the technology of curiosity mars rover

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Mars Rover

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The Technology of Curiosity

Saturday, September 01 2012 On April 14, 2004, NASA announced an opportunity for researchers to propose science investigations for the Mars Science Laboratory (MSL) mission. Eight months later, the agency announced selection of eight investigations. In addition, Spain and Russia would each provide an investigation through international agreements. The instruments for these ten investigations make up the science payload on the Curiosity rover.

Curiosity examines a rock on Mars with a set of tools at the end of its arm, which extends about 7 feet. Two instruments on the arm can study rocks up close. A drill can collect sample material from inside of rocks, and a scoop can pick up samples of soil. The arm can sieve the samples and deliver fine powder to instruments inside the rover for thorough analysis. (NASA/JPL-Caltech)

The ten instruments on Curiosity have a combined mass of 165 pounds. Curiosity carries the instruments plus multiple systems that enable the science payload to do its job and send home the results. Key systems include six-wheeled mobility, sample acquisition and handling with a robotic arm, navigation using stereo imaging, a radioisotope power source, avionics, software, telecommunications, and thermal control.

Curiosity is 10 feet long (not counting its arm), 9 feet wide, and 7 feet high at the top of its mast, with a mass of 1,982 pounds, including the science instruments. Curiositys mechanical structure provides the basis for integrating all of the other rover subsystems and payload instruments.

Mobility

Curiositys mobility subsystem is a scaled-up version of what was used on the three earlier Mars rovers: Sojourner, Spirit, and Opportunity. Six wheels all have driver motors, and the four corner wheels all have steering motors. Each front and rear wheel can be independently steered, allowing the vehicle to turn in place, as well as to drive in arcs. The suspension is a rocker-bogie system, enabling Curiosity to keep all its wheels in contact with the ground, even on uneven terrain. Curiositys wheels are aluminum and 20" in diameter. They have cleats for traction and structural support. Curving titanium spokes give springy support.

The rover has a top speed on flat, hard ground of about 1.5 inches per second. However, under autonomous control with hazard avoidance, the vehicle achieves an average speed of less than half that.

Arm and Turret

The Robot Arm (RA) is a five-degrees-of-freedom manipulator used to place and hold the turret-mounted devices and instruments on rock and soil targets, as well as manipulate the turretmounted sample processing hardware.

The science instruments on the arms turret are the Mars Hand Lens Imager (MAHLI) and the Alpha Particle X-ray Spectrometer (APXS). The other tools on the turret are components of the rovers Sample Acquisition/Sample Processing and Handling (SA/SPaH) subsystem: the Powder Acquisition Drill System (PADS), the Dust Removal Tool (DRT), and the Collection and Handling for In-situ Martian Rock Analysis (CHIMRA) device.

This drawing of Curiosity indicates the location of science instruments and some other tools. (NASA/JPL-Caltech)

The SA/SPaH subsystem is responsible for the acquisition of rock and soil samples from the Martian surface, and the processing of these samples into fine particles that are then distributed to the analytical science instruments SAM and CheMin. The SA/SPaH subsystem is also responsible for the placement of the two contact instruments, APXS and MAHLI, on rock and soil targets. SA/SPaH also includes drill bit boxes, the Organic Check Material (OCM), and an observation tray, which are all mounted on the front of the rover, and inlet cover mechanisms that are placed over the SAM and CheMin solid sample inlet tubes on the rover top deck.

The Powder Acquisition Drill System is a rotary percussive drill to acquire samples of rock material for analysis. It can collect a sample from up to 2" beneath a rocks surface. The drill penetrates the rock and powders the sample to the appropriate grain size for use in SAM and CheMin. If the drill bit becomes stuck in a rock, the drill can disengage from that bit and replace it with a spare. The Dust Removal Tool is a metal-bristle brushing device used to remove the dust layer from a rock surface or to clean the rovers observation tray.

A clamshell-shaped scoop collects soil samples from the Martian surface. The other turret-mounted portion of this device has chambers used for sorting, sieving, and portioning the samples collected by the drill and the scoop. An observation tray on the rover allows the MAHLI and the APXS a place to examine collected and processed samples of soil and powdered rock.

