Mars Exploration Rovers
| Artist impression of one of the Mars Exploration
Rovers on the martian surface
NASA mission to Mars consisting of two identical
rovers, called Spirit and Opportunity, each with a mass of about 180 kg,
that will be landed by an airbag system similar to that used by Mars
Pathfinder. Spirit was launched on Jun. 10, 2003, and Opportunity on
Jul. 7, 2003. The landings took place successfully on January 4 (Spirit)
and 24 (Opportunity), 2004, at two widely-separated sites on Mars selected
because they appear to have been associated with liquid water in the past
and may therefore have been favorable to life. Spirit landed in at Gusev
Crater, a possible ancient lake feature. Opportunity touched down on
Meridiani Planum, which contains
minerals often associated with water.
| Airbags deployed
Although the rovers will not search for organic remains directly, they will
seek to determine the history of climate and water at their sites, which
has a direct bearing on the issue of possible martian biology. For this
reason, the vehicles are often referred to as roving field geologists. Immediately
after landing, the rovers will begin reconnaissance of their landing sites
by taking 360° visible color and infrared image panoramas. After several
days of evaluating the surrounding terrain, and deploying and calibrating
instruments, they will drive off to begin their exploration.
| Models of Sojourner and Mars Exploration
Using images and spectra taken daily from the rovers, mission scientists
on Earth will command the vehicles toward rock and soil targets of particular
interest, and then evaluate their compositions and textures at microscopic
scales. Initial targets will be close to the landing sites, but later targets
are expected to be much farther afield. The rovers will be able to travel
up to 100m per martian day (24 h 37 min.) – as far as Pathfinder's
Sojourner rover did in its entire lifetime.
Each rover will carry the Athena scientific
package (originally designed for a rover mission in 2001 but cancelled in
the wake of two mission failures in 1998), including cameras and tools to
grind and analyse rocks. Developed at Cornell University, the instrument
package consists of a panoramic camera (Pancam), a rock abrasion tool (RAT)
to expose fresh surfaces of rock, a miniature thermal infrared spectrometer
(MiniTES), a microscopic camera, a Mossbauer spectrometer, and an alpha-proton-X-ray
spectrometer (APXS). The rovers are each expected to function for at least
at least 90 days.
| Main components of MER labeled
|| Each rover has nine cameras. Two "navcams" and four
"hazcams" help it orientate itself and avoid hazards. Two panoramic
cameras mounted on a mast above the body of the rover take high-resolution
images to be sent back to Earth. The rovers also have microscopic
imagers – combining a microscope and camera – for taking
|| Each rover can travel up to 100m a day. Scientists
tell it a point to go to, but it works out how to get there itself.
It creates a 3D map of the terrain, and stops approximately every
30cm to calculate the safest path towards its target. The rovers have
special "rocker-bogie" systems enabling them to stay balanced
on rough terrain.
|| Each rover has three spectrometers – instruments
which can identify minerals from the way rocks emit radiation. By
analysing infra-red radiation, the Nasa team have identified carbonates
– rocks formed in the presence of water – on Mars. A second
spectrometer looks at X-rays and alpha
particles, a third examines iron-rich substances.
|| A rock abrasion tool mounted on each rover's robotic
arm can drill 45 mm into rock. This will enable scientists to compare
the surfaces and insides of rocks, giving clues about any weathering
processes taking place. Each rover also carries an array of magnets,
which will collect dust and analyze its magnetic properties.
AND SPACE PROBES
Rover Mission (NASA/JPL)