Mariner 6 and 7

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[3] and Mariner 7 from Launch Complex 36A at Cape Kennedy.[2] 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
Mariner 6-7
Mariner 6
Mission typeFlyby Mars
OperatorNASA / JPL
COSPAR ID1969-014A
SATCAT no.3759
Mission duration1 year and 10 months (launch to deactivation)
Spacecraft properties
ManufacturerJet Propulsion Laboratory
Launch mass411.8 kilograms (908 lb)
Power449 W
Start of mission
Launch dateFebruary 25, 1969, 01:29:02 UTC[1]
RocketAtlas SLV-3D Centaur-D1A
Launch siteCape Canaveral LC-36B
End of mission
DisposalDecommissioned
Deactivated23 December 1970
Flyby of Mars
Closest approachJuly 31, 1969
Distance3,431 kilometers (2,132 mi)
Mariner 7
Mariner 6-7
Mariner 7
Mission typeFlyby Mars
OperatorNASA / JPL
COSPAR ID1969-030A
SATCAT no.3837
Mission duration1 year and 9 months (launch to deactivation)
Spacecraft properties
ManufacturerJet Propulsion Laboratory
Launch mass411.8 kilograms (908 lb)
Power449 W
Start of mission
Launch dateMarch 27, 1969, 22:22:00 UTC[2]
RocketAtlas SLV-3D Centaur-D1A
Launch siteCape Canaveral LC-36A
End of mission
DisposalDecommissioned
Deactivated28 December 1970
Flyby of Mars
Closest approachAugust 5, 1969
Distance3,430 kilometers (2,130 mi)

Launch

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.[4]

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.[2] 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.[5]

Closest approach for Mariner 6 occurred July 31, 1969, at 05:19:07 UT[3] at a distance of 3,431 kilometers (2,132 mi)[3] above the martian surface. Closest approach for Mariner 7 occurred August 5, 1969 at 05:00:49 UT[2] 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.[5]

Both spacecraft are now defunct in heliocentric orbits.[5]

Science data and findings

Mars full disk approach view from Mariner 7
Two full disc views of Mars from Mariner 7 as it approached, 1969

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,[5] showing the dark features long seen from Earth, but none of the canals mistakenly observed by ground-based astronomers. In total 201 photos were taken and transmitted back to Earth, adding more detail than the earlier mission, Mariner 4.[5] Both craft 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.

The ultraviolet spectrometer onboard Mariners 6 and 7 was constructed by University of Colorado's Laboratory for Atmospheric and Space Physics (LASP).

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.[6][7] The Mariner 6 & 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 water on the surface of Mars.[8]

Spacecraft and subsystems

The Mariner 6 and 7 spacecraft were identical, consisting of an octagonal magnesium frame base, 138.4 cm (54.5 in) diagonally and 45.7 cm (18.0 in) deep. A conical superstructure mounted on top of the frame held the high-gain 1 meter diameter parabolic antenna and four solar panels, each measuring 215 x 90 cm (35 in), were affixed to the top corners of the frame. The tip-to-tip span of the deployed solar panels was 5.79 m. A low-gain omnidirectional antenna was mounted on a 2.23 m high mast next to the high-gain antenna. Underneath the octagonal frame was a two-axis scan platform which held scientific instruments. Overall science instrument mass was 57.6 kg (127 lb). The total height of the spacecraft was 3.35 m.

The spacecraft was attitude stabilized in three axes, referenced to the sun and the star Canopus. It utilized 3 gyros, 2 sets of 6 nitrogen jets, which were mounted on the ends of the solar panels, a Canopus tracker, and two primary and four secondary sun sensors. Propulsion was provided by a 223-newton rocket motor, mounted within the frame, which used the mono-propellant hydrazine. The nozzle, with 4-jet vane vector control, protruded from one wall of the octagonal structure. Power was supplied by 17,472 photovoltaic cells, covering an area of 7.7 square meters (83 sq ft) on the four solar panels. These could provide 800 watts of power near Earth, and 449 watts while at Mars. The maximum power requirement was 380 watts, once Mars was reached. A 1200 watt-hour, rechargeable, silver-zinc battery was used to provide backup power. Thermal control was achieved through the use of adjustable louvers on the sides of the main compartment.

Three telemetry channels were available for telecommunications. Channel A carried engineering data at 8⅓ or 33⅓ bit/s, channel B carried scientific data at 66⅔ or 270 bit/s and channel C carried science data at 16,200 bit/s. Communications were accomplished through the high- and low-gain antennas, via dual S-band traveling wave tube amplifiers, operating at 10 or 20 watts, for transmission. The design also included a single receiver. An analog tape recorder, with a capacity of 195 million bits, could store television images for subsequent transmission. Other science data was stored on a digital recorder. The command system, consisting of a central computer and sequencer (CC&S), was designed to actuate specific events at precise times. The CC&S was programmed with both a standard mission and a conservative backup mission before launch, but could be commanded and reprogrammed in flight. It could perform 53 direct commands, 5 control commands, and 4 quantitative commands.

