Daily Update - 3/31/08
Opportunity Studies Martian Dust and 'Victoria Crater' Rocks
Opportunity Status for sol 1451-1456
Opportunity continues to be healthy with all subsystems performing as expected. Energy has been declining slowly, from 440 watt-hours at the start of the period to 415 watt-hours at the end. Some of that decline is due to the advancing winter season but much of it is due to heavy battery usage. By dipping into the battery, the rover lowers its bus voltage (the bus is the main power distribution cable. All systems get their power through their connection to the bus.) As power is the product of voltage and array current, for a given amount of sunlight, power will be lower when the batteries are discharged compared to when they are more fully charged. This lower power is by design -- the rover uses the batteries to execute the science plan and then recharges the batteries to increase energy.
Tau, a measure of the amount of dust in the atmosphere blocking incoming sunlight, has averaged about 0.74. (A Tau of zero would correspond to a perfectly clear atmosphere.) A Tau of 0.74 means only about 45 percent of the direct sunlight reaches the solar array. (Note that atmospheric dust both absorbs and scatters sunlight. The absorbed light is lost as it turns to heat and warms the atmosphere. Scattered sunlight is not lost. It makes the whole sky "glow" and gives it a pinkish color. It also reaches the solar panels and generates a significant fraction of the rover's total power.)
For example, during the worst of the Martian dust storms some 200 sols ago,
Tau hit 5.6, which meant only about 0.4 percent of the direct sunlight reached Opportunity's solar arrays. Scattered light generated virtually all the rover's power, about 130-160 watt-hours per sol. Currently, scattered light generates as much as half the rover's power depending on the time of day.
The rover measures Tau at various times of day, sometimes using two different cameras. The reason for this is that dust accumulates on the camera lenses, affecting the measurement. By taking Taus at different times, the rover sees the Sun through different depths of the atmosphere. If Tau is constant (and to a first approximation, it is), engineers can estimate how much sunlight is blocked by atmospheric dust and how much by camera dust. Comparing measurements from both the navigation and panoramic cameras, each with different amounts of dust, provides another means of determining how much sunlight is being blocked by the atmosphere or the camera. And as every photographer knows, different lighting conditions require different exposure times. The rover does the same thing by changing the exposure at different times of the Sol. Typically, the rover uses the panoramic camera to measure Tau, taking regular Tau measurements between mid-morning and early afternoon, "new Tau" measurements in mid-afternoon, and a sunset Tau near sunset.
Opportunity's dust factor, which is different from Tau, has been steady at 0.73, meaning that 73 percent of the sunlight reaching the solar arrays penetrates the dust layer to generate electricity.
While studying the various layers of rock in "Victoria Crater," Opportunity has discovered that the "Steno" layer is coarse-grained with well-defined, fine layering called laminae. The "Smith" rock layer is lighter in color and has still finer laminae. "Lyell" is darker again and has slightly coarser layers. "Gilbert," the lowest layer examined so far, appears similar to Lyell but without apparent layering. Scientists are comparing the layers in Victoria Crater to other craters Opportunity has visited to determine whether the processes that produced them were local or regional.
One of the interesting features at Gilbert is a line of "fins." These look like thin, little burrs of rock along one edge of the rock slab. A few have broken off and are lying flat on the surface of Gilbert. One of these, named "Dorsal," will be studied over the next week.
Sol-by-sol summary
In addition to receiving instructions directly from Earth via the rover’s high-gain antenna and relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, Opportunity completed the following activities:
Sol 1451 (Feb. 22, 2008): Opportunity acquired 6 movie frames in search of clouds with the navigation camera in addition to regular Tau, new Tau, and sunset Tau measurements with the panoramic camera. The rover spent about 6.3 hours measuring argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer and went into a mini-deep sleep.
Sol 1452: Upon awakening, Opportunity measured Tau with the navigation camera. The rover took spot images of the sky with the panoramic camera and acquired 6 movie frames in search of clouds with the navigation camera. Opportunity took a regular Tau measurement, followed by a 2-by-2-by-3 stack of microscopic images of dust on the capture magnet and a 2-by-2-by-3 stack of microscopic images of dust on the filter magnet. Before sending data to Odyssey, the rover took a sunset Tau measurement. After communicating with Odyssey, Opportunity studied the elemental composition of dust on the filter magnet by integrating data from the alpha-particle X-ray spectrometer for 5.5 hours. The rover went into a mini-deep sleep.
Sol 1453: Upon solar array wakeup, Opportunity took Tau measurements with the navigation camera and thumbnail images of the sky with the panoramic camera. The rover acquired 6 movie frames in search of clouds with the navigation camera. Opportunity took a regular and a new Tau measurement. After sending data to Odyssey, Opportunity spent about 6.3 hours studying the elemental chemistry of dust on the filter magnet with the alpha-particle X-ray spectrometer. The rover went into a mini-deep sleep.
