Two of the great space observatories, the NASA/ESA/CSA James Webb Space Telescope and the NASA/ESA Hubble Space Telescope, have captured views of a unique experiment to smash a spacecraft into a small asteroid. Observations of NASA’s Double Asteroid Redirection Test (DART) impact mark the first time that Webb and Hubble were used to simultaneously observe the same celestial target.
On 26 September 2022 at 01:15 CEST, DART intentionally crashed into Dimorphos, the asteroid moonlet in the double-asteroid system of Didymos. It was the world’s first test of the kinetic impact technique using a spacecraft to deflect an asteroid by modifying the object’s orbit. DART is a test for defending Earth against potential asteroid or comet hazards.
The observations are more than just an operational milestone for each telescope – there are also key science questions relating to the makeup and history of our Solar System that researchers can explore when combining the capabilities of these observatories.
Observations from Webb and Hubble together will allow scientists to gain knowledge about the nature of the surface of Dimorphos, how much material was ejected by the collision, and how fast it was ejected. Additionally, observing the impact across a wide array of wavelengths between Webb and Hubble will reveal the distribution of particle sizes in the expanding dust cloud, helping to determine whether it threw off lots of big chunks or mostly fine dust. Combining this information will help scientists to understand how effectively a kinetic impact can modify an asteroid’s orbit.