Mars Rover’s Laser Zaps First Target

NASA's Mars rover Curiosity fired its laser for the first time on Mars this week, hitting a fist-sized rock with 30 pulses, each delivering more than 1 million watts of power. The achievement was just the beginning of a two-year mission that will use the laser device to help unravel mysteries of the Red Planet.

The locations of the 17 cameras on NASA's Curiosity rover. The rover's mast features seven cameras: the Remote Micro Imager, part of the Chemistry and Camera suite; four black-and-white Navigation Cameras (two on the left and two on the right) and two color Mast Cameras (Mastcams). The left Mastcam has a 34-mm lens and the right Mastcam has a 100-mm lens. One camera on the end of a robotic arm is stowed in this graphic and is called the Mars Hand Lens Imager (MAHLI). Nine cameras are hard-mounted to the rover: two pairs of black-and-white Hazard Avoidance Cameras in the front, another two pair mounted to the rear of the rover (dashed arrows in the graphic), and the color Mars Descent Imager (MARDI). (Image: NASA/JPL-Caltech)

Curiosity landed on Mars two weeks ago, beginning a two-year mission (equivalent to one Martian year) using 10 instruments to assess whether a carefully chosen study area inside Gale Crater has ever offered environmental conditions favorable for microbial life. It has yet to move from its landing site; NASA engineers have wiggled its wheels in anticipation of embarking on Curiosity's first drive later this week.

This composite image, with magnified insets, depicts the first laser test by the Chemistry and Camera, or ChemCam, instrument aboard NASA's Curiosity Mars rover. The composite incorporates a Navigation Camera image taken prior to the test, with insets taken by the camera in ChemCam. The circular insert highlights the rock before the laser test. The square inset is further magnified and processed to show the difference between images taken before and after the laser interrogation of the rock. The test took place Aug. 19, 2012. (Photo: NASA/JPL-Caltech/LANL/CNES/IRAP)

The mission's Chemistry and Camera instrument, or ChemCam, hit the rock, dubbed "Coronation," during a 10-second period, with each laser pulse lasting for about five one-billionths of a second (5 ns). The laser energy excited atoms in the rock to form into an ionized, glowing plasma. ChemCam uses laser-induced breakdown spectroscopy (LIBS) to record spectra from the object and is equipped with three spectrometers. Sunday's investigation of Coronation marks the first time the technique has been used in interplanetary exploration, mission officials say.

ChemCam is designed to look for lighter elements such as hydrogen, carbon, nitrogen and oxygen, all of which are crucial for life, as well as to determine abundances of other elements. It can deliver three laser pulses each second to a single area, or it can quickly zap multiple areas, providing researchers with great versatility for sampling the surface of the planet. The first few laser pulses act as sort of a long arm that can reach out and brush off dust that would otherwise obscure the target surface, enabling scientists to observe the underlying sample.

Block diagram of the ChemCam instrument suite. (Image: ChemCam/LANL/IRAP/CNES)

The laser, mounted high on the rover's camera mast, sends its light back to the ChemCam through the instrument's 4.3-in.-aperture telescope, which directs the light down an optical fiber to the spectrometers inside the rover. Spectrographs divide the plasma light into its constituent wavelengths for chemical analysis; the spectrometers record intensity at 6144 different wavelengths of ultraviolet, visible and infrared light. The system is designed to capture as many as 14,000 observations throughout the mission.

Curiosity's telescope doubles as the optics for the camera part of ChemCam, which records images on a 1-megapixel detector. The telescopic camera will show context of the spots hit with the laser and also can be used independently of the laser.

The camera can resolve features five to 10 times smaller than those visible with cameras on NASA's two Mars Exploration rovers (Spirit and Opportunity), which began exploring the planet in January 2004. In the event that the Mars Science Laboratory (MSL) rover can't reach a rock or outcrop of interest, ChemCam will have the capability to analyze it from a distance of up to 7 m (23 ft).

A size comparison between the Mars Science Laboratory mockup (right), the Mars Exploration rovers Spirit and/or Opportunity (left) and Sojourner (center), by the Jet Propulsion Laboratory in 2008. Two times larger and five times heavier than Spirit and Opportunity, Curiosity rivals a small SUV in size and carries 15 times the weight of the scientific instruments that those vehicles have carried. (Photo: NASA/JPL-Caltech)

The SUV-sized Curiosity is the first rover sent to another planet capable of not only navigating the terrain, but also of scooping up and analyzing rock and dust samples. Its mission is to venture up to 12 miles from its landing site and explore the area for past or present conditions favorable for life, and for conditions capable of preserving a record of life. The rover is expected to collect, grind and analyze about 70 samples of soil and rock.

It is also the first rover to not have solar panels, the performance of which was impacted by frequent dust accumulations.

The goal of this initial use of the laser on Mars is to serve as target practice for characterizing the instrument, but the activity may provide additional value. Researchers will check whether the composition changes as the pulses progress. If it does change, that could indicate dust or other surface material being penetrated to reveal various composition beneath the surface.

