The precise rate at which Dimorphos’ orbit accelerates itself around larger companion Didymos must be determined in order for the mission to be successful. Mission personnel depend on ground-based telescopes to follow the impact’s aftereffects because the DART spacecraft won’t be in good shape to perform that measurement independently.
According to Cristina Thomas, the head of DART’s working group for investigations and a planetary astronomer at Northern Arizona University, there are very few missions wherein telescope observations are important to understanding the success of the mission. Such a mission is DART.
However, the effort started even before the November 2021 introduction of DART.
Didymos and its companion were discovered by astronomers in 1996 and 2003, respectively, but at the time, they were thought to be merely another binary asteroid. According to Thomas, the DART observations depend on started in earnest in 2015, before the DART mission had received official approval but at a time when debates about it were well underway. These initial, in-depth studies were vital in re-engaging scientists with the asteroids after 12 years of no attention being paid to the Didymos system, according to Thomas.
Those observations persisted as the spacecraft for the DART mission concept developed. The most significant finding for DART was the exact duration it takes Dimorphos to orbit Didymos. The time is 11 hours & 55 minutes.
That has evolved into the starting point for the experiment DART will run on Monday. To be successful, DART must reduce that orbital period by 73 seconds, even though experts believe the effect may be closer to 10 minutes. According to the theory, if we intercepted an actual asteroid that was threatening Earth sufficiently far in advance, the asteroid would pass Earth’s orbit while our planet was somewhere else.