James Webb Telescope to Support NASA's DART mission by Observing Didymos for impact

Credits: Johns Hopkins Applied Physics Laboratory

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September 26, 2022

As NASA undertakes the DART mission today, James Webb Telescope will have front row seat to the impact and will be focusing on observing Didymos asteroid for several hours.

A binary asteroid system, in which the smaller moon orbits the bigger body, is made up of the asteroid Didymos A and its small moonlet Didymos B. Although the two asteroids don't pose a threat to Earth, they have been selected as the subject of NASA's Double Asteroid Redirection Test (DART) mission, the organization's first mission to test planetary defense technology. One day, this technology might be used to divert dangerous asteroids that are headed straight for Earth.

At Kitt Peak National Observatory in Tucson, Arizona, researcher Joseph Montani of Spacewatch made the discovery of Didymos, which means "twin" in Greek. The name was also proposed by Montani.

Scientists discovered several echoes in data from NASA's Goldstone Solar System Radar, which is located in the Mojave Desert near Barstow, California, and gave rise to indications that Didymos might have a moon. Analyzing optical light curves, which are telescopic measurements that reveal an object's brightness over time, together with radar photos from the Arecibo Observatory in Puerto Rico recorded on November 23, 2003, proved the theories.

On November 24, 2021, at 1:21 a.m. EST, a SpaceX Falcon 9 rocket carrying NASA's DART mission to Didymos lifted out from the Californian base of Vandenberg Air Force Station.

The smaller moonlet asteroid will be intercepted by DART on September 26, 2022, at 7:14 p.m. EDT. DART will strike Dimorphos at a fast rate of speed—roughly 4 miles per second or 6.6 kilometers per second. At the time of DART's impact, Dimorphos will be around 6.8 million miles (11 million kilometers) from Earth.

The mission's objective is to measure the change in the moonlet's orbit around Didymos in order to ascertain how much DART's impact changes the moonlet's velocity in space. According to experts, the collision will cause Dimorphos' speed to change by less than 1%. It ought to change the moonlet's orbital period around the larger asteroid by a few minutes, enough for telescopes on Earth to see and measure.

On September 29, 2022, NASA released this image. About 4 hours after NASA's Double Asteroid Redirection Test (DART) made impact, the Near-Infrared Camera (NIRCam) instrument on board the NASA/ESA/CSA James Webb Space Telescope captured this image of the asteroid moonlet Dimorphos in the Didymos double-asteroid system. The image shows a tight, compact core and material plumes that seem like wisps streaming away from the collision site. The eight diffraction spikes that distinguish Webb are an artifact of the telescope's design and are those sharp points. Scientists will be able to learn more about the makeup of Dimorphos' surface, how much material was ejected by the collision, and how quickly it was ejected when these observations are merged with Hubble Space Telescope data.

Credit: NASA, ESA, CSA, and STScI