posted on 09/30/2022 06:00
Hubble: records 22 minutes, 5 hours and 8.2 hours after unprecedented impact – (Credit: Reproduction / NASA)
The unprecedented test to “save the Earth” orchestrated by NASA earlier this week was followed, in real time, by scientists and onlookers from various corners of the world and also by two major observatories of the American space agency: the James Webb and Hubble telescopes. Yesterday, the first images made by the equipment were released — which, for the first time, simultaneously observed the same celestial target. They indicate that the impact may have been greater than expected, which reinforces the expectation that the mission had its objective achieved.
The Double Asteroid Redirection Test (DART) was launched last November to collide with Dimorphos 11 million kilometers away from Earth and, with the shock, change the asteroid’s course. The collision took place as planned. Now, data gathered by the telescopes will help the team conclude whether the deviation happened. According to Ian Carnelli of the European Space Agency (ESA), the photographs depict an apparently “much greater than expected” impact.
“I was really worried that there was nothing left of Dimorphos,” Carnelli admitted to the France-Presse news agency (AFP). ESA will launch the Hera mission, scheduled for October 2024, to reach the asteroid in 2026 and assess the crater. It was expected to be approximately 10m in diameter. Carnelli says that, with the images made by the telescopes, the plans changed. “It looks like it will be much bigger if there is a crater. Perhaps a part of Dimorphos has been cut off”, he ponders.
DART, which was the size of a passenger car, collided, on Monday, with the 160m-diameter asteroid, the equivalent of four Christ the Redeemer, at a speed of over 20,000km/h. Dimorphos was one kilometer from the asteroid Didymos, with 780m, and orbits it in 11 hours and 55 minutes. The expectation is that, with the shock, this time will be reduced by 10 minutes.
It is likely that Earth-bound telescopes and radars will take at least a week for a first estimate of how much the asteroid’s orbit has changed. For an accurate measurement, Carnelli says the timeframe is three or four weeks. “I’m expecting a much bigger deflection than we planned,” confesses the project manager for the Hera mission.
Astronomer at Queen’s Universisty Belfast, Alan Fitzsimmons claims that even if no matter had been “thrown out” of the Dimorphos, DART would have slightly affected its orbit. “But the more matter and the faster it is moving, the greater the deflection,” he explains.
According to NASA, the images taken by the telescopes showed a vast cloud of dust expanding out of Dimorphos and Didymos. In a statement, the agency reports that Webb took five hours of recording and captured 10 images. One of them shows “plumes of material appearing as wicks coming out of the center of where the impact occurred”. “This is an unprecedented view of an unprecedented event,” summarized Andy Rivkin, leader of the DART research team at Johns Hopkins University in Laurel.
The Hubble images — 22 minutes, five and eight hours after the unprecedented collision — show the spray of expanding matter from the place where DART crashed. “When I saw the data, I was literally speechless, stunned by the incredible detail of the ejecta that Hubble captured,” said Jian-Yang Li of the Planetary Science Institute in Tucson, Arizona, who led the telescope’s observations.
The equipment captured the impact in different wavelengths of light — Webb in infrared and Hubble in visible. This diversity of data will allow scientists access to details of the impact, such as the distribution of particle sizes in the dust cloud and whether large chunks of the rocky body or fine particles were released.
A positive outcome from the DART mission also raises expectations for the operation’s use against rocky bodies capable of wreaking havoc on Earth. “This would have major implications for planetary defense, as it means this technique can be used for much larger asteroids,” Carnelli said.
In the vicinity of the planet, there are about 25,000 cataloged asteroids, of different sizes, and none of them threatens Earth for the next 100 years, according to scientists. The largest, one kilometer or more in diameter, have almost all been sighted. However, only 40% of the smallest, which measure 140 meters or more, are known.
NASA’s planetary defense agent Lindley Johnson said, just before the historic test, that it is the space agency’s job to “find the missing”. Shortly after the impact, Lori Glaze, NASA’s director of Planetary Sciences, assessed that, with the completion of the first stages of the mission, humanity was “embarking on a new era, where we potentially have the ability to protect ourselves from a dangerous impact from Earth. asteroid”.
In addition to advances in space defense, the agency believes that the records made by Hubble and Webb can help deepen “important scientific questions related to the composition and history of the Solar System.” The unprecedented joint operation of the equipment is also highlighted by the agency. “Webb and Hubble show what we’ve always known to be true: we learn more when we work together,” says Bill Nelson, the agency’s administrator, in a statement.