Posted on 07/08/2022 6:51:20 AM PDT by Red Badger
OSIRIS REx Spacecraft Leaving Bennu Surface
NASA’s OSIRIS-REx spacecraft leaving the surface of asteroid Bennu after collecting a sample. Credit: NASA’s Goddard Space Flight Center/CI Lab/SVS
Scientists have learned something astonishing after analyzing data gathered when NASA’s OSIRIS-REx spacecraft collected a sample from asteroid Bennu in October 2020. The spacecraft would have sunk into the asteroid had it not fired its thrusters to back away immediately after it grabbed its sample of dust and rock from Bennu’s surface.
“Our expectations about the asteroid’s surface were completely wrong.” — Dante Lauretta, principal investigator of OSIRIS-REx
Unexpectedly, it turns out that the particles making up Bennu’s exterior are so loosely packed and lightly bound to each other that if a person were to step onto the asteroid they would feel very little resistance. It would be like stepping into a pit of plastic balls that are popular play areas for kids.
“If Bennu was completely packed, that would imply nearly solid rock, but we found a lot of void space in the surface,” said Kevin Walsh, a member of the OSIRIS-REx science team from Southwest Research Institute, which is based in San Antonio.
NASA's OSIRIS REx Spacecraft Surface of Asteroid Bennu
Side-by-side images from NASA’s OSIRIS-REx spacecraft of the robotic arm as it descended towards the surface of asteroid Bennu (left) and as it tapped it to stir up dust and rock for sample collection (right). OSIRIS-REx touched down on Bennu at 6:08 pm EDT on October 20, 2020. Credit: NASA’s Goddard Space Flight Center
The latest findings about Bennu’s surface were published on July 7, 2022, in a pair of papers in the journals Science and Science Advances, led respectively by Dante Lauretta, principal investigator of OSIRIS-REx, based at University of Arizona, Tucson, and Kevin Walsh. These surprising results add to the intrigue that has gripped scientists throughout the OSIRIS-REx mission, as Bennu has proved consistently unpredictable.
The first surprise the asteroid presented was in December 2018, when NASA’s spacecraft arrived at Bennu. The OSIRIS-REx team found a rough surface littered with boulders instead of the smooth, sandy beach they had expected based on observations from Earth- and space-based telescopes. Reasearchers also discovered that Bennu was ejecting particles of rock from its surface into space.
“Our expectations about the asteroid’s surface were completely wrong,” said Lauretta.
The latest clue that Bennu was not what it seemed came after the OSIRIS-REx spacecraft picked up a sample and beamed stunning, close-up images of the asteroid’s surface to Earth. “What we saw was a huge wall of debris radiating out from the sample site,” Lauretta said. “We were like, ‘Holy cow!’”
VIDEO AT LINK.................
Near-Earth asteroid Bennu is a rubble pile of rocks and boulders left over from the formation of the solar system. On October 20, 2020, NASA’s OSIRIS-REx spacecraft briefly touched down on Bennu and collected a sample for return to Earth. During this event the spacecraft’s arm sank far deeper into the asteroid than expected, confirming that Bennu’s surface is loosely bound. Now, scientists have used data from OSIRIS-REx to revisit the sample-collection event and better understand how Bennu’s loose upper layers are held together. Credit: NASA’s Goddard Space Flight Center/CI Lab/SVS
Mission scientists were perplexed by the abundance of pebbles strewn about, given how gently the spacecraft tapped the surface. Even more bizarre was that the spacecraft left a big crater that was 26 feet (8 meters) wide. “Every time we tested the sample pickup procedure in the lab, we barely made a divot,” Lauretta said. The mission team decided to send the spacecraft back to take more photographs of Bennu’s surface “to see how big of a mess we made,” Lauretta said.
Researchers analyzed the volume of debris visible in before and after images of the sample site, nicknamed “Nightingale.” They also looked at acceleration data collected during the spacecraft’s touch down. This data revealed that as OSIRIS-REx touched the asteroid it experienced the same amount of resistance – very little – a person would feel while squeezing the plunger on a French press coffee carafe. “By the time we fired our thrusters to leave the surface we were still plunging into the asteroid,” said Ron Ballouz, an OSIRIS-REx scientist based at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
Ballouz and the research team ran hundreds of computer simulations to deduce Bennu’s density and cohesion based on spacecraft images and acceleration information. Engineers varied the surface cohesion properties in each simulation until they found the one that most closely matched their real-life data.
