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Magellan Fact Sheet
The Magellan spacecraft, named after the sixteenth-century
Portuguese explorer whose expedition first circumnavigated the
Earth, was launched May 4, 1989, and arrived at Venus on
August 10, 1990. Magellan's solid rocket motor placed it into
a near-polar elliptical orbit around the planet. During the
first 8-month mapping cycle around Venus, Magellan collected
radar images of 84 percent of the planet's surface, with
resolution 10 times better than that of the earlier Soviet
Venera 15 and 16 missions. Altimetry and radiometry data also
measured the surface topography and electrical
characteristics. During subsequent cycles the map will be
completed, filling gaps in coverage from the first cycle and
imaging the south polar region for the first time. Precision
radio tracking of the spacecraft will measure Venus'
gravitational field to show the planet's internal mass
distribution and the forces which have created the surface
features. Magellan's data will permit the first global
geological understanding of Venus, the planet most like Earth
in our solar system.
Distance from Sun: 1.1 x 108 km
Orbit Period: 225 Earth days
Radius: 6051 km
Rotational Period (sidereal): 243 Earth days
Average Density: 5.2 g/cm3
Surface Gravity: .907 times that of Earth
(8.87 m/s2)
Surface Temperature: 850 F (730 K)
Surface Atmospheric Pressure: 90 times that of Earth
(90 q 2 bar)
Atmospheric Composition: Carbon dioxide (96%); nitrogen
(3+%); trace amounts of sulfur
dioxide, water vapor, carbon
monoxide, argon, helium, neon,
hydrogen chloride, hydrogen
fluoride
- ** Major Mission Characteristics ***
Interplanetary Cruise: May 4, 1989, to August 10, 1990
First Mapping Cycle: September 15, 1990 to May 15,
1991
Orbit Period: 3.25 hours
Orbit Inclination: 86 degrees
Radar Mapping Per Orbit: 37.2 minutes
Planetary Coverage: 84%
Extended Mission Plan: May 16, 1991 to May 15, 1993
Cycle 2: Image the south pole region and
gaps from Cycle 1
Cycle 3: Fill remaining gaps and collect
stereo imagery
Cycle 4: Measure Venus' gravitational
field
- ** Mission Objectives ***
Obtain near-global radar images of Venus' surface, with
resolution equivalent to optical imaging of 1 km per line pair
Obtain a near-global topographic map with 50km spatial and
100m vertical resolution
Obtain near-global gravity field data with 700km resolution
and 2-3 milligals accuracy
Develop an understanding of the geological structure of the
planet, including its density distribution and dynamics
NASA/Solar System Exploration Division
- Elizabeth E. Beyer, Program Manager
- Joseph M. Boyce, Program Scientist
- David J. Okerson, Program Engineer
JPL
- James F. Scott, Project Manager
- R. Stephen Saunders, Project Scientist
- Douglas G. Griffith, Mission Directory
Principal Investigators
- Radar: Gordon Pettengill (MIT)
- Gravity: William Sjogren (JPL)
Georges Balmino (France)
System Contractors
- Spacecraft: Martin Marietta/Denver
F. McKinney, Manager
- Radar: Hughes Aircraft
B. Dagarin, Manager
- ** Key Spacecraft Characteristics ***
Single radar instrument operates simultaneously (by
interleaving) in Synthetic Aperture Radar (SAR), altimeter,
and radiometer modes
High Gain Antenna (3.7m diameter) is used as both the radar
and telecommunications antenna
X-band downlink data rate of 268.8 or 115 kbps
Coherent X- and S-band radio subsystem used for gravity field
measurement by precision tracking of the spacecraft's orbit
Spacecraft on-orbit dry mass of 1035 kg
Monopropellant hydrazine thruster system (0.9 to 445N thrust)
Powered by solar panels with rechargeable batteries
Three orthogonal electrically powered reaction wheels used for
spacecraft pointing control
- ** Key Radar Characteristics ***
Synthetic Aperture Radar (SAR)
- Frequency 2.385 GHz
- Peak Power 325 W
- Pulse Length 26.5 msec
- PRF 4400-5800 Hz
- Swath Width 25 km (variable)
- Data Acquisition Rate 806 kbps
- Downlink Quantization 2 bits
Operates in SAR, altimeter, and radiometer modes
- SAR Resolution 150m range/150m azimuth
- Altimeter Resolution 30m
- Radiometer Accuracy 2 C
Operating parameters controlled by ground command
- ** Key Scientific Results ***
A preliminary assessment of the Magellan high-resolution
global images is providing evidence to understand the role of
impacts, volcanism, and tectonism in the formation of Venusian
surface structures.
The surface of Venus is mostly covered by volcanic materials.
Volcanic surface features, such as vast lava plains, fields of
small lava domes, and large shield volcanoes are common.
There are few impact craters on Venus, suggesting that the
surface is, in general, geologically young - less than 800
million years old.
The presence of lava channels over 6,000 kilometers long
suggests river-like flows of extremely low-viscosity lava that
probably erupted at a high rate.
Large pancake-shaped volcanic domes suggest the presence of a
type of lava produced by extensive evolution of crustal rocks.
The typical signs of terrestrial plate tectonics - continental
drift and basin floor spreading - are not in evidence on
Venus. The planet's tectonics is dominated by a system of
global rift zones and numerous broad, low domical structures
called coronae, produced by the upwelling and subsidence of
magma from the mantle.
Although Venus has a dense atmosphere, the surface reveals no
evidence of substantial wind erosion, and only evidence of
limited wind transport of dust and sand. This contrasts with
Mars, where there is a thin atmosphere, but substantial
evidence of wind erosion and transport of dust and sand.
- ** For More Information on Data ***
Photographic images, digital data (CD ROMs) and display
software, and videotapes showing computer-generated flights
over Venus are available to researchers, educators, and the
public through the National Space Science Data Center, Goddard
Space Flight Center, Mail Code 933.4, Greenbelt, MD 20771,
(301) 286-6695, Fax: (301) 286-4952.
Detailed catalog information is available to researchers funded by
NASA's Solar System Exploration Division through the Planetary Data
System, Geosciences Node, Earth and Planetary Remote Sensing
Laboratory, Washington University St. Louis, MO 63130-4899,
(314) 935-5493, Fax: (314) 935-7361.
Photographic imagery, CD-ROMs, and videotapes are available
for browsing at NASA's 15 Regional Planetary Image Facilities.
For additional information, call Mary Ann Harger at the Lunar
and Planetary Institute at (713) 486-2136 or -2172, Fax: (713)
486-2153.
Teachers can obtain information about Magellan, including
copies of the videotapes, through NASA's Teacher Resource
Centers. For more information, call the Jet Propulsion
Laboratory's Teacher Resource Center at (818) 354-6916, Fax:
(818) 354-8080.