ORIENTATION AND MIDCOURSE MANEUVER As Mariner II headed into space, the Deep Space Instrumentation Facility (DSIF) network began to track the spacecraft. At 2:23.59 a.m., DSIF 5 at Johannesburg, aided by the Mobile Tracking Station, installed in vans in the vicinity, was “looking” at the spacecraft, just four minutes after injection. Johannesburg was able to track Mariner until 4:04 p.m. because, as the trajectory took Mariner almost radially away from the Earth, our planet began in effect to turn away from under the spacecraft. On an Earth map, because of its course and the rotation of the Earth, Mariner II appeared to describe a great arc over the Indian Ocean far to the west of Australia, then to turn north and west and to proceed straight west over south-central Africa, across the Atlantic, and over the Amazon Basin of northern South America. Johannesburg finally lost track at a point over the middle of South America. While swinging over the Indian Ocean on its first pass, the spacecraft was acquired by Woomera’s DSIF 4 at 2:42.30 a.m., and tracked until 8:08 a.m., when Mariner was passing just to the north of Madagascar on a westerly course. Goldstone did not acquire the spacecraft until it was approaching the east coast of South America at 3:12 p.m., August 27. With Mariner slowly tumbling in free space, it was now necessary to initiate a series of events to place the spacecraft in the proper flight position. At 2:27 a.m., 44 minutes after launch, the Mariner Central Computer and Sequencer (CC&S) on board the spacecraft issued a command for explosively activated pin pullers to release the solar panels and the radiometer dish from their launch-secured positions. At 2:53, 60 minutes after liftoff, the attitude control system was turned on and the Sun orientation sequence began with the extension of the directional antenna to a preset angle of 72 degrees. [Illustration: _Mariner II was launched while Venus was far behind the Earth. During the 109-day flight, Venus overtook and passed the Earth. It rendezvoused with the spacecraft at a point about 36,000,000 miles from the Earth._] [Illustration: _During the midcourse maneuver, the trajectory of Mariner II was corrected so that the spacecraft would approach within 21,598 miles of Venus._] ROLL MANEUVER ANTENNA UP PITCH MANEUVER MOTOR BURN SUN REAQUISITION ANTENNA REPOSITION EARTH REAQUISITION The Sun sensors then activated the gas jets and moved the spacecraft about until the roll or long axis was pointed at the Sun. This maneuver required only 2½ minutes after the CC&S issued the command. The solar panel power output of 195 watts was somewhat higher than anticipated, as were the spacecraft temperatures, which decreased and stabilized six hours after the spacecraft oriented itself on the Sun.