Sol 1454: Shortly after sunrise, Opportunity measured Tau and acquired 6 movie frames in search of clouds with the navigation camera. Opportunity monitored the physical characteristics of dust on the rover mast assembly, surveyed the horizon with the panoramic camera, and created 6 more movie frames in search of clouds with the navigation camera. The rover made standard Tau measurements and, after the overpass of Odyssey, a new Tau measurement. Opportunity spent about 7.25 hours collecting data from the filter magnets with the alpha-particle X-ray spectrometer before going into a mini-deep sleep.
Sol 1455: Upon solar array wakeup, Opportunity measured Tau with the navigation camera, created two six-frame movies in search of clouds with the navigation camera, and took spot images of the sky for calibration purposes with the panoramic camera. The rover acquired a 4-by-1 panel of panoramic camera images of a target called "Shrock." Opportunity made a regular Tau measurement and took full-color images, using all 13 filters of the panoramic camera, of a rock exposure dubbed "Gilbert_A." The rover placed the microscopic imager on Gilbert_A and acquired a 2-by-2-by-14 stack of stereo (3-D) microscopic images, then switched tools and placed the alpha-particle X-ray spectrometer on the target. The rover took a new Tau measurement and, after sending data to Odyssey, spent about 6.25 hours acquiring compositional data from Gilbert_A.
Sol 1456 (Feb. 27, 2008): First thing in the morning, Opportunity took full-color images, using all 13 filters of the panoramic camera, of both magnets. The rover made regular Tau measurements with the panoramic camera as well as a Tau measurement with the navigation camera and created a 6-frame movie in search of clouds with the navigation camera. Opportunity took full-color images of Gilbert_A as well as panoramic-camera images of the brush on the rock abrasion tool. The rover ran diagnostic tests related to a stall in Joint 1 (controlling shoulder position), placed the microscopic imager over Gilbert_A, and acquired a 2-by-2-by-12 stack of stereo images of the target. Opportunity then placed the alpha-particle X-ray spectrometer on Gilbert_A. After communicating with Odyssey, Opportunity collected compositional data from Gilbert_A for about 4 hours. The following morning, the rover was to acquire regular Tau measurements, navigation-camera Tau measurements, and a 3-by-1 panel of panoramic-camera images of the promontory known as "Cape Verde."
Daily Update - 3/12/08
Sturdy Rover Gets No Penalty for Tilting
Spirit Status for sol 1471-1477
Scarcely a pinball wizard on Earth could tilt the machine nearly 30 degrees without ending play, yet engineers tilted NASA's Spirit rover 29.9 degrees and completed the robotic equivalent of a one-armed toe-touch to test its stability. The rover remained in play, racking up scientific data points after remaining perfectly balanced even while pressing the ground with the Mössbauer spectrometer at the end of its robotic arm.
During the past week, Spirit began work on a 360-degree, full-color panorama of the rover's winter surroundings as viewed from the north edge of the elevated, volcanic plateau known as "Home Plate." The resulting mosaic of high-resolution images, to be acquired during approximately 60 individual pointings of the panoramic camera, will be nicknamed the "Bonestell panorama" in honor of Chesley Bonestell (pronounced BON-es-tell), a science fiction illustrator and designer. (Last year's spectacular image mosaic of Spirit's winter haven was called the "McMurdo panorama.")
Spirit took microscopic images of dust that has settled out of the Martian sky onto the solar panels. The rover also made two attempts to complete the first of a two-part process for brushing the surface of a rock target dubbed "Wendell Pruitt" with the rock abrasion tool, another of the instruments on the rover's robotic arm. Because the results were inconclusive after the first try, Spirit's handlers decided to have the rover repeat the procedure, known as a "grind scan," during which the rover locates the surface by touching it with the brush and the grinding bit, two days later. The second attempt was successful, clearing the way for actual brushing of Wendell Pruitt.
Spirit is healthy and all subsystems are performing as expected.
Sol-by-sol summary
In addition to measurements of atmospheric dust levels with the panoramic camera and daily communications activities, which include morning direct-from-Earth uplinks over the rover's high-gain antenna and evening relays to Earth via the UHF antenna on the Mars Odyssey orbiter, Spirit completed the following activities:
Sol 1471 (Feb. 22, 2008): Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer, touched the ground and exerted 10 newtons of force with the Mössbauer spectrometer to test the rover's stability at the new tilt of 29.9 degrees, and acquired super-resolution images of a target dubbed "Gekko." Spirit took spot images of the sky for calibration purposes using the panoramic camera.
