text: The use of Lunar Orbiters for tracking to evaluate the Manned Space Flight Network tracking stations and Apollo Orbit Determination Program was successful, with three of the Lunar Orbiters (2, 3, and 5) being tracked simultaneously from August through October 1967. The Lunar Orbiters were all eventually commanded to crash on the Moon before their attitude control fuel ran out so they would not present navigational or communications hazards to later Apollo flights.  The Lunar Orbiter program was managed by NASA Langley Research Center at a total cost of roughly $200 million.
  Doppler tracking of the five orbiters allowed mapping of the gravitational field of the Moon and discovery of mass concentrations (mascons), or gravitational highs, which were located in the centers of some (but not all) of the lunar maria.
  Below is the flight log information of the five Lunar Orbiter photographic missions:
  Lunar Orbiter 1
  Launched August 10, 1966
  Imaged Moon: August 18 to 29, 1966
  Impact with Moon: October 29, 1966
  Apollo landing site survey mission
  Lunar Orbiter 2
  Launched November 6, 1966
  Imaged Moon: November 18 to 25, 1966
  Impact with Moon: October 11, 1967
  Apollo landing site survey mission
  Lunar Orbiter 3
  Launched February 5, 1967
  Imaged Moon: February 15 to 23, 1967
  Impact with Moon: October 9, 1967
  Apollo landing site survey mission
  Lunar Orbiter 4
  Launched May 4, 1967
  Imaged Moon: May 11 to 26, 1967
  Impact with Moon: Approximately October 31, 1967
  Lunar mapping mission
  Lunar Orbiter 5
  Launched August 1, 1967
  Imaged Moon: August 6 to 18, 1967
  Impact with Moon: January 31, 1968
  Lunar mapping and hi-res survey mission