NASA's Dawn mission ends, but his legacy lives on

The NASA Dawn spacecraft, which studied two large objects in the asteroid belt, officially broke down fuel, ending its mission to clear up the early days of the solar system, but its scientific legacy will continue.

Dawn was the first spacecraft to orbit two different extraterrestrial objects. The mission was technically canceled twice before the launch of the satellite, but Dawn was launched in September 2007 and was aimed at the asteroid Vesta and the dwarf planet Ceres, chosen for their poor resemblance. Although they represent only two of the millions of objects in the asteroid belt, they contain 45% of its mass. NASA announced the end of Dawn's asteroid mission on Thursday, Nov. 1.

"Previously, Vesta and Ceres were only seen as light faded stars," said Marc Rayman, Dawn's mission director at NASA, Space.com. "We now have these intimate and detailed portraits of extraterrestrial terrains and complex geology, as well as a wealth of detail that we have never imagined before, unveiling the secrets that these bodies have kept for billions of years." 39, years. " [Photos: Asteroid Vesta and NASA’s Dawn Spacecraft]

To succeed, the Dawn spacecraft needed a cautious trajectory and a secret weapon: an ion propulsion system that had only fueled a previous NASA mission. As the mission unfolded, this system gave engineers the opportunity to spend twice as long as planned at Vesta and nearly five times longer at Ceres.

Scientists were strangely aware of Dawn's first destination, Vesta, thanks to a cosmic whim: the majority of meteorites that fell on Earth with an identified house are actually pieces of this distant object. But seeing planetary debris pounding our planet is not the same as seeing an asteroid in all its splendor – and that's exactly what Dawn let us do, from his arrival in 2011.

"All of Vesta's images were super cool," Kristina Larson, NASA's Mission Engineer at Space.com, told Space.com. She began working on Dawn as a junior summer intern and gradually assumed more and more responsibilities with the spaceship, and the first commandment she sent him brought some of these images on Earth. "Vesta is a body so funky in appearance, it is not very spherical and it is just very strongly cratered."

The funky aspect of Vesta is also interesting from the scientific point of view: it has known two events so important that the shocks have created a network of more than 90 notches. "The whole body resembling a planet has reverberated," Rayman said. During his stay at Vesta, Dawn stated that he was continually impressed by the success of the mission and by the time scientists had taken out of his visit. "I've always thought that if the probe had just died mysteriously that day, we would at least have a valuable return on what we had invested."

The spacecraft had an imminent death experience when leaving Vesta, when the second of the four reaction wheels she had routinely crashed, jeopardizing Dawn's ability to send data at home. The engineers of the team rushed to a solution replacing the fuel maneuvers, which saved the mission.

In 2015, Dawn reached its second destination, the dwarf planet Ceres. His discoveries include particularly reflective areas, now called bright spots, which, according to scientists, now represent salts sprayed on the surface of Ceres from below. But for Rayman, they are also beautiful. "How can you not be fascinated by these things?" he said. "The way I like to think about it, is that Ceres illuminates its light as a lighthouse illuminating the interplanetary ocean." [Photos: Dwarf Planet Ceres, the Solar System’s Largest Asteroid]

Dawn also revealed that Ceres was not a dead world. 250 million years ago, a giant ice volcano dubbed Ahuna Mons sprang liquid water with dozens of compatriots, making the composition and geology of the dwarf planet a particularly complex puzzle. "It's a bit of a hybrid world," Lynnae Quick, a global scientist at the National Museum of Air and Space who works with Dawn, told Lynn's Space.com. "Because Ceres has this kind of exotic composition, you can not think only about water and salts, you have to think about water, salts and mud, and that makes it very interesting . "

As the spacecraft approached – when it ran out of fuel, it traveled 35 km above the surface of the dwarf planet – its views of Ceres became even more incredible. The time Dawn spent at Ceres reshaped the scientists' opinion of the subject, team members said, and he is now a viable candidate for a return mission . In large part, this is because of the boxes that scientists have ticked for their life search criteria.

"Before, it was just an asteroid, and now he's playing with the big boys," Julie Castillo-Rogez, planetary science scientist in charge of the mission at NASA, told Space.com. who have been astrobiological suitors for much longer. In order to protect the life that may be hiding on Ceres, the spacecraft's demise is carefully organized to keep it away from the dwarf planet for at least 20 years, in case NASA decides to set up a monitoring mission.

NASA is already working on a successor to the Dawn mission, worth $ 467 million: Psyche. Like Dawn, he will visit an asteroid – and like Dawn, he will do it through an ionic propulsion system. And the scientists behind Dawn hope to have paved the way for new excursions into tiny corners of our solar system.

"I hope that there will be many, many missions like [Dawn] Carol Raymond, senior mission investigator at NASA, told Space.com. "We have a new way of going deeper into the solar system and getting smaller objects, which may not have been appreciated in the past. information that they hold. "

Copyright 2018 Space.com, a future society. All rights reserved. This material may not be published, disseminated, rewritten or redistributed.