Osiris-Rex before (left) and after the grounding, the surrounding gravel is all scattered. Courtesy of NASA
The US probe ‘OSIRIS-REx’ is returning to Earth with a sample from the asteroid ‘Bennu’, but it turns out that if the recoil engine had not been activated as soon as the sample was landed, it would have been buried in the asteroid. .
The particles on the surface of Benu are so loosely coupled that if a person stepped on it, he would hardly feel any resistance as if he had entered a ‘ball pit’.
According to the National Aeronautics and Space Administration (NASA), the scientists of the Osiris-Rex operation team published two papers in the scientific journal ‘Science’ on the results of the initial Benu-related research that included these details.
Osiris-Rex arrived near Benu, about 277 million km from Earth in December 2018, and after about two years of remote sensing and preparation, it collected samples of gravel and dust from the surface in October 2020. collected and returned to Earth. Samples are expected to be delivered to Earth on September 24 next year.
Scientists from the Osiris-Rex operation team said they were puzzled by the fact that the spacecraft flew off the pebbles and created a pool of about 8 meters even when it landed gently on the surface of Benu.
Lead researcher Dante Loretta, a professor at the University of Arizona, said: “Whenever we tested the sample collection in the lab, it left almost no trace.” explained.
The research team measured the amount of scattered gravel through photos before and after sampling at ‘Nightingale’, where the sample was taken. In addition, by analyzing the acceleration data collected when the spacecraft landed on the surface, it was confirmed that only a very small resistance was induced, such as when pressing the filter of a ‘French Press’ that filters coffee.
“When the Osiris-Rex injected its recoil propulsion engine to take off, it was still sinking into the Venu,” said Dr Ron Ballouze of the Johns Hopkins Institute of Applied Physics (JHAPL).
The research team confirmed the density and cohesion of Bennu through computer simulations based on the nightingale image and the spacecraft acceleration information.
It has been suggested that an asteroid with a density and cohesiveness like Benu would pose a different type of threat from asteroids that were tightly packed and shattered in the process of entering the atmosphere if they collide with Earth.
Osiris-Rex scientist Dr. Patrick Michel from the French National Center for Scientific Research (CNRS) said: “These asteroids behave counter-intuitively, and we are still in the early stages of understanding what they really are.” In fact, it is said that from the beginning, Bennu defied the expectations of scientists.
First of all, contrary to the prediction that Osiris-Rex will have sand as soft as a beach through remote observation through a telescope, etc., when Osiris-Rex arrives, the surface is littered with rocks, and the fact that it is blowing rock particles into space is also considered an unexpected result. done.
Osiris-Rex, an acronym for ‘Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer’ (Apophis) Goes on an expedition. The name of the spacecraft is also changed to ‘Osiris-Apex’ (APEX) with the meaning of ‘Apophis Explorer’.
As for the asteroid sample, ‘Hayabusa 2’ launched by the Japan Aerospace Exploration Agency (JAXA) was delivered from the asteroid Ryugu about 320 million km away in December 2020, one step ahead of the United States, and the research results have already been reported. presenting the situation.
Soil and rock samples taken from the surface of the asteroid Ryugu. Provided by JAXA/ Provided by EPA Yonhap News