Instrumentation:

  1. IR Spectrometer
  2. Two-Channel IR Radiometer Mars Surface Temperature
  3. UV Spectrometer
  4. S-Band Occultation
  5. Thermal Control Flux Monitor (Conical Radiometer)
  6. Mars TV Camera
  7. Celestial Mechanics
  8. General Relativity

See also

References

  1. ^ "Mariner 6: Trajectory Details". National Space Science Data Center. Retrieved December 28, 2011.
  2. ^ a b c d "Mariner 7: Details". National Space Science Data Center. Retrieved December 28, 2011.
  3. ^ a b c "Mariner 6: Details". National Space Science Data Center. Retrieved December 28, 2011.
  4. ^ Mariner-Mars 1969: A Preliminary Report NASA SP-225, p21
  5. ^ a b c d e Pyle, Rod (2012). Destination Mars. Amherst, N.Y: Prometheus Books. pp. 61–66. ISBN 978-1-61614-589-7.
  6. ^ [1]
  7. ^ Chdse, S. C. (1969-03-01). "Infrared radiometer for the 1969 mariner mission to Mars". Applied Optics. 8 (3): 639. doi:10.1364/AO.8.000639. ISSN 1559-128X. PMID 20072273.
  8. ^ [2]

External links

Climate of Mars

The climate of the planet Mars has been a topic of scientific curiosity for centuries, in part because it is the only terrestrial planet whose surface can be directly observed in detail from the Earth with help from a telescope.

Although Mars is smaller than the Earth, at 11% of Earth's mass, and 50% farther from the Sun than the Earth, its climate has important similarities, such as the polar ice caps, seasonal changes and the observable presence of weather patterns. It has attracted sustained study from planetologists and climatologists. While Mars's climate has similarities to Earth's, including periodic ice ages, there are also important differences, such as much lower thermal inertia. Mars' atmosphere has a scale height of approximately 11 km (36,000 ft), 60% greater than that on Earth. The climate is of considerable relevance to the question of whether life is or was present on the planet. The climate briefly received more interest in the news due to NASA measurements indicating increased sublimation of one near-polar region leading to some popular press speculation that Mars was undergoing a parallel bout of global warming, although Mars' average temperature has actually cooled in recent decades, and the polar caps themselves are growing.

Mars has been studied by Earth-based instruments since the 17th century but it is only since the exploration of Mars began in the mid-1960s that close-range observation has been possible. Flyby and orbital spacecraft have provided data from above, while landers and rovers have measured atmospheric conditions directly. Advanced Earth orbital instruments today continue to provide some useful "big picture" observations of relatively large weather phenomena.

The first Martian flyby mission was Mariner 4 which arrived in 1965. That quick two-day pass (July 14–15, 1965) with crude instruments contributed little to the state of knowledge of Martian climate. Later Mariner missions (Mariner 6, and Mariner 7) filled in some of the gaps in basic climate information. Data-based climate studies started in earnest with the Viking program landers in 1975 and continue with such probes as the Mars Reconnaissance Orbiter.

This observational work has been complemented by a type of scientific computer simulation called the Mars general circulation model. Several different iterations of MGCM have led to an increased understanding of Mars as well as the limits of such models.

Exploration of Mars

The planet Mars has been explored remotely by spacecraft. Probes sent from Earth, beginning in the late 20th century, have yielded a large increase in knowledge about the Martian system, focused primarily on understanding its geology and habitability potential. Engineering interplanetary journeys is complicated and the exploration of Mars has experienced a high failure rate, especially the early attempts. Roughly two-thirds of all spacecraft destined for Mars failed before completing their missions and some failed before their observations could begin. Some missions have met with unexpected success, such as the twin Mars Exploration Rovers, which operated for years beyond their specification.

Geology of Mars

The geology of Mars is the scientific study of the surface, crust, and interior of the planet Mars. It emphasizes the composition, structure, history, and physical processes that shape the planet. It is analogous to the field of terrestrial geology. In planetary science, the term geology is used in its broadest sense to mean the study of the solid parts of planets and moons. The term incorporates aspects of geophysics, geochemistry, mineralogy, geodesy, and cartography. A neologism, areology, from the Greek word Arēs (Mars), sometimes appears as a synonym for Mars's geology in the popular media and works of science fiction (e.g. Kim Stanley Robinson’s Mars trilogy).

