NASA recently announced that the Osiris Rex probe, which aims to sample and return asteroids, will land on the asteroid Bennu (asteroid 101955) on October 20. The probe will make a careful 4.5-hour landing and then touch and leave the asteroid within seconds. < / P > < p > after 4.5 hours of slow descent, osiris-rex will land on asteroid bernu in a few seconds and sample (image) < / P > < p > the truck size probe has a robotic arm to collect samples from the asteroid’s surface. Scientists hope that this mission will deepen our understanding of planet formation and the origin of life, and further explore asteroids that may affect the earth. Nightingale was chosen for the landing site because it is one of the clearest areas on bernu’s surface, and it is easy to get in touch with fine particles. < / P > < p > however, there are some huge, building size rocks around the landing site, and there is only one place about the size of a few parking spaces for landing. On the other hand, if the landing is slightly deviated, the situation of Osiris Rex may be very bad. NASA also revealed some details of how the Osiris Rex probe will land on the asteroid surface. The four and a half hour trial will be divided into three steps. The first step is to ignite the thruster on the Osiris Rex detector, which is about 770 meters away from the surface. Bernu is located between the earth and Mars, about 334 million kilometers away from the earth. At such a distance, the signal from the Osiris Rex probe to NASA Headquarters takes about 18.5 minutes. This means that artificial landing is impossible, and all the hope of successful landing lies in the airborne autonomous system. < / P > < p > according to the plan, the Osiris Rex probe should collect at least 57 grams of asteroid rock material back to earth. This will be the largest sample collection mission since the Apollo mission, which received more funding and more help on the ground when collecting samples. The Osiris Rex probe will return to earth on September 24, 2023, if the material on the bernu surface is successfully collected. NASA also revealed some details of how the Osiris Rex probe will land on the asteroid surface. The four and a half hour trial will be divided into three steps. The first step is to ignite the thruster on the Osiris Rex detector, which is about 770 meters away from the surface. < / P > < p > the reason why the orbital height is so low is that bernu’s average radius is only 246m, and the overall gravity is very small. At this point, the sampling arm of the detector, known as the “touch and go sample acquisition mechanism” (tagsam), will expand and point downward toward bernu. The fragile solar panels will be deployed in a Y-shaped airfoil above the detector to safely avoid any danger. < p > < p > the sampling head of tagsam will be the only part of the detector that will touch the bernould surface. Mike morrow, deputy director of the Osiris Rex project, said the mission had taken years of planning and hard work, and tagsam would basically only touch the surface of the asteroid for five to 10 seconds. < / P > < p > NASA staff will authorize the Osiris Rex probe to land autonomously. It will use a navigation system called natural feature tracking (NFT) to control its landing. The system uses all the detailed images of the asteroid’s surface taken by the Osiris Rex mission and converts it into a map, pointing out all the potential dangers. If the landing deviates from various pre-defined limits, which may put the detector in danger, the system will perform a pre programmed abort mission. < / P > < p > if this happens, NASA will reorganize the mission team and try again at a later date. The slow and steady descent of the detector takes about four hours, and then it performs a so-called “checkpoint” maneuver at an altitude of about 125 meters. < / P > < p > as the thruster ignites again, the slow descent will become steeper and faster, and the probe will be closer to the asteroid surface. In about 11 minutes, there will be a third and final maneuver, the match point. At this point, the computer system will use thrusters to stabilize the probe at an altitude of 54 meters from the landing site. The Osiris Rex probe will again slow down and try to match its rotation before approaching the asteroid. < / P > < p > NASA predicts that the Osiris Rex probe will not land on the asteroid surface for more than 16 seconds. After that, the detector’s nitrogen bottle will eject gas, blowing debris from bernould’s surface. The detector will try to collect some debris before igniting again, and then withdraw to a safe track. Only a week after the landmark landing, NASA will know if it can successfully acquire about 60 grams of asteroid material. < / P > < p > on October 22, an airborne camera will photograph the telescopic sampling arm to see if any substance has been collected. On October 24, the Osiris Rex detector will try to determine the mass of these substances. If the sample size is sufficient, the materials will be safely packed and placed in the “sample return capsule” (SRC) to start the journey back to earth. < / P > < p > if the sample size is not satisfactory to NASA, the Osiris Rex probe will return to the asteroid and try again because it carries enough nitrogen to make three attempts. If that happens, NASA will give up Nightingale, change its landing site to an osprey, and it won’t land again until January 2021 at the earliest. < / P > < p > NASA images of the asteroid bernu show that it has debris from another asteroid on its surface, and it is “extremely bright.”. The fragments, from Vesta, range in size from 1.5 meters to 4.3 meters, and are scattered in bernu’s southern hemisphere and near its center. < / P > < p > NASA images of the asteroid bernu show that it has debris from another asteroid on its surface, and it is “extremely bright.”. The fragments, from Vesta, range in size from 1.5 meters to 4.3 meters, and are scattered in bernu’s southern hemisphere and near its center. < / P > < p > the researchers detected the boulders in images from the Osiris Rex detector, which looked much brighter than the surrounding dark carbon rich areas. The probe analyzed the debris using an onboard spectrometer and found signs of pyroxene, a known compound on Vesta. < / P > < p > NASA researchers believe the material came from bernu’s parent asteroid, which was hit by debris from Vesta. Hannah Kaplan of NASA’s Goddard Space Flight Center said: “our main assumption is that a fragment of Vesta hit bernu’s parent asteroid, and bernu inherited the material from the parent asteroid. Later, some of the debris from the Vesta asteroid, including Vesta’s own debris, formed when it came down from the gravity of the asteroid Scientists say the ancient asteroid may contain clues to the origin of life. It is believed to have been formed 4.5 billion years ago, carrying the remnants of the birth of the solar system. < / P > < p > the Osiris Rex probe was launched with Atlas 5 rocket at 19:05 on September 8, 2016. After carefully investigating the characteristics of the bernu asteroid and determining the most suitable sampling site, Osiris Rex will use a robotic arm to collect about 60 to 2000 grams of asteroid surface material and send the samples back to earth in 2023 via a detachable capsule. < / P > < p > to collect samples on the asteroid surface, the Osiris Rex probe will hover over a specific area and land slowly and gently at a rate of 10 cm per second. The probe also carries a laser altimeter and a set of cameras provided by the University of Arizona, as well as a spectrometer and lidar. After 12 years, “world class Super project” Shantou Bay Tunnel ushers in a historic breakthrough today

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