Mariner 6 and 7
Encyclopedia
As part of NASA
's wider Mariner program
, Mariner 6 and Mariner 7 (Mariner Mars 69A / 69B) completed the first dual mission to Mars
in 1969. Mariner 6 was launched from Launch Complex 36B at Cape Kennedy 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 5 days later.
On July 29, 1969, less than a week before closest approach, NASA Jet Propulsion Laboratory lost contact with Mariner 7. The center regained the signal via the backup low-gain antenna and were able to start using the high gain antenna again shortly after Mariner 6's close encounter. It was later determined a battery onboard Mariner 7 had exploded. Based on the observations made by Mariner 6, Mariner 7 was reprogrammed in flight to take further observations of areas of interest and actually returned more pictures than Mariner 6, despite the explosion.
By chance, both 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, but none of the canals
mistakenly observed by ground-based astronomers. In total 198 photos were taken and transmitted back to Earth, adding more detail than the earlier mission, Mariner 4
. Both craft also studied the atmosphere of Mars.
Closest approach for Mariner 6 occurred July 31, 1969, at 05:19:07 UT at a distance of 3431 kilometres (2,131.9 mi) above the martian surface. Closest approach for Mariner 7 occurred August 5, 1969 at 05:00:49 UT at a distance of 3430 kilometres (2,131.3 mi) above the martian surface.
The ultraviolet
spectrometer
onboard Mariners 6 and 7 was constructed by the Laboratory for Atmospheric and Space Physics
.
The engineering model of Mariners 6 and 7 still exists, and is owned by the Jet Propulsion Laboratory
. It is currently on loan to the Laboratory for Atmospheric and Space Physics
, and is on display in the lab's lobby.
The craft are now defunct in heliocentric orbit
s.
frame base, 138.4 cm (54.5 in) diagonally and 45.7 cm (18 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 (35.4 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 metres (9.2 sq yd) 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:
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's wider Mariner program
Mariner program
The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury from 1963 to 1973...
, Mariner 6 and Mariner 7 (Mariner Mars 69A / 69B) completed the first dual mission to Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
in 1969. Mariner 6 was launched from Launch Complex 36B at Cape Kennedy and Mariner 7 from Launch Complex 36A at Cape Kennedy. The craft flew over the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
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 5 days later.
On July 29, 1969, less than a week before closest approach, NASA Jet Propulsion Laboratory lost contact with Mariner 7. The center regained the signal via the backup low-gain antenna and were able to start using the high gain antenna again shortly after Mariner 6's close encounter. It was later determined a battery onboard Mariner 7 had exploded. Based on the observations made by Mariner 6, Mariner 7 was reprogrammed in flight to take further observations of areas of interest and actually returned more pictures than Mariner 6, despite the explosion.
By chance, both flew over cratered regions and missed both the giant northern volcanoes
Tharsis
The Tharsis region on Mars is a vast volcanic plateau centered near the equator in Mars’ western hemisphere. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons, which are collectively known as...
and the equatorial grand canyon
Valles Marineris
Valles Marineris is a system of canyons that runs along the Martian surface east of the Tharsis region...
discovered later. Their approach pictures did, however, photograph about 20 percent of the planet's surface, showing the dark features long seen from Earth, but none of the canals
Martian canals
For a time in the late 19th and early 20th centuries, it was erroneously believed that there were canals on Mars. These were a network of long straight lines that appeared in drawings of the planet Mars in the equatorial regions from 60° N. to 60° S. Lat., first observed by the Italian astronomer...
mistakenly observed by ground-based astronomers. In total 198 photos were taken and transmitted back to Earth, adding more detail than the earlier mission, Mariner 4
Mariner 4
Mariner 4 was the fourth in a series of spacecraft, launched on November 28, 1964, intended for planetary exploration in a flyby mode and performed the first successful flyby of the planet Mars, returning the first pictures of the Martian surface...
