The actual injection into space occurred at 26 minutes 3.08 seconds after liftoff from the Cape (2:19.19 a.m., EST) at a point above 14.873 degrees south latitude and 2.007 degrees west longitude. Thus, Mariner made the break for Venus about 360 miles northeast of St. Helena, 2,500 miles east of the Brazilian coast, and about 900 miles west of Angola on the west African shore.
During injection, the vehicle was being tracked by Ascension, telemetry ship Twin Falls Victory, and Pretoria. Telemetry ship Whiskey secured the spacecraft signal just after injection and tracked until 2:26 a.m. Pretoria began its telemetry track at 2:21 and continued to track for almost two hours, until 4:19 a.m.
Injection velocity was 7.07 miles per second or 25,420 miles per hour, just beyond Earth-escape speed. The distance at the time of injection from Canaveral’s Launch Complex 12 was 4,081.3 miles.
The Agena and Mariner flew the escape path together for another two minutes after injection before they were separated at 2:21 a.m. Agena then performed a 140-degree yaw or retro-turn maneuver by expelling unused propellants. The purpose was to prevent the unsterilized Agena from possibly hitting the planet, and from following Mariner too closely and perhaps disturbing its instruments.
Now, Mariner II was flying alone and clear. Ahead lay a journey of 109 days and more than 180 million miles.
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.