Sol 1472: Spirit checked for drift (changes over time) in the miniature thermal emission spectrometer, surveyed the external calibration target and completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer, and acquired super-resolution images of a rock target known as "Monolith" with the panoramic camera.
Sol 1473: Spirit acquired full-color images, using all 13 filters of the panoramic camera, of a rock target dubbed "William A. Johnston," a deceased member of the Tuskegee Airmen. Spirit checked for drift in the miniature thermal emission spectrometer, completed a mini-survey of the sky and ground with the instrument, and acquired a 2-by-2-by-1 stack of microscopic images of a target on the rover's solar panels as well as microscopic images of the external capture magnet and filter magnet. The rover acquired single-frame, lossless-compression (high-definition) images of the area directly in front of the rover with the navigation camera.
Sol 1474: Spirit monitored dust on the rover mast, surveyed the sky at varying elevations and the ground with the miniature thermal emission spectrometer, completed another mini-survey of the sky and ground, and checked for drift in the spectrometer.
Sol 1475: Spirit took full-color images, using all 13 filters of the panoramic camera, of a rock target nicknamed "Bennett Hardy" (also a Tuskegee Airman). The rover checked for drift in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. Spirit made the first attempt to use a grind-scan procedure to contact the surface of Wendell Pruitt. The rover took single-frame, lossless-compression (high-definition) images with the navigation camera.
Sol 1476: Spirit acquired super-resolution images of a rock target dubbed "Reuben C. Franklin" (a Tuskegee Airman) with the panoramic camera, checked for drift in the miniature thermal emission spectrometer, and completed a mini-survey of the sky and ground with the instrument. The rover took diagnostic images of the rock abrasion tool and recharged the batteries.
Sol 1477 (Feb. 28, 2008): Spirit acquired column 1 of part 1 of the full-color Bonestell panorama, using all 13 filters of the panoramic camera. The rover checked for drift in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. Spirit completed the second, successful attempt to locate the surface of Wendell Pruitt using the grind-scan procedure with the rock abrasion tool. The rover acquired single-frame, lossless-compression images with the navigation camera. Plans for the following morning called for Spirit to point the panoramic camera starboard and take thumbnail images of the sky.
Odometry
As of sol 1476 (Feb. 27, 2008), Spirit’s total odometry remained at 7,528.07 meters (4.68 miles).
Daily Update - 3/11/08
Multi-Tasking Rover Helps Pave the Way for Next Mars Mission
Opportunity Status for sol 1444-1450
Opportunity completed the first leg of a two-part drive toward an area of scientific interest known as "Gilbert" that involved moving backward in order to continue the drive without running into some unexpectedly deep soil to the rover's right. En route, Opportunity spent two Martian days acquiring compositional data from a rock exposure dubbed "Lyell-Exeter," measured argon gas in the Martian atmosphere, and conducted remote-sensing activities.
In addition, Opportunity tested relay communications in support of NASA's Phoenix mission, due to land on Mars in late May. The first test, with the European Space Agency's Mars Express spacecraft, took place on sol 1444 (Feb. 15, 2008) and was primarily a trial of a new command strategy to permit the orbiter to acquire a larger amount of data from the surface of Mars. The second test was a possible relay through the NASA's Mars Reconnaissance Orbiter on sol 1446 (Feb. 17, 2008). This was an attempt to take advantage of an anomaly on the orbiter that turned off science instruments and placed the orbiter on standby to await instructions from Earth. The recovery timeline ended up not supporting this particular test. The third, with Mars Express on sol 1449 (Feb. 20, 2008), was part of a series of tests to determine differences in performance when the orbiter receives data from directly overhead and when the orbiter receives data when not directly overhead.
Opportunity remains healthy, with all subsystems performing as predicted. On sol 1449 (Feb. 20, 2008), the rover had 447 watt-hours of power (100 watt-hours is the amount of energy needed to light a 100-watt bulb for 1 hour).
Assuming Opportunity successfully completes a planned drive on sol 1450 (Feb. 21, 2008), the rover will be in position to begin a full complement of scientific investigations of Gilbert.
Sol-by-sol summary
In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:
Sol 1444 (Feb. 15, 2008): After sending overnight data to Odyssey as it passed overhead, Opportunity measured the composition of Lyell-Exeter with the alpha-particle X-ray spectrometer.
Sol 1445: Opportunity acquired early-morning, full-color images of a scuff made by the rover's left wheel using all 13 filters of the panoramic camera. The rover took spot images of the sky for calibration purposes with the panoramic camera and scanned the sky for clouds with the navigation camera. After communicating with Odyssey, Opportunity continued to acquire data from Lyell-Exeter with the alpha-particle X-ray spectrometer. The rover surveyed the sky at high Sun with the panoramic camera.