Asteroid Bennu Particles
This view of asteroid Bennu ejecting particles from its surface on Jan. 19, 2019, was created by combining two images taken on board NASA’s OSIRIS-REx spacecraft. Other image processing techniques were also applied, such as cropping and adjusting the brightness and contrast of each image. (Credit: NASA/Goddard/University of Arizona/Lockheed Martin)
Now, this precise information about Bennu’s surface can help scientists better interpret remote observations of other asteroids, which could be useful in designing future asteroid missions and for developing methods to protect Earth from asteroid collisions.
It’s possible that asteroids like Bennu — barely held together by gravity or electrostatic force — could break apart in Earth’s atmosphere and thus pose a different type of hazard than solid asteroids. “I think we’re still at the beginning of understanding what these bodies are, because they behave in very counterintuitive ways,” said Patrick Michel, an OSIRIS-REx scientist and director of research at the Centre National de la Recherche Scientifique at Côte d’Azur Observatory in Nice, France.
References:
“Spacecraft sample collection and subsurface excavation of asteroid (101955) Bennu” by D. S. Lauretta, C. D. Adam, A. J. Allen, R.-L. Ballouz, O. S. Barnouin, K. J. Becker, T. Becker, C. A. Bennett, E. B. Bierhaus, B. J. Bos, R. D. Burns, H. Campins, Y. Cho, P. R. Christensen, E. C. A. Church, B. E. Clark, H. C. Connolly, M. G. Daly, D. N. DellaGiustina, C. Y. Drouet d’Aubigny, J. P. Emery, H. L. Enos, S. Freund Kasper, J. B. Garvin, K. Getzandanner, D. R. Golish, V. E. Hamilton, C. W. Hergenrother, H. H. Kaplan, L. P. Keller, E. J. Lessac-Chenen, A. J. Liounis, H. Ma, L. K. McCarthy, B. D. Miller, M. C. Moreau, T. Morota, D. S. Nelson, J. O. Nolau, R. Olds, M. Pajola, J. Y. Pelgrift, A. T. Polit, M. A. Ravine, D. C. Reuter, B. Rizk, B. Rozitis, A. J. Ryan, E. M. Sahr, N. Sakatani, J. A. Seabrook, S. H. Selznick, M. A. Skeen, A. A. Simon, S. Sugita, K. J. Walsh, M. M. Westermann, C. W. V. Wolner and K. Yumoto, 7 July 2022, Science. DOI: 10.1126/science.abm1018
“Near-zero cohesion and loose packing of Bennu’s near-subsurface revealed by spacecraft contact” by Kevin J. Walsh, Ronald-Louis Ballouz, Erica R. Jawin, Chrysa Avdellidou, Olivier S. Barnouin, Carina A. Bennett, Edward B. Bierhaus, Brent J. Bos, Saverio Cambioni, Harold C. Connolly, Marco Delbo, Daniella N. DellaGiustina, Joseph DeMartini, Joshua P. Emery, Dathon R. Golish, Patrick C. Haas, Carl W. Hergenrother, Huikang Ma, Patrick Michel, Michael C. Nolan, Ryan Olds, Benjamin Rozitis, Derek C. Richardson, Bashar Rizk, Andrew J. Ryan, Paul Sánchez, Daniel J. Scheeres, Stephen R. Schwartz, Sanford H. Selznick, Yun Zhang and Dante S. Lauretta, 7 July 2022, Science Advances. DOI: 10.1126/sciadv.abm6229
NASA’s Goddard Space Flight Center provides overall mission management, systems engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator. The university leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Littleton, Colorado, built the spacecraft and provides flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate Washington.
Thanks Red Badger. Buh buh buh buh Bennu meets some jets. Or somethin'.
Mostly planets transiting their stars are deduced through periodic slight dimming or the wobble of the star that is deduced as a planet’s gravitational pull in orbit.
I think the resolution from something 100K miles away and 100 light years would differ.
Excellent news when things are not as simple as originally thought...
Budget propagandists rejoice...
Sounds like the science wasn’t settled.
Actual working scientists already know that. Do you think we’re stupid?
Thanks anyway, though ...
That's the kind of "big if" they use on Ancient Aliens. The data do not support your premise.
Wobble (or Doppler) and transit methods are the most used methods, yes, in that order. Resolution beyond a single pixel using direct observation is of course not possible without an objective lens the size of the whole solar system or something. But even a single pixel can reveal a lot, such as chemical composition using spectrography. We’ll see what the James Webb can do over the next few years.
“Do you think we’re stupid?”
What does Hockey Stick Mann say?
Do you know any actual working scientists? Does your education in the natural sciences extend past high school?
Your immediate resort to a media-political celebrity suggests a negative answer to both questions.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
