The DART impact into asteroid moon Dimorphos wowed astronomers with an unexpectedly dramatic plume.


October 11, 2022: Additional photos have become available with NASA's announcement of a wildly successful test that shortened the orbit of the asteroidal moon.

October 3, 2022: Scroll down to see a new image from the Southern Astrophysical Research (SOAR) Telescope in Chile showing the more than 10,000-kilometer-long debris pluming from the impact site. Find more details in NSF's NOIRLab press release.

September 29, 2022: Scroll down to see newly released images from the Hubble and Webb Space Telescopes.

The final five-and-a-half minutes of images leading up to the DART spacecraft’s intentional collision with asteroid Dimorphos. The DART spacecraft streamed these images from its DRACO camera back to Earth in real time as it approached the asteroid. This replay movie is 10 times faster than reality, except for the last six images, which are shown at the same rate that the spacecraft returned them.
NASA / Johns Hopkins APL

Yesterday, as NASA’s DART spacecraft sped toward its inevitable demise against the blocky surface of Dimorphos, most space fans’ eyes were on the NASA Television feed of DART spacecraft photos, streamed to Earth at a rate of one per second. Dimorphos and its larger companion Didymos resolved into worlds with fascinating surfaces covered with gullies and angular blocks. Then, this morning, the Italian Space Agency shared the first photos from DART’s companion LICIAcube minisatellite: before-and-after images of the impact crash.

But DART and LICIAcube weren’t the only cameras watching the impact. Around the world, astronomers pointed telescopes at the pinpoint of light from the Didymos system, hoping to catch an impact flash. “What we should see with telescopes on the ground is a dot in the sky that should, suddenly, increase in brightness,” the European Space Agency (ESA) predicted in a pre-impact press release about the ground-based observing campaign. Their hopes were rewarded — and then some.

DART Impact from the Ground

Professionals and amateurs alike were wowed by the dramatic effects of the tiny spacecraft’s crash into the asteroid moon. Not only did the pointlike light from the Didymos system brighten; as astronomers watched, the system shed a crescent-shaped plume of dust, brilliantly illuminated by sunlight. The visible plume didn’t last long, spreading out into invisibility, but the stunning view was captured from numerous locations.

ESA’s Le Makes Observatory in Le Reunion obtained one view of the expanding crescent, but the best images so far came from the Hawai`i-based ATLAS (the Asteroid Terrestrial-impact Last Alert System). Designed to be an early-warning system for near-Earth asteroids approaching Earth, ATLAS scans the entire sky several times a night. Its view of the impact shows the effects in breathtaking detail. At least two separate plumes are visible: one, crescent-shaped, spreads out in the direction opposite to the impact, while another, fainter one jets at an angle behind Didymos’ apparent motion across the sky.

a small white dot moves across a black background
ATLAS Project, University of Hawai`i/NASA
collection of still images showing a small white dot moving across a black background and dissolving into a plume of white dust
The ATLAS project captured stills of the DART mission's impact on Dimorphos. (Scroll down for the animated version.)
Images: ATLAS Project (University of Hawai`i / NASA); Image processing: Emily Lakdawalla.

Although not as finely detailed, a similar view from the South African Astronomical Observatory’s Lesedi telescope provides long parallax and thus an opportunity for astronomers to study the evolution of the plume in stereo.

a white dot moves closer and gets bigger until dissolving into grey dust
Nicolas Erasmus (SAAO) and Amanda Sickafoose (PSI)
collection of thumbnails of a white dot moves closer and gets bigger until dissolving into grey dust
Nicolas Erasmus (SAAO) and Amanda Sickafoose (PSI).

Other ground-based telescopes that captured the impact and shared preliminary versions of their images via Twitter include:

In addition, many telescopes were performing spectral observations in order to study the composition of the plume. Those results must await calibration, but it looks like the Infrared Telescope Facility in Hawai`i obtained good data!

