Surveyor II will impact southeast of the crater Copernicus at 8:18 p.m. PDT tonight. The landing time and zone is based on analysis of the flight path prior to loss of contact.
Contact with the spacecraft was lost at 2:35 a.m. today when there was a failure in the communications or power system during the firing of the 10,000 pound thrust retro engine. Up to the time of loss of contact, despite the tumbling motion of the spacecraft, there was no evidence of further failure in the spacecraft beyond the failure of vernier engine number 3 to fire upon command.
The retro was ignited to provide valuable engineering information on the firing of a large solid fuel motor in the vacuum of space when it became apparent that Surveyor II could not be soft landed on the moon. It is not possible to test fire the large Surveyor retro motor in a vacuum on Earth to obtain engineering data.
Engineers at the Jet Propulsion Laboratory made 38 attempts yesterday to ignite vernier engine number 3 that had failed to fire during an attempt to perform a midcourse correction Tuesday night. The failure of one of the three vernier engines to fire threw Surveyor II into an uncontrolled tumbling motion. Efforts to re-stabilize the spacecraft failed. The attempts to re-establish control were continued until early today. When it became apparent that the soft landing could not be performed, a series of engineering experiments to check terminal descent systems aboard the spacecraft were conducted, ending with the firing of the main retro.