Spirit has finished acquiring images for the "McMurdo panorama" and began adding some finishing touches around the edges. The rover is healthy and continues to make progress on its winter science campaign of observations on Mars.
Plans called for Spirit to complete a winter check-up of all the rover's cameras by calibrating the microscopic imager. To accomplish this procedure, known as a photon transfer observation, Spirit acquired 20 pairs of images, each pair taken during a different exposure time. Engineers used these images to form a baseline for estimating unwanted electronic signals using a Poisson distribution.
The Poisson curve measures probability over a fixed time interval based on a known average. Using this probability, engineers correlated the signal measured by the camera with differences in signals acquired in the image pairs to calculate the efficiency with which the camera's imaging sensors convert photons from sunlight into electrical energy. They used the same approach to characterize the electrical system's ability to translate measurements of voltage into digital numbers.
Spirit is collecting about 280 watt-hours of electrical power each sol from the rover's solar array (a hundred watt-hours is the amount of electricity needed to light one 100-watt bulb for one hour).
Sol-by-sol summary:
Sol 915 (July 30, 2006): Spirit acquired flat-field images for calibrating variations in the field of light in the McMurdo panorama.
Sol 916: Spirit surveyed the sky and ground using the miniature thermal emission spectrometer.
Sol 917: Spirit searched for clouds using the navigation camera.
Sol 918: Spirit added some finishing touches to the McMurdo panorama.
Sol 919: Spirit added more finishing touches to the McMurdo panorama.
Sol 920: Plans called for Spirit to conduct a photon transfer observation to measure electronic noise (unwanted signals) picked up by CCDs (charge-coupled devices -- imaging sensors that convert light into electrical current) in the microscopic imager.
Sol 921 (Aug 5, 2006): Plans called for Spirit to acquire panoramic camera images of a soil target known as "Tyrone."
Odometry
As of sol 918 (Aug. 2, 2006), Spirit's total odometry remained at
6,876.18 meters (4.27 miles).------------------------------------------------------------------------
OPPORTUNITY UPDATE: Opportunity Examines Crater Ejecta, Grinds into Rock
- sol 893-899, August 04, 2006:
After traversing the sandy plains of Meridiani to "Beagle Crater," Opportunity investigated a patch of outcrop pavement thought to be representative of the Martian surface beyond the reach of materials excavated by the impacts that dug Beagle and the nearby, much larger Victoria Crater. Opportunity used its rock abrasion tool to grind away the surface of rock for the first time since the rover's 691st sol, or Martian day (Jan. 3, 2006).
Both before and after grinding beneath the surface of the rock target known as "Baltra," Opportunity took microscopic images and collected data with the alpha particle X-ray spectrometer and the Moessbauer spectrometer. The rover remains healthy. This weekend, the science team plans to launch a three-day imaging campaign of Beagle Crater and the surrounding area.
Sol-by-sol summaries:
Sol 893 (July 29, 2006): Opportunity took microscopic images of Baltra and the grinding bit on the rock abrasion tool, ground 3 millimeters (0.12 inch) beneath the surface of Baltra, and took images of the magnets on the rock abrasion tool both before and after the grind. After communicating with NASA's Mars Odyssey orbiter, the rover began a study of Baltra with the alpha particle X-ray spectrometer and surveyed the sky and ground with the miniature thermal emission spectrometer. The rover turned off the alpha particle X-ray spectrometer at 11:13 p.m., local Mars time, before going into a mini-deep sleep.
Sol 894: Opportunity took stereo microscopic images of Baltra following the grind. The rover spent 12 hours collecting data from the freshly ground surface with the Moessbauer spectrometer. Opportunity acquired panoramic camera images of the rim of Beagle Crater and a transitional area around Beagle Crater known as "Espa?ola."
Sol 895: Opportunity acquired panoramic camera images of a flat rock target known as "Bartolom?" and conducted Moessbauer analysis of Baltra. Opportunity completed a very long survey of atmospheric dust, known as a tau measurement, with the panoramic camera and surveyed the sky and ground with the miniature thermal emission spectrometer. The rover went into deep sleep to recharge the batteries.
Sol 896: Opportunity rolled back 1 meter (3.3 feet) and acquired color images of Baltra using all 13 filters of the panoramic camera, then drove 21 meters (69 feet) toward the edge of Beagle Crater. At the end of the drive, the rover acquired images of the terrain using the navigation and panoramic cameras.
Sol 897: Opportunity recharged the batteries and conducted untargeted remote sensing of infrared energy and dust using the miniature thermal emission spectrometer (beginning with looking at the calibration target) and the panoramic camera. The rover surveyed the ground and sky with the miniature thermal emission spectrometer while communicating with the Odyssey orbiter.
Sol 898: Opportunity acquired panoramic camera images before driving 5 meters (16 feet) toward the rim of Beagle Crater. After the drive, Opportunity acquired images with the navigation camera and data with the miniature thermal emission spectrometer.
Sol 899 (Aug. 4, 2006): Plans called for a deep sleep followed by turning on the miniature thermal emission spectrometer heaters at 7 a.m., surveying the sky with the panoramic camera, and collecting data from the sky and ground using the miniature thermal emission spectrometer.
Odometry
As of sol 897 (Aug. 2, 2006), Opportunity's total odometry was 8,681.96 meters (5.39 miles).