OPPORTUNITY UPDATE: Still Grinding After All These Years
Feb 06, 2008:
OPPORTUNITY UPDATE: Still Grinding After All These Years
sol 1389-1395, Feb 06, 2008:
||With only about a month remaining before Opportunity's fourth anniversary (in Earth years) of Mars exploration, NASA's robotic geologist is still grinding into the surface of rocks to unlock the secrets of their interior chemistry. Meanwhile, fall arrived in the southern hemisphere of Mars on Dec. 9, 2007, Opportunity's 1,378th Martian day, or sol, of exploration of the Red Planet. Ten days later, Earth made its closest approach to Mars, coming within 88 million kilometers (54.8 million miles).
Opportunity used the rock abrasion tool to bore a shallow hole into a rock target known as "Lyell_1" and then spent about 70 hours integrating data about iron minerals inside the rock using the Mössbauer spectrometer.
During integration with the Mössbauer spectrometer, the rover adds measurements in a running total, sort of like exposing film. A longer exposure builds up the light areas, improves contrast, and results in a clearer, more distinct image, whereas a shorter exposure produces an image that is somewhat underexposed, darker, and less well defined. Similarly, longer integrations with the Mössbauer spectrometer yield more distinct signatures of iron content and the chemical state of the iron.
At the end of the Mössbauer campaign, Opportunity re-positioned the robotic arm to take images of the grind hole. The rover's handlers postponed acquiring images until after the holidays. On sol 1395 (Dec. 27, 2007), Opportunity acquired a mosaic of microscopic images of the ground rock surface before placing the alpha-particle X-ray spectrometer on a new rock target known as "Lyell_2." The resulting 2-by-2-by-14 mosaic was a collection of microscopic images arranged side-by-side like the four windowpanes in a square window. Within each of the four panes, Opportunity took 14 microscopic images at various distances from the rock surface. Because the microscopic imager is a fixed-focus camera, this process of acquiring images at different heights enables the rover to obtain images with different focal points. Because engineers don't always know where the best focus point will be, they start high, move closer, and finish low. Ideally, the middle pictures will be perfectly focused and higher and lower images will be slightly fuzzy.
Usually, the rover takes a stack of five microscopic images. This time, however, Opportunity took one image up high, one image down low, and four images at each of the three intervening heights. The multiple images will allow image processing experts to determine a digital average and cancel out unwanted data, known as "noise" to engineers.
In addition to studies using the Mössbauer and alpha-particle X-ray spectrometers, Opportunity conducted routine atmospheric tests, acquiring so-called Tau measurements of atmospheric dust with the panoramic camera. The rover took additional panoramic camera images of the immediate area using multiple filters. By combining images taken with different filters, engineers can create both true- and false-color views.
Following is a typical sol in the life of the Opportunity rover: Each Martian day is divided into blocks of activities separated by naps. The first block, known as the "engineering block," begins when sunlight is strongest and temperatures are warmest. This is when the rover performs the bulk of the day's activities, including drives and housekeeping activities such as arm movements. After this, Opportunity takes a "nap" with no activities to allow the early afternoon sun to recharge the rover batteries.
In the late afternoon, the rover wakes up for a communication session with the orbiting Odyssey spacecraft. This period is known as the "Odyssey block" and involves "pre-Odyssey," "Odyssey," and "post-Odyssey" activities. Afterward, the rover naps or goes into a deep sleep. During deep sleep, the rover shuts off power to almost everything on board. The following morning, the rover may wake up autonomously if there is enough solar power -- this time period is called "solar array wakeup." During this block, engineers usually schedule one or two small activities, followed by another nap to recharge the batteries. If there isn't enough solar power, the rover omits the solar array wakeup block.
Finally, the rover wakes up for the daily X-band communication session with Earth. This is known as the "AM block." At this time, the rover generally does imaging activities in parallel with communications. This block ends with a so-called "handover" from the previous sol's plan to the new sol's plan.
In addition to morning uplinks directly from Earth via the rover's high-gain antenna, evening downlinks to Earth via the Odyssey orbiter at UHF frequencies, and panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:
Sol 1389 (Dec. 20, 2007): Opportunity acquired panoramic camera images of the turret, placed the Mössbauer spectrometer on Lyell_1, and acquired approximately 12 hours worth of data with the instrument.
Sol 1390: In the morning, Opportunity surveyed the horizon with the panoramic camera. The rover restarted the Mössbauer spectrometer and spent approximately 12 hours integrating data with the instrument. Opportunity acquired a 13-by-1 mosaic of panoramic camera images of Lyell_1 and used the navigation camera to pinpoint the Sun's location in support of the upcoming Mars Science Laboratory mission. The rover went into a mini-deep sleep.
Sol 1391: Upon solar array wakeup, Opportunity monitored atmospheric dust and then monitored dust on the rover mast assembly. The rover restarted the Mössbauer spectrometer and spent about 12 hours integrating data from Lyell_1 with the instrument. Opportunity acquired a 5-by-1 tier of navigation camera images and, after communicating with Odyssey, went into a mini-deep sleep.
Sol 1392: Opportunity restarted the Mössbauer spectrometer integration of Lyell_1 and spent about 12 hours collecting data with the instrument. Opportunity acquired a 4-by-1 mosaic of images looking downslope at a target known as "Gilbert." The rover went into a mini-deep sleep.
Sol 1393: Upon solar array wakeup, Opportunity measured atmospheric dust and acquired Part 1 of a panoramic camera mosaic of foreground images. Opportunity spent another 12 hours engaged in Mössbauer spectrometer analysis of Lyell_1 and, after communicating with Odyssey, went into a mini-deep sleep.
Sol 1394: Following solar array wakeup, Opportunity monitored atmospheric dust and acquired Part 2 of the panoramic camera mosaic of foreground images. The rover conducted a survey at high Sun with the panoramic camera, restarted the Mössbauer spectrometer, and spent about 12 hours integrating data from the instrument. The rover went into a mini-deep sleep.
Sol 1395 (Dec. 27, 2007): Upon solar array wakeup, Opportunity measured atmospheric dust and scanned the sky for clouds with the navigation camera. Opportunity swung the robotic arm out of the way of the hazard avoidance camera, acquired full-color images of Lyell_1 using all 13 filters of the panoramic camera, and swung the robotic arm back into place over Lyell_1. The rover acquired stereo microscopic images of Lyell_1 and placed the alpha-particle X-ray spectrometer on Lyell_2. After communicating with Odyssey, Opportunity spent approximately 17 hours integrating Mössbauer spectrometer data from Lyell_2. The following morning, after communicating with Odyssey, Opportunity was scheduled to measure atmospheric dust and take thumbnail images of the sky with the panoramic camera.
As of sol 1395 (Dec. 27, 2007), Opportunity's total odometry remained at 11,591.21 meters (7.2 miles).
||NASA / JPL