LAUNCH

• Each Mars Exploration Rover will be launched on a Delta II launch vehicle from Cape Canaveral, Florida.
• The Delta II stands about 100 feet tall and the rover is housed in a payload fairing that sits on top of the rocket. The first MER spacecraft launches in the daytime and the second one at night.
• The Delta II engines produce more than 140,000 pounds of thrust to break the grip of Earth’s gravity.
• Nine solid rocket boosters ring the Delta launch vehicle. Six are ignited at launch and then discarded after they use up their fuel. The remaining three boosters are ignited in mid-air.
• After the first stage of the rocket stops firing, it is discarded. Then the second stage engine ignites.
• The payload fairing separates and reveals the MER spacecraft.
• Small rockets are fired to spin up the third stage. The spinning motion helps to stabilize the spacecraft, acting like a gyroscope.
• A burn of the third stage pushes the spacecraft out of Earth orbit and on a trajectory to Mars
• The spacecraft must be de-spun so that it can achieve its proper cruise orientation. A set of weights called “yo-yos” are released from the spinning vehicle on flexible lines. They slow the spin of the spacecraft in much the same way that an ice skater decreases the velocity of a spin by extending his or her arms
• The MER spacecraft separates from the Delta's third stage and begins its seven-month journey to Mars.

ENTRY, DESCENT AND LANDING

• The cruise stage carries the items necessary to support the vehicle on its long journey through space. As the spacecraft approaches Mars, this stage is no longer needed and separates from the spacecraft.
• Each MER spacecraft will enter the martian atmosphere in January of 2004. They will be protected by a heat shield as they plummet toward the planet's surface.
• A supersonic parachute slows the spacecraft's descent.
• The heat shield separates and the lander is lowered by a bridle.
• During the descent, gas generators inflate a cluster of airbags around the lander in less than one second.
• Rockets are fired to bring the lander to a near-stop above the martian surface.
• At less than 20 meters above the surface, the bridle is cut and the lander drops to the ground. The airbags cushion the impact.
• After what could be many bounces, the lander will roll to a stop.

LANDED OPERATIONS

• The airbags deflate and retract, the lander “petals” open, and the lander rights itself.
• When the lander structure first opens, the rover is tightly folded.
• A series of steps are involved in the deployment of the rover. They could take as many as several days to complete.
• After deployment is complete, scientists and engineers can begin to command the rover
• They use the Pancam camera to get a color panoramic view of the rover’s surroundings. An instrument called Mini-TES also uses the rover’s mast to view the martian surface in the infrared. Both instruments help scientists decide which rocks should be studied more closely.
• Once a rock target is selected, the rover is sent a command to travel to that target.
• The rover is programmed to avoid hazards. It knows enough to go around any rock that is larger than the size of its wheels.
• When the rover reaches a rock target, its arm is deployed. The arm of the rover has three science instruments and a Rock Abrasion Tool (RAT). In this simulation, the RAT grinds into a rock to reveal a fresh surface for study.
• The Microscopic Imager offers a close-up view of the exposed rock.
• Not shown in the video are two other science instruments on the arm of the rover. They are APXS or Alpha-Particle-X-ray Spectrometer, and the Mössbauer Spectrometer. The APXS reads the elemental make-up of rocks; the Mössbauer detects iron-bearing minerals.
• Information gathered from all six instruments will be used to understand how Mars evolved geologically. Scientists will investigate the role water may have played in the planet’s past and try to determine how suitable the conditions would have been for life.