Asteroid Bennu’s Mysterious Particle Gatherings Discussed by NASA’s OSIRIS-REx [Video] – SciTechDaily


Asteroid Bennu Ejecting Particles

This check out of asteroid Bennu ejecting particles from its surface area on January six, 2019, was created by combining two pictures taken by the NavCam 1 imager onboard NASA’s OSIRIS-REx spacecraft: a small publicity picture (1.4 ms), which demonstrates the asteroid obviously, and a long publicity impression (5 sec), which reveals the particles evidently. Other impression processing techniques ended up also utilized, this kind of as cropping and changing the brightness and distinction of each individual layer. Credit rating: NASA/Goddard/College of Arizona/Lockheed Martin

Soon after NASA’sOSIRIS-RExspacecraft arrived at asteroid Bennu, an surprising discovery by the mission’s science group discovered that the asteroid could be energetic, or constantly discharging particles into room. The ongoing evaluation of Bennu – and its sample that will inevitably be returned to Earth – could likely shed mild on why this intriguing phenomenon is happening.

The OSIRIS-REx team first observed a particle ejection party in images captured by the spacecraft’s navigation cameras taken on January 6, 2019, just a 7 days soon after the spacecraft entered its 1st orbit close to Bennu. At 1st glance, the particles appeared to be stars guiding the asteroid, but on closer examination, the group recognized that the asteroid was ejecting materials from its area. Following concluding that these particles did not compromise the spacecraft’s safety, the mission started focused observations in order to entirely document the exercise.

“Among Bennu’s quite a few surprises, the particle ejections sparked our curiosity, and we’ve put in the previous quite a few months investigating this mystery,” claimed Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “This is a great opportunity to grow our understanding of how asteroids behave.”

Just after researching the final results of the observations, the mission group unveiled their conclusions in a Science paper that will be revealed December 6. The workforce observed the 3 premier particle ejection functions on January six and 19, and February 11, and concluded that the occasions originated from distinct locations on Bennu’s floor. The first event originated in the southern hemisphere, and the second and 3rd events happened close to the equator. All three occasions took place in the late afternoon on Bennu.

This animation illustrates the modeled trajectories of particles that ended up ejected from Bennu’s surface on January 19, 2019. Just after ejecting from the asteroid’s surface, the particles possibly briefly orbited Bennu and fell again to its area or escaped away from Bennu and into place. Credit rating: NASA/Goddard/University of Arizona/Lauretta & Hergenrother et al., Science ten.1126

The group found that, following ejection from the asteroid’s surface, the particles possibly briefly orbited Bennu and fell again to its surface area or escaped from Bennu into space. The observed particles traveled up to 10 toes (three meters) for each 2nd, and calculated from smaller than an inch up to 4 inches (10 cm) in sizing. Somewhere around two hundred particles were being observed throughout the major occasion, which took position on January six, 2019.

The staff investigated a broad wide range of possible mechanisms that may perhaps have brought on the ejection occasions, and narrowed the listing to a few candidates: meteoroid impacts, thermal stress fracturing, and unveiled of drinking water vapor.

Meteoroid impacts are popular in the deep area neighborhood of Bennu, and it is possible that these little fragments of place rock could be hitting Bennu in which OSIRIS-REx is not observing it, shaking free particles with the momentum of their impression.

The crew also decided that thermal fracturing is a further reasonable clarification. Bennu’s area temperatures differ considerably about its four.three-hour rotation time period. Whilst it is very chilly in the course of the evening hours, the asteroid’s area warms significantly in the mid-afternoon, which is when the a few significant occasions occurred. As a outcome of this temperature alter, rocks could commence to crack and crack down, and sooner or later particles could be ejected from the area. This cycle is regarded as thermal tension fracturing.

Drinking water release may possibly also explain the asteroid’s exercise. When Bennu’s h2o-locked clays are heated, the water could start to release and generate tension. It is possible that as strain builds in cracks and pores in boulders wherever absorbed water is released, the floor could turn into agitated, triggering particles to erupt.

But mother nature does not often let for very simple explanations. “It could be that more than a person of these feasible mechanisms are at play,” reported Steve Chesley, an creator on the paper and Senior Investigation Scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “For instance, thermal fracturing could be chopping the floor material into small items, creating it much a lot easier for meteoroid impacts to start pebbles into house.”

If thermal fracturing, meteoroid impacts, or both equally, are in truth the causes of these ejection functions, then this phenomenon is possible happening on all small asteroids, as they all knowledge these mechanisms. On the other hand, if water launch is the result in of these ejection activities, then this phenomenon would be specific to asteroids that comprise drinking water-bearing minerals, like Bennu.

Bennu’s exercise presents larger sized possibilities when a sample is gathered and returned to Earth for research. Numerous of the ejected particles are modest adequate to be collected by the spacecraft’s sampling mechanism, meaning that the returned sample could potentially have some product that was ejected and returned to Bennu’s surface area. Identifying that a unique particle experienced been ejected and returned to Bennu may possibly be a scientific feat similar to getting a needle in a haystack. The content returned to Earth from Bennu, nonetheless, will pretty much definitely improve our knowledge of asteroids and the strategies they are equally unique and similar, even as the particle ejection phenomenon proceeds to be a thriller whose clues we’ll also return residence with in the kind of data and more content for review.

Sample selection is scheduled for summer months 2020, and the sample will be shipped to Earth in September 2023.

NASA’s Goddard Room Flight Heart in Greenbelt, Maryland delivers over-all mission management, devices engineering, and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also qualified prospects the science staff and the mission’s science observation scheduling and information processing. Lockheed Martin Area in Denver created the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are dependable for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Method, which is managed by NASA’s Marshall Room Flight Heart in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington.