* Astronomy

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RE: Mars Exploration Rover Spirit

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SPIRIT UPDATE: Serious but Stable - sol 1730-1736, November 14 - November 20, 2008:

Spirit's condition has improved during the past week, though skies remain fairly dusty after the recent Martian dust storm. Since sol 1730 (Nov. 14, 2008), solar-array energy has averaged 169 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for 1 hour). The latest measurement of atmospheric darkness caused by dust, known as Tau, is 0.858. The dust factor, representing the portion of sunlight penetrating the coating of dust on the solar panels, is 0.2912.
Spirit performed a cursory check of the health of the miniature thermal emission spectrometer. After three nights with the spectrometer's heaters disabled, the instrument appeared to be undamaged as of sol 1730. Power is not yet sufficient to re-enable those heaters, though Spirit will continue to monitor the spectrometer while waiting for power to improve. For the most part, Spirit is limiting activities to those necessary for maintaining engineering health and safety.
Spirit endured another challenge when new commands from Earth for sol 1734 (Nov. 18, 2008) did not arrive. At that point, Spirit began to execute a backup set of activities known as a runout plan. On Earth, engineers created a new sequence of commands for sol 1736 (Nov. 20, 2008) to manage communications and preserve power. Meanwhile, they are investigating why Spirit did not receive their previous commands.
According to the latest Martian weather report for Nov. 15 (sol 1731), skies are expected to continue to clear during the next couple of weeks. No other storms have been identified within a couple of thousand kilometres of Spirit's location.
Spirit is preparing for solar conjunction, where the Sun is between Earth and Mars, preventing communications. This period begins Nov. 29th. Before and during solar conjunction, Spirit's activities will remain conservative as the rover waits for the skies to clear and for the power situation to improve.

Sol-by-sol summary:
In addition to measuring dust-related changes in atmospheric opacity with the panoramic camera, Spirit completed the following activities:

Sol 1730 (Nov. 14, 2008): Spirit observed the sky briefly with the miniature thermal emission spectrometer.

Sol 1731: Spirit rested and soaked up the Sun's rays to recharge the batteries.

Sol 1732: Spirit rested and soaked up the Sun's rays to recharge the batteries.

Sol 1733: Spirit rested and soaked up the Sun's rays to recharge the batteries.

Sol 1734: Spirit completed basic activities in the runout plan.

Sol 1735: Spirit completed basic activities in the runout plan.

Sol 1736 (Nov. 20, 2008): Spirit completed basic activities in the runout plan.

Odometry:
As of sol 1736 (Nov. 20, 2008), Spirits total odometry was 7,529.02 metres.

Blobrana · L

Mars Rover Team Sets Low-Power Plan for NASA's Spirit
After assessing data received from NASA's Mars Exploration Rover Spirit on Thursday, mission controllers laid out plans for the rover to conserve its modest energy during the next few weeks.
Spirit's solar panels produced 161 watt hours of energy on the Martian day that ended Thursday, under a sky that had cleared appreciably from four days earlier, when a dust storm slashed energy output to 89 watt hours. However, the dust buildup on the panels themselves has worsened. Only 30 percent of the light hitting them gets through the dust and is usable by the photovoltaic cells, down from 33 percent before the storm.

On Nov. 30, Spirit will begin a two-week period with no new commands sent from Earth.

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NASA's Mars Exploration Rover Spirit communicated via the Mars Odyssey orbiter today right at the time when ground controllers had told it to, prompting shouts of "She's talking!" among the rover team at NASA's Jet Propulsion Laboratory, Pasadena, California.

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Dust Storm Cuts Energy Supply of NASA Mars Rover Spirit
A dust storm on Mars has cut into the amount of sunlight reaching the solar array on NASA's Mars Exploration Rover Spirit, leaving the rover in a vulnerable state.
Spirit's solar array produced only 89 watt hours of energy during the rover's 1,725th Martian day, which ended on Nov. 9. This is the lowest output by either Spirit or its twin, Opportunity, in their nearly five years on Mars, and much less energy than Spirit needs each day. The charge level of Spirit's batteries is dropping so low, it risks triggering an automated response of the rover trying to protect itself.

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NASA's Spirit rover, which is nearing its fifth year on Mars, is struggling to survive after a dust storm sapped its power, mission scientists said Tuesday.

