New study finds that DART changed both orbit and shape of Dimorphos asteroid

Date:
Sun, 24 Mar 2024 21:47:12 +0000

Description:
On Sept. 26, 2022, NASAs Double Asteroid Redirection Test (DART) spacecraft slammed into the side The post New study finds that DART changed both orbit and shape of Dimorphos asteroid appeared first on NASASpaceFlight.com .

FULL STORY ======================================================================On
Sept. 26, 2022, NASAs Double Asteroid Redirection Test (DART) spacecraft slammed into the side of the 170-meter-wide asteroid Dimorphos to test future asteroid deflection tactics in the event an asteroid was threatening Earth. Following impact, DART teams confirmed that the spacecrafts collision with
the asteroid had successfully deflected the asteroid by a small amount proving the design of the deflector and allowing scientists and engineers to better understand the ways we can protect Earth from asteroids.

However, a new study from a group of scientists shows that DARTs collision with Dimorphos not only changed the shape of its orbit around its host asteroid Didymos but also significantly changed the shape of the asteroid.



Before the collision, Dimorphos was known to be a roughly symmetrical oblate spheroid shaped asteroid, similar to a squished ball that is wider than it is tall. Additionally, it took the asteroid around 11 hours and 55 minutes to complete one orbit around Didymos, which, as mentioned, has since been
altered following DARTs impact with Dimorphos.

When DART made impact, things got very interesting. Dimorphos orbit is no longer circular: Its orbital period is now 33 minutes and 15 seconds shorter. And the entire shape of the asteroid has changed, from a relatively symmetrical object to a triaxial ellipsoid something more like an oblong watermelon, said navigation engineer and lead author Shantanu Naidu of NASAs Jet Propulsion Laboratory (JPL) in California. Illustration showing the shape of Dimorphos both before and after DARTs impact. (Credit: NASA/JPL-Caltech)

To better understand how Dimorphos shape and orbit changed following DARTs impact, Naidu et al. employed computer models that utilized three data
sources that collected data during DARTs impact. The first source was the images DARTs Didymos Reconnaissance and Asteroid Camera for Optical
navigation (DRACO) camera captured of Didymos in the hours, minutes, and seconds before impact. DRACOs images were transmitted from DART to the Deep Space Network (DSN), and the images allowed the scientists to perform
close-up measurements and gauge the dimensions of both Didymos and Dimorphos before impact. See Also DART Updates Space Science Section NSF Store Click here to Join L2

The DSNs Goldstone Solar System Radar was the second data source, which is located in Barstow, California. During DARTs impact sequence, the Goldstone Radar bounced radio waves off of Dimorphos and Didymos to measure the
position and velocity of Dimorphos around Didymos precisely before and after DARTs collision. These measurements are what allowed NASA teams to quickly discern whether or not DARTs impact had indeed deflected Dimorphos in its orbit around Didymos. Teams would eventually find that the effect of DARTs impact on the asteroid greatly exceeded the minimum expectations for the mission.

The final and most significant data source utilized in Naidu et al.s study
was ground telescopes located around Earth that measured the light curve how sunlight reflects off the surface of the asteroids over time from both asteroids. Comparing the asteroids light curves before and after impact allowed the team to learn more about how DART altered Dimorphos position around Didymos.

We used the timing of this precise series of light-curve dips to deduce the shape of the orbit, and because our models were so sensitive, we could also figure out the shape of the asteroid. Before impact, Chesley continued, the times of the events occurred regularly, showing a circular orbit. After impact, there were very slight timing differences, showing something was askew. We never expected to get this kind of accuracy, said co-author Steve Chesley of JPL.



Naidu even confirmed that their models were so sensitive that they were able to detect a slight back-and-forth rocking of Dimorphos as it orbits around Didymos.

Whats more, Naidu et al.s models were also able to calculate how Dimorphos orbital period around Didymos was altered and evolved over time. Immediately following impact, teams found that DART had reduced Dimorphos orbital period by 32 minutes and 42 seconds, making its total orbital period around Didymos 11 hours, 22 minutes, and 37 seconds.

However, the asteroids orbit would continue to shorten as the asteroid continuously lost more and more surface material from the impact to space. Dimorphos orbital period would finally settle to be approximately 11 hours,
22 minutes, and three seconds, meaning that DARTs impact officially altered the orbit of the asteroid by 33 minutes and 15 seconds. The scientists calculations are accurate to within 1.5 seconds, and Dimorphos now sits at a mean orbital distance from Didymos of 1,152 meters, which is around 37 meters closer to the asteroid than before DARTs impact.

The results of this study agree with others that are being published. Seeing separate groups analyze the data and independently come to the same conclusions is a hallmark of a solid scientific result. DART is not only showing us the pathway to an asteroid-deflection technology, its revealing
new fundamental understanding of what asteroids are and how they behave, said NASAs lead scientist for solar system small bodies Tom Statler of NASA HQ in Washington D.C. That left a mark! The #DARTMission proved that an impactor could deflect a hazardous asteroid, should one ever be on a collision course with Earth. A new study shows DART's test impact changed not only the motion of a small asteroid, but also its shape. https://t.co/Jx8rx9vYVu pic.twitter.com/jzfCLy0bRK

NASA Solar System (@NASASolarSystem) March 19, 2024



The results from Naidu et al.s study, along with observations of material
left around Dimorphos after the impact, indicate that Dimorphos is a loosely-packed rubble pile asteroid, similar to asteroid Bennu that was visited and sampled by NASAs OSIRIS-REx mission. The European Space Agencys upcoming Hera mission will travel back out to the Didymos-Dimorphos system to further investigate the long-term changes made to Dimorphos by DARTs impact.

Naidu et al.s results were recently published in the Planetary Science Journal .

(Lead image: Dimorphos imaged by DARTs DRACO cameras just two seconds before impact. Credit: NASA/Johns Hopkins APL)

The post New study finds that DART changed both orbit and shape of Dimorphos asteroid appeared first on NASASpaceFlight.com .



======================================================================
Link to news story:
https://www.nasaspaceflight.com/2024/03/dart-study/


--- Mystic BBS v1.12 A47 (Linux/64)
* Origin: tqwNet Science News (1337:1/100)