When NASA's Double Asteroid Redirection Test (DART) mission launched on 24 November 2021, its mission was simple, but spectacular:
To travel to the the Didymos system – an asteroid orbited by moon Dimorphos - and smash into the latter.
The mission's goal was to see whether a human-made spacecraft would be able to significantly deflect an asteroid that happened to be on a collision course with planet Earth.
DART arrived at the system on 26 September 2022 and made its successful impact into Dimorphos’s surface.
Professional telescopes around the world - and, indeed the Hubble and James Webb space telescopes - captured the impact, providing important data to mission scientists as to whether or not the DART mission had been a success.
But a team of citizen scientists were also observing DART's impact, using a network of telescopes made by Unistellar.
The company makes 'smart' telescopes that can automatically locate and track celestial objects and display them on a computer screen, rather than through an eyepiece.
Using Unistellar's eVscopes, observers in Kenya and Réunion Island were able to observe the DART impact.
The team of citizen scientists, which included 8 astronomers from the SETI Institute and which was led by SETI Institute postdoctoral fellow Ariel Graykowski, published the results in the journal Nature in March 2023.
Key moments from the Unistellar observations included observations of brightening of the Didymos system by a factor of 10, caused by material ejected during the impact.
The team were also able to calculate the ejected material's mass, speed and energy.
They were even able to measure a change in colour at the time of impact of the DART spacecraft; an effect that currently remains unexplained.
The citizen scientists were able to do so using their own telescopes, observing and collecting data on the NASA mission as the impact played out.
While citizen science has long been a big part of astronomy, from observations of meteor showers and sunspots to the work of online citizen scientists in projects like Galaxy Zoo, this particular study was a significant contribution by observational astronomers to the question of planetary defence.
The paper was co-authored by 31 citizen scientists of the Unistellar network.
Patrice Huet, Matthieu Limagne, Bruno Payet from Réunion Island, and the Traveling telescope team in Kenya observed the impact.
From the SETI Institute, Ariel Graykowski, Ryan Lambert, Franck Marchis, Dorian Cazeneuve, Paul Dalba, Thomas Esposito, Daniel Peluso and Lauren Sgro contributed to the scientific research.
Watch our interview with Franck Marchis
Read the full paper at www.nature.com/articles/s41586-023-05852-9
