A color composite image of Earth taken on Sept. 22 by the MapCam camera on NASA’s OSIRIS-REx spacecraft. This image was taken just hours after the spacecraft completed its Earth Gravity Assist at a range of approximately 106,000 miles (170,000 kilometers). MapCam is part of the OSIRIS-REx Camera Suite (OCAMS) operated by the University of Arizona. Visible in this image are the Pacific Ocean and several familiar landmasses, including Australia in the lower left, and Baja California and the southwestern United States in the upper right. The dark vertical streaks at the top of the image are caused by short exposure times (less than three milliseconds). Short exposure times are required for imaging an object as bright as Earth, but are not anticipated for an object as dark as the asteroid Bennu, which the camera was designed to image.
OVIRS, the OSIRIS-REx Visible and Infrared Spectrometer, captured this visible and infrared spectral curve, which shows the amount of sunlight reflected from the Earth, hours after the spacecraft’s closest approach during Earth Gravity Assist on Sept. 22 2017. The features in the curve are caused by solar absorption due to different substances (water vapor, carbon dioxide, and oxygen). The smooth red curve is the spectrum of the sun and shows what would be reflected if there these substances were not present in the atmosphere. OVIRS was built and is operated by NASA’s Goddard Space Flight Center in Greenbelt, Md. The inset shows an image of Earth captured by OCAMS on the same date showing the approximate location of the “spot” (400 kilometers in diameter) on the Earth that was scanned by the OVIRS instrument to produce this spectral curve.
OTES, the OSIRIS-REx Thermal Emission Spectrometer, captured these infrared spectral curves during Earth Gravity Assist on Sept. 22 2017, hours after the spacecraft’s closest approach. The peaks and valleys in the curves are known as absorption features and show differences in absorption of the sun’s energy due to different substances (water vapor, carbon dioxide, methane and ozone) in Earth’s atmosphere. The curves also provide temperature information for different heights in the atmosphere. The smooth red and blue curves show the temperatures of the ocean surface and the stratosphere without the effects of the absorption features. OTES was built and is operated by Arizona State University in Tempe, Ariz. The inset shows an image of Earth captured by OCAMS on the same date shows the approximate locations and sizes of the “spots” (each 800 kilometers in diameter) on the Earth that were scanned by the OTES instrument to produce these spectral curves.