body is about 780 meters long, but its secondary (or "moon") body is about 160 meters in size, which is more typical of the size of asteroids that could pose the most likely significant threat to Earth. The double asteroid Didymus is being intensively observed by ground-based telescopes to precisely measure its properties before DART arrives.

Fourteen Arecibo Radar images of the near-Earth asteroid (65803) Didymus and its moon, taken on November 23, 24, and 26, 2003. The capabilities of NASA's Planetary Radar allow scientists to distinguish the shape, large globules and rocks possible on the surface of these small worlds. Photometric light curve data showed that Didymus is a binary system, and radar images clearly show the secondary body.

The diameter of the main body is about 780 meters and the size of the moon is about 160 meters. The distance between them is a little more than a kilometer. The main body rotates every 2.26 hours and the tidally locked moon rotates around the main body every 11.92 hours. Almost one-sixth of the population of known near-Earth asteroids are double or multi-body systems.

Imaging image of the Didymos system, produced from photometric light curve and radar data Naidu et al., AIDA Workshop, 2016
Imaging image of Didymos system, produced from photometric light curve and radar data Naidu et al., AIDA Workshop, 2016

The DART spacecraft will achieve the diversion by means of a kinetic approach by self-directed crash into the Moon at a speed of approximately 6.6 km per second, aided by an onboard camera (named DRACO) and sophisticated autonomous navigation software. The collision will change the speed of the moon in its orbit around the main body by a fraction of a percent, but it will change the moon's orbital period by a few minutes - enough for telescopes on Earth to notice and measure.

Once launched, DART will deploy its deployable solar arrays (ROSA) to provide the solar electricity needed for DART's electric propulsion system. The DART spacecraft will demonstrate the NEXT-C solar electric propulsion system as part of its propulsion in space. NEXT-C is a next-generation system based on the propulsion system of the Dawn spacecraft, and was developed at NASA's Glenn Research Center in Cleveland, Ohio. By using electric propulsion, DART can enjoy great flexibility in the mission schedule while demonstrating the next generation of ion engine technologies, with applications in future NASA missions. The ROSA array was tested on the International Space Station in June 2017.

The ROSA array was tested on the International Space Station in June 2017. Photo: NASA
The ROSA array was tested on the International Space Station in June 2017. Photo: NASA

The launch window for the DART spacecraft begins in late July 2021. DART will be launched on a SpaceX Falcon 9 rocket from Vandenberg Air Force Base, California. After separating from the launch vehicle and more than a year of cruising, it will intercept the Didymos moon at the end of September 2022, when the Didymos system will be within 11 million km of Earth, which allows ground telescopes to make observations and a planetary radar to make measurements of the change in momentum that will be imparted to the moon.

Illustration of the DART spacecraft with the deployable solar arrays (ROSA) deployed. The dimensions of each of the ROSA arrays are 8.6 meters by 2.3 meters. Image: NASA
Illustration of the DART spacecraft with the deployable solar arrays (ROSA) deployed. The dimensions of each of the ROSA arrays are 8.6 meters by 2.3 meters. Illustration: NASA

 

Details on the double asteroid Didymus and the DART mission

Disclosure (by Joe Montany, Spachwatch, KPNO) April 11 1996
Temporary marking 1996 GT
discrimination 2.2755 XNUMX
perihelion 1.0141 XNUMX
semi-heliocentric major axis (a) 1.64444 XNUMX
eccentricity (e) 0.38388
coffee cycle (around the sun) 2.11 years
Heliocentric tilt of the lap (i) ˚3.4078
Known satellites 1
rotation cycle (of the main body) 2.26 hours
Distance between the primary and the lunar 1.18 km
The monthly coffee cycle 11.92 hours (locked in tide lock)
the main diameter 780 meter
The diameter of the moon 160 meter
The mass of the system 527.8 billion
density 1.7 (±0.4) g/cc
spectral type Xk (optical); S (infrared)
Absolute size H 18.16
Last close approach to Israel (November 2003) 7.18 million km
Close approach to the DART mission (October 2022) 11 million km

To the article on the NASA website

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