Mars Rovers From Spirit & Opportunity To Curiosity

September 19, 2019 0 By William Hollis

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.