Malin Space Science Systems, Inc. (MSSS), has delivered the last two of four science cameras it developed for the NASA/Jet Propulsion Laboratory 2011 Mars Science Laboratory (MSL) rover mission. These cameras, known collectively as the Mast Camera (or Mastcam--see Figure 1a and b) are designed to be the science imaging "workhorse" for the MSL rover. The cameras, capable of taking full color images analogous to those taken by consumer digital cameras, will be mounted on the rover's remote sensing mast, where they can be panned and tilted to proved image coverage around the rover, both near the rover and out to the horizon. One of the two Mastcams has a telephoto lens, providing the rover with a long-distance reconnoitering capability. Also delivered to JPL for MSL with the two Mastcams was the Digital Electronics Assembly (DEA), which compresses and buffers the images from the Mast Cameras, and the Mars Hand Lens Imager (MAHLI) and Mars Descent Imager (MARDI), cameras also developed by MSSS for the MSL mission.
Figure 1a. The Mast Camera 34 mm fixed focal length flight camera head with a Swiss Army Knife (88.9 mm; 3.5 inches long) for scale. The Mastcam 34 consists of a refractive optics with a focus mechanism and a filter wheel, and a CCD sensor and associated electronics. Figure credit: Malin Space Science Systems.
Figure 1b. The Mast Camera 100 mm fixed focal length flight camera head with a Swiss Army Knife (88.9 mm; 3.5 inches long) for scale. The Mastcam 100 is a duplicate of the 34 mm Mastcam except for the lens, which has three times the focal length. The only external indication of which camera is which is that the front baffle opening for the Mastcam 100 is smaller than the front baffle opening of the Mastcam 34. Figure credit: Malin Space Science Systems.
The Mastcams were transported from the MSSS facility in San Diego to JPL on 17 March 2010 for an extremely sensitive contamination measurement. Prior the contamination test, the each camera was shown to be operating normally and capable of taking in-focus images (Figure 2). The contamination test was completed satisfactorily on 18 March, and instrument functionality was verified in testing the following day. The cameras and the DEA now await integration with the MSL rover.
Figure 2. During post-transportation instrument checkout in the Building 306 Low Bay Cleanroom at JPL, the Mastcam 34 mm flight unit was used to take this picture of Dr. Michael Malin, the Mastcam's Principal Investigator. A test target derived from the "1951 U. S. Air Force Resolution Chart" can be used to determine the spatial resolution of the camera as a function of contrast, a standardized test to demonstrate that the camera is functioning properly and that the optics have not experienced any change during transport to JPL. In this image, the camera is demonstrating a resolution of about 4.5 line pairs per millimeter (9 pixels per mm, or about 111 micrometers per pixel) at a distance of 2 meters. Figure credit: Malin Space Science Systems.
The Mastcam focus and filter wheels are driven by precision mechanisms developed by Alliance Spacesystems (www.alliancespacesystems.com). The focus mechanism uses a stepper motor to position an internal focus group by means of a cam. The filter wheel mechanisms use stepper motors to drive 8-filter wheels to position the desired color filters in front of each camera's CCD detector.
The versions of the Mastcams delivered to JPL have fixed focal lengths (34 mm and 100 mm), and relatively small fields of view (15 degrees and 5 degrees). They would be used to build up coverage of the martian landscape around the rover from a series of small individual images.
The two Mastcams were originally proposed to have the identical 15:1 zoom (variable focal length) lenses on each camera [each camera could image from 100 mm focal length (telephoto) down to 6.5 mm focal length (wide angle)]. NASA directed that the development of the zoom lens be abandoned in 2007 as a cost saving measure, and the Fixed Focal Length Mastcams just delivered were developed to replace the zoom versions. With the two completed and delivered fixed focal length cameras in hand, NASA recently decided to fund completion of the zoom cameras by the Mastcam team, with the possibility of swapping out the old cameras for the new ones provided they can be assembled and tested in the time remaining before the MSL rover begins final testing early next year. The effort to build the zoom lens cameras has just started at MSSS.
"Restoring the zoom is not a science issue," said Michael Malin, Mastcam Principal Investigator, "although there will be some science benefits." "The fixed focal length Mastcams we just delivered will do almost all of the science we originally proposed. But they cannot provide a wide field of view with comparable eye stereo. With the zoom Mastcams, we'll be able to take cinematic video sequences in 3D on the surface of Mars. This will give our public engagement Co-Investigator, James Cameron, tools similar to those he used on his recent 3D motion picture projects."
MSSS has also provided two other cameras for the MSL mission: the Mars Hand Lens Imager (MAHLI) and the Mars Descent Imager (MARDI). The MAHLI, delivered to JPL in October of 2008, will be mounted at the end of the rover's robotic arm, and will be used to acquire very high resolution color images of the grain structure of individual rocks. The MARDI, delivered to JPL in July of 2008, will obtain color images of the martian surface during the descent of the MSL spacecraft to the surface, and may be used during rover traverses to acquire millimeter scale 3D views of the surface beneath the rover.
The Mastcam, MAHLI, and MARDI investigations were selected in 2004 by NASA's Science Mission Directorate in an open competition. The instruments share a common electronics design and were developed by Malin Space Science Systems, Inc., of San Diego, CA, under a single $18.9 million contract with Caltech's NASA-funded Jet Propulsion Laboratory in Pasadena, CA. MSSS will also be responsible for operating the cameras during the mission to Mars.
MSSS is currently building a camera for the Juno mission to Jupiter, that will also launch in 2011. MSSS built, and is presently operating two cameras onboard NASA's Mars Reconnaissance Orbiter (MRO), the Mars Color Imager (MARCI) and the Context Camera (CTX). MARCI provides a daily global weather map of Mars in five colors and two ultraviolet bands. CTX has already mapped more than 53% of Mars at 6 m per pixel resolution. Pictures from these cameras and other activities of the company are described at www.msss.com.