Mariner 10

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Characteristics of the mission:
Name	Mariner 10
Nation	United States
Objective(s)	Measure Mercury's environment, atmosphere, surface, and body characteristics and to make similar investigations of Venus. Secondary objectives were to perform experiments in the interplanetary medium and to obtain experience with a dual-planet gravity-assist mission.
Craft	Mariner Venus Mercury 73 / Mariner-J
Craft – Mass	473.9 kg
Administration and planning of mission	JPL - NASA
Launch vehicle	Atlas-Centaur
Date and time of launch	03 November 1973 at 05:45:00 UTC
Launched from	Cape Canaveral Air Force Station
Scientific instruments/ Technology experiments	Twin narrow-angle cameras with digital tape recorder Ultraviolet spectrometer Infrared radiometer Solar plasma Charged particles Magnetic fields Radio occultation Celestial mechanics

Mariner 10 was an unmanned space mission launched on November 3, 1973 to fly by the planets Mercury and Venus. It was launched approximately 2 years after Mariner 9 and was the last spacecraft in the Mariner program (Mariners 11 and 12 were redesignated Voyager 1 and Voyager 2).

Mariner 10 was the first spacecraft to make use of a "gravitational slingshot" maneuver, using Venus to bend its flight path and bring its perihelion down to the level of Mercury's orbit. It used the solar radiation pressure on its solar panels and its high-gain antenna as a means of attitude control during flight.

Contents 1 Cruise to Venus 2 Venus flyby 3 First Mercury flyby 4 Second Mercury flyby 5 Third Mercury flyby 6 End of mission 7 Discoveries 8 Notes 9 External links

[edit] Cruise to Venus

A trajectory correction maneuver was made on November 13, 1973. Immediately following this maneuver the star-tracker locked onto a bright flake of paint which had come off the spacecraft and lost lock on the guide star Canopus. An automated safety protocol recovered Canopus, but the problem of flaking paint recurred throughout the mission. The on-board computer also experienced unscheduled resets occasionally, which would necessitate reconfiguring the clock sequence and subsystems. Periodic problems with the high-gain antenna also occurred during the cruise. In January 1974 Mariner 10 made ultraviolet observations of Comet Kohoutek. Another mid-course correction was made on January 21, 1974.

[edit] Venus flyby

The spacecraft passed Venus on February 5, 1974, at a closest range of 5768 km at 17:01 UT. Using a near-ultraviolet filter, it photographed the Venusian chevron clouds and performed other atmospheric studies. It was discovered that extensive cloud detail could be seen via Mariner's ultra-violet camera filters. Venus's cloud cover is nearly featureless in visible light. Earth-based ultra-violet observation did reveal some indistinct blotching even before Mariner 10. But, the detail seen by Mariner was a surprise to most researchers.

[edit] First Mercury flyby

The first Mercury encounter took place at 20:47 UT on March 29, 1974 at a range of 703 kilometres (437 miles).

[edit] Second Mercury flyby

After looping once around the Sun while Mercury completed two orbits, Mariner 10 flew by Mercury again on September 21, 1974 at a more distant range of 48,069 km (29,870 mi).

[edit] Third Mercury flyby

A third and final encounter, the closest to Mercury, took place on March 16, 1975 at a range of 327 km (203 mi).

[edit] End of mission

Engineering tests were continued until March 24, 1975, when the supply of attitude-control gas was depleted and the mission was terminated.

Presently, Mariner 10 is still orbiting the sun, although its onboard electronics have probably been damaged by the sun's radiation ^[1].

[edit] Discoveries

During its flyby of Venus, Mariner 10 discovered evidence of rotating clouds and a very weak magnetic field.

Venus in real colors, processed from clear and blue filtered Mariner 10 images

Mariner photograph of Venus in ultraviolet light

Mariner 10 flew past Mercury three times in total. Owing to the geometry of its orbit — its orbital period was almost exactly twice Mercury's — the same side of Mercury was sunlit each time, so it was able to map only 40-45% of Mercury’s surface, taking over 2,800 photos. It revealed a more or less moon-like surface. It thus contributed enormously to our understanding of the planet, whose surface had not been successfully resolved through telescopic observation.

View of Mercury from Mariner 10	Planet Mercury, photographed by Mariner 10	A prominent scarp, Discovery Rupes, photographed by Mariner 10 during its first encounter with Mercury	Representation of the thrust fault at Discovery Rupes
Mercury in false colors	Old basin, 190 km in diameter, filled by smooth plains. The basin's hummocky rim is partly degraded and cratered by later events	Mercury, Australia region	Mercury, Aurora region
Mercury, Caduceata region

Mariner 10 also discovered that Mercury has a tenuous atmosphere consisting primarily of helium, as well as a magnetic field and a large iron-rich core. Its radiometer readings suggested that Mercury has a night time temperature of -183°C (-297°F) and maximum daytime temperatures of 187°C (369°F).

[edit] Notes

[edit] External links

• The Voyage of Mariner 10: Mission to Venus and Mercury (NASA SP-424) 1978 This is an entire book about Mariner 10, with all pictures and diagrams, on-line! Scroll down to click on the "Table of Contents" link. PDF version
• 'Mariner 10', NASA's 1973-75 Venus/Mercury Mission
• NASA-JPL Guide to Mariner 10
• Calibrated images from the Mariner 10 mission to Mercury and Venus
• http://nssdc.gsfc.nasa.gov/nmc/tmp/1973-085A.html

v • d • e  Mariner Program
Previous mission: Mariner 9	Next mission: Voyager 1
Mariner 1 | Mariner 2 | Mariner 3 | Mariner 4 | Mariner 5 | Mariner 6 and 7 | Mariner 8 | Mariner 9 | Mariner 10

Mercury Spacecraft Missions v • d • e
Flybys: Mariner 10
Future: MESSENGER · BepiColombo
See also: Mercury · Exploration of Mercury

Venus Spacecraft Missions v • d • e
Flybys: Venera 1 · Mariner 2 · Zond 1 · Venera 2 · Mariner 5 · Mariner 10 · Venera 11 · Venera 12 · Galileo · Cassini-Huygens · MESSENGER
Orbiters: Venera 9 · Venera 10 · Pioneer Venus Orbiter · Venera 15 · Venera 16 · Magellan probe · Venus Express
Descent probes: Venera 3 · Venera 4 · Venera 5 · Venera 6 · Pioneer Venus Multiprobe
Landers: Venera 7 · Venera 8 · Venera 9 · Venera 10 · Venera 11 · Venera 12 · Venera 13 · Venera 14 · Vega 1 · Vega 2
Balloon probes: Vega 1 · Vega 2
Future: PLANET-C · BepiColombo · Venera-D
See also: Venus · Exploration of Venus