Much of the research centers on a series of unexpected surface features spotted over the first few months.
The particle plumes were discovered on January 6, only days after the spacecraft arrived at Bennu.
Now it's clear that what actually speckles Bennu's surface is a shocking series of hefty boulders, some of which could be as large as 150 feet across. This is the first time scientists have had close-up observations of particle plumes erupting from an asteroid's surface, the agency said.
To understand the driving forces behind this action, the spacecraft's navigation team members are tracking the ejected material image by image, following the path of the particles, Adam said.
"The discovery of plumes is one of the biggest surprises of my scientific career", Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson, said in a NASA news release. And the rugged terrain went against all of our predictions. "Bennu is already surprising us, and our exciting journey there is just getting started", Lauretta added.
Before OSIRIS-REx launch from Cape Canaveral back in 2016.
Scientists say the ancient asteroid could hold clues to the origin of life. The asteroid is on an oval-formed path that takes it directly inside Earth's orbit at its closest level to the solar, and there's a 1-in-2,700 likelihood Bennu might influence Earth late within the 22nd century.
The surface of asteroid Ryugu is not what Japanese mission planners anticipated either.
An artist's concept of the OSIRIS-REx's sample collection instrument TAGSAM. Image courtesy NASA
An asteroid some 50 million miles away is spewing pebble and rock-sized debris - and scientists don't know why.
Other highlighted findings included that Bennu contains hydrated minerals, including magnetite, which could indicate that the asteroid once had water. "And you could gain enough energy so that you'd roll off the equator and maybe up into orbit and then out into space".
The scientists were also surprised by Bennu's terrain, which is covered with large boulders. Although, some remained in orbit of the asteroid.
NASA scientists now are scrambling to find a large, smooth spot on Bennu's surface for OSIRIS-REx to work. Instead, it's rough and crowded with boulders.
During this phase, OSIRIS-REx will dip down to collect a sample.
"Throughout OSIRIS-REx's operations near Bennu, our spacecraft and operations team have demonstrated that we can achieve system performance that beats design requirements", said Rich Burns, the mission's project manager at NASA's Goddard Space Flight Center.
"Bennu's rough surface has thrown up a big challenge to the OSIRIS-REx spacecraft, but the team is confident that it is up to the task", he said.
This image shows a view across asteroid Bennu's southern hemisphere and into space.
Lauretta believes that the team simply made the wrong inferences on Bennu's boulders based on the data they had, but that they were correct in some aspects of their interpretation.
"This is what discovery is all about - surprises, quick thinking and doing what it takes to get good science", said Lori Glaze, acting director of NASA's planetary-science division.More news: McCain's widow, daughter punch back at Trump's Twitter tirade