* Astronomy

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RE: Mars Exploration Rover Spirit

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SPIRIT UPDATE: Spirit Nears 'Home Plate' - sol 730-735, Jan 27, 2006:

Spirit continues to make progress toward "Home Plate," a conspicuous circular feature scientists hope to investigate before the Martian winter, in search of layered rock outcrops that may provide additional information about the geology of the "Columbia Hills." During the past week, the rover has driven nearly 100 metres, and has still had time to do some targeted remote sensing. Spirit is currently just less than 170 meters from Home Plate.

During the past week, engineers noticed some anomalies in dynamic braking on two of the steering motors, similar to previous events on Spirit. Based on analysis and testing, they were able to continue the drive without incident.

Sol-by-sol summaries:

Sols 730 and 731 (Jan. 22 and 23, 2006): The weekend plan included a 10.8-meter drive to the crest of "Lorre Ridge." Spirit acquired targeted pre-drive and post-drive images. The rover spent most of Sunday recharging the battery to allow a longer drive on Monday.

Sol 732: Spirit drove 40 meters, using a combination of commanded and autonomous navigation along with a parallel obstacle-check sequence to keep from getting too close to potential hazards. The rover acquired a pre-drive image of a target called "FuYi." After the drive, the panoramic camera and navigation camera acquired forward-looking mosaics. The next morning, Spirit acquired rear-looking images with the navigation camera and forward-looking mosaics with the panoramic camera using two more filters.

Sol 733: Spirit completed an automous drive of approximately 40 meters. Just before beginning autonomous navigation, Spirit experienced a dynamic brake error in the left front and right rear steering actuators, at which point engineers halted the drive.

On the surface, this appeared to be similar to dynamic brake anomalies experienced on sols 265 (Oct. 1, 2004) and 277 (Oct. 13, 2004), which involved the right front and left rear steering motors. Analysis and testing at the time indicated that the problem was consistent with a delayed contact on the status relay. The rover engineering team sent a command to ignore the relay status, and since then, the rover has driven (with all steering motors enabled) without incident.

In the meantime, the team determined that it was safe to continue driving, but without using the left front and right rear steering motors.

Sol 734: Spirit drove approximately 9 meters autonomously.
Engineers conducted the same diagnostic tests they ran following the sol 265 incident in the testbed, to verify that the procedures worked with the current flight software. While awaiting dynamic brake diagnostics, they disabled Spirit's left front and right rear steering motors and allowed Spirit to drive only where they could clearly see the surrounding terrain and it was not necessary to steer around any obstacles.

Sol 735 (Jan. 27, 2006): Planned activities included a short, autonomous drive with the left front and right rear steering motors disabled, following a short diagnostic activity to characterise the behaviour of the dynamic brakes and the dynamic brake relay switch.

Odometry:
As of sol 735, Spirit's total odometry was 6,279.01 meters.

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Navcam view on Sol 735

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SPIRIT UPDATE: Spirit Completes Studies of 'Arad,' Moves On - sol 723-729, Jan 25, 2006:

Spirit is healthy and continues to pursue the short-term goal of driving to "Home Plate." Results from scientific instruments on the rover's robotic arm indicate that the white soil target called "Arad" has a salty chemistry dominated by iron-bearing sulphates. The composition is similar to that of a more silica-rich target, "Paso Robles," encountered earlier in the rover's journey through the "Columbia Hills." The presence of salt can be considered another clue to the existence of past water on Mars.

Spirit had a bit of difficulty driving out of the sandy area near Arad.
Rover instruments recorded slip rates as high as 92 percent on the wheels before Spirit's drivers designed a command strategy that took Spirit away from the sand dunes and closer to Home Plate.

Spirit's engineering team broke a record the previous week, on sol 720 (Jan. 12, 2006), by taking only 2 hours and 35 minutes to plan and validate the uplink commands for the rover. To put that in perspective, at the beginning of the mission, when all of the rover's systems and science team members were brand new, the process took more than 13 hours.

Sol-by-sol summaries:

Sols 723 to 725 (Jan. 14 to 17, 2006): Spirit began a campaign to study different targets of the feature named Arad, using instruments on the robotic arm, including the microscopic imager, Moessbauer spectrometer, and alpha particle X-ray spectrometer.