“We got a great spectrum of Coronation — lots of signal,” said ChemCam principal investigator Roger Wiens of Los Alamos National Laboratory (LANL) in New Mexico. “Our team is both thrilled and working hard, looking at the results. After eight years building the instrument, it’s payoff time!”

This mosaic image with a close-up inset, taken prior to the test, shows the rock chosen as the first target for NASA's Curiosity rover to zap with its Chemistry and Camera (ChemCam) instrument. ChemCam fired its laser at the fist-sized rock, called "Coronation" (previously “N165”), with the purpose of analyzing the glowing, ionized gas, called plasma, that the laser excites. (Image: NASA/JPL-Caltech/MSSS/LANL)

“It’s surprising that the data are even better than we ever had during tests on Earth, in signal-to-noise ratio,” said ChemCam deputy project scientist Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planetologie (IRAP) in Toulouse, France. “It’s so rich, we can expect great science from investigating what might be thousands of targets with ChemCam in the next two years.”

ChemCam was developed, built and tested by LANL in partnership with scientists and engineers funded by the French national space agency, Centre National d'Etudes Spatiales (CNES) and research agency, Centre National de la Recherche Scientifique (CNRS). The massive Gale Crater, located close to the equator near the boundary between the southern highlands and the more featureless northern low plains of Mars, spans 96 miles in diameter, an area roughly equivalent to the size of Connecticut and Rhode Island combined. A towering mountain, informally named Mount Sharp, rises up nearly three miles above the crater floor. This gigantic feature will provide opportunities for ChemCam to sample geologic layers on the mountainside. “The amazing thing about the mountain in Gale Crater is that it appears from orbit to be entirely sedimentary material,” said Nina Lanza, a postdoctoral researcher in LANL’s International, Space and Response (ISR) division. “This is a collection of sedimentary layers that is nearly three times higher than the Grand Canyon is deep.”

A number of optics and photonics companies have played a role in the success of Curiosity:

Ocean Optics
The company's three modular HR2000 high-resolution miniature fiber optic spectrometers were modified to handle the extreme temperature ranges, radiation, shock and vibration associated with space travel and descent. Each ChemCam spectrometer is configured to detect elemental signatures over a different wavelength of light: 240 to 336 nm, 380 to 470 nm and 470 to 850 nm. The use of the three spectrometers simplifies the design and creates redundancy, as many elements under study have spectral lines in more than one of the spectral ranges covered by the three units.

Optimax
“The optics we made for the Mars rover were significantly smaller than most of the optics we make – about the size of a dime. There’s some challenge to that,” Optimax's Matt Brule told 13-WHAM TV in Rochester, N.Y.

The company made a second lens for the rover's articulating arm. “That has the ability to zoom and see features half the size of a human hair,” Josh Dennie, a production manager at Optimax, told the news station. “It’s also got the ability to drill and scoop and examine the rocks, soil and ice, if it’s present."

Emcore
The provider of semiconductor components and subsystems for the fiber optic and solar markets made the solar panels to power the Mars Science Laboratory spacecraft, which launched Nov. 26, 2011, to carry Curiosity to Mars. The solar panels were designed and manufactured by Emcore's Photovoltaic Div. in Albuquerque, N.M. The company also is supplying solar panels for several other NASA missions, including the Lunar Atmosphere and Dust Environment Explorer, Lunar Reconnaissance Orbiter and the Magnetospheric Multiscale missions.

3S Photonics
The France-based optical and optoelectronic components maker supplied the laser technology for the Mars Science Laboratory mission. In 2004-2005, 3S Photonics’ laser diodes were selected and integrated into ChemCam‘s laser for spectroscopy.

maxon motor
The company's MR Encoder technology is built into the electromechanical joints of the rover. The magnetic sensors are mounted on the drive shafts and are responsible for controlling the motors.

Vigo System
Uncooled MCT (mercury cadmium telluride) infrared detectors developed at Vigo System are being used in the ChemCam instrument.

Teledyne Dalsa
A number of Teledyne companies contributed components to the mission: Teledyne Energy Systems developed the thermoelectric system that powers the rover. Teledyne Microelectronics manufactured two complex radio frequency (RF) modules that are part of the terminal descent and landing unit. Teledyne Relays supplied electromechanical relays used on Curiosity's communication suite; the company supplied similar components for the earlier Spirit and Opportunity rovers. Teledyne Impulse supplied electromechanical power transfer switches that were used on the Atlas V rocket that launched the mission.

Malin Space Science Systems
The company provided Curiosity's mast cameras, Mars hand lens imager and Mars descent imager.

OPCO Laboratory
Several diffraction gratings that are integrated into the spectrometers in the ChemCam instrument package were provided by OPCO Laboratory.

For more information on ChemCam, visit: www.msl-chemcam.com. For more information on Curiosity, visit: www.nasa.gov/msl.