Curiosity morphs into a mobile lab
The large team of engineers and scientists living on Mars time at the here are rapidly learning to operate the nuclear-powered Curiosity rover, which continues to perform almost faultlessly on the floor of Gale Crater.
Checkout of the complex suite of instruments designed to gauge the habitability of Mars, past and perhaps present, continues to go well. The Mars Science Laboratory (MSL) engineering team has completed a changeout from the software designed to transport the rover from Earth to the surface of Mars over to the package Curiosity will need to operate semiautonomously for the next two Earth years.
Scientists have started mapping the terrain it must cross to reach the canyon in the side of the crater's central mountain, dubbed Mount Sharp in tribute to planetary scientist Robert P. Sharp, that is the scientific target of the mission. And the team that must write as many as 1,000 rover commands a day during full-up operations has started working without a net, with the preloaded command sequences for the most part all run now (see p. 30).
The MSL Curiosity team will have its first chance to conduct geochemical science, and even go for a short drive, sometime late this week, assuming the commissioning process continues to stay on schedule, says.
So far, John Grotzinger, the mission chief scientist, says the chances are extremely good that this activation process will go well, judging by the success of the mission to date.
“We're pinching ourselves,” says Grotzinger, who oversees the elite group of planetary-science specialists who will try to wring as much knowledge as possible out of the rover's instruments. “All the instruments have passed their 'liveness' checks. Everything is fine, as far as we can tell.”
However, Grotzinger cautions that the true health of some of the more sophisticated instruments, such as the Sample Analysis at Mars (SAM), will not be confirmed for “weeks, if not months” because of the many complex subsystems in play. SAM is the largest of the 10 instruments on Curiosity. It combines in a single microwave-oven-sized box three analytical tools that the space agency says would take up a “good portion” of a standard laboratory on Earth. Using samples collected with Curiosity's 6.2-ft. robotic arm, SAM will study chemistry relevant to life, and check for carbon-based compounds with mass and laser spectrometers and a gas chromatograph.
However, before Curiosity can feed any samples to the SAM or perform any other geochemistry, JPL must continue the process of slowly morphing Curiosity from a preprogrammed spacecraft into a fully-functioning, tactical, mobile laboratory. The process is divided into two major commissioning phases, CAP1 and CAP2. The initial part, CAP1, is itself divided into two, with CAP1A just completed, says Grotzinger. This included activating Curiosity's remote-sensing suite of cameras and instruments, including the Rover Environmental Monitoring Station (REMS) weather station and the Radiation Assessment Detector, both of which automatically began collecting data about conditions at the landing site after touchdown.
Cameras commissioned in CAP1A included the mast-mounted Chemistry and Camera (ChemCam), Navigation Camera (Navcam) and Mast Camera. Navcam imaged the sky after landing to help pinpoint the craft's location and precisely aim Curiosity's high-gain communications antenna toward Earth. The new flight-software (version 10.0) was then uploaded Aug. 10-13. During the delicate operation, which optimized Curiosity's primary and backup computers for surface operations, engineers halted the transfer of spectacular surface imagery already collected by the cameras to keep the complex software reload as simple as possible. The new load includes improved image processing for obstacles and other potential hazards, which will aid the rover's driving autonomy, as well as software for controlling the tools at the end of Curiosity's robotic arm.
JPL is now in CAP1B, which delves into the heart of commissioning the bulk of the rover's science instruments as well as the actuators for the wheels and other elements of the mobility system. Instruments commissioned in this phase include the Dynamic Albedo of Neutrons (DAN), a Russian-built instrument that will fire neutrons into the ground below the rover in search of hydrogen atoms signifying water.
Also to be commissioned will be the Alpha Particle X-Ray Spectrometer, which identifies chemical elements, as well as parts of the SAM and Chemistry and Mineralogy (CheMin) experiments. “The REMS will also begin diurnal observations that it will do for the rest of the mission,” Grotzinger says.
The ChemCam, which incorporates a-made laser capable of ionizing rock or soil up to 23 ft. away, will be given additional health checks. As the target is zapped with the laser, the instrument observes the glowing spot of plasma with its telescopic lens and analyzes the light to identify chemical elements. Testing will include the first passive spectra checks and evaluation of the instrument's pointing characteristics. After all the “jostling around” on Curiosity's long journey to Mars, the team will point it at a calibration target to “find out how much slack there is in the mechanism,” Grotzinger says.
The CAP1B will take “no fewer than six sols [Martian days], and up to 10 to complete,” Grotzinger estimates. By the end of 1B, “we will be able to use ChemCam as an instrument for the first time, and we will look at burn marks in rocks and soil with the remote imager,” he says.
Other work will include checks of the rover's steering actuators and mechanism, as well as tests in CAP2 of the surface-sampling system mounted on Curiosity's arm. As part of that process, controllers will move the arm and its various drills and sieves for the first time. “We will unstow and stow the robotic arm—sort of stretch it out,” Grotzinger adds.
Also slated for checkout is the functioning of inlet covers designed to prevent stray material from entering the SAM and chemical instruments.
“At the end of 1B, we've set an entire day aside for a set of rover mobility tests concerned with actuation and wheel-rotation tests,” Grotzinger says. After this, the team will enter an “intermission” phase while it faces the choice of whether to move the rover first, or “roll straight into CAP2” for final instrument checkouts.
However, “there are a few activities we'd like to do like calibrate the mast camera and ChemCam laser,” Grotzinger says. “We could do an instrument test on the tunable laser spectrometer because, as we go through CAP2, the principal investigators would benefit from having the data to chew over while the drill and sampling system are checked.”
As a result, the intermission will therefore likely include these tasks, and “if we want to drive to a distance of say 500 meters [1,640 ft.], then we have the option of getting the first 100 to 200 meters out of the way while we're dealing with CAP2,” he says.
Given progress to date, the team is leaning toward using the intermission for a drive on Sol 15. “It will just be a short drive—a few meters,” says MSL Mission Manager Michael Watkins. The initial maneuver will include a drive forward, followed by a turn and then a reverse. “We want to turn in an area that we can see,” he adds.
|Elevation: 4.4 km (14,400 ft.) below the Martian aeroid (“sea level”)|
|Grand Canyon (Arizona)|
|Elevation (canyon floor): 2.4 km (8,000 ft.) below the canyon’s North Rim|
|Elevation (above Gale Crater floor): 5.5 km (18,000 ft.)|
|Mount McKinley (Alaska)|
|Elevation: 6.2 km. (20,320 ft.) above sea level|
|Sources:, U.S. Geological Survey and the National Park Service|