GENWiki

                     Magellan Fact Sheet

* Mission Summary *

 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.

* Venus *

 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,

 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

* Magellan Team *

 NASA/Solar System Exploration Division

JPL

 Principal Investigators

                               Georges Balmino (France)

 System Contractors

                               F. McKinney, Manager

                               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)

 Operates in SAR, altimeter, and radiometer modes

 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.