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Past Missions

For nearly 50 years, our civilization has been attempting to send spacecraft to Mars. By the beginning of the 21st century, only 10 missions out of 33 tries had been a complete success. Journey with us down the rocky road of Mars exploration.

Mars Exploration Rovers
Spirit: June 10, 2003
Opportunity: July 7, 2003

The Mars Exploration Rover mission (MER) renews a NASA tradition of launching twin vehicles to the Red Planet. The tradition began in 1964 with Mariner 3 and 4, and continued with Mariner 6 and 7, Mariner 8 and 9, and Viking 1 and 2. Now, more than 25 years later, America is again sending twin spacecraft to the surface of Mars. NASA has returned to this strategy to double the mission’s science return and, at the same time, increase the odds of mission success.

Spirit and Opportunity are large, powerful rovers that will land on opposite sides of Mars this January. Both landing sites are located near the equator of the planet in order for the solar-powered vehicles to capture as much sun as possible. Spirit lands in Gusev Crater on the evening of January 3 (EST). Gusev Crater is a region that may have once been the site of a former lake. A large valley, probably the site of an ancient river, extends from the Gusev impact basin. Opportunity lands at Meridiani Planum just past midnight on January 25 (EST). This region is a smooth plain that contains deposits of gray crystalline hematite – a mineral that often forms where liquid water has been present.

The Mars Rovers carry everything they need for energy, communication, and science. Unlike Pathfinder which had a lander that contained the bulk of the science and communication equipment, the landers for the Mars Exploration Rovers are shells – vehicles to get the rovers to the surface of Mars. Once the rovers are off their landers, they are free to roam the Red Planet in any direction that the MER team deems fit. They will each be able to travel tens of yards per day as they search for evidence of ancient water.

Spirit and Opportunity will examine Martian rocks, soils, and atmosphere with a sophisticated set of science instruments called the Athena Science Payload. On the mast of each rover is a Pancam camera, which is a high resolution color stereo camera; and a Miniature Thermal Emission Spectrometer (Mini-TES), which is an infrared spectrometer that can determine the composition of rocks and soils from a distance. On each rover’s arm is a Microscopic Imager for close-up views of rocks and soils; an Alpha Particle X-Ray Spectrometer (APXS) and Mössbauer Spectrometer for measuring the composition of rocks and soils in detail; and a Rock Abrasion Tool (RAT) for grinding the outer coatings of rocks to expose fresh surfaces for study.

The Mars Exploration Rovers will use the Athena Science Payload to read the geologic history that is preserved in the rocks at each landing site. They will use Pancam and Mini-TES to scan their surroundings for interesting science targets. When a target is chosen, each rover will be commanded to drive to the target and deploy the instruments on its arm for further study. It may take several sols for a rover to inspect just one rock target.

To maximize the accuracy of science data, each science instrument has a calibration target onboard the rover to use as reference point. The most unusual calibration target on the rover belongs to Pancam. It was built in the shape of a sundial. The MarsDial sits on the rear solar panel and will be used by Pancam to correct brightness and color in Mars images.

While the rovers do their work, another science experiment is passively collecting information. Three sets of magnet arrays will collect airborne dust for analysis by the science instruments. Some of the dust on Mars is very magnetic. The patterns of accumulation on these magnets of varying strength can reveal clues about the content of the dust grains and, in turn, about the planet’s geologic history.

Communication with Earth is limited to once per day. This means that each rover must travel the surface of Mars unsupervised. They will use their hazard avoidance software to safely move around boulders and over rocks in their path. Hazcams (Hazard-Identification Cameras) are positioned under the solar panel deck at the front and rear of the rover’s warm electronics box to provide a wide-angle view of the terrain. Navigation software analyzes the images to identify obstacles. Each sol, as the rovers strive to complete a daily set of instructions from Earth, they will be on their own to carefully creep through a rugged landscape.

Spirit and Opportunity will only work during daylight hours. Each has a large solar panel deck that can produce, at the beginning of the mission, nearly 900 watt-hours of energy per sol and repeatedly recharge two batteries inside the body of the rover. As dust builds up on the solar panels, power output will be reduced. Eventually, the dust will become so thick that the rovers will not be able to recharge their batteries and will cease to function.

The primary mission for each Mars Exploration Rover is 90 sols.

Mars Express: June 2, 2003

The Beagle has a PAW, the PAW has a Mole and their objective is to search for evidence of life in martian soil. It’s all part of the European Space Agency’s first mission to Mars.

The Mars Express orbiter and the Beagle 2 lander were launched from Baikonur Cosmodrome, a facility steeped in Russian space history, on June 2, 2003. The location of the launch was fitting since Mars Express inherited many of its science goals from Russia’s failed Mars 96 mission. Mars 96 consisted of an orbiter and two small landers that were to probe the surface, interior, and atmosphere of Mars. Mars Express consists of an orbiter and one small lander that will examine the planet’s geology, structure, and atmosphere to search for water and signs of life.

The Mars Express orbiter carries seven science instruments – a high resolution stereoscopic camera (HRSC), a visible and near-infrared spectrometer for mapping minerals (OMEGA), an infrared spectrometer to measure water vapor in the martian atmosphere (PFS), an ultraviolet atmospheric spectrometer (SPICAM), particle sensors to learn how the solar wind interacts with the martian atmosphere (ASPERA), subsurface radar and altimeter to map the distribution of water ice in the planet’s crust (MARSIS), and a radio science experiment that will use radio waves to study the surface and atmosphere of Mars (MaRS).

