July 10, 2013
Lunar Reconnaissance Orbiter Surveys Moon Landing Sites
April Flowers for redOrbit.com - Your Universe Online
Like the Lunar Reconnaissance Orbiter (LRO), the Lunar Orbiter program's primary design function was to obtain images that would allow scientists and engineers to characterize the moon's surface in order to find safe and engaging landing sites for future missions.Five unmanned Orbiters were sent to the moon between 1966 and 1967, collectively photographing most of the lunar surface at 66 to 656 yards resolution. Some of Lunar Orbiter 5's photographs had resolutions as high as 3.3-feet-per-pixel. Lunar Orbiter 3, launched by NASA in 1967, had a primary objective of finding safe landing sites for the Surveyor and Apollo missions. Both missions visited one area photographed by the Orbiter -- a small, 650-foot crater inside Oceanus Procellarum.
Surveyor 3 landed on April 20, 1967, and two-and-a-half years later, Apollo 12 demonstrated the lunar module's capability to make a pinpoint landing by setting down on the edge of what had been named Surveyor Crater, about 170 yards from the deactivated Surveyor 3 spacecraft on November 19, 1969.
The LROC -- Lunar Reconnaissance Orbiter Camera -- has now imaged the same area of Oceanus Procellarum, 45 years later. New features were revealed in the LROC images, however. These features include the Apollo 12 lunar module (Intrepid), Surveyor 3, and astronaut tracks, which are all visible in the images. The most notable difference, however, is that Surveyor crater and the area around the lunar module are noticeably brighter than in the Lunar Orbiter 3 image.
The increased reflectivity is a result of rocket exhaust blasting the lunar surface during Intrepid's descent. The surface appears darker directly beneath and around the lunar module because the exhaust gas disrupted and roughed up the surface. Starting a few yards out and extending for several hundred yards, the surface was altered in such a way that it became more reflective.
The descent of Apollo 12 experienced greater thrust, causing greater soil erosion rates than Apollo 11. As astronaut Pete Conrad flew Intrepid around the edge of Surveyor crater to find the safe landing spot he wanted, the crater likely acted as a mechanism to contain the rocket exhaust, causing the entire crater to experience disturbance and appear more reflective.
Image Below: This image from the Lunar Reconnaissance Orbiter shows the Apollo 12 and Surveyor 3 landing sites.Image Credit: NASA/Goddard/Arizona State University