September 23, 2022 19:00:43 IST
For years, scientists around the world have been working on a number of ways to alter the trajectory of an asteroid or any interstellar body heading towards Earth that has the potential to wipe out life from the planet.
On Monday, NASA will release its first attempt to alter an asteroid’s orbit, a capability that will be essential if we detect an asteroid threatening to collide with Earth.
The whole operation centers on whether DART, a new system for using spacecraft to alter the course of an asteroid, works as NASA engineers and scientists hope.
DART stands for Double Asteroid Redirection Test and it is a space mission to see if we can place objects in the path of an asteroid or minor interstellar body and change its path, if it was heading towards planet Earth.
What DART mission will NASA be conducting this week?
The mission NASA will fly on Monday will target a small asteroid called Dimorphos which orbits the larger 65803 Didymos, forming a binary system. If all goes as planned, DART will head into a head-on collision that will slow Dimorphos, altering its orbit around Didymos.
What type of spacecraft will this mission use?
The DART spacecraft itself that is used for this mission weighs over 600 kg and lacks instruments that you would normally find in a spacecraft. Its solar arrays include an experimental concentrating solar cell that takes up less space to generate the same amount of power as existing space hardware, and its primary transmitter is testing a new antenna configuration.
The most important piece of equipment on the DART spacecraft is the single camera, the Didymos Asteroid Reconnaissance and Camera for Optical Navigation, or DRACO, a 2560×2160 pixel camera. DRACO and the transmission equipment are able to send an image back to Earth every second.
How is the DART mission supposed to unfold?
On its final approach to Dimorphos, DART will be far enough away that round-trip transmissions will take over a minute. Thus, the final approach and targeting of the asteroid will be ensured by an onboard navigation system called SMART Nav (Small-body Maneuvering Autonomous Real-Time Navigation).
Once the DART spacecraft is close enough to Dimorphos, the SMART Nav will follow the larger Didymos and use it for navigation until approximately 50 minutes before it collides with Dimorphos. Until 2.5 minutes before the collision, the DART spacecraft will maintain its trajectory thanks to its internal ion engines.
At 2.5 minutes before the collision, the ion engine will be shut down and DART will collide at approximately 6 kilometers per second. Even though Dimorphos is only about 120 meters in diameter, at this point it should completely fill the view from DRACO.
We will know that the collision was successful if we stop receiving images or when the transmission stops. DART is accompanied by a small craft called LICIACube, built by the Italian Space Agency. He was released from DART in early September and is on a trajectory that will take him past Dimorphos approximately three minutes after impact. LICIACube has two cameras (wide and narrow field, one of which carries RGB color filters) and will capture images of the asteroid as well as any material ejected by the impact.
However, it may take several months for NASA to find out whether the mission was successful or not, before it can be sure that Dimorphos’ orbit has been successfully altered.
What happens if the mission is successful?
If the mission is successful, NASA hopes to launch several more of these spacecraft and DART modules toward major asteroids that we know are heading for Earth, especially if we know for sure there will be a collision.
NASA plans to launch these DART spacecraft at least 10 or more years in advance to give it time to transition to a less threatening orbit. Having a method that has been successfully demonstrated to do this will be a big step forward for NASA’s planetary defense programs.
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