Dart's Mission Accomplished

(MENAFN- Gulf Times)

After a 10-month journey through outer space, it was a historic moment when Nasa's $325mn, buggy-sized 570kg Dart (Double Asteroid Redirection Test) probe crashed into the 5bn kg asteroid Dimorphos at about 22,530km per hour on September 26, in humanity's first planetary defence test – an attempt to change the orbit of an asteroid. Though the live streamed test was deemed a success, it will be some weeks before scientists know for sure whether their experiment has worked. Scientists will determine by studying the changes to the orbit of Dimorphos around another asteroid called Didymos. 
Dimorphos is one part of a double-asteroid system and the smaller of the two. Measuring 530ft across, Dimorphos orbits its much larger, 2,560ft companion, Didymos. Neither poses a threat to Earth. It will be another two years before the European Space Agency launches its Hera mission to the system, to carry out a detailed post-impact analysis of the binary asteroid. Hera, like Dart, is a mission supported by an international collaboration called the Asteroid Impact and Deflection Assessment. With these missions, scientists are working to develop and hone the techniques that may one day be necessary to prevent a potentially catastrophic asteroid strike on Earth.
The Dart mission lead Dr Andy Rivkin described the mission as a“very simple idea” - ramming the spacecraft into the object you are worried about, and using the mass and speed of the craft“to slightly change the orbit of that object enough so that it would miss the Earth.” The investigation team will now observe Dimorphos using dozens of telescopes stationed around the world and in space to confirm that Dart's impact altered the asteroid's orbit around Didymos. Researchers expect the impact to shorten Dimorphos' orbit by about 1%, or roughly 10 minutes; precisely measuring how much the asteroid was deflected is one of the primary purposes of the full-scale test.
With the asteroid pair within 11mn km of Earth, a global team over the coming weeks will characterise the ejecta produced and precisely measure Dimorphos' orbital change to determine how effectively Dart deflected the asteroid. The results will help validate and improve scientific computer models critical to predicting the effectiveness of this technique as a reliable method for asteroid deflection. Two days after the collision, the Southern Astrophysical Research Telescope in Chile captured the remarkable picture of a comet-like plume spreading behind Dimorphos and stretching more than 10,000km. The trail is expected to get even longer until it disperses completely, and looks like other space dust floating around.
“Planetary Defence is a globally unifying effort that affects everyone living on Earth,” said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at Nasa Headquarters in Washington.“Now we know we can aim a spacecraft with the precision needed to impact even a small body in space. Just a small change in its speed is all we need to make a significant difference in the path an asteroid travels.”
“Dart's success provides a significant addition to the essential toolbox we must have to protect Earth from a devastating impact by an asteroid,” said Lindley Johnson, Nasa's planetary defence officer.“This demonstrates we are no longer powerless to prevent this type of natural disaster. Coupled with enhanced capabilities to accelerate finding the remaining hazardous asteroid population by our next Planetary Defence mission, the Near-Earth Object Surveyor, a Dart successor could provide what we need to save the day.”

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