Mariner 6 & 7: "Mariner - Mars '69" 1969 NASA-JPL (Patreon)

more at http://quickfound.net/

Originally a public domain film from NASA, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Mariner_6_and_7

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

Mariner 6 and Mariner 7 (Mariner Mars 69A and Mariner Mars 69B) were two unmanned NASA space probes that completed the first dual mission to Mars in 1969 as part of NASA's wider Mariner program. 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...

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, BEMO 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.

The Centaur stage on both flights was set up to perform a retrorocket maneuver after capsule separation. This served two purposes, firstly to prevent venting propellant from the spent Centaur from contacting the probe, secondly to put the vehicle on a trajectory that would send it into solar orbit and not impact the Martian surface, potentially contaminating the planet with Earth microbes.

Spaceflight

On July 29, 1969, less than a week before closest approach, Jet Propulsion Laboratory (JPL) lost contact with Mariner 7. The center regained the signal via the backup low-gain antenna and regained use of the high gain antenna again shortly after Mariner 6's close encounter. Leaking gases from a battery (which later failed) were thought to have caused the anomaly. Based on the observations that Mariner 6 made, Mariner 7 was reprogrammed in flight to take further observations of areas of interest and actually returned more pictures than Mariner 6, despite the battery's failure.

Closest approach for Mariner 6 occurred July 31, 1969, at 05:19:07 UT at a distance of 3,431 kilometers (2,132 mi) above the martian surface. Closest approach for Mariner 7 occurred August 5, 1969 at 05:00:49 UT at a distance of 3,430 kilometers (2,130 mi) above the martian surface. This was less than half of the distance used by Mariner 4 on the previous US Mars flyby mission.

Both spacecrafts are now defunct and in heliocentric orbits...

By chance, both spacecrafts flew over cratered regions and missed both the giant northern volcanoes and the equatorial grand canyon discovered later. Their approach pictures did, however, photograph about 20 percent of the planet's surface, showing the dark features long seen from Earth – in the past, these features had been mistaken for canals by some ground-based astronomers. When Mariner 7 flew over the martian south pole on August 4, 1969, it sent back pictures of ice-filled craters and outlines of the south polar cap. Despite the communication defect suffered by Mariner 7 earlier, these pictures were of better quality than what had been sent by its twin, Mariner 6, a few days earlier when it flew past the martian equator. In total, 201 photos were taken and transmitted back to Earth, adding more detail than the earlier mission, Mariner 4. Both crafts also studied the atmosphere of Mars.

Coming a week after Apollo 11, Mariner 6 and 7's flyby of Mars received less than the normal amount of media coverage for a mission of this significance...