| 4th of July on the Red Planet
NASA and the Hubble Space Telescope Institute have released new images
of Mars to commemorate the landing of Mars Pathfinder on July 4, 1997 and
Mars Viking on July 20, 1976.
July 1, 1999: In
late April and early May of 1999, Mars was brighter and nearer to Earth than at any time
since 1990. Astronomers using the Hubble Space Telescope took advantage of the close encounter to capture some of the sharpest views yet
of the Red Planet. NASA is releasing these images to commemorate the July 4,
1997 anniversary
of the Mars Pathfinder
landing, one of the space agency's most celebrated recent missions, and the
July 20, 1976 anniversary of the Mars
Viking landing, the agency's first Mars mission to bring back
high-resolution images from the Martian surface. |
Above: A
DigiScene™ Java applet showing the
surface of Mars as recorded by the Viking mission 20 years ago.
Click and drag the mouse
within the applet to rotate Mars around its pole. Compare this image
with the recent Hubble images of Mars below.
Credit: Digital
Radiance, Inc.
Cloud-free 1976 Mars surface data provided by the
USGS. |
| The Hubble telescope snapshots show that
Mars is a dynamic and ever-changing planet. Some regions that were dark 20 years ago, when
Viking first mapped Mars, are now bright red; some areas that were bright red are now
dark. Winds move sand and dust from region to region, often in spectacular dust storms.
Over long timescales, many of the larger bright and dark markings remain stable, but
smaller details come and go as they are covered and then uncovered by sand and dust. Right: An animation of Mars showing four
hemispheric views at 90 degree intervals as seen by the Hubble Space Telescope between
April 27 and May 6, 1999. |
|
The telescope's Wide Field and Planetary Camera 2 snapped these images between April 27
and May 6, when Mars was 54 million miles from Earth. From this distance the telescope
could see Martian features as small as 12 miles wide. The telescope obtained four images,
which, together, show the entire planet. Each view depicts the planet as it completes one
quarter of its daily rotation.
High resolution pictures
Above: Click on any of the
four pictures above for a striking high resolution view of that hemisphere as seen by the
Hubble Space Telescope. Each image is (approximately) a 200KB jpg image with 200dpi
resolution.
Visit the Mars Pathfinder
Web Site |
The four hemispheric views of Mars obtained by the HST
are striking for their clarity and detail. In the gallery above, hemisphere A is centered near the location of the
Pathfinder landing site. Dark sand dunes that surround the polar cap merge into a large,
dark region called Acidalia. This area, as shown by images from the Hubble telescope and
other spacecraft, is composed of dark, sand-sized grains of pulverized volcanic rock.
Below and to the left of Acidalia are the massive Martian canyon systems
of Valles Marineris, some of which form long
linear markings that were once thought by some to be canals. Early morning clouds can be
seen along the left limb of the planet, and a
large cyclonic storm composed of water ice is churning near the polar cap. |
Hemisphere B
features a region of the planet known as Tharsis, home of the largest volcanoes in the
solar system. The bright, ring-like feature just to the left of center is the volcano
Olympus Mons, which is more than 340 miles
across and 17 miles high.
Hemisphere C is centered near another volcanic
region known as Elysium. This area shows many small, dark markings that have been observed
by the Hubble telescope and other spacecraft to change as a result of the movement of sand
and dust across the Martian surface. In the upper left of this image, at high northern
latitudes, a large chevron-shaped area of water ice clouds mark a storm front. Along the
right limb, a large cloud system has formed around the Olympus Mons volcano.
Hemisphere D features a dark area known as Syrtis
Major, first seen telescopically by the astronomer Christiaan Huygens in the 17th century.
Many small, dark, circular impact craters can be seen in this region, attesting to the
Hubble telescope's ability to reveal fine detail on the planet's surface. To the south of
Syrtis is a large circular feature called Hellas. Viking and more recently Mars Global
Surveyor have revealed that Hellas is a large and deep impact
crater.
See for yourself
If you would like to see Mars for yourself
on the 4th of July, it's easy! After sunset (or around 9:30 p.m. local time) the Red
Planet can be seen approximately 30 degrees above the southwestern horizon from
mid-latitude sites in the Northern hemisphere. The "Red Planet" will appear just
over 5 degrees to the left of the bright bluish star Spica. Mars, shining brightly at
magnitude -0.4, has a distinctive pumpkin color. You won't discern as much detail as the
HST, but it's still a satisfying sight.
Based on a
STScI press release
and a science.nasa.gov
story.
Photo credits: Steve Lee (University of Colorado), Jim Bell (Cornell University), Mike
Wolff (Space Science Institute), and NASA
Other researchers involved in the collection and analysis of these Hubble telescope data
are R. Todd Clancy (Space Science Institute), Philip James (University of Toledo), and
Michael Ravine (Malin Space Science Systems, Inc.).
DigiScene is a trademark of Digital Radiance, Inc. |