George C. Pimentel

George Claude Pimentel (May 2, 1922 – June 18, 1989) was the inventor of the chemical laser. He also developed the technique of matrix isolation in low-temperature chemistry. In theoretical chemistry, he proposed the three-center four-electron bond which is now accepted as the best simple model of hypervalent molecules. In the late 1960s, Pimentel led the University of California team that designed the infrared spectrometer for the Mars Mariner 6 and 7 missions that analyzed the surface and atmosphere of Mars.An alumnus of University of California, Los Angeles (B.S. 1943) and University of California, Berkeley (Ph.D. 1949), Pimentel began teaching at Berkeley in 1949, where he remained until his death in 1989.

List of NASA missions

This is a list of NASA missions, both crewed and robotic, since its establishment 1958.

Mariner 9

Mariner 9 (Mariner Mars '71 / Mariner-I) was an unmanned NASA space probe that contributed greatly to the exploration of Mars and was part of the Mariner program. Mariner 9 was launched toward Mars on May 30, 1971 from Cape Canaveral Air Force Station and reached the planet on November 14 of the same year, becoming the first spacecraft to orbit another planet – only narrowly beating the Soviets' Mars 2 and Mars 3, which both arrived within a month. After months of dust storms it managed to send back clear pictures of the surface.

Mariner 9 returned 7329 images over the course of its mission, which concluded in October 1972.

Mars 2M No.521

Mars 2M No.521, also known as Mars M-69 No.521 and sometimes identified by NASA as Mars 1969A, was a Soviet spacecraft which was lost in a launch failure in 1969. It consisted of an orbiter. The spacecraft was intended to image the surface of Mars using three cameras, with images being encoded for transmission back to Earth as television signals. It also carried a radiometer, a series of spectrometers, and an instrument to detect water vapour in the atmosphere of Mars. It was one of two Mars 2M spacecraft, along with Mars 2M No.522, which was launched in 1969 as part of the Mars programme. Neither launch was successful.The Mars 2M probes were originally intended to consist of both an orbiter and a lander. Time constraints did not permit the development of a soft lander, so engineers decided to simply use a hard lander that would crash into the Martian surface but gather data during its descent. At first, a modified Luna E-8 bus was to be used for the spacecraft, however it had a number of limitations that made it unsuitable for the long journey to Mars. Halfway through the project, Lavochkin Bureau design chief Georgi Babakin decided to simply discard the Luna E-8 derived probe and design a completely new one from scratch.

However, the 2M probes ended significantly heavier than intended and engineers also ran out of time to conduct drop tests of the lander, so that part was abandoned which left only the orbiter. If successful, this would still be a major propaganda success for the Soviets as NASA was nearly three years away from attempting a Mars orbiter.

As 1968 drew to a close, the project was lagging behind schedule and the US was also making significant headway in the space race with Mariner 6 and 7 scheduled to launch to Mars early in the next year and Apollo 8 taking astronauts into lunar orbit. The Kremlin wanted the Mars probes readied as soon as possible and the second of the two probes was completed in the middle of January. Despite doubts that the probes were ready to fly, they were delivered to Baikonour.

NASA

The National Aeronautics and Space Administration (NASA, ) is an independent agency of the United States Federal Government responsible for the civilian space program, as well as aeronautics and aerospace research.NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA). The new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, and later the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the Space Launch System and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches.

NASA science is focused on better understanding Earth through the Earth Observing System; advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program; exploring bodies throughout the Solar System with advanced robotic spacecraft missions such as New Horizons; and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs.

Outline of Mars

The following outline is provided as an overview of and topical guide to Mars:

Mars – fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often referred to as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.

SWAP (instrument)

The "Sun Watcher using Active Pixel System Detector and Image Processing" (SWAP) telescope is a compact EUV imager on board the PROBA2 mission that will observe the Sun in extreme ultraviolet (EUV).

SWAP will provide images of the solar corona at a temperature of roughly 1 million degrees. This instrument was built upon the heritage of the Extreme ultraviolet Imaging Telescope (EIT) which monitors the solar corona since 1996.

SWAP will continue the systematic CME (coronal mass ejection) watch program at an improved image cadence (typically 1 image every minute). With this higher cadence, SWAP will monitor events in the low solar corona that might be relevant for space weather. These events include EIT waves (global waves propagating across the solar disc from the CME eruption site), EUV dimming regions (transient coronal holes from where the CME has lifted off) and filament instabilities (a specific type of flickering during the rise of a filament). SWAP will also take advantage of offpointings provided by the agility featured of PROBA2 platform to follows coronal mass ejections.

SWAP was built at the Centre Spatial de Liege and will be operated from the PROBA-2 Science Center at the Royal Observatory of Belgium.

SWAP has been used to study coronal brightspot dynamics.

William George Fastie

William George Fastie (6 December 1916 – 14 July 2000) was an American optical physicist and spectroscopist who played a part in the Johns Hopkins University space program of the late 1950s.

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