I’m pretty sure almost every one of you has watched a movie in which a asteroid is on a collision course with Earth. And most of those movies come with the use of nukes as a solution to destroy the asteroid before it gets to Earth. If used, this technique will have consequences for peoples living on Earth. So what other solution do we have to this problem? NASA’s DART mission is one such mission that will test for the deflection of an asteroid by crashing into an asteroid. It is NASA’s first planetary defense mission.
Double Asteroid Redirection Test (DART) is a space mission launched by NASA to test a technique called Kinetic Impactor. In this technique a spacecraft is collided with an asteroid to prevent the collision of asteroid with Earth. DART was successfully launched in November 2021. In this mission, DART will crash into Dimorphos, moon of asteroid Didmos. The crash will lead to a small change in trajectory of asteroid system but over time, it leads to a large shift in path. The spacecraft collision with Dimorphos will be between September 26 and October 2nd 2022. It is a collaboration project between NASA and Applied Physics Laboratory (APL) of John Hopkins University. The project is administered by NASA’s Planetary Defense Coordination office. Other space agencies like ESA, JAXA and ASI are contributing to DART and future missions related to DART mission that I will later describe in the episode.
Spacecraft
DART is an Impactor with a mass of 610 kg. DART carries a star tracker called SMART Nav, a 20 cm aperture camera called DRACO and a secondary spacecraft called LICIACube, which is designed by the Italian Space Agency.
SMART Nav (Small-body Maneuvering Autonomous Real Time Navigation) is an star tracker, a device that measures the positions of stars using a camera. DART uses SMART Nav to navigate through space with respect to the position of stars. And for this another instrument called DRACO is helping SMART Nav to find its way to Didymos system.
DRACO (Didymos Reconnaissance and Asteroid Camera for Optical navigation) is a high resolution camera that will capture images of Didymos and Dimorphos.
LICIACube (Light Italian CubeSat for Imaging of Asteroids) is a secondary spacecraft that have mass no more than 14 kg is an Italian spacecraft designed by Italian Space Agency to witness the DART’s impact on Dimorphos surface. It is a CubeSat, which is a class of miniature satellites that have mass no more than 2kg per unit.
Course of Impact
- A month before the DART impacts the Dimorphos; DRACO camera detects Didymos and refines its trajectory to this asteroid system.
- Ten days before the impact LICIACube will be separated from DART.
- 4 hours before impact, DART will take control of navigation system in its control by switching SMART Nav guidance system.
- Until impact, DRACO will continuously take images of Dimorphos and will transmit them in real time.
- The collision will take place between 26th September and 2nd October 2022.
- LICIACube will communicate directly with Earth, sending back images of the ejecta and plume of DART’s impact as well as do asteroidal study during its flyby of Didymos system from a distance of 55 KMs, 3 days after DART’s impact.
Didymos and Dimorphos System
The mission’s target is Dimorphos in a binary asteroid system called 65803 Didymos, in which one asteroid is orbited by another one. In Astronomy, an asteroid orbiting another asteroid is called a Minor-Planet Moon. Thus, Dimorphos is a minor planet moon of the asteroid Didymos. The primary asteroid (Didymos A) is about 780 m in diameter while the secondary asteroid (Didymos B or Dimorphos) is about 160 m in diameter. Dimorphos orbits about 1km from the primary asteroid. DART will target smaller asteroid for its test of planet saving technique. Neither this test poses any threat to Earth nor the Didymos system poses any threat to Earth because it orbits too far from our planet and is not a Earth crossing asteroid.
Future Mission
After DART’s impact on Dimorphos, a follow-up mission called Hera will be launched by European Space Agency. ESA is developing Hera that will be launched to Didymos in 2024 which will arrive 5 years after DART’s impact in the year 2027. Hera will study the Didymos system and DART’s impact on both the system and its moon Dimorphos.