Last September, NASA deployed its first test mission for planetary defense, the Double Asteroid Redirection Test (DART). The aim was to test and validate a method to protect Earth in case of an asteroid impact threat.
The DART mission, of course, succeeded and shifted an asteroid’s orbit through kinetic impact.
Here is a Tech Briefs interview, edited for clarity and length, with DART team member Dr. Saverio Cambioni.
1) Tech Briefs: What was going through your mind as DART was approaching the asteroids? I presume the team was together during impact; what was the mood/atmosphere like before/during/after?
Dr. Saverio Cambioni: It was extremely exciting! We were watching the impact on the NASA TV channel, and I could not wait for the Didymos system to grow from a blurred pixel to a spatially resolved asteroid pair. The most thrilling moment was when the last five-and-a-half minutes of images were streamed to Earth . Didymos was well-resolved, and the spacecraft was closing in on its moonlet Dimorphos for its intentional collision.
While watching the collision, I started to realize the importance of what the DART mission was accomplishing, not only for the planetary science community, but also for us all. NASA was on the cusp of demonstrating that a kinetic impact is a viable mitigation technique for protecting the planet from an Earth-bound asteroid or comet, if one were discovered.
After the impact occurred and was successful, perhaps strangely, I thought about the dinosaurs. They did not have the technology to protect themselves and their planet from the impactor that wiped them out. After DART, humankind is now a step closer to creating a planetary defense system.
2) Tech Briefs: What did you learn from the images and the mission in general? How will that help in future similar missions?
Cambioni: DART’s impact was observed by several telescopes around the world and in space. The telescopes revealed that the impact shortened Dimorphos’ orbit, remarkably, by about 33 minutes — more than 25 times the minimum benchmark for mission success. At the same time, the impact liberated at least 1 million kilograms of rock from Dimorphos’s 4.3-billion-kilogram mass and formed a tail stretching more than 1,500 kilometers. The team observed the tail with the Hubble Space Telescope for about three weeks and found that its morphology is similar to “active asteroids” that have an asteroid-like orbit and comet-like tail. What this means is that impacts can “activate” asteroids, as we discuss here .
From a technological perspective, DART showed that it is technologically possible to intercept and impact a sub-kilometer asteroid, with limited prior knowledge of its shape and surface properties. This is great as it means that we do not need a mission to characterize a hazardous asteroid before sending another mission to deflect its trajectory.
3)Tech Briefs: Do you think we’ll need to use such technology again?
Cambioni: Dimorphos and Didymos are not a hazard to Earth, and no known asteroid poses a threat to Earth for at least the next century. However, it is important to note that the catalog of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation, as we discuss here . To fill the gaps in our catalog of hazardous asteroids, it is paramount that we develop planetary defense systems that include Earth-based survey systems too, as we discuss here .
4)Tech Briefs: You’re quoted as saying, “To find all the hazardous asteroids before they find us, in 2026 NASA will launch the NEOSurveyor mission…” Please talk about that (any info you can divulge).
Cambioni: As described here , NEO Surveyor is a planetary defense mission aimed at meeting the U.S. Congress’ mandate to find more than 90 percent of all near-Earth objects (NEOs) larger than 140 meters in diameter. Objects of this size could cause significant regional damage, although they are not likely capable of causing global extinction. To find these objects, NEO Surveyor will scan near-Earth space with a telescope in two heat-sensing infrared wavelengths. As described in this cartoon , infrared wavelengths are sensitive to the warmth of objects allowing for a more accurate determination of an asteroid's size and, relatedly, its potential hazardousness.
The NEO Surveyor mission is led by Survey Director Prof. Amy Mainzer of the University of Arizona. University of Arizona has a long history of discovering NEOs, as the SPACEWATCH® project and the Catalina Sky Survey have detected nearly 50 percent of all known NEOs to date. In addition to NEOs, the expectation is that the NEO Surveyor will likely detect more than one million asteroids in the Main Belt between Mars and Jupiter and about a thousand new comets. This will be a goldmine for planetary scientists who can use those data to advance our understanding of how asteroids formed and evolved.
5)Tech Briefs: Is there anything else you’d like to add?
Cambioni: I wanted to share an interesting bit of information about the importance of the surface of an asteroid and how it can yield information about the way it formed over time. We haven’t seen many small bodies like Dimorphos and Didymos, and, every time we visit one, we learn a lot about asteroid science and the diversity of their surfaces.
The DART images revealed that Dimorphos’ surface is covered in rocks, with boulders as large as shipping containers near the impact site. Such a boulder-strewn surface suggests that Dimorphos is a rubble-pile asteroid similar to other asteroids that we have recently visited such as Bennu, Ryugu, and Itokawa. What this suggests is that these asteroids formed through re-accumulation of fragments of larger asteroids that got destroyed by collisions. This confirms the importance of collisions in shaping the formation and evolution of celestial bodies. I am really looking forward to the rendezvous of Dydimos and Dimorphos by the European Space Agency’s Hera mission in late 2026 to learn more about this fascinating pair!
Johns Hopkins Applied Physics Lab built and operated the DART spacecraft and manages the DART mission for NASA’s Planetary Defense Coordination Office as a project of the agency’s Planetary Missions Program Office. For more information about the DART mission, please visit www.nasa.gov/dart or https://dart.jhuapl.edu/ .