Hubble captures an 'unexpected' twin tail produced by NASA's spacecraft asteroid impact

NASA's DART mission successfully altered an asteroid's motion for the first time.
Chris Young
The latest Hubble image of the Didymos asteroid system.
The latest Hubble image of the Didymos asteroid system.

Source: NASA, ESA, STScI, Jian-Yang Li (PSI); Image Processing: Joseph DePasquale 

NASA's asteroid spacecraft impact last month has had an unintended and surprising consequence.

The Hubble Space Telescope captured a new image of the Didymos-Dimorphos asteroid system, whose trajectory was successfully altered when NASA's Double Asteroid Redirection Test (DART) slammed into it on September 26.

The new capture is one of 18 observations Hubble has made of the asteroid since the impact event and it is the first to show a surprising and unexpected development — a twin tail of debris is coming from the asteroid system, a press statement reveals.

New Hubble image reveals split asteroid tail

The new image, released on Thursday, October 20, comes a few days after NASA announced its DART mission had successfully altered the orbital period of Dimorphos. Dimorphos is part of a double asteroid system called Didymos and it orbits the larger Didymos asteroid. The orbital period refers to the time it takes for the smaller space rock to complete one full orbit around the system.

NASA's planetary defense test results show that we should be able to slam a spacecraft into a hypothetical hazardous asteroid as a means to alter its trajectory and prevent it from hitting Earth.

In an update on Twitter, NASA wrote that after the impact, "experts expected the ejecta to expand and fade in brightness as time went on after impact. However, the twin tails are a surprising development."

“Repeated observations from Hubble over the last several weeks have allowed scientists to present a more complete picture of how the system’s debris cloud has evolved over time,” a separate statement from NASA and the European Space Agency reads.

“The observations show that the ejected material, or 'ejecta,' has expanded and faded in brightness as time went on after impact, largely as expected,” the statement continues. "The twin tail is an unexpected development, although similar behavior is commonly seen in comets and active asteroids. The Hubble observations provide the best-quality image of the double-tail to date."

More Didymos observations to come

Scientists will carry out more observations and analysis to better understand how the split tail formed, and whether it's relevant to DART's overall mission. NASA pointed out that the northernmost tail is the one that was newly created.

DART won't be the only mission to send a spacecraft to the Didymos asteroid system. In four years' time, the European Space Agency (ESA) plans to have three spacecraft — from a mission called Hera — carrying out follow-up investigations to cover all bases and investigate the long-term effects of the DART mission.

Hubble started capturing images of the Didymos asteroid system soon after the DART spacecraft crashed into its target. The space observatory has also captured images of the asteroid at the same time as the James Webb Space Telescope, marking the first time the observatories worked in tandem.

NASA's DART mission is another historic world first for a space agency that also recently flew the first off-world helicopter and extracted the first oxygen from Mars' atmosphere. The planetary defense DART mission was the first time a space mission intentionally altered the trajectory of an asteroid in space.

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