Exploring Mars


Curiosity Rover with Mars Science Laboratory 

Credit: NASA, JPL

The heat of summer is upon us, lingering into evenings as Mars remains a tantalizing sight low in our southern sky. For years NASA’s mantra in the great endeavor to find life on other worlds has been “follow the water.” Evidence the red planet, which harbored substantial amounts liquid water, was considered a requisite for eventual discovery of “life as we know it” on that neighboring world.

This chapter in the quest is now being supplanted. Evidence of Martian water has been found. Our Hayden blog back on October 6 illustrated cascades of water periodically flowing from walls of Horowitz Crater at Martian coordinates 32.04° S, 219.36° W.

Searching for signs of life, evaluating sites for future habitation, and plans for personal human exploration are now in play. Previous missions including the Mars Odyssey, Mars Exploration Rovers, Mars Reconnaissance Orbiter, and Mars Phoenix Lander were primarily designed to seek water. They did their jobs well, finding that evidence, allowing Mars Science Laboratory and its carrier, Curiosity Rover, to be tasked with a fresh mission “seeking signs of life.”

Curiosity was launched in November 2011 and set down on Mars August 6, 2012 at a site called Bradbury Landing, named for the renowned science fiction writer.  The vehicle then navigated to a feature called Mt. Sharp. Curiosity has traveled 8.31 miles to its current location at 4.41o S, 137.21o E near Murray Buttes. It’s an area where previous orbiting missions suggested water flowed at some time in the past. Mars Science Laboratory aboard Curiosity examines samples looked for evidence of organic materials—the building blocks of life. That discovery would indicate an environment capable of providing water and chemical needs of living organisms existed at some time in the past.

NASA’s Jet Propulsion Laboratory designed the Curiosity Rover to climb over obstacles up to 25 inches high as it rolls along on its six wheels as far as 660 feet per day, more than the length of two football fields. It’s powered by a plutonium-238 radioactive source to heat its thermoelectric generator yielding more than 100 watts of power.

To accomplish its mission, the Mars Science Laboratory relies on a remarkable array of instruments grouped in four categories.

  1. The twin-lens Mastcam camera on Curiosity’s remote sensing mast is at human eye height, giving viewers a sense of strolling across Mars with the Rover. It gives high-definition video images of the Martian surface in color and 3-D. On top of the mast, ChemCam provides microscopic viewing and spectroscopic analyses of samples. It can work in conjunction with precise blasts of laser light that vaporize thin sections of Martian surface material from as far as 23 feet distant. It has telescopic optics for remote imaging and analysis of the spray produced by laser hits. ChemCam is may also be used to study ambient Martian atmosphere. Lower on the mast is REMS, the Rover Environmental Monitoring Station, REMS measures surface temperature, atmospheric pressure. In addition, a REMS sensor atop the Rover’s body monitors ultraviolet radiation levels. 
  2. Mounted on the Rover’s robotic arm is the APXS (Alpha Particle X-ray Spectrometer), providing measurements of chemical elements in soil and rock samples. Also on the arm is MAHLI (Mars Hand Lens Imager), a device yielding magnified pictures of rocks and soil. It is capable of resolving details smaller than a human hair! It also can take wide-angle images of the craft and its surroundings.
  3. Snug inside Curiosity’s body is the analytic laboratory instrument CheMin (Chemistry and Mineralogy) with ability to do X-ray diffraction analyses to identify and measure mineral content of soil and rock samples. Also within is the SAM (Sample Analysis at Mars) device. It analyzes materials collected by the Rover’s arm as well as whiffs of the Martian atmosphere. SAMS’s suite of instruments includes a mass spectrometer, a gas chromatograph, and a laser spectrometer to identify chemical compounds featuring carbon atoms. In addition the instrument can also discern specific isotopes of elements in samples.
  4. Mounted on the outside of Curiosity’s body are several environmental research instruments including the RAD (Radiation Assessment Detector) measuring radiation in the Rover’s neighborhood. At the tail end of Curiosity is DAN, the Dynamic Albedo of Neutrons instrument. It detects and measures the presence hydrogen, as far down as three feet below the surface. Hydrogen could be an indicator of water. Also outside the Rover is MARDI, the Mars Descent Imager. It made a video record of the landing site immediately before the craft touched down. Now it’s used to monitor ground passing directly under Curiosity.

During the voyage to Mars, RAD instruments detected dangerously high levels of radiation in the form of galactic cosmic rays from supernova explosions and powerful winds of sub-atomic particles emitted by solar flares and coronal mass ejections. It confirmed astronauts travelling to Mars certainly will need lots of radiation protection. 

SAM and CheMin instruments have shown evidence of elements important for the existence of life including sulfur, nitrogen, oxygen, phosphorus, and carbon in Martian rocks. SAM also discovered organic molecules in the sampled clay.

SAM confirms Mars once had much more atmosphere and water. Clay samples drilled from the area of Yellowknife Bay also indicate the past existence of flowing fresh water.

The Turnable Laser Spectrometer in SAM has detected an increase by a factor to ten of atmospheric methane in just a two month period. Methane, the gas we burn at home as “natural gas” can be produced by living organisms as well as by geologic activity. That’s an exciting discovery, but currently it’s unknown which of the processes is generating the dramatic increase of methane detected by Curiosity. 

The Rover and its Mars Science Laboratory are now working and travelling near Gale Crater’s Murray Butte formation, assessing things and looking around. Join the ride and check out what the mission's doing this week.