FP . interpretersSeptember 23, 2022, 19:00:43 IST
For years now, scientists from around the world have been working on a number of methods on how to alter the course of an asteroid or other interstellar object heading toward Earth, which has the potential to wipe life off the planet.
On Monday, NASA will broadcast its first attempt to modify the orbit of an asteroid, a capability that will be necessary if we discover an asteroid that poses a collision threat to Earth.
The entire process focuses on whether DART, a new system for using spacecraft to alter an asteroid’s path, 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 put objects in the path of an asteroid or a small interstellar object and change its path, if it is destined for planet Earth.
What DART mission will NASA have this week?
NASA’s mission on Monday will target a small asteroid called Demorphos that orbits the largest 65803 Didymos, forming a binary system. If all goes according to plan, DART will orient itself for a head-on collision slowing the Dimorphos, changing its orbit around Didymos.
What type of spacecraft will this mission use?
The DART spacecraft itself that is being used for this mission weighs over 600kg and lacks the tools you would normally find in a spacecraft. Its solar panels include an experimental concentrated solar cell that takes up less space to generate the same amount of power as devices in space, and the main transmitter is testing a new antenna configuration.
The most important piece of equipment on the DART spacecraft is the Single Camera, the Didymos Reconnaissance Camera and the Asteroid Optical Navigation Camera, or DRACO, a 2560 x 2160-pixel camera. DRACO and transmitters can send an image to Earth every second.
How is the DART task supposed to unfold?
As it makes its final approach to the Dimorphos, DART will be far enough away that the round trip transmissions will take more than a minute. As such, the final approach and targeting of the asteroid will be handled by an onboard navigation system called SMART Nav (Real-time Autonomous Small Object Navigation).
Once the DART spacecraft is close enough to the Dimorphos, SMART Nav will track the larger Didymos and use that for navigation until about 50 minutes before colliding with the Dimorphos. Until 2.5 minutes before impact, the DART spacecraft will remain in its trajectory using its internal ion engines.
Within 2.5 minutes before impact, the ion engine will shut down, and DART will crash at about 6 kilometers per second. Although Dimorphos are only about 120 meters wide, at this point they should fill the entire landscape of DRACO.
We will know that the collision was successful if we stop receiving images or stop sending. DART accompanies a small craft called LICIACube, built by the Italian Space Agency. It was released from DART in early September and is on a track that will cut it after Dimorphos after about three minutes of impact. The LICIACube has two cameras (wide and narrow fields, one of which holds RGB color filters) and will take pictures of the asteroid as well as any material ejected by the impact.
However, it may take several months for NASA to know whether the mission was successful or not, before they can confirm that Demorphos’ orbit has been successfully modified.
What happens if the mission succeeds?
If the mission is successful, NASA hopes to launch more of these spacecraft and DART units toward large asteroids that we know are coming toward Earth, especially if we know for sure that there will be a collision.
NASA plans to launch these DART spacecraft at least 10 years or more in advance to give them time to move to a less threatening orbit. Having a successfully proven method for doing this would be a huge step forward for NASA’s planetary defense programs.