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SPIRIT UPDATE: Still Trying to Drive Uphill - sol 1716-1722, October 30 - November 06, 2008:

Spirit has been trying to drive back up the slope toward the top of "Home Plate" to achieve a more favourable tilt of the solar panels toward the Sun as it moves higher in the sky. Spirit at first made promising progress on sols 1709 (Oct. 23, 2008) and 1713 (Oct. 27, 2008). Subsequent drives have not been as successful. Spirit began veering to the rover's right, which resulted in the right front wheel getting close to slipping off the top of Home Plate and onto the slope. The right front wheel is the one that no longer drives, so if it moves onto the slope it could be difficult to get it back on top of Home Plate.
Fortunately, rover planners have a seemingly bottomless bag of tricks and they continue to try different strategies to make progress up the slope. If necessary, they can direct the rover to drive downslope and take an alternate route back up Home Plate. They can save time if Spirit can make it up the slope from the rover's present location.
Spirit is also preparing for solar conjunction. This is a period of approximately two weeks, beginning November 29, when the Sun will be between Earth and Mars, preventing communication. Preparations include making sure that Spirit's battery is charged and that Spirit has sufficient computer memory available to store data collected during conjunction until it can be sent to Earth.
Spirit is healthy, with all subsystems performing as expected as of the latest transmission from NASA's Odyssey orbiter on sol 1722 (Nov. 6, 2008). Energy from Spirit's solar arrays has been averaging 230 watt-hours (equivalent to the amount of energy needed to light a 100-watt bulb for about 2 hours and 20 minutes).

Sol-by-sol summary:
In addition to measuring dust-related changes in atmospheric clarity each day with the panoramic camera, Spirit completed the following activities:

Sol 1716 (Oct. 30, 2008): Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. Spirit resumed inching uphill. After the drive, Spirit took a single-frame image with the navigation camera as well as images with the hazard-avoidance cameras.

Sol 1717: Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. The rover recharged the batteries.

Sol 1718: Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. Spirit continued inching uphill and, after the drive, acquired images with the navigation and hazard-avoidance cameras.

Sol 1719: Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. The rover made observations of the spectrometer's calibration target and recharged the batteries.

Sol 1720: Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. The rover acquired four, time-lapse movie frames in search of clouds with the navigation camera and took spot images of the sky for calibration purposes with the panoramic cameras. Spirit completed a "quick fine attitude" adjustment to determine the rover's precise position relative to the Sun. Spirit acquired images with the rear and front hazard-avoidance cameras and used visual odometry to track the rover's actual position based on the surface imprints made by its wheels.

Sol 1721: Spirit continued trying to inch upslope. After stopping, Spirit acquired a single-frame image with the navigation camera as well as images with the hazard-avoidance cameras.

Sol 1722 (Nov. 6, 2008): Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer, completed a mini-survey of the sky and ground with the instrument, and recharged the batteries.

Odometry:
As of sol 1721 (Nov. 4, 2008), Spirit's total odometry was 7,528.56 metres.

Blobrana · L

SPIRIT UPDATE: Getting Ready to Make the Next Move - sol 1695-1701, October 09-15, 2008:

In recent weeks, increasing solar power has enabled Spirit to complete more science activities. Spirit has finished the 360-degree, full-colour view of its winter surroundings, known as the "Bonestell panorama," and acquired extra frames at super resolution to enhance details in the imagery. The rover also has documented seasonal changes in the atmosphere by measuring argon gas with the alpha-particle X-ray spectrometer.
The trade-off has been that by funnelling most available power into science activities, Spirit has not had much power for sending data to Earth. That is about to change, because Spirit's on-board memory is nearly full. Instead of sending data only every fourth day, Spirit will begin relaying data every day to NASA's Odyssey orbiter for transmission to Earth.
Rover operators will use the data to plan Spirit's first, post-winter drive to adjust the rover's position to keep the solar panels facing the Sun. The move will put the rover in optimum position before solar conjunction, when Earth and Mars will be on opposite sides of the Sun and communication will not be possible. Solar conjunction will take place on Martian days, or sols, 1745-1760 (Nov. 29-Dec. 15, 2008).
Meanwhile, Spirit is healthy, with all subsystems performing as expected as of sol 1700 (Oct. 14, 2008). Solar-array energy has been 242 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). After weeks of remarkably clear skies, atmospheric opacity or tau, a measure of the decrease in sunlight caused by atmospheric dust, has risen slightly to 0.294. Atmospheric dust levels remain low, but are beginning to trend upward and affect solar power levels. This increase is expected, as it has occurred at this time of year in each of the previous three Martian years.
The dust factor -- the percentage of light penetrating dust on Spirit's solar arrays -- has remained steady. Only 32 percent of the sunlight reaching the arrays penetrates the dust to generate electricity.