Sol 1446: Opportunity surveyed the horizon with the panoramic camera and scanned the morning sky for clouds in movie frames taken with the navigation camera. Opportunity stowed the robotic arm, drove toward Gilbert, acquired images just before completing the drive with the hazard avoidance cameras, and acquired a 4-by-1, post-drive mosaic of images with the navigation camera. The rover then unstowed the robotic arm.
Sol 1447: Opportunity surveyed and took spot images of the sky with the panoramic camera and documented potential clouds in movie frames taken with the navigation camera. After sending data to Odyssey, Opportunity measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.
Sol 1448: Opportunity took thumbnail images of the sky with the panoramic camera and acquired movie frames in search of clouds with the navigation camera. The rover surveyed the horizon and surveyed the sky at high Sun with the panoramic camera.
Sol 1449: Upon awakening, Opportunity made a movie to document potential clouds with the navigation camera. The rover took spot images of the sky and surveyed the horizon with the panoramic camera. Opportunity surveyed the evening sky at low Sun prior to communicating with the Odyssey orbiter.
Sol 1450 (Feb. 21, 2008): Opportunity took early-morning thumbnail images of the sky with the panoramic camera. The rover also took spot images of the sky with the panoramic camera and acquired movie frames in search of clouds with the navigation camera. Opportunity stowed the robotic arm, drove toward Gilbert, acquired images just before completing the drive with the hazard avoidance cameras, unstowed the arm, and acquired a 360-degree mosaic of images with the navigation camera. The rover created 6 movie frames in search of clouds with the navigation camera. The following morning, Opportunity was to measure atmospheric dust with both the navigation and panoramic cameras, create another 6-frame movie in search of clouds with the navigation camera, and complete a survey of the horizon with the panoramic camera.
Odometry
As of sol 1449 (Feb. 20, 2008), Opportunity's total odometry was 11,669.13 meters (7.25 miles).
Daily Update - 3/3/08
Tenacious Rover Just Might Make It
Spirit Status for sol 1464-1470
Spirit has achieved a northerly tilt of 29.9 degrees! As a result, based on
power projections, Spirit has a fighting chance of surviving another winter
on Mars, if the weather and environment cooperate.
Plans for sol 1471 (Feb. 22, 2008) called for a test of the stability of Spirit's
new perch prior to using the rock abrasion tool by having the rover touch the
Martian surface with the Mössbauer spectrometer and apply 10 newtons of
pressure (called a pre-load).
Sol-by-sol summary
In addition to measurements of atmospheric dust levels with the panoramic camera
and daily communications activities, which include morning direct-from-Earth
uplinks over the rover's high-gain antenna and evening relays to Earth via the
UHF antenna on the Mars Odyssey orbiter, Spirit completed the following activities:
Sol 1464 (Feb. 14, 2008): Spirit edged downslope another 4 centimeters (about
1.5 inches). The rover took thumbnail images of the sky for calibration purposes
with the panoramic camera.
Sol 1465: Spirit took mid-field images and spot images of the sky for calibration
purposes with the panoramic camera.
Sol 1466: Spirit acquired images for updating the rover's precise attitude
relative to the Sun, surveyed the horizon and took spot images of the sky with
the panoramic camera, and surveyed the external calibration target with the
miniature thermal emission spectrometer.
Sol 1467: Spirit acquired images of the "El Dorado" dune field with
the panoramic camera and snapped movie frames in search of dust devils with
the navigation camera. The rover took thumbnail images of the sky with the panoramic
camera.
Sol 1468: Spirit surveyed the sky at high Sun using the panoramic camera.
Sol 1469: Spirit surveyed the sky and ground with the miniature thermal emission
spectrometer and took before-and-after stereo images with the navigation camera
to enable the on-board visual odometry software to determine the rover's position.
Spirit acquired a 5-by-1 mosaic of forward-looking images and a 5-by-1 mosaic
of rearward-looking images with the navigation camera. Also with the navigation
camera, the rover assessed atmospheric opacity caused by dust and scanned the
sky for clouds.
Sol 1470 (Feb. 21, 2008): Spirit unstowed the robotic arm and moved it to test
the rover's stability. Spirit measured atmospheric opacity caused by dust using
both the panoramic and navigation cameras. The rover took spot images of the
sky with the panoramic camera and surveyed the sky and ground with the miniature
thermal emission spectrometer.
Odometry
As of sol 1470 (Feb. 21, 2008), Spirit's total odometry was 7,528.07 meters
(4.68 miles).
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