Site Nightingale was selected as the primary sample collection site because it holds the greatest amount of unobstructed fine-grained material. Nightingale is located in a crater (with a 33 ft, or 10 m, radius) near Bennu’s north pole. The site's sampling region has a 26 ft (8 m) radius. Nightingale’s regolith – or rocky surface material – is dark, and images show that the crater is relatively smooth. Because it is located so far north, temperatures in the region are lower than elsewhere on the asteroid and the surface material is well-preserved. The crater also is thought to be relatively young, and the regolith is freshly exposed. This means the site would likely allow for a pristine sample of the asteroid, giving the team insight into Bennu’s history.
Reconnaissance A Imagery
This is the highest-resolution image captured of candidate sample site Nightingale as of October 26. Site Nightingale is located near asteroid Bennu’s north pole. The crater’s center is visible in the top center of the image, which contains an accumulation of smaller rocks. The image was taken by the PolyCam camera on NASA’s OSIRIS-REx spacecraft on October 26, from a distance of 0.6 miles (1 km). The field of view is 47 ft (14.4 m). For reference, the light-colored boulder (far left center) is 5 ft (1.4 m) long, which is about the length of a bicycle. The image was obtained during the mission’s Reconnaissance A phase. When the image was taken, the spacecraft was over the northern hemisphere, pointing PolyCam north and to the west.
Digital Terrain Model
This 3D printed model shows the steep slopes on the crater’s northern wall and the large boulders perched on the rim.
Credit: NASA/Goddard/University of Arizona/CSA/York/MDA
This set of stereoscopic images provides a 3D view of site Nightingale, located in Bennu’s northern hemisphere. The two images in this stereo pair were taken from slightly different viewpoints, with one of the images meant for the left eye and the other for the right. The two images are then combined by the brain to give the perception of depth. To see the pair in 3D, download the image and view it through a stereoscope. The cropped and processed images were obtained on March 21, 2019, by the PolyCam camera during Flyby 3 of the mission’s Detailed Survey: Baseball Diamond phase.
This anaglyph of site Nightingale was made from the above stereo pair. Each stereoscopic image was encoded using filters of chromatically opposite colors—one made with red and the other with cyan. When viewed through color-coded anaglyph glasses, each of the two images reaches the eye it’s intended for, and a 3D image is produced. Anaglyphs are helpful for selecting a sample collection site because they allow the team to intuitively understand the three-dimensional structure of objects like boulders and craters.
Boulder Count Maps
These Boulder Maps for site Nightingale detail the number and location of boulders present within the region. Because Nightingale has several possible sampling regions, a boulder count map was produced for each of these regions. The boulders are counted by the human eye, using a single image at a time. Many of these boulder counts were made by members of the public who participated in the CosmoQuest Bennu Mappers citizen science campaign. The boulder counter marks each boulder by the longest axis (point to point) in order to calculate maximum boulder size. Rocks that are 10-21 cm are marked in yellow. Anything larger than 21 cm is marked in red. Rocks and debris that are ingested by the spacecraft’s Touch-and-Go Sample Mechanism (TAGSAM) head must be no more than 2.5 cm wide.
The OSIRIS-REx spacecraft is about the size of a 15-passenger van, so for a familiar perspective, this is site Nightingale superimposed over a standard parking lot. Nightingale, which lies within the white circle, covers roughly 6 parking spaces. The width of each parking space is 9 ft (2.7 m).
Sample Site Location