In 2004, 2 robotic geologists named Spirit and Opportunity landed on opposite sides of
the red planet. With far greater mobility than the 1997 Mars Pathfinder, these robotic
explorers have trekked for miles across the Martian surface, conducting field geology
and making atmospheric observations. During the rovers’ landings parachutes deployed
to slow the descending spacecraft, rockets fired to slow them still more just before
impact, and airbags inflated to cushion their landing.
After bouncing and rolling to a halt, a protective structure of petals opened and brought the
landers to an upright position, providing a platform from which the rovers drove onto
the Martian surface. Since leaving their landing sites, the twin
rovers have sent more than 100,000 spectacular, high-resolution, full-color images of the
Martian terrain as well as detailed microscopic images of rocks and soil surfaces to Earth.
Each rover weighs nearly 400 pounds. Their initial warranties of 90 days on Mars has,
to everyone’s surprise and delight, has turned into years.
It can take nearly 20 minutes for radio signals sent from earth to reach Mars…so the Rovers
couldn’t be driven in real time. Typical speed was just yards per hour…but Rover
driving was always a white knuckle experience. After an 8-week, mile and a half trek through
a desert of broken lava, Spirit finally reached the Columbia Hills. After reaching the Columbia
Hills Spirit found a variety of rocks indicating that early Mars was characterized by impacts,
explosive volcanism, and subsurface water….but it had become a monumental challenge for Spirit
because its solar panels….its only source of energy had gotten dusty and produced just
half as much power as they used to. Over 1,300 commands were sent to Spirit in
an attempt to elicit a response but no communication has been received from Spirit since March
22, 2010. Its total mileage remains unchanged at 4.80 miles. A series of attempts to revive
Spirit finally ended. What is really important is not only how long Spirit worked or how
far Spirit drove, but how much exploration and scientific discovery Spirit accomplished.
Opportunity however continues to function.
The next generation Rover however is ready to carry on with even more advanced instrumentation……and
its name is CURIOSITY. Curiosity is almost twice as long and five
times heavier (2,000 pounds) as Spirit and Opportunity. But before Curiosity can explore
Mars, it has to get there. The nose cone, or fairing, carrying the Mars
Science Laboratory (Curiosity) falls open like a clamshell and falls away. After this,
the rocket’s first stage cuts off and drops into the Atlantic Ocean.
The rocket’s second stage, a Centaur engine, is started and boosts the spacecraft out of
Earth orbit and sends it toward Mars. Once the spacecraft is in cruise stage toward
Mars, it begins communicating with Earth. The last stage gives the spacecraft a final
push for its 8 ½ month cruise to the red planet.
Hitting the atmosphere at about 13,000 miles per hour, the spacecraft begins to slow down.
While slowing down, the spacecraft uses thrusters to help steer toward the landing site.
It throws off weights to rebalance the spacecraft, so that it is lined up for the parachute deployment.
Once it is below the speed of sound, the heat shield separates and the spacecraft looks
for the ground with the landing radar. Once it reaches an altitude of about 1 mile,
the spacecraft drops out of the back-shell at about 200 miles an hour. It then fires
up the landing engine to slow it down even further.
Once it has descended to about 60 feet above the ground, and going only about 2 miles per
hour, the rover separates from the descent stage. As the rover is lowered, the wheels
deploy in preparation for landing. Once the rover is safely on the ground, and
touchdown has been detected, the descent stage cuts the rover loose. It flies away leaving
Curiosity safe on the surface of Mars. One of the first things Curiosity does after
landing is to deploy the mast, which supports many cameras and instruments.
The Curiosity rover has 10 science instruments including:
A gas chromatograph, a gas spectrometer, and a tunable laser spectrometer to identify a
wide range of organic compounds. An x-ray diffraction and fluorescence instrument
named CheMin designed to identify and quantify minerals in rocks and soils.
A Hand Lens Imager to take extreme close-up pictures of rocks and soil revealing details
smaller than the width of a human hair. An Alpha Particle X-Ray Spectrometer to detect
different elements in rocks and soils. A Camera mounted on the Mast capable of capturing images
of the rover’s surroundings in high resolution and color.
An instrument named ChemCam capable of vaporizing thin layers of material from rocks or soil
designed to identify atoms and capture detailed images of the area.
The drill on the arm allows it to grab some of that rock and deliver it to the laboratory
instruments inside the body of the rover. And the Radiation Assessment Detector to analyze
the radiation environment at the surface. This information will be necessary for planning
human exploration of Mars and its ability to sustain life.
Those instruments can get us even closer to understanding whether life could have existed
on Mars.
Curiosity will be exploring the red planet for at least 2 years ……and ….there’s
no telling what we will discover.