1,000 Days On Mars
This 360-degree view, called the "McMurdo"
panorama, comes from the panoramic camera on NASA's Mars Exploration Rover
Spirit. From April through October 2006, Spirit has stayed on a small hill known
as "Low Ridge." There, the rover's solar panels are tilted toward the
sun to maintain enough solar power for Spirit to keep making scientific
observations throughout the winter on southern Mars. This view of the
surroundings from Spirit's "Winter Haven" is presented in
approximately true colour. Oct. 26th, 2006, marks Spirit's 1,000th sol of
what was planned as a 90-sol mission. (A sol is a Martian day, which lasts 24
hours, 39 minutes, 35 seconds). The rover has lived through the most challenging
part of its second Martian winter. Its solar power levels are rising
again. Spring in the southern hemisphere of Mars will begin in early
2007. Before that, the rover team hopes to start driving Spirit again
toward scientifically interesting places in the "Inner Basin" and
"Columbia Hills" inside Gusev crater. The McMurdo panorama is
providing team members with key pieces of scientific and topographic information
for choosing where to continue Spirit's exploration adventure.
This beautiful scene reveals a tremendous amount of detail in Spirit's surroundings. Many dark, porous-textured volcanic rocks can be seen around the rover, including many on Low Ridge. Two rocks to the right of center, brighter and smoother-looking in this image and more reflective in infrared observations by Spirit's miniature thermal emission spectrometer, are thought to be meteorites. On the right, "Husband Hill" on the horizon, the rippled "El Dorado" sand dune field near the base of that hill, and lighter-toned "Home Plate" below the dunes provide context for Spirit's travels since mid-2005. Left of center, tracks and a trench dug by Spirit's right-front wheel, which no longer rotates, have exposed bright underlying material. This bright material is evidence of sulphur-rich salty minerals in the subsurface, which may provide clues about the watery past of this part of Gusev Crater.
Spirit has stayed busy at Winter Haven during the past six months even without driving. In addition to acquiring this spectacular panorama, the rover team has also acquired significant new assessments of the elemental chemistry and mineralogy of rocks and soil targets within reach of the rover's arm. The team plans soon to have Spirit drive to a very nearby spot on Low Ridge to access different rock and soil samples while maintaining a good solar panel tilt toward the sun for the rest of the Martian winter. Despite the long span of time needed for acquiring this 360-degree view -- a few images at a time every few sols over a total of 119 sols because the available power was so low -- the lighting and colour remain remarkably uniform across the mosaic. This fact attests to the repeatability of wintertime sols on Mars in the southern hemisphere. This is the time of year when Mars is farthest from the sun, so there is much less dust storm and dust devil activity than at other times of the year. There is a full resolution image here (1.4Mb)
A Martian Sunset
On May 19th, 2005, NASA's Mars Exploration Rover
Spirit captured this stunning view as the Sun sank below the rim of Gusev crater
on Mars. This Panoramic Camera mosaic was taken around 6:07 in the evening of
the rover's 489th Martian day, or sol. Spirit was commanded to stay awake
briefly after sending that sol's data to the Mars Odyssey orbiter just before
sunset. This small panorama of the western sky was obtained using Pancam's
750-nanometer, 530-nanometer and 430-nanometer colour filters. This filter
combination allows false colour images to be generated that are similar to what
a human would see, but with the colours slightly exaggerated. In this image, the
bluish glow in the sky above the Sun would be visible to us if we were there,
but an artefact of the Pancam's infrared imaging capabilities is that with this
filter combination the redness of the sky farther from the sunset is exaggerated
compared to the daytime colours of the Martian sky. Because Mars is farther from
the Sun than the Earth is, the Sun appears only about two-thirds the size that
it appears in a sunset seen from the Earth. The terrain in the foreground is the
rock outcrop "Jibsheet", a feature that Spirit has been investigating
for several weeks (rover tracks are dimly visible leading up to Jibsheet). The
floor of Gusev crater is visible in the distance, and the Sun is setting behind
the wall of Gusev some 80 km (50 miles) in the distance.
This mosaic is yet another example from Mars Exploration Rovers of a beautiful, sublime Martian scene that also captures some important scientific information. Specifically, sunset and twilight images are occasionally acquired by the science team to determine how high into the atmosphere the Martian dust extends, and to look for dust or ice clouds. Other images have shown that the twilight glow remains visible, but increasingly fainter, for up to two hours before sunrise or after sunset. The long Martian twilight (compared to Earth's) is caused by sunlight scattered around to the night side of the planet by abundant high altitude dust. Similar long twilights or extra-colourful sunrises and sunsets sometimes occur on Earth when tiny dust grains that are erupted from powerful volcanoes scatter light high in the atmosphere.