1969 жылғы Марсқа жіберілген роботтық ғарыш кемелері

Robotic spacecraft sent to Mars in 1969

Mariner 6 and Mariner 7 (Mariner Mars 69A and Mariner Mars 69B) were two uncrewed NASA robotic spacecraft 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. Mariner 6 lifted off from LC 36B at Cape Canaveral on February 25, 1969, using the Atlas Centaur AC 20 rocket, while Mariner 7 lifted off from LC 36A on March 27, using the Atlas Centaur AC 19 rocket. 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 (Booster Engine Cut Off, the event during launch of a rocket with boosters where they stop firing) occurred a few seconds early due to a faulty cutoff switch, resulting in longer than intended burn time of the sustainer engine, 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.

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.

By chance, both spacecraft 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, 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. The engineering model of Mariners 6 and 7 still exists, and is owned by the Jet Propulsion Laboratory (JPL). It is on loan to LASP, and is on display in the lab's lobby. Mariner 6 and 7 infrared radiometer observations helped to trigger a scientific revolution in Mars knowledge. The Mariner 6 and 7 infrared radiometer results showed that the atmosphere of Mars is composed mostly of carbon dioxide (CO2), and they were also able to detect trace amounts of water on the surface of Mars.