Sol-by-sol summary:
In addition to making daily measurements of the amount of atmospheric dust preventing sunlight from reaching the rover's solar arrays, Spirit completed the following activities:

Sol 1695 (Oct. 9, 2008): Spirit checked for drift (changes with time) in the miniature thermal emission spectrometer, surveyed the sky and ground with the instrument, did survey work with the panoramic camera, and surveyed a surface target dubbed "Jules Verne" with the miniature thermal emission spectrometer.

Sol 1696: Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and made some finishing touches to the lower edge of the full-colour, 360-degree view of the rover's winter surroundings by acquiring 3 panels of images known as "Bonestell lower tiers" 1, 2, and 3.

Sol 1697: Spirit used the miniature thermal emission spectrometer to survey the sky, the ground, and a target known as "Stapledon." Spirit parked the panoramic camera mast assembly with the panoramic camera pointed below the horizon to minimise dust accumulation.

Sol 1698: Spirit took spot images of the sky for calibration purposes with the panoramic camera and spent much of the day recharging the battery.

Sol 1699: Spirit surveyed the sky at different elevations as well as the ground with the miniature thermal emission spectrometer and used the panoramic camera to survey the horizon and take thumbnail images of the sky on the rover's right (starboard).

Sol 1700: Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and took spot images of the sky with the panoramic camera. Spirit relayed information from Mars to NASA's Odyssey orbiter for transmission to Earth.

Sol 1701 (Oct. 15, 2008): Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and monitored dust accumulation on the panoramic-camera mast assembly.

Odometry:
As of sol 1700 (Oct. 14, 2008), Spirit's total odometry remained at 7,528.0 metres.

Blobrana · L

SPIRIT UPDATE: Spirit and Earth Stick Together - sol 1685-1689, September 28 - October 03, 2008:

Spirit is poised to begin making more "phone calls" to Earth and engineers are preparing to contact Spirit more frequently as a result of improving solar power input on Mars. Though Spirit's energy levels are still low, they are improving significantly as Martian winter gradually fades into spring. The rover will use some of the energy to let engineers and scientists know how things are going on Mars.
Spirit stays in touch by transmitting data at UHF frequencies to NASA's Odyssey orbiter. Odyssey sends it to Earth. On the other end of the line, engineers send new activity plans to Spirit using X-band transmissions from Earth that go directly to the rover's dish antenna. More frequent communication allows greater operational flexibility as the rover gradually returns to a normal planning schedule and prepares to drive again in mid- to late October.
Spirit's first post-winter drive will be short, just far enough to adjust the rover's position so its solar panels remain tilted toward the Sun as it moves higher in the sky. The goal is to have Spirit in the best possible position before solar conjunction -- the time of year when the Sun passes between Mars and Earth and temporarily prohibits communication.
Meanwhile, Spirit has been working hard to complete the full-colour "Bonestell panorama" of the rover's winter surroundings. After a long hiatus caused by power limitations, Spirit resumed making measurements of argon gas in the Martian atmosphere.
Spirit is healthy, with all subsystems performing as expected as of sol 1686 (Sept. 30, 2008). Solar-array energy increased to 262 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Skies remained clear, with tau, a measure of the amount of sunlight blocked by atmospheric dust, at 0.134. Historically, dust levels at this time of year have been higher. Rover operators are keeping close tabs on atmospheric dust because of its potential impact on the rover's power state.

Sol-by-sol summary:

Sol 1685 (Sept. 28, 2008): Spirit listened for communications from Earth with the rover's low-gain antenna, checked for drift -- changes with time -- in the miniature thermal emission spectrometer, surveyed the sky and ground with the instrument, and measured atmospheric opacity caused by dust (tau) with the panoramic camera. Spirit monitored dust accumulation on the panoramic-camera mast assembly and acquired column 22, part 2, and column 24, part 2 of the so-called "Bonestell panorama," a full-colour, 360-degree view of the rover's winter surroundings, created with all 13 colour filters of the panoramic camera.