Power

Rover power is provided by a multi-mission radioisotope thermoelectric generator (MMRTG) supplied by the U.S. Department of Energy. This generator is essentially a nuclear battery that reliably converts heat into electricity. It consists of two major elements: a heat source that contains plutonium-238 dioxide, and a set of solid-state thermocouples that convert the plutoniums heat energy to electricity. It contains 10.6 pounds of plutonium dioxide as the source of the steady supply of heat used to produce the onboard electricity, and to warm the rovers systems during the Martian nights.

Computing

Curiositys mast features seven cameras: the Remote Micro Imager, part of the ChemCam suite; four black-and-white Navigation Cameras (two on the left and two on the right); and two color Mast Cameras (Mastcams). (NASA/JPL-Caltech)

Curiosity has redundant main computers, or rover compute elements. Of this A and B pair, it uses one at a time, with the spare held in cold backup. So, at a given time, the rover is operating from either its A side or its B side. Each computer contains a radiation-hardened central processor with PowerPC 750 architecture, a BAE RAD 750 processor operating at up to 200 MHz speed. Each of Curiositys redundant computers has 2 gigabytes of flash memory, 256 megabytes of DRAM, and 256 kilobytes of EEPROM. The MSL flight software monitors the status and health of the spacecraft during all phases of the mission, checks for the presence of commands to execute, performs communication functions, and controls spacecraft activities.

Navigation

Two sets of engineering cameras on the rover Navigation cameras (Navcams) up high, and Hazard-avoidance cameras (Hazcams) down low inform operational decisions both by Curiositys onboard autonomy software and by the rover team on Earth. Information from these cameras is used for autonomous navigation, engineers calculations for maneuvering the robotic arm, and scientists decisions about pointing the remote-sensing science instruments.

Each of the Navcams captures a square field of view 45 degrees wide and tall, comparable to the field of view of a 37-millimeter-focal-length lens on a 35- millimeter, single-lens-reflex camera. Curiosity has four pairs of Hazcams: two redundant pairs on the front of the chassis, and two at the rear. The rover can drive backwards as well as forward, so both the front and rear Hazcams can be used for detecting potential obstacles in the rovers driving direction. The Hazcams have one-time-removable lens covers to shield them from potential dust raised during the rovers landing.

Mast Camera (Mastcam)

This artists concept depicts Curiosity as it uses its ChemCam to investigate the composition of a rock surface. ChemCam fires laser pulses at a target and views the resulting spark with a telescope and spectrometers to identify chemical elements. The laser is in an invisible infrared wavelength, but is shown here as visible red light for purposes of illustration. (NASA/JPL-Caltech)

Two two-megapixel color cameras on Curiositys mast are the left and right eyes of the Mastcam. These cameras have complementary capabilities for showing the rovers surroundings in exquisite detail and in motion. The right-eye Mastcam looks through a telephoto lens with about three-fold better resolution than any previous landscape-viewing camera on the surface of Mars. The left-eye Mastcam provides broader context through a medium-angle lens. Each can acquire and store thousands of full-color images. Each is also capable of recording high-definition video.

The telephoto Mastcam is called Mastcam 100 for its 100-millimeter focal-length lens. The camera provides enough resolution to distinguish a basketball from a football at a distance of seven football fields. Its left-eye partner, called Mastcam 34 for its 34-millimeter lens, catches a scene three times wider on an identical detector.

Chemistry and Camera (ChemCam)

The ChemCam instrument consists of two remote sensing instruments: the first planetary science Laser-Induced Breakdown Spectrometer (LIBS), and a Remote Micro- Imager (RMI). The LIBS provides elemental compositions, while the RMI places the LIBS analyses in their geomorphologic context.

ChemCam uses a rock-zapping laser and a telescope mounted atop Curiositys mast. It also includes spectrometers and electronics inside the rover. The laser can hit rock or soil targets up to about 23 feet away with enough energy to excite a pinhead-size spot into a glowing, ionized gas called plasma. The instrument observes that spark with the telescope and analyzes the spectrum of light to identify the chemical elements in the target. The telescope doubles as the optics for the camera of ChemCam, which records monochrome images. The telescopic camera, called the remote micro-imager, will show context of the spots hit with the laser. It can also be used independently of the laser for observations of targets at any distance.

The spot hit by ChemCams infrared lase

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