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NASA̵7;s OSIRIS-REx spacecraft traveled about 131 feet, or 40 meters, of the asteroid Bennu this week during the final practice of a $ 1 billion mission before landing and Move on the asteroid in October to collect samples to return to Earth.
During Tuesday’s sampling rehearsal, engineers overseeing the spacecraft’s operations from Earth confirmed that navigation algorithms, software for automated operations, scientific tools, and multiple systems The mechanical system was all working as expected.
On Tuesday, the OSIRIS-Rex rocket-propelled spacecraft left a “home safety orbit” about 0.6 miles (1 km) from the asteroid Bennu, then down to a point about 410 feet (125 meters). on the surface of the asteroid. The spacecraft then fires off propulsion engines to perform the so-called “checkpoint” burn to start free-falling towards the asteroid.
Eight minutes later, OSIRIS-REx pulses its control jets again to create a “joint point” burn to match the spacecraft’s motion to the asteroid’s rotation. That allows the spacecraft to finally land on the surface at the targeted sampling location.
The spacecraft continued down towards the asteroid for three minutes after the combined burn point, reaching a point 131 feet from Bennu before firing the propulsion again to perform a backward move.
The position OSIRIS-REx achieved during Tuesday’s maneuvers was marked as the closest the spacecraft had reached to the asteroid Bennu, following a similar sampling exercise in April, practicing the the mission’s landing maneuvers up to a point 213 feet or 65 meters from the asteroid.
After launching from Earth in 2016 and reaching its asteroid target in 2018, Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer or NASA’s OSIRIS-REx, spacecraft The pole mapped Bennu with a camera, a mineral scenting spectrometer and a Canadian-laser was built to measure its roughness.
Shaped like a spinning top, Bennu measures about 492 meters wide. At the time of Tuesday’s maneuvers, the asteroids were located about 179 million miles (288 million km) from Earth. At that distance, it took 16 minutes for commands from ground teams to approach the OSIRIS-REx spacecraft.
“This time delay has prevented the direct command of ground-based flight operations during the exercise,” NASA said in a statement. “As a result, the spacecraft did the entire series of maneuvers automatically.”
The ground controllers linked the down-chain to the spacecraft ahead of time, and OSIRIS-REx had the configuration fly down on autopilot, just like during actual sampling.
OSIRIS-REx has been tracing sites to run the sample collection, but the scientists discovered Bennu was more rugged than expected.
The spacecraft’s sampling exercise on Tuesday targeted a site called Nightingale, the mission’s primary sampling site located in a 460-foot (140-meter) crater in the northern hemisphere of Bennu. The site is surrounded by boulders and sharp terrain, and that forced engineers to develop upgraded navigational capabilities to allow the spacecraft to guide themselves to a safe landing.
OSIRIS-REx uses a ability known as natural feature tracking to take a series of photos with the navigation camera to automatically identify rocks, craters, and other markers on the asteroid surface, providing relative speed and position data. The spaceship’s computer compares the images to a map of hazards loaded into the computer before landing. If OSIRIS-REx detects that it is entering a dangerous area, it can order its cancellation and retreat from Bennu.
Natural feature tracking algorithms were successfully tested in rehearsal Tuesday. The spacecraft’s cameras captured higher resolution scenes of the Nightingale sampling site as OSIRIS-REx was flying live over the site, allowing ground crews to update and refine their capabilities. track natural performance before trying to get real samples in October.
Dante Lauretta, OSIRIS-REx lead investigator from the University of Arizona, Tucson, said: “A lot of important systems were put in place during this exercise – from communications, propulsion engines. pillars and most importantly, the ship’s nature tracking guidance system and hazard maps. “Now that we have completed this milestone, we are confident in finalizing the TAG (Touch-And-Go) event procedures. This exercise confirmed that the team and all of the spacecraft’s systems are ready to collect a sample by October.
OSIRIS-REx also expanded its sampling branch, called TAGSAM, during Tuesday’s rehearsal. The spacecraft also moved its solar array wings to a “Y-wing” configuration to position them safely away from the asteroid surface, as if they would be positioned during landing. wings touch and move.
The TAGSAM arm was then retracted back into stowed position after OSIRIS-REx began flying out of Bennu at the end of rehearsals on Tuesday.
During the mission’s actual sampling, a device attached to the end of the spacecraft’s TAGSAM arm will contact the asteroid surface for a few seconds and shoot out compressed nitrogen gas. The gas box will break up the rock at the sampling site, and the spacecraft will capture some of the material in a chamber to return to Earth.
Scientists hope to collect at least 2.1 ounces (60 grams) of pristine samples from Bennu’s surface and return the material back to Earth by September 2023 for analysis in laboratories. complex. Scientists will examine samples for signs of organic matter and other chemicals important to the origin of life.
Built and operated by Lockheed Martin, the OSIRIS-REx spacecraft was launched from Cape Canaveral in September 2016. A limited number of staff managed a checkpoint drill on Tuesday from a hub. controls Lockheed Martin in Colorado, plus locations at the Goddard Space Flight Center in Maryland and the University of Arizona.
Other team members joined remotely due to the coronavirus pandemic, NASA said.
Earlier this year, the mission managers decided to give the groups more time to prepare for the OSIRIS-REx sampling effort as officials revise the new operational plans to mitigate risks from COVID. -19.
That decision delayed OSIRIS-REx’s second sampling rehearsal from June 23 to August 11 and pushed back the actual sampling process from August 25 to October 20.
If the first sampling was left empty in October, scientists would have had a chance for additional tests before the spacecraft departed from Bennu next year to begin a return trip to Earth.
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