Sol 1686: Spirit received new instructions from Earth at X-band frequencies sent to the rover's high-gain antenna and spent three hours measuring argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer. Spirit relayed data to NASA's Odyssey orbiter to be transmitted to Earth.

Sol 1687: Spirit measured dust-related changes in atmospheric darkness with the panoramic camera and acquired column 23, part 2 and column 25, part 2 of the Bonestell panorama.

Sol 1688: Spirit checked for drift in the miniature thermal emission spectrometer, surveyed the sky and ground with the instrument, and measured atmospheric opacity caused by dust with the panoramic camera. Spirit acquired column 27, part 2 and column 26, part 2 of the Bonestell panorama. The rover supplemented panoramic-camera measurements of atmospheric dust with measurements from the navigation camera and acquired a four-frame movie in search of clouds with the navigation camera.

Sol 1689 (Oct. 3, 2008): Plans called for Spirit to measure dust-related changes in atmospheric darkness with the panoramic camera and acquire column 19, part 3 and column 21, part 3 of the Bonestell panorama. The rover was to assess atmospheric dust levels with the navigation camera and produce a four-frame, time-lapse movie of potential clouds passing overhead.

Odometry:
As of sol 1686 (Sept. 30, 2008), Spirit's total odometry remained at 7,528.0 metres.

Blobrana · L

SPIRIT UPDATE: Warming Up on Mars - sol 1669-1677, September 12-20, 2008:

With Martian winter on the wane, Spirit is using significantly less energy to stay warm. During the winter solstice, Spirit needed 90 watt-hours to run the heater. Now, the rover uses between 30 and 40 watt-hours. The reduced demand for power, more than the slow increase in solar-array input, has freed up energy for other things. In particular, Spirit has added more images to the 360-degree view of its winter surroundings, known as the "Bonestell panorama." The top tier, one of three tiers needed for the final image mosaic, is almost complete.
Plans called for Spirit to use the miniature thermal emission spectrometer for the first time in several months. The last time the rover used the instrument was on Martian day, or sol, 1558 (May 21, 2008). On sol 1675 (Sept. 18, 2008), Spirit's schedule of activities included calibrating the spectometer and using it to observe the sky and ground. Normally, scientists use the observations to measure temperatures at different heights and create a temperature profile of the ground and atmosphere. In this case, the purpose of the measurements is to verify that the spectrometer is still working after a long, cold period of disuse. The measurements will also enable scientists to estimate the amount of dust on the optics. They may or may not provide a useful temperature profile.
Spirit is healthy and all subsystems are performing as expected as of the most recent report from NASA's Odyssey orbiter on sol 1674 (Sept. 17, 2008). Solar-array energy has inched upward to 255 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Skies are clearer than last week, with tau, a measure of the amount of sunlight blocked by atmospheric dust, dropping to 0.141.

Sol-by-sol summary:
In addition to taking daily measurements of dust-related changes in atmospheric opacity (tau), Spirit completed the following activities:

Sol 1669 (Sept. 12, 2008): Spirit recharged the batteries.

Sol 1670: Spirit received new instructions directly from Earth sent at X-band frequencies to the rover's high-gain antenna. The rover relayed data to NASA's Odyssey orbiter to be transmitted to Earth.

Sol 1671: Spirit acquired column 20, part 1 and column 21, part 1 of the full-colour Bonestell panorama, using all 13 colour filters of the panoramic camera. The rover took spot images of the sky for calibration purposes with the panoramic camera.

Sol 1672: Spirit recharged the batteries.

Sol 1673: Spirit recharged the batteries.

Sol 1674: Spirit received new instructions from Earth via the rover's high-gain antenna. The rover relayed data to Odyssey to be sent to Earth.

Sol 1675: Plans called for Spirit to acquire column 22, part 1 and column 23, part 1 of the Bonestell panorama and then verify that the miniature thermal emission spectrometer was still functional. This involved warming up the actuator, calibrating the instrument, measuring ground temperature, and measuring atmospheric temperatures at different heights. Plans also called for Spirit to calibrate the panoramic camera by taking images in darkness while the instrument was warm.

Sol 1676: Plans called for Spirit to recharge the batteries.

Sol 1677 (Sept. 20, 2008): Plans called for Spirit to recharge the batteries.

Odometry:
As of sol 1674 (Sept. 17, 2008), Spirit's total odometry remained at 7,528.0 metres.