Work continues on readying Curiosity for surface operations on Mars, with characterisation phase well underway.
The week has seen the rover’s Chemistry and Camera system – ChemCam – undergoing its calibration tests using a target system located towards the back of the rover, while scientists have been looking for candidates for the first full test firing of the system at a suitable surface target.
ChemCam is a complex system split between Curiosity’s mast and body. The mast unit is the large box-like unit at the top of the mast. It contains a laser unit, a remote micro-imager (RMI) and a telescope for focusing both.
The body unit carries three spectrographs for chemical analysis and has its own power supply and an electronic interface to the rover’s central computer system.
ChemCam has two main functions, split between the laser system (the Laser-induced Breakdown Spectroscopy (LIBS), to give it its proper name) and the Remote Micro-Imager (RMI).
LIBS is designed to fire series of laser pulses at a target spot smaller than 1 millimetre on the surface of rocks and soils, vaporizing it. Light from the resultant plasma is captured by the telescope and sent via fibre-optics to the on-board spectrographs for analysis, which should provide information in unprecedented detail about minerals and micro structures in Martian rocks. Additionally, the laser can be used to remove dust from the surfaces of rocks, allowing the drill on Curiosity’s hand to obtain samples of the rock free from surface contaminants.
The RMI provides black-and-white images at 1024×1024 resolution in a 0.02 radian (1.1 degree) field of view – approximately equivalent to a 1500mm lens on a 35mm camera. RMI has two functions. In the first, it will be used in conjunction with LIBS to identify suitable targets and target locations (targets can be selected autonomously or via Earth-based selection and command). Working independently of LIBS, it will be used to obtain close-up images in support of robot arm-mounted experiments or provide images of very distant objects.
This week, ChemCam was calibrated using a target system mounted on the rear section of the rover, mounted below the UHF antenna. As a result of this, ChemCam was confirmed ready for operations, and is expected to make it first test-firing on an actual Martian rock sample on Saturday August 18th. The sample is provisionally designated N165, and sits a short distance from the rover.
ChemCam is a joint US / French experiment, with the US Los Alamos National Laboratory providing the body unit, the French national space agency (CNES) proving the mast unit (RMI, laser, etc.) and JPL the fibre-optic link between the two.
Getting Ready to Roam
Curiosity is drawing closer to its first planned drive on the surface of Mars. The first stage in preparing for this is a static test of the steering actuators, due some time in the next couple of Sols following the ChemCam test firing.
The front and rear wheels on the rover are steerable, and the initial tests will comprise turning the wheels on the spot to confirm the actuators are all working. This will then be followed by the rover taking a very short drive – literally a handful of metres – around Sol 15 of the mission. This will comprise driving the rover forward for a few metres (turning it through about 90-degrees in the process), taking a look back at its landing-point, and then reversing a few metres.
In the meantime, mission planners have already selected Curiosity’s first excursion. This will be for a distance of some 400 metres (1,300 feet) to the south-west of the landing point to a natural intersection of three types of terrain which has been dubbed Glenelg. The traverse is liable to take a while, but once there, the rover will be able to commence a comprehensive check-out of the robot arm and its “hand” of scientific instruments.
Also in preparation for the rover’s coming trek to “Mount Sharp”, JPL released a high-resolution image of the lower slopes of the mound captured by the MastCam’s 34mm camera system and gives a very clear indication of the kind of terrain the rover is liable to be traversing as it climbs the lower slopes of the mount in the months ahead. A scale has been added to the image, and the mesa visible are thought to be equally to buildings around 2 or 3 floors tall.
As with the majority of the colour images released to date, the picture has been white balanced, so the colours are pretty much as they would appear if the scene were illuminated by terrestrial levels of sunlight. This helps scientists in recognising rocks by colour in the more familiar lighting. As Mars receives between one- and two-thirds the amount of sunlight received by Earth, were the images rendered using typical Martian lighting levels, they would appear far more bland, as with the images in my last MSL article.
Mohawk Guy Returns
One of two unexpected celebrities during the liver coverage of MSL’s landing on Mars was Bobak Ferdowsi. He is a mission flight director with responsibilities for “driving” Curiosity, but found fame when images of his Mohawk haircut featured prominently in the mission landing coverage from JPL, leading to him being globally dubbed “Mohawk Guy”. The haircut itself is one of a number Ferdowski, who has been a part of the MSL team since 2003, has sported to mark various parts of the mission. NASA has been quick to recognise and embrace his celebrity, and he’s given numerous “personal interest” interviews that have helped keep the mission in the public eye. This week he’s back, hosting JPL’s weekly updates on the mission, and filling-in on the bits I’ve not covered here.
The Mars Descent Imager recorded just over 1,000 high-resolution images during the MSL’s descent through the last 3.7 kilometres of the Martian atmosphere. This represents a period spanning the parachute descent and the power descent phase once the rover / descent stage had separated from their protective aeroshell. These images have been returned to Earth along with the other images being returned by the Navcams, Mastcam systems, et al, and are being worked on to present what is hoped will be a video montage of the vehicle’s descent to a point shortly before landing.
On Friday August 17th, the mission team released a short piece of footage put together from the images received which shows the MSL’s heat shield as it impacts the surface of Mars.