Venus Research in CEPS
Venus, our closest neighbor beyond the Moon, is nearly the same size as
Earth. In stark contrast, however, to Earth's warm, water-rich environment,
Venus is a harsh place where even advanced spacecraft survive only a few
hours. Surface temperatures are near 900° F, and the atmospheric pressure
is comparable to that 3000 feet below Earth's ocean surface. This tremendous
difference in environmental conditions between two neighboring worlds raises
a host of questions about the evolution of Earth-like planets. Venus is
a natural laboratory for observing how geophysical and atmospheric processes
may lead to conditions completely inhospitable to life. As such, studies
of Venus contribute to our understanding of Earth's past, its potential
future, and the possibility for life-supporting worlds around other stars.
|Recent advances in Earth-based radar astronomy,
and the success of the Venera and Magellan orbital radar mapping missions,
have provided the first global maps of the surface of Venus (right).
These maps differ from standard photographs, so specialized techniques
must be used to interpret the data. Scientists in the National Air
and Space Museum's Center for Earth and Planetary Studies (CEPS) have
been very active in analysis of these maps and in the planning for
possible future missions to explore the atmosphere and surface of
Venus. To better understand both the radar image data and the types
of features seen on Venus, these researchers also study volcanoes
on Earth through field work and remote sensing.
Arecibo Observatory mosaic of Venus, centered on 332° E. Polarized
(LR) data, normalized to the average angular scattering properties
of the plains (courtesy D. Campbell, Cornell University).
Magellan radar images of representative Venus landforms. Each image
is approximately 800 km wide. (a) Sif Mons, a shield volcano; (b)
Aruru Corona; (c) a portion of north-central Alpha Tessera.
|On Venus, there is little evidence for the plate
tectonic processes that form Earth's ocean crust and cause the continents
to move over time. This difference is likely due to the absence of
water, which plays an important role in how rock behaves under high
temperature and pressure. The surface of Venus is dominated by volcanic
landforms such as smooth plains, massive shield volcanoes, tectonically
deformed tessera, and circular features called coronae that may represent
areas of hot upwelling magma (left). Many of the larger volcanoes
are similar to those on Hawaii, making this island a natural laboratory
for studying lava surface properties and eruption behaviors.
Field studies of volcanoes like Kilauea include measurement of the surface
topography down to very fine scales (below left), which when compared to
aircraft radar observations (below right) creates a technique for interpreting
the roughness of lava flows on Venus. Highly accurate surveying with the
Global Positioning System is a major advance for this type of work, particularly
in remote areas. The density and chemical properties of the surface rock
are also measured as a guide to how the venusian environment might affect
similar types of magma as it erupts. Other field work focuses on the nature
of landslides, which are an important erosional process on Venus. Comparisons
between tectonic fracture patterns and computer simulations of the underlying
crust are being used to map the depth and size of large magma chambers beneath
volcanoes on the two planets.
An automated laser profiling system for small-scale topography. The
carriage moves along the horizontal tube, and the distance to the
ground is measured every 5 cm.
Three-wavelength color composite HV-polarization radar image of Kilauea
Volcano and Ka'u Desert, Hawai'i. Red tones correspond to C-band (5.7-cm
wavelength), green to L-band (24 cm), and blue to P-band (68 cm) echoes.
(Calibrated data courtesy T. Farr, JPL, and P. Mouginis-Mark, University
(a) Synthetic Aperture Radar image mosaic of the Kawelu Planitia (V16)
quadrangle (25° to 50° N. lat., 240° to 270° long.),
Venus (courtesy U. S. Geological Survey, Flagstaff, AZ). (b) Geologic
map of the V16 quadrangle, Venus (courtesy J. Zimbelman, CEPS).
|The results of these studies provide a more complete
view of the history of volcanic regions on Venus, and aid in the creation
of geologic maps from radar data (left). Such maps are needed to understand
how different geologic and geophysical processes affect the surface
over time. There is a great deal of debate at present over the possibility
of a venusian global resurfacing event 300-500 million years ago,
and only detailed geologic mapping can test the validity of these
theories. CEPS researchers are developing a number of Venus geologic
maps, using advanced digital presentation and cartographic techniques.
|CEPS staff are also involved in the design of new
technologies for studying the surface and lower atmosphere of Venus.
One design focuses on balloon platforms that float in the relatively
temperate regions high in the clouds. From these platforms, small
"sondes" equipped with miniature cameras and insulated against
the heat are dropped to the surface on gliding parachutes. As they
emerge from the cloud deck, it is possible to collect photographs
of the surface. A more ambitious plan calls for development of controllable
balloons called aerobots, which will be insulated to survive multiple
descents to the surface (right). New technology may also permit long-lived
surface landers, which could measure rock compositions, conduct seismic
experiments, and study changes in the atmosphere over time. Venus
remains an enigmatic neighbor, but scientific studies are gradually
revealing its history and defining questions for new research.
Artist's conception of a balloon probe floating above the surface
of Venus (courtesy NASA/JPL).
List of Venus Research Projects