The Beagle 2 lander is a British-led project named for the HMS Beagle – the ship that Charles Darwin used to explore the Earth in 1831. The small lander weighs only 60 kg (about 132 lbs) and is mounted on the orbiter for its journey to Mars. Packed inside the Beagle 2 is a suite of instruments and a laboratory designed to search for evidence of past or present microbes in the martian soil. The science package includes a robotic arm called PAW (Payload Adjustable Workbench) which carries a microscope, two cameras, two spectrometers, and a flashlight for night work. The workbench also contains a corer/grinder and the “Mole” – a robotic instrument that can crawl across flat surfaces and burrow into soil to collect samples.

The Mars Express mission will arrive at Mars this December. The Beagle 2 lander will be released from the orbiter on Dec. 19 and coast for five days before it enters the martian atmosphere. A parachute will slow its descent, and airbags will cushion its landing. The landing site, Isidis Planitia, is a large, flat, low lying impact basin near the planet’s equator. On Christmas Day, the same day that Mars Express is scheduled to enter orbit around Mars, Beagle 2 is scheduled to land.

After the Beagle 2 is on the surface of Mars, its top will open and solar panels will unfold. The antenna will be deployed and the robotic arm released. Panoramic images will be taken as well as images of the soil and rocks surrounding the lander. When a rock target is chosen, the PAW’s grinder will be used to expose a fresh rock surface for study by the microscope and spectrometers. A sample of the rock may be collected with the corer and delivered to the lander’s laboratory with the PAW. When the Mole is deployed, it remains attached to the PAW by a power cable which retracts after the instrument has gathered its soil sample. Then the PAW delivers the sample to laboratory ovens for heating. A mass spectrometer will be used to search for signs of life.

The Beagle 2 lander is expected to operate for about 180 sols on the martian surface. The Mars Express orbiter mission will continue for one martian year (687 days).

2001 Mars Odyssey: Apr. 7, 2001

“2001: A Space Odyssey” is a book and film from the 1960s that many science fiction fans still enjoy. When it came time to name to the first spacecraft to travel to Mars in the 21st century, the word “Odyssey” seemed like a natural.

Mars Odyssey was the first American mission to Mars following the loss of Mars Climate Orbiter and Mars Polar Lander. It was important that it be a success. When Odyssey reached Mars, a critical event was facing the spacecraft – an event that triggered the loss of the Mars Climate Orbiter – orbit insertion. On Oct. 23, 2001, Odyssey fired its main engine to slow its speed. As planned, it disappeared behind the planet and was out of contact for 20 minutes. Those 20 minutes felt like hours to Odyssey scientists and engineers. When the spacecraft emerged from behind Mars, its radio signal was greeted with cheers and a collective sigh of relief. Odyssey had safely achieved Mars orbit insertion.

Mars Odyssey carries three science experiments. They are designed to study the planet’s climate and geologic history, search for shallow subsurface ice, create global maps of elements and minerals, and analyze radiation levels to determine harmful effects on future human explorers.

The spacecraft took its first look at Mars on Oct. 30, 2001. It was a thermal infrared image of the planet’s southern hemisphere taken as part of the calibration and testing of the Thermal Emission Imaging System (THEMIS).

THEMIS collects information in both infrared and visible wavelengths. It is studying the minerals on the martian surface, especially those minerals that are formed in water. In the infrared spectrum, different minerals show up as different colors. THEMIS can detect their spectral fingerprints. A recent infrared discovery showed distinct layers of rock with very different physical properties. Scientists suggest that Mars may have weathered a series of past environmental changes fueled by volcanoes, water, or climate.

THEMIS visible imaging will help scientists determine where water may have flowed on the surface of Mars. Using images from the visible light camera, Odyssey scientists posed a theory that the gullies first seen on Mars in 2000 by the Mars Global Surveyor may have been formed by melting snow. Prior to Odyssey’s images, the martian gullies were thought to have been created by underground springs.

More than 15,000 visible images will be taken by THEMIS to aid in the study of the martian surface, provide views of the Mars Exploration Rover landing sites, and identify landing sites for future missions.

The Gamma Ray Spectrometer (GRS) experiment uses a gamma ray spectrometer, a neutron spectrometer, and a high energy neutron detector (HEND) to probe the chemical elements in the surface and subsurface of Mars. Each element has a distinct gamma-ray signature. The GRS experiment looks at these signatures to get a global view of their distribution and quantities. Neutrons emitted from Mars are helping scientists determine the abundance of hydrogen on or just below the martian surface. Hydrogen often indicates the presence of water or ice.

The GRS suite of instruments started to make important discoveries as soon as the formal science mapping mission began in February, 2002. It found significant amounts of hydrogen in the south polar region of Mars – most likely due to water ice. By May of that year, scientists concluded that there are enormous amounts of water ice just below the surface of Mars.

The Martian Radiation Environment Experiment (MARIE) is designed to gather information about the level of radiation it encounters throughout the entire mission. But three months before Odyssey reached Mars, the instrument stopped communicating and was shut down. Troubleshooting efforts traced the source of the problem to memory error in the instrument’s software. MARIE was revived and is returning information that suggests humans who travel to Mars would receive more than twice the dose of radiation that reaches astronauts on the International Space Station.

Mars Odyssey’s primary science mission will continue through August 2004. It will serve as a communications relay for the Mars Exploration Rovers arriving at Mars in January, 2004, and will continue to act as a relay for missions to Mars until October 2005.

Web content editor/writer: Pamela R. Smith