Sol 726: Spirit terminated the sol's drive early because of high slippage on sandy surfaces. The rover took images and conducted atmospheric observations using the miniature thermal emission spectrometer.

Sol 727: Spirit drove 26 meters, took images with the navigation and panoramic cameras after the drive, and conducted atmospheric studies using the miniature thermal emission spectrometer.

Sol 728: Rover planners successfully designed a drive that took Spirit away from the sand dunes and closer to Home Plate. Spirit took images following the drive.

Sol 729 (Jan. 21, 2006): Spirit conducted untargeted atmospheric remote sensing.

Odometry:
As of sol 728 (Jan. 20, 2006), Spirit's total odometry was 6178.96 meters.

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The Mars Exploration Rover Spirit spent the US Martin Luther King, Jr. holiday weekend analysing a remarkable exposure of bright, loose material. Spirit discovered the material while driving toward "Home Plate" along the floor of the basin south of "Husband Hill" in Gusev Crater. These images from Spirit's panoramic camera (Pancam) show some of the most colourful deposits yet photographed on the surface of Mars.

Spirit uncovered several types of materials distinctive in their colour, physical properties and chemistry as a result of accidentally digging a trench 30 centimetres wide during a turn at the end of a drive. The white material in this image is brighter than any seen previously by the rover. It has a powdery and cloddy texture and exhibits a high abundance of salts. The materials appear similar in some ways to bright soil deposits seen back at the "Paso Robles" site that Spirit encountered on the rover's Martian day, or sol, 431 (March 20, 2005) while climbing the northern flank of "Husband Hill."

This view is a false-colour composite combining images taken with the Pancam's 750-nanometer, 530-nanometer and 430-nanometer filters on Jan. 12, 2006, the rover's 721st sol on Mars.

Medium Image (221 kB) | Large (1.5 MB)
Image credit: NASA/JPL/Cornell

Spirit analysed the bright, yellowish exposures in the lower left part of the frame using instruments on the rover's robotic arm. Scientists hypothesized and then confirmed that these materials have a salty chemistry dominated by iron-bearing sulphates. These salts may record the past presence of water, as they are most easily mobilized and concentrated in liquid solution. Spirit also examined the unusual, pitted rock about 10 centimetres wide in the lower centre of the frame. Scientists continue to study the origin of these rocks and soils and the role that water have played in their formation.

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Spirit is healthy and is driving as efficiently as possible toward "Home Plate."
On the way to Home Plate, Spirit stopped to look at "Arad," where scientists encountered a cluster of white, powdery soil. Researchers decided to stop for a few days and use the robotic arm to conduct some measurements on it.
Results are expected soon.

Sol-by-sol summaries

Sol 715 (Jan. 6, 2006): Spirit performed untargeted remote sensing.

Sol 716: Spirit drove 54 meters (177 feet), using a combination of commanded and autonomous navigation.

Sol 717: Spirit drove only 1.38 meters (4.5 feet) on slippery terrain, experiencing slippage of 80 percent as the wheels were turning.

Sol 718: Spirit conducted untargeted remote sensing.

Sol 719: Spirit drove 9.3 meters (30.5 feet). The rover stopped when the slip rate of its wheels exceeded 80 percent in an area of sandy, unfamiliar terrain.

Sol 720: Spirit conducted untargeted remote sensing and atmospheric studies.

Sol 721: Spirit adjusted position to place the robotic arm next to Arad for a weekend of scientific measurements. The rover also used its panoramic camera and miniature thermal emission spectrometer to take images of targets called "Arad1" and "Arad2."

Sol 722: Spirit conducted untargeted remote sensing and took panoramic camera images of tracks created by the rover's wheels.

As of sol 722 (Jan. 14, 2006), Spirit's total odometry was 6,096 meters (3.79 miles).

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SPIRIT UPDATE: Spirit Meets 'Gallant Knight' - sol 701-707, Jan 05, 2006:

Spirit is in excellent health after a busy holiday weekend. The rover team made several three-sol plans in single working days so that while the rover was busy, the crew could take the holidays off (though with a few late nights on the work days).

After completing work on an outcrop called "Comanche," Spirit entered a dune field called "El Dorado," where the rover began digging in a little and looking closely for evidence about whether the deposited material there originated locally or globally. All of the week's objectives were achieved, including some ambitious drive sols that exceeded the team's expectations.