. Both craft also studied the atmosphere of Mars.
Closest approach for Mariner 6 occurred July 31, 1969, at 05:19:07 UT at a distance of 3431 kilometres (2,131.9 mi) above the martian surface. Closest approach for Mariner 7 occurred August 5, 1969 at 05:00:49 UT at a distance of 3430 kilometres (2,131.3 mi) above the martian surface.
The ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
spectrometer
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
onboard Mariners 6 and 7 was constructed by the Laboratory for Atmospheric and Space Physics
Laboratory for Atmospheric and Space Physics
The Laboratory for Atmospheric and Space Physics is a research organization at the University of Colorado at Boulder. LASP is a research institute with over 100 research scientists ranging in fields from solar influences, to Earth's and other planetary atmospherics processes, space weather, space...
.
The engineering model of Mariners 6 and 7 still exists, and is owned by the Jet Propulsion Laboratory
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
. It is currently on loan to the Laboratory for Atmospheric and Space Physics
Laboratory for Atmospheric and Space Physics
The Laboratory for Atmospheric and Space Physics is a research organization at the University of Colorado at Boulder. LASP is a research institute with over 100 research scientists ranging in fields from solar influences, to Earth's and other planetary atmospherics processes, space weather, space...
, and is on display in the lab's lobby.
The craft are now defunct in heliocentric orbit
Heliocentric orbit
A heliocentric orbit is an orbit around the Sun. All planets, comets, and asteroids in our Solar System are in such orbits, as are many artificial probes and pieces of debris. The moons of planets in the Solar System, by contrast, are not in heliocentric orbits as they orbit their respective planet...
s.
Spacecraft and subsystems
The Mariner 6 and 7 spacecraft were identical, consisting of an octagonal magnesiumMagnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
frame base, 138.4 cm (54.5 in) diagonally and 45.7 cm (18 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 (35.4 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
Canopus
Canopus |Alpha]] Carinae) is the brightest star in the southern constellation of Carina and Argo Navis, and the second brightest star in the night-time sky, after Sirius. Canopus's visual magnitude is −0.72, and it has an absolute magnitude of −5.53.Canopus is a supergiant of spectral...
. It utilized 3 gyros, 2 sets of 6 nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
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
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
. 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 metres (9.2 sq yd) 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
Traveling wave tube
A traveling-wave tube is an electronic device used to amplify radio frequency signals to high power, usually in an electronic assembly known as a traveling-wave tube amplifier ....
amplifiers, operating at 10 or 20 watts, for transmission. The design also included a single receiver. An analog tape recorder
Tape recorder
An audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape machine is an audio storage device that records and plays back sounds, including articulated voices, usually using magnetic tape, either wound on a reel or in a cassette, for storage...
, 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:
- IR Spectrometer
- Two-Channel IR Radiometer Mars Surface Temperature
- UV Spectrometer
- S-Band Occultation
- Thermal Control Flux Monitor (Conical Radiometer)
- Mars TV Camera
- Celestial Mechanics
- General Relativity
External links
- Mariner Mars 1969 Launches - Press Kit
- Tracking and data system support for the Mariner Mars 1969 mission. Volume 1 - Planning phase through midcourse maneuver
- Tracking and data system support for the Mariner Mars 1969 mission. Volume 2: Midcourse maneuver through end of nominal mission
- Tracking and data system support for the Mariner Mars 1969 mission. Volume 3: Extended operations mission
- The Mariner 6 and 7 flight paths and their determination from tracking data
- Two over Mars - Mariner 6 and Mariner 7, February - August 1969
- Mariner 6 Mission Profile by NASA's Solar System Exploration
- Mariner 7 Mission Profile by NASA's Solar System Exploration
- Mariner 6 and 7 Data Set Information (highly technical)
- Mariner 6 and 7 Data Viewer Page (includes many images)
- Page with reprocessed Mariner 7 images