|Hubble's Sharpest View Of Mars
The sharpest view of Mars ever taken from Earth was obtained by
the recently refurbished NASA Hubble Space Telescope (HST). This
stunning portrait was taken with the HST Wide Field Planetary Camera- 2
(WFPC2) on March 10, 1997, just before Mars opposition, when the red
planet made one of its closest passes to the Earth (about 60 million
miles or 100 million km).
At this distance, a single picture element (pixel) in WFPC2's Planetary
Camera spans 13 miles (22 km) on the Martian surface.
The Martian north pole is at the top (near the center of the bright
polar cap) and East is to the right. The center of the disk is at about
23 degrees north latitude, and the central longitude is near 305 degrees.
This view of Mars was taken on the last day of Martian spring in the
northern hemisphere (just before summer solstice). It clearly shows familiar
bright and dark markings known to astronomers for more than a
century. The annual north polar carbon dioxide frost (dry ice) cap is
rapidly sublimating (evaporating from solid to gas), revealing the much
smaller permanent water ice cap, along with a few nearby detached
regions of surface frost. The receding polar cap also reveals the dark,
circular sea' of sand dunes that surrounds the north pole (Olympia
Other prominent features in this hemisphere include Syrtis Major
Planitia, the large dark feature seen just below the center of the disk.
The giant impact basin Hellas (near the bottom of the disk) is shrouded
in bright water ice clouds. Water ice clouds also cover several great
volcanos in the Elysium region near the eastern edge of the planet
(right). A diffuse water ice haze covers much of the Martian
equatorial region as well.
The WFPC2 was used to monitor dust storm activity to support
the Mars Pathfinder and Mars Global Surveyor Orbiter Missions, which
are currently en route to Mars. Airborne dust is most easily seen in
WFPC2's red and near-infrared images. Hubble's "weather report"
from these images in invaluable for Mars Pathfinder, which is scheduled
for a July 4 landing. Fortunately, these images show no evidence for
large-scale dust storm activity, which plagued a previous Mars mission
in the early 1970s.
The WFPC2 was used to observe Mars in nine different colors
spanning the ultraviolet to the near infrared. The specific colors were
chosen to clearly discriminate between airborne dust, ice clouds, and
prominent Martian surface features. This picture was created by
combining images taken in blue (433 nm), green (554 nm), and red
(763 nm) colored filters.
This image and other images and data received from the Hubble
Space Telescope are posted on the World Wide Web on the Space
Telescope Science Institute home page at http://oposite.stsci.edu/pubinfo/
Photo Credit: David Crisp and the WFPC2 Science Team (Jet Propulsion Laboratory/California Institute of Technology)