Two days after the impact, the Southern Astrophysical Research (SOAR) Telescope in Chile obtained an image of the impact, showing a debris tail more than 10,000 kilometers (6,200 miles) long:

Trailing plume ejected from bright Dimorphos
Astronomers using the NSF’s NOIRLab’s SOAR telescope in Chile captured the vast plume of dust and debris blasted from the surface of the asteroid Dimorphos by NASA’s DART spacecraft when it impacted on 26 September 2022. In this image, the more than 10,000 kilometer long dust trail — the ejecta that has been pushed away by the Sun’s radiation pressure, not unlike the tail of a comet — can be seen stretching from the center to the right-hand edge of the field of view.
CTIO / NOIRLab / SOAR / NSF / AURA / T. Kareta (Lowell Observatory), M. Knight (US Naval Academy); Image processing: T.A. Rector (University of Alaska Anchorage / NSF’s NOIRLab), M. Zamani & D. de Martin (NSF’s NOIRLab)

DART Impact From Space

In space, both the Hubble and James Webb Space Telescopes were observing, as was the Lucy mission. NASA has now released images from both space telescopes, though no word yet from Lucy.

Hubble images of DART impact
These Hubble images, taken through an ultraviolet filter 22 minutes, 5 hours, and 8.2 hours, respectively DART's impact, show expanding plumes of ejecta from the body of Dimorphos. The bolder, fanned-out spike of ejecta to the left of the asteroid is in the general direction from which DART approached. From these images, astronomers estimate that the brightness of the Didymos system increased by 3 times after impact and somehow held steady even hours later.
Webb image of DART impact
Webb captured a near-infrared image Dimorphos and the impact ejecta around it about 4 hours after DART crashed into it. A tight, compact core and plumes of material appearing as wisps streaming away from the center of where the impact took place are visible in the image. The sharp points are Webb’s distinctive diffraction spikes.

The Hubble observations, when combined with Webb data, will provide information about the nature of the surface of Dimorphos, how much material was ejected by the collision, how fast it was ejected, and the distribution of particle sizes in the expanding dust cloud. Hubble will observe Dimorphos 10 more times over the next three weeks to monitor the ejecta cloud as expands and fades. Webb will also continue to observe the system.

And then there are the DART and LICIAcube images: DART revealed Didymos to be smooth in some places, gullied in others. The smoothly bulging equator is reminiscent of Bennu, the asteroid visited by NASA’s OSIRIS-Rex mission, while the gullies look like those on Saturn’s moon Helene. Dimorphos is extremely blocky, like all near-Earth asteroids seen in such detail: Bennu, Itokawa, and Ryugu.

two large grey rocks pictured next to each other with small yellow circles above each
This reprocessing of DART images allows you to see Didymos in 3D. To see the 3D effect, you'll need to look view the image with your eyes crossed so that the two yellow dots overlap.
NASA / JHUAPL / Alain Mir

And these are the views the Italian Space Agency released from LICIAcube this morning, taken before the spacecraft’s close (55-kilometer) flyby of Didymos. The photos show a streaky plume expanding in all directions from the CubeSat’s point of view:

a white dot floating on a black background in front of a smaller white dot emananting light
a close up of a white dot floating on a black background in front of a smaller white dot emananting light

Hundreds more images await download from LICIAcube, and we have yet to see photos from Hubble and Lucy. Professional study of these many images will enable astronomers to generate 4D models of the plume evolving over time and space. A special session at December’s American Geophysical Union meeting will feature the early results from this research, so stay tuned for science!


Image of David-Stoltzmann


September 30, 2022 at 8:14 pm

The stereo-pair 3D images DO NOT want the eyes to be "crossed" to view the stereo. Keep your eyes uncrossed and then the 3D will stand out correctly.

You must be logged in to post a comment.

Image of Michal


October 1, 2022 at 9:34 am

I believe you need to slightly "cross eyes" until you see three images. The center image will be the merged 3-D image. The effect is subtle, not especially pronounced.

You must be logged in to post a comment.

Image of David-Stoltzmann


October 1, 2022 at 10:39 am

The LEFT Eye stays looking at the LEFT yellow dot, and the RIGHT Eye stays looking at the RIGHT yellow dot. This is normal vision, not cross-eyed. With the somewhat wide separation of the two yellow dots, it takes a bit of relaxation of the eyes to achieve this overlap for stereo viewing. You are correct that the 3D is subtle, compared to most stereo-pairs.

You must be logged in to post a comment.

You must be logged in to post a comment.