Double Asteroid Redirection Test (DART) Mission: NASA

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    Context

    • NASA will launch the agency’s first planetary defence test mission named the Double Asteroid Redirection Test (DART) on November 24, 2021.

    About the DART Mission 

    • It is a planetary defence-driven test of technologies for preventing an impact on Earth by a hazardous asteroid. 
    • The spacecraft will be launched on a SpaceX Falcon 9 rocket from Vandenberg Space Force Base in California.
    • Objectives: DART is the first technology demonstration of the kinetic impactor technique that could be used to mitigate the threat of an asteroid hitting Earth. 
      • The kinetic impactor mitigation technique is the impulsive deflection of the asteroid through the sudden addition of momentum. In simpler terms, DART is being sent to collide with an asteroid to change its orbital period.
    • Configuration 
      • Weight : A considerably low-cost spacecraft DART weighs about 610 KG at the time of its launch and will shed a little of its weight during its flight and weigh about 550 KG during the impact. 
      • Structure: The main structure is a box (1.2 × 1.3 × 1.3 metres). It has two solar arrays and uses hydrazine propellant for manoeuvring the spacecraft.
      • The spacecraft has been appended with a high-resolution imager called Didymos Reconnaissance and Asteroid Camera for Optical Navigation (DRACO) which will give precise images and information to the scientists to study the impact of the collision on the trajectory of the asteroid.
      • DART will also carry a small satellite or CubeSat named LICIACube (Light Italian CubeSat for Imaging of Asteroids).

    Image Courtesy : NASA

    [Two different views of the DART spacecraft. The DRACO (Didymos Reconnaissance & Asteroid Camera for OpNav) imaging instrument is based on the LORRI high-resolution imager from New Horizons. The left view also shows the Radial Line Slot Array (RLSA) antenna with the ROSAs (Roll-Out Solar Arrays) rolled up. The view on the right shows a clearer view of the NEXT-C ion engine.]

    Targeted asteroid by the DART mission

    • It will target Dimorphos, the much smaller “moonlet” of a binary (two-body) asteroid system .
    • Dimorphos orbits a larger asteroid named Didymos (Greek for “twin”) which has a diameter of 780 metres
    • Why Dimorphos?
      • Didymos is a perfect system for the test mission because it is an eclipsing binary which means it has a moonlet that regularly orbits the asteroid and it can be seen when it passes in front of the main asteroid. 
      • Earth-based telescopes can study this variation in brightness to understand how long it takes Dimorphos to orbit Didymos.

    DART  Importance to planetary defence

    • NASA established the Planetary Defense Coordination Office to manage its ongoing mission of planetary defence. 
      • The PDCO’s goals are to provide early detection of potentially hazardous objects, track and characterize the objects, study strategies and technologies for mitigating possible impacts, and play a leading role in U.S. government response planning for an actual impact. 
      • DART is the first planetary defence test mission for PDCO.

    What are Asteroids?

    • Asteroids, sometimes called minor planets, are rocky, airless remnants left over from the early formation of the solar system about 4.6 billion years ago.
    • Most of this ancient space rubble can be found orbiting the Sun between Mars and Jupiter within the main asteroid belt.
      • Some asteroids go in front of and behind Jupiter, which are called Trojans
      • Asteroids that come close to Earth are called Near-Earth Objects (NEOs) for short. NASA keeps close watch on these asteroids.
    • Asteroids range in size from Vesta (the largest at about 329 miles in diameter) to bodies that are less than 33 feet across. The total mass of all the asteroids combined is less than that of Earth’s Moon.
    • Asteroids are not all round like planets. They have jagged and irregular shapes.
    • Structure
      • Most asteroids are made of different kinds of rocks, but some have clays or metals, such as nickel and iron.

     

    (Image Courtesy: LTS)

    • NASA Space Missions
      • Several NASA space missions have also flown by and observed asteroids. The NEAR Shoemaker spacecraft landed on Eros, an asteroid near Earth, in 2001.
      • The Dawn spacecraft travelled to the asteroid belt in 2011 to orbit and study the second largest object there, Vesta.
      • In 2016, NASA launched the OSIRIS-REx spacecraft to study Bennu, an asteroid near Earth.
    • Detecting Asteroids Mission
      • Asteroid Impact and Deflection Assessment (AIDA): This includes NASA’s Double Asteroid Redirection Test (DART) mission and Hera Mission.
      • Hera Mission: It is the asteroid deflection mission of European Space Agency (ESA) that is scheduled to be launched in 2024 to measure the impact crater produced by the DART collision and study the change in the asteroid’s orbital trajectory. It will arrive at the Didymos system in 2027.

    Source: FE