Mariner 10
NASA
Other Mariner 10 Information/Data at NSSDC
Mariner 10 images of Mercury (Catalog of Spaceborne Imaging)Mariner 10 images of Mercury (NSSDC Photo Gallery)
Retrieve heliospheric data from NSSDC's anonymous FTP site
Related Information/Data at NSSDC
NSSDC Mercury PageNSSDC Venus Page
MESSENGER mission to Mercury
Bepi-Colombo mission to Mercury
Other Sources of Mariner 10 Information/Data
The Voyage of Mariner 10: Mission to Venus and Mercury (NASA History Office)Atlas of Mercury (NASA History Office)
Mariner 10 Mercury Image Project (Northwestern Univ.)
Mariner 10
On Nov. 3, 1973, the Mariner Venus/Mercury 1973 spacecraft, also known as Mariner 10, was launched from NASA's Kennedy Space Center, becoming the first spacecraft designed to use gravity assist. Three months after launch it flew by Venus, changed speed and trajectory, then crossed Mercury's orbit in March 1974.This photo identifies the spacecraft's science instruments, which were used to study the atmospheric, surface and physical characteristics of Venus and Mercury. This was the sixth in the series of Mariner spacecraft that explored the inner planets beginning in 1962.
Image Credit: NASA/JPL
Description
Mariner 10 was the seventh successful launch in the Mariner series and
the first spacecraft to visit Mercury. It was also the first spacecraft
to use the gravitational pull of one planet (Venus) to reach another
(Mercury), and the first spacecraft mission to visit two planets. The
spacecraft flew by Mercury three times in a retrograde heliocentric
orbit and returned images and data on the planet. Mariner 10 returned
the first-ever close-up images of Venus and Mercury. The primary
scientific objectives of the mission were to 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.
Spacecraft and Subsystems
The spacecraft structure was an eight-sided forger magnesium framework
with eight electronics compartments. It measured 1.39 m diagonally and
0.457 m in depth. Two solar panels, each 2.69 m long and 0.97 m wide,
were attached at the top, supporting 5.1 sq m of solar cell area. Fully
deployed the spacecraft measured 8.0 m across the solar panels and 3.7 m
from the top of the low-gain antenna to the bottom of the heat shield. A
scan platform with two degrees of freedom was mounted on the
anti-sunward face. A 5.8 m long hinged magnetometer boom extended from
one of the octagonal sides of the body. Total launch mass was 502.9 kg,
of this 29 kg were propellant and attitude control gas. The total mass
of instruments onboard was 79.4 kg.
The rocket engine was a 222-N liquid monopropellant hydrazine motor
situated below a spherical propellant tank which was mounted in the
center of the framework. The nozzle protruded through a sunshade. Two
sets of three pairs of orthogonal reaction nitrogen gas jets, mounted on
the tips of the solar panels, were used to stabilize the spacecraft on
three axes. Command and control were the responsibility of an on-board
computer with a 512-word memory augmented by ground commands
Mariner 10 carried a motor driven high-gain dish antenna, a 1.37 m
diameter aluminum honeycomb-disk parabolic reflector, which was mounted
on a boom on the side of the spacecraft. A low-gain omnidirectional
antenna was mounted at the end of a 2.85 m boom extending from the
anti-solar face of the spacecraft. Feeds enabled the spacecraft to
transmit at S- and X-band frequencies; data could be transmitted at a
maximum rate of 117.6 kilobits/s. The spacecraft carried a Canopus star
tracker, located on the upper ring structure of the octagonal satellite,
and acquisition sun sensors on the tips of the solar panels. The
interior of the spacecraft was insulated with multilayer thermal
blankets at top and bottom. The sunshade was deployed after launch to
protect the spacecraft on the solar-oriented side. Louvered sides on
five of the eight electronics compartments also helped control the
interior temperatures.
Instruments on-board the spacecraft measured the atmospheric, surface,
and physical characteristics of Mercury and Venus. Experiments included
television photography, magnetic field, plasma, infrared radiometry,
ultraviolet spectroscopy, and radio science detectors. An experimental
X-band, high-frequency transmitter was flown for the first time on this
spacecraft.
Mission Profile
Mariner 10 (also known as Mariner Venus Mercury 1973) was placed in a
parking orbit after launch for approximately 25 minutes, then placed in
orbit around the Sun en route to Venus. The protective cover of the
sunward-facing electrostatic analyzers did not open fully after launch,
and these instruments, part of the Scanning Electrostatic Analyzer and
Electron Spectrometer experiment, could not be used. It was also
discovered that the heaters for the television cameras had failed, so
the cameras were left on to prevent low temperatures from damaging the
optics.
A trajectory correction maneuver was made 10 days after launch.
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 and another mid-course correction was made on 21 January.
The spacecraft passed Venus on 05 February 1974, at a closest range of
5768 km at 17:01 UT and returned the first close-up images of Venus.
This also marked the first time a spacecraft used a gravity assist from
one planet to help it reach another.
En route to Mercury an attitude control anomaly occurred for the second
time, using up attitude control gas. Some new procedures were used from
that point on to orient the spacecraft, including Sun-line maneuvers and
the use of solar wind on the solar panels to orient the spacecraft.
Mariner 10 crossed the orbit of Mercury on 29 March 1974, at 20:46 UT,
at a distance of about 704 km from the surface. A second encounter with
Mercury, when more photographs were taken, occurred on 21 September
1974, at an altitude of 48,069 km. Unfortunately the lighted hemisphere
was almost the same as the first encounter, so a large portion of the
planet remained unimaged. A third and last Mercury encounter at an
altitude of 327 km, with additional photography of about 300 frames and
magnetic field measurements occurred on 16 March 1975. Engineering tests
were continued until 24 March 1975, when the supply of attitude-control
gas was depleted and the mission was terminated.
Mariner 10 results showed a Hadley-type circulation existed in Venus'
atmosphere and showed that Venus had at best a weak magnetic field, and
the ionosphere interacted with the solar wind to form a bow shock. At
Mercury, it was confirmed that Mercury had no atmosphere and a cratered,
dormant Moon-like surface was shown in the images. Mercury was shown to
have a small magnetic field and a relatively large iron-rich core.
Total research, development, launch, and support costs for the Mariner
series of spacecraft (Mariners 1 through 10) was approximately $554
million. The total cost of the Mariner 10 mission was roughly $100
million
Mariner 10's Portrait of Venus
On Feb. 5, 1974, Mariner 10 took this first close-up photo of Venus.Made using an ultraviolet filter in its imaging system, the photo has been color-enhanced to bring out Venus's cloudy atmosphere as the human eye would see it. Venus is perpetually blanketed by a thick veil of clouds high in carbon dioxide and its surface temperature approaches 900 degrees Fahrenheit.
Launched on Nov. 3, 1973 atop an Atlas-Centaur rocket, Mariner 10 flew by Venus in 1974.
Image Credit: NASA
NASA
Guillermo Gonzalo Sánchez Achutegui
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