Hopefully, transferring momentum – mass times velocity – from the spacecraft on Dimorphus will change the moon’s speed by a fraction of a percentage.
This would change the period of Dimorphos’ orbit around Didymus by several minutes, estimated to be between 3 and 10 minutes. This is sufficient for observations and measurements with telescopes on Earth. The press conference said Demorphos is now orbiting Didymus for 11 hours 55 minutes, and if that time changes to 73 seconds, that’s enough to pass the test.
The researchers also want to measure the transfer of momentum so they have an idea of what it would take to confront an asteroid that threatens Earth. Although it must be said that this depends on the distance at which the interference will occur. The best time to deflect a dangerous asteroid from its orbit is years, even decades, before it approaches Earth. After all, the farther away they are, the less force is needed to sufficiently change the orbit.
To measure impulse transmission, the researchers relied primarily on Italy’s LICIACube, a small spacecraft that traveled on DART and was ejected 10 days before the collision. This cube will then follow DART and will also fly past Dimorphus after the collision. In doing so, it will send images to Earth of impact and ejection, the material being thrown off by impact.
The researchers estimate that tons of material will be thrown into space, perhaps tens of tons, and they were able to calculate the impulse transmission using images from the LICIACube of the projectile.
Observations with telescopes on Earth will continue at Dimorphus until February/March 2023 and the European Space Agency (ESA) is scheduled to launch Hera to Didymos in 2024. The probe will have to reach the asteroid system in 2027 to see the consequences of further collisions. detailed.
By the way, the orbit of the large asteroid Didymos will also change due to the collision, because the two asteroids are bound together by gravity, but since Demorphos is so small in proportion, this change will be too small to measure.
An English-language video from the Johns Hopkins University Applied Physics Laboratory of the mission.
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