Observations from these telescopes confirmed that DART’s impact successfully deflected the asteroid moonlet Dimorphos and decreased its orbital period around its asteroid companion Didymos. The observations also characterized the double asteroid system and the ejecta produced from DART's impact. Numerical figures in parentheses next to telescope names indicate the telescope size.
Chile: Las Cumbres Observatory Global Telescope Network (LCOGT). South Africa: Las Cumbres Observatory Global Telescope Network (LCOGT). Image Credit: NASA/Johns Hopkins APL/Nancy Chabot/Mike Halstad.
The NASA Double Asteroid Redirection Test mission — the first test mission for NASA’s Planetary Defense Coordination Office — launched a spacecraft in November of 2021 with the aim to crash into the binary near-Earth asteroid system Didymos. The DART impact with the smaller asteroid Dimorphos occurred on September 26, 2022. The goal of the mission was to alter the period of Dimorphos in its orbit. Analysis of data taken since the impact has shown that the experiment was a great success. Four papers published on March 1 in the journal Nature document the full scope of the experiment and the ongoing research.
NASA issued a press release that summarizes the research that went into the calculation of the 33-minute alteration in the period of Dimorphos:
“The second paper uses two independent approaches based on Earth-based lightcurve and radar observations. The investigation team, led by Cristina Thomas of Northern Arizona University, arrived at two consistent measurements of the period change from the kinetic impact: 33 minutes, plus or minus one minute. This large change indicates the recoil from material excavated from the asteroid and ejected into space by the impact (known as ejecta) contributed significant momentum change to the asteroid, beyond that of the DART spacecraft itself.
The key to kinetic impact is that the push to the asteroid comes not only from colliding spacecraft, but also from this ejecta recoil. The authors conclude: ‘To serve as a proof-of-concept for the kinetic impactor technique of planetary defense, DART needed to demonstrate that an asteroid could be targeted during a high-speed encounter and that the target’s orbit could be changed. DART has successfully done both.’”
LCO scientists Dr. Tim Lister, Dr. Joey Chatelain, and Dr. Edward Gomez are coauthors on this paper. Dr. Lister heads the LCO group studying Near-Earth Objects, which employed data taken from LCO 1-m telescopes in South Africa and Chile for analysis. The data from the LCO telescopes, along with two others in Chile and planetary radar observations from Goldstone, CA, were used to measure the new period of Dimorphos after the DART impact. Dr. Lister has also been busy over the months following the DART impact continuing to observe Didymos and Dimorphos and the still present plume of ejecta to gain more insights into Dimorphos’s properties and the effect of the impact.
Dr. Tim Lister is pleased that LCO played a vital role in the DART mission, “It’s been a great privilege to be involved with and contribute to such an important mission for planetary defense. Having LCO telescopes in both Chile and South Africa allowed us to compare with other telescopes in Chile and also capture parts of Dimorphos’s orbit that other telescopes couldn’t. LCO’s extensive telescope network in the Southern Hemisphere was important in being able to measure the period change so soon after the impact.”
Please visit this press release from the Hubble Space Telescope, which includes some spectacular images and a video of Dimorphos and its plume of ejecta.
This work is supported by the DART mission, NASA Contract No. 80MSFC20D0004. Johns Hopkins Applied Physics Lab manages the DART mission for NASA's Planetary Defense Coordination Office as a project of the agency's Planetary Missions Program Office. DART is the world's first planetary defense test mission, intentionally executing a kinetic impact into Dimorphos to slightly change its motion in space. While the asteroid does not pose any threat to Earth, the DART mission’s purpose is to demonstrate that a spacecraft can autonomously navigate to a kinetic impact on a relatively small asteroid and to prove this is a viable technique to deflect an asteroid on a collision course with Earth if one is ever discovered.
