Mariner 6 and 7
Mariner 6
|
|
| Mission type | Flyby Mars |
|---|---|
| Operator | NASA / JPL |
| COSPAR ID | 1969-014A |
| SATCAT no. | 3759 |
| Spacecraft properties | |
| Manufacturer | Jet Propulsion Laboratory |
| Launch mass | 411.8 kilograms (908 lb) |
| Power | 449 W |
| Start of mission | |
| Launch date | February 25, 1969, 01:29:02 UTC |
| Rocket | Atlas SLV-3D Centaur-D1A |
| Launch site | Cape Canaveral LC-36B |
| End of mission | |
| Disposal | Decommissioned |
| Deactivated | |
| Flyby of Mars | |
| Closest approach | July 31, 1969 |
| Distance | 3,431 kilometers (2,132 mi) |
|
Mariner 7
|
|
| Mission type | Flyby Mars |
|---|---|
| Operator | NASA / JPL |
| COSPAR ID | 1969-030A |
| SATCAT no. | 3837 |
| Spacecraft properties | |
| Manufacturer | Jet Propulsion Laboratory |
| Launch mass | 411.8 kilograms (908 lb) |
| Power | 449 W |
| Start of mission | |
| Launch date | March 27, 1969, 22:22:00 UTC |
| Rocket | Atlas SLV-3D Centaur-D1A |
| Launch site | Cape Canaveral LC-36A |
| End of mission | |
| Disposal | Decommissioned |
| Deactivated | March 24, 1975 |
| Flyby of Mars | |
| Closest approach | August 5, 1969 |
| Distance | 3,430 kilometers (2,130 mi) |
As part of NASA's wider Mariner program, Mariner 6 and Mariner 7 (Mariner Mars 69A and Mariner Mars 69B) completed the first dual mission to Mars in 1969. Mariner 6 was launched from Launch Complex 36B at Cape Canaveral Air Force Station and Mariner 7 from Launch Complex 36A at Cape Kennedy. The craft flew over the equator and south polar regions, analyzing the atmosphere and the surface with remote sensors, and recording and relaying hundreds of pictures. The mission's goals were to study the surface and atmosphere of Mars during close flybys, in order to establish the basis for future investigations, particularly those relevant to the search for extraterrestrial life, and to demonstrate and develop technologies required for future Mars missions. Mariner 6 also had the objective of providing experience and data which would be useful in programming the Mariner 7 encounter five days later.
Three Mariner probes were constructed for the mission, with two intended to fly and one as a spare in the event of a mission failure. The spacecraft were shipped to Cape Canaveral with their Atlas-Centaur boosters in December 1968 – January 1969 to begin pre-launch checkouts and testing. On February 14, Mariner 6 was undergoing a simulated countdown on LC-36A, electrical power running, but no propellant loaded in the booster. During the test run, an electrical relay in the Atlas malfunctioned and opened two valves in the pneumatic system which allowed helium pressure gas to escape from the booster's balloon skin. The Atlas began to crumple over, however two pad technicians quickly activated a manual override switch to close the valves and pump helium back in. Although Mariner 6 and its Centaur stage had been saved, the Atlas had sustained structural damage and could not be reused, so they were removed from the booster and placed atop Mariner 7's launch vehicle on the adjacent LC-36B, while a different Atlas was used for Mariner 7. NASA awarded the quick-thinking technicians, Bill McClure and Jack Beverlin, an Exceptional Medal of Bravery for their courage in risking being crushed underneath the 124-foot rocket. In 2014, a recently discovered escarpment on Mars was named the McClure-Beverlin Ridge in honor of the pair, who had since passed on.
Mariner 6 lifted from LC-36B at Cape Canaveral on February 25, 1969, using Atlas-Centaur AC-20 and Mariner 7, from LC-36A on March 27, using AC-19. The boost phase for both spacecraft went according to plan and no serious anomalies occurred with either launch vehicle. A minor LOX leak froze some telemetry probes in AC-20 which registered as a drop in sustainer engine fuel pressure; however, the engine performed normally through powered flight. In addition, BECO occurred a few seconds early due to a faulty cutoff switch, resulting in longer than intended burn time of the sustainer engine and Centaur, but this had no serious effect on vehicle performance or the flight path. AC-20 was launched at a 108-degree azimuth.
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