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Mars will be getting a curious new rover

By Seth Humphries, Contributor  |  Posted Nov 18th, 2011 @ 9:16am



SALT LAKE CITY -- Next week, after most of us have eaten and stuffed ourselves beyond common sense, a group of scientists and engineers will be gathered in Florida for the long anticipated launch of the robotic rover Mars Science Lab (MSL). Like the other rovers, MSL has undergone a name change and is now called Curiosity. This curious robot is designed to wander the surface of Mars as Pathfinder, Spirit and Opportunity have done before it. Curiosity is the next phase in capabilities, science and size.

Pathfinder was the first of the rovers. It was about the size of a large cat, six-wheeled, solar powered and had limited scientific instruments. It did have an early version of the Alpha Particle X-ray Spectrometer (APXS) that can detect elemental abundances. It had a short mission life but blazed the path for those to come.

Spirit and Opportunity came next. Like Pathfinder, they bounced their way across the surface for a landing in giant-sized air bags. They then crawled the surface for seven-plus years, despite their 90-day expected life time. They, too, are solar powered but are significantly larger, about the size of a St. Bernard, and have much more in the way of scientific instrumentation.

Photo credit: NASA

They have an improved version of APXS on a movable arm so that the rovers do not have to get so close to rocks for inspection. The arm also contains an abrasion tool so that underlying layers of rocks can also be inspected. Spirit, since March of this year, is unresponsive. Meanwhile, Opportunity continues to be on the move with a limp. However, it will be powered down soon for the approaching Martian winter as there will not be enough solar energy available to keep it running full time.

Curiosity is a super-sized rover and is set for launch, after a 26-month delay, between Nov. 25 and Dec. 18. It will arrive in August of next year and land using Apollo-style retro-rockets; it is too big and heavy for air bags. It is super-sized in many aspects: the science scope is larger, expected mission lifetime is longer, number of scientific instruments is larger, roaming range is larger and is expected to be farther north and much colder.

It is like a six-wheel-drive, nuclear-powered, laser-blaster-toting Mini Cooper with heated leather seats. There are no seats, but the instruments do receive heat as needed from the RTG (radio-isotope thermal generator) power source. Including the mast, it stands nearly 7 feet tall. It has a 6-foot-long extendible arm with a 200-pound hand on the end. The hand can bore holes in rocks, grind them and sift the remains into fine power. It will then return the samples to several instruments in the body for further analysis.

As for scientific instruments, it has a super-sized number. It has a neutron probe that can detect hydrogen, in particular H2O as a liquid or solid. This will add to the findings of other instruments that there is water on Mars. It has an upgraded version of APXS in the hand next to a microscope that will image rocks from close up.

One instrument, named SAM, will receive the crushed and sieved samples from the arm and perform analysis using a gas chromatograph, mass spectrometer and a tunable laser spectrometer, just as scientists would do in their labs to determine carbon content, and isotopic ratios of important elements.

Another instrument in the body receiving the crushed samples is CheMin, which uses X-ray diffraction and fluorescence to determine chemical composition and mineral type. Minerals are formed under specific conditions. Knowing the mineral type of a rock leads directly to understanding the processes that produced that rock. For example, some minerals are only formed in the presence of liquid water. If those minerals exist on Mars, then at one point so did liquid water.

There are more scientific instruments that measure the weather, the surrounding radiation levels and take 3-D panoramic images. The crown jewel of Curiosity is an instrument called ChemCam. ChemCam uses a small telescope to focus a high-powered laser onto rocks up to about 23 feet away. There is so much energy concentrated into a spot smaller than a pin prick that small particles, molecules and excited atoms are ejected from the target. Those excited atoms emit light that ChemCam's telescope collects and the light spectrum is analyzed to determine chemical composition and mineral type.

The crown jewel of Curiosity is an instrument called ChemCam, which uses a small telescope to focus a high-powered laser onto rocks up to about 23 feet away.

Without touching, ChemCam can target a rock, determine what the surface is and then with repeated laser blasts measure deeper into the rock. This all can happen on Mars within minutes, just as it does in a lab on Earth in seconds. So within an hour or two, ChemCam can target and analyze dozens of rocks to determine which one the rover should approach for further analysis with the other instruments. ChemCam with its laser adds speed, accuracy and a coolness factor to Curiosity.

I watch with much excitement and anticipation the launch next week of Curiosity. I envy those with a close-up view of both the launch and the science of discovery as it lands and journeys across the martian surface.

Seth Humphries is a product development scientist at Apogee Instruments, headquartered in Logan, Utah.

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