Six nights of observations through two powerful telescopes confirmed that the orbit of double asteroid Didymos is perfectly aligned for NASA’s asteroid-crushing DART spacecraft that will arrive in late September.
The observations, carried out at the beginning of July by the
Lowell Discovery Telescope in Arizona and the Magellan Telescope in Chile, previous orbit calculations from 2021 confirmed. The new data comes as the Double Asteroid Redirection Test ( DART) spacecraft races towards the pair with plans to crash into the smaller rock called Dimorphos to test a possible technique to create a asteroid who threatens the earth, which Didymos and Dimorphos do not.
“The measurements taken by the team in early 2021 were critical to ensuring DART arrived at the right place and time for its kinetic impact on Dimorphos,” Andy Rivkin, the DART research team co-lead to the Johns Hopkins University Applied Physics Laboratory in Maryland, said in a
pronunciation. “Confirming those measurements with new observations shows us that we don’t need course changes and that we are already right on track.”
Related: NASA’s DART Asteroid Impact Mission Explained in Photos
Didymos and his moon Dimorphos will make their closest approach to Soil in late September years, at a distance of about 10.8 million kilometers from the planet. During this time, on September 26, DART spacecraft will collide with the 560-foot-wide (170 meters) Dimorphos in an attempt to change its orbit around the 0.5-mile-wide (780 m) Didymos. The experiment, the first-ever attempt to alter an asteroid’s orbit, could pave the way for a future planetary defense mission if an asteroid were to ever threaten Earth.
Scientists don’t just need the detailed orbital parameters of the two space rocks to reliably guide DART to its target. After the impact, astronomers around the world will measure the orbits of the asteroids again to see how Dimorphos’ orbit accelerated after the collision. The change can be quite minor and therefore extremely accurate measurements of the initial configuration are required.
“The before-and-after nature of this experiment requires excellent knowledge of the asteroid system before we do anything about it,” said Nick Moskovitz, an astronomer at the Lowell Observatory in Arizona and co-leader of the July observation campaign, in the declaration . “We don’t want to say at the last minute, ‘Oh, here’s something we hadn’t thought of or phenomena we hadn’t thought of.’ We want to make sure that any change we see is entirely due to what DART has done.”
Apart from the obvious forces, such as the gravitational pull of larger bodies,
asteroid orbits can be affected by more subtle phenomena, such as the pressure of solar radiation, the scientists said in the statement.
Dimorphos’ orbit around Didymos is expected to shorten several minutes after the impact as the moon gets closer to the larger asteroid. By measuring the change with maximum precision, astronomers can gather important information about the structure of Dimorphos and the properties of the material from which it is made.
The recent measurement campaign determined the orbital period of Dimorphos around Didymos by observing the change in brightness that occurs as one asteroid passes in front of another. However, it has been difficult to get enough observations because conditions for skywatching at this time of year are not favorable due to the short summer nights that coincided with Arizona’s rainy season, the researchers said. Earlier this year, the asteroids were too far from Earth to be detectable.
“It was a tricky time of year to get these observations,” Moskovitz said. “We asked for six half-nights of observation with some expectation that about half of that would be lost to the weather, but we only lost one night. We’ve been really lucky. We’re really confident now that the asteroid system is well understood and we’re designed to understand what happens after an impact.”
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