Spirit Completes Camera Check-Up
7 Aug 2006
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 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."
As of sol 918 (Aug. 2, 2006), Spirit's total odometry remained at 6,876.18 meters (4.27 miles).