The latest NASA launch into space is going to have an impact. In fact, that is its whole mission.
This is all part of a long-term planetary defense strategy to avoid an “Armageddon” scenario, and the NAU planetologist Cristina Thomas is part of the team studying this event.
DART (Double Asteroid Redirection Test), which launched on November 23 from Vandenberg Space Force Base in California, is NASA’s first test of a kinetic impactor. This mission will demonstrate the deflection of an asteroid via kinetic impact. The objective is to collide with the target – in this case the Dimorphos moon in the Didymos asteroid system – to see how the orbit changes. It’s a test to understand how scientists might approach this problem if we ever find an asteroid on a collision course with Earth.
Thomas, assistant professor of astronomy and planet and head of the DART Observations Task Force, was in California for the launch, which went as planned and the spacecraft is operating as planned. She and her international team have been working for years to achieve an accurate orbit before Dimorphos, the satellite asteroid, impacts Didymos, the main asteroid in a near-Earth asteroid system.
Near Earth, of course, is relative; the planet is not in danger because of Didymos. However, an asteroid heading towards Earth is possible, and scientists around the world are working on ways to identify and mitigate these potential threats. If this mission goes as planned, this technique, called kinetic impact deflection, could be an important part of a planetary defense system.
“DART is a critical next step in planetary defense,” Thomas said. “This is, on the surface, a simple test, but we won’t fully understand what will happen until we do.”
Using data from 2003, when the satellite was first discovered, through early 2021, the task force was able to precisely constrain the orbit characteristics and Dimorphos’ position in the orbit at the time of the impact in the fall of 2022. They take repeated images of the same object, which shows drops in brightness as the satellite passes in front of or behind the primary. The timing of these drops in brightness, called mutual events, allows scientists to determine the satellite’s orbital period.
“Essentially, this is to think of the Dimorphos satellite as a clock, which will return to its position in front of or behind Didymos at regular intervals,” said Thomas. “Our working group will resume observations in the months preceding the DART impact. We want to have the most complete picture of the current orbit before we modify it by impact. “
The spacecraft has a long way to go before it reaches the asteroids; Thomas said they expected an impact in late September. At this moment, the
The team will complete a series of publications on what is known about the Didymos-Dimorphos system before impact. They will resume observing in June for a final glimpse of the asteroids before impact. After impact, they will make a number of observations called light curves to measure the change in the Dimorphos orbital period around Didymos.
This information allows them to compare this new orbital period after impact with what is known before impact to determine the magnitude of the change. His team will also make observations of the moment of impact itself from a small number of observatories to see how much material is being thrown out of the surface and will take the opportunity to do as much as possible to understand the objects, such as taking spectra to further study the composition.
This is an exciting opportunity for space exploration and the potential for this type of interaction; this kind of mission has never been done before.
“On the surface, this is a fairly straightforward physics experiment, but the properties of the asteroid and the amount of material that will be ejected from the surface will affect what happens during impact,” Thomas said. “Our observations will tell us a lot of information that we need to know if we are to plan for a kinetic impactor in the future.”
Heidi Toth | AUA Communications
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