NASA's OSIRIS-REx spacecraft first arrived at the large space rock known as Bennu late last year, and it's spent the first few months of 2019 observing its new space companion and teaching NASA more about the rock's surface. For the NASA engineers, asteroid's surface is nothing like what they assumed would be, and that poses a serious challenge going forward.
The OSIRIS-REx mission includes multiple objectives, with the first being the successful insertion of the spacecraft into orbit around the rock itself. NASA nailed it and things seemed to be great, or until scientists got a good look at Bennu's surface. As Sky and Telescope reports, it has complicated matters greatly.
With limited capability to observe the asteroid from Earth or in-flight towards the rock, scientists believe the asteroid would be fairly smooth. A smooth surface would make the spacecraft's final maneuver ̵
Bennu is, The asteroid is covered in debris of all sizes ranging from dust and small rocks to massive boulders and everything in between. (19659002) The plan has always been for OSIRIS-REx to remain in orbit around Bennu for about a year, making observations of its surface and relaying data and images back to its handlers on Earth. However, NASA will need to work diligently to find a safe place on the asteroid for the spacecraft to gather a sample before leaving Bennu and returning home.