Sol-by-sol summaries:

Sols 701 to 703 (Dec. 23 to Dec. 25, 2005): Spirit completed a long Mössbauer spectrometer integration on the brushed target "Palomino," along with an overnight reading by the alpha particle X-ray spectrometer on the same target. The panoramic camera took a 16-frame mosaic from Comanche over two sols. That camera and the miniature thermal emission spectrometer observed targets in the immediate vicinity with informal names "Cheyenne," "Apache," "Kickapoo," "Chickasaw," and "Winnebago." On sol 703, microscopic images were taken of a fin-shaped feature on Comanche.

Sol 704 and 705: Sol 704's activities wrapped up the work on Comanche. Spirit drove toward El Dorado on both sols 704 and 705 as part of a three-sol plan starting on sol 703. The first driving sol began with 22 meters of directed driving followed by autonomous navigation toward the dune fields. The second driving sol would not have the benefit of humans in the loop, and so was purely autonomous navigation, picking up on the heels of the previous sol to get Spirit within striking range of El Dorado. The team expected to get perhaps 80 to 90 meters from the two sols of driving. However, by the end of Sol 705, Spirit had driven 118 meters, and was about a one-sol drive away from El Dorado.

Sol 706: This was the week's only normal, single-sol plan, which allowed engineers and scientists to plan a drive into El Dorado and to respond on the next sol with a plan to attack the science objectives there. The team expected to use the subsequent three-sol plan to trench in El Dorado and the three-sol plan after that to examine the trench. In order to prepare for the trench, the team planned a scuff at the end of the drive. The scuff was to be just a third of a wheel turn to push up some of the sandy material. That would give engineers some data on the consistency of the material so the team would know how long to trench.
Again the rover drivers came through, and Spirit successfully drove 38 meters right into the dunes of El Dorado on sol 706. The rover got a nice little mound and cut into a dune with the wheel scuff. The science team took a look at the scuff and decided it was in fact good enough for the science objectives without a need for trenching, so the team ended up three sols ahead of the game.

Sol 707 (Dec. 29): The microscopic imager inspected the scuff in El Dorado on the targets "Gallant Knight" and "Pilgrim." Spirit also began a long Mössbauer spectrometer integration on Pilgrim. As of sol 707, Spirit's total odometry was 5,829 meters.

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SPIRIT UPDATE: Studying 'Algonquin' - sol 680-688, Dec 12, 2005:

This week Spirit drove to an outcrop area informally named "Algonquin." On sol 685, Spirit successfully drove for 15 meters and prepared for a series of robotic-arm activities planned for sol 687 to 690 at Algonquin. Plans are to proceed downhill to "Comanche" after that.

Sol-by-sol summaries:

Sol 680 (Dec. 1, 2005): Spirit drove 30 meters toward a feature between "Miami" and Comanche.
Sol 681: Spirit performed remote sensing during the day and observed the moon Phobos at night.
Sol 682: Spirit took images of Algonquin, "Miami," "Pima," and "Yaqui" with the panoramic camera. Spirit observed Yaqui, Pima, Algonquin, "Meentwioni," and "Myammia" with the miniature thermal emission spectrometer.
Sol 683: A planned drive toward Algonquin was not executed.
Sol 684: Spirit took images of a dust devil, did a near-field survey with the panoramic camera, and used the miniature thermal emission spectrometer during the day and at night.
Sol 685: Spirit successfully drove 16 meters to the Algonquin outcrop.
Sol 686: Spirit performed remote sensing during the day and observed the moon Phobos at night.
Sol 687: Spirit used the microscopic imager and alpha particle X-ray spectrometer to study a feature informally called "Iroquet," which is located on the Algonquin outcrop.
Sol 688: Spirit used the rock abrasion tool's brush on Iroquet for 25 minutes, and then continued observations of Iroquet with the microscopic imager and alpha particle X-ray spectrometer.
As of the end of sol 686, (Dec. 8, 2005), Spirit had driven 5,510 meters.

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This chart shows the variation in available solar power for each of the Mars Exploration Rovers over the course of approximately two Mars years. Two factors affect the amount of available power: the tilt of Mars' axis and the eccentricity of the Mars' orbit about the sun.