In the late 1800's astronomers first observed what looked like canals on the planet Mars, giving rise to several decades of speculation that life existed on "the red planet." Science fiction writers fueled this concept with tales of ancient Martian civilizations and little green men invading the Earth. By the early 20th century, modern astronomical instruments showed the canals were an optical illusion, but the idea that life on Mars might be possible never quite faded.
While telescopic observations showed Mars to be cold and dry, equipment sent to the planet's surface detected signs of a watery past and that water still exists there today. Some scientists believe that microbes may be able to survive in Mars' extreme environment, while others think such microbes may have existed during a warmer and wetter past.
In the continuing search for answers, NASA's latest rover Curiosity--aka the Mars Science Laboratory, or MSL--will be landing on the red planet's surface about 05:31 UTC on August 6 to begin collecting information on geology, atmosphere, environmental conditions, and the possibility of living organisms, either ancient or contemporary.
"If you had to reduce the MSL's scientific mission to one word, it would be habitability," says MSL deputy project scientist Dr. Ashwin Vasavada. "For better than a decade, we've been doing what we call ‘following the water.' So now we're asking the next question-what about the other ingredients that life would require? We do this broad survey of the environmental conditions at our landing site to see if we can call anything we find a habitable environment."
Curiosity landing site in Gale Crater. This is a southward-looking view of Gale Crater, seen by the Mars Odyssey MOLA Thermal Emission Imaging System.
About the size of a small SUV, the Curiosity rover is crowded with state-of-the-art optical instruments including cameras, spectrophotometers, radiation detectors, and sensors.
Several views of Mars will be available through three cameras. The Mars Descent Imager (MARDI) will provide an "astronaut's view" of Curiosity's descent to the surface, allowing mappers to locate the rover after landing. The Mast Camera (Mastcam) will take color images and video footage of the terrain, while the Mars Hand Lens Imager (MAHLI) will provide close-up views of the textures and structures of the planet.
The Alpha Particle X-Ray Spectrometer (APXS) and Chemistry & Mineralogy X-Ray Diffraction/X-Ray Fluorescence Instrument (CheMin) will measure the abundance of chemical elements and minerals on Mars. The Sample Analysis at Mars (SAM) Instrument Suite, which makes up more than half the science payload on board Curiosity, includes a mass spectrometer, gas chromatograph, and tunable laser spectrometer.
Using the Chemistry & Camera (ChemCam), Bethany Ehlmann, California Institute of Technology (USA), will be able to remotely fire a laser from the rover, blowing holes into rock and creating clouds of atoms that may indicate the presence of water.
"This is the first time anyone has zapped rocks with lasers on another planet," Ehlmann told the Chronicle of Higher Education. "The laser vaporizes a patch of surface, creating a plasma. Light reflecting off the plasma forms a "fingerprint" based on the particular atoms that made up the rock. We can tell from the ratios of these elements if they may have been formed by upwelling groundwater or by settling sediments in a lake."
The Radiation Assessment Detector (RAD), about the size of a toaster, will assess the amount of radiation on the planet and how radiation might affect potential life. This is one of the first instruments sent to Mars to prepare for possible human exploration. The Rover Environmental Monitoring Station (REMS), will measure ultraviolet radiation and provide daily and seasonal updates on the planet's atmospheric conditions.
Curiosity was designed to assess whether Mars ever had an environment able to support small life forms called microbes.
Whether or not the question of life on Mars will be answered by the Curiosity rover remains to be seen. But whatever the outcome, this mission will greatly advance our knowledge of Mars and the solar system.
"Curiosity is a bold step forward in learning about our neighboring planet, but this mission does not stand alone. It is part of a sustained, coordinated program of Mars exploration," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "This mission transitions the program's science emphasis from the planet's water history to its potential for past or present life."
SPIE Member Gilbert Levin, Arizona State Univ. (USA) and Univ. of Buckingham (UK), will present the paper, Stealth life detection instruments aboard Curiosity, at the Astrobiology of Mars session at SPIE Optics + Photonics 2012.
Recommended reading from the SPIE Digital Library
From the SPIE Newsroom
Curiosity: Mars Science Laboratory arrives in Florida