Lander and rover images of soils, rocks and other surface features were obtained and rover positions logged during traverses. Analysis performed after the mission shall determine terrain feature classes as well as statistical size and location distributions.
Data Collected:
The rover logs positions regularly during traverses. The rover took "drive's end" images from each front camera, providing a stereo image of the terrain in front of the rover after every traverse. The lander took a 360° panorama of the landing site during the first few days of the mission. In addition, at the end of each sol's rover traverse, the lander camera imaged the rover in the terrain. The telemetry collected by the rover during traverses combine with the rover and lander images provide the data set for classifying terrain features.
Lander cameras provided the panorama in color and stereo. The lander camera images of the rover in the terrain are black and white, stereo 'patches' of sufficient size to show the rover with an error bound consistent with modeled rover navigation uncertainty. Lander camera resolution is 1mrad/pixel. Camera images are compressed at 6:1 (nominally for each sol's rover image). This represents approximately 0.5Mbit to 1.0Mbit of data, depending on rover distance from the lander.
Rover cameras have resolution of about 3mrad/pixel. The "drive's end" rover images are full frame (768x484 pixels, nominally 127.5° x 94.5° degrees) uncompressed. Each image represents about 3Mbit of data.
Each image data packet is proceeded by a 'record position' header which assists in correlating the image with the status of the rover in particular the position of the rover in a lander referenced coordinate system.
Rover traverse data is listed under the experiment entitled "Dead Reckoning Sensor Performance".
Data collected at "drive's end": Image Data
| processed rover X position (mm) | 32bits (I) | lsb=1 mm |
| processed rover Y position (mm) | 32bits (I) | lsb=1 mm |
| processed rover heading (BAMs) | 16bits (U) | lsb=0.0055 deg |
| measured X,Y accelerometers | 2, 16bits (I) | lsb=,0.0009765g |
| measured CCD (camera) temperature | 16bits (I) | lsb=0.381ohm |
| exposure duration (msec) | 16bits (U) | lsb=1 msec |
| camera ID | 8bits (U) | 0 = left, 1 = right, 2 = rear |
| starting row | 16bits (U) | 0-500 |
| starting column | 16bits (U) | 0-767 |
| ending row | 16bits (U) | |
| ending column | 16bits (U) |
| number of pixels per row | 16bits (U) |
| either: image data | n, 8bits (U) |
| or: image blocks | n, 104bits (U) |
Image data is collected from each of the front cameras.
Data is taken as the result of a command. The header of the image data telemetry packet contains the mission time (5bytes) and the unique command identified (2bytes). The 'take image' command is parameterized as follows:
| Capture image with camera (c) at exposure (t), return region from (r1,c1) to (r2,c2) with APID (a) [compressed] |
byte 0 (c) = camera ID (0-2) byte 1-2 (t) = exposure time (1msec increments) byte 3 (a) = APID (bits 0-6; 8, 9, 10, 24, 25 bit 7, compression mode: 0=none, 1=BTC) byte 4-5 (r1) = start row (1-500) byte 6-7 (c1) = start column (0-767) byte 8-9 (r2) = end row byte 10-11 (c2) = end column |
Analysis of rover telemetry collected during traverses over terrain types shall be used to determine basic Martian soil mechanics parameters needed for future Mars rover design. These parameters are sinkage, rolling resistance and traction. At specified locations, the rover will be commanded to collect motor currents, inclinometer angles, wheel revolutions, temperatures, and other engineering data while driving a single wheel.
Data Collected:
At a given soil location, the rover rotates wheels in the soil measuring the torque output by the motors and the depth of wheel sinkage in the soil to determine the soil cohesion, c, and ø, the angle of internal friction.
Now where
As the wheel sinks, area is increased, but the wheel thrust change may not be perceptible if the soil has low cohesion.
To attempt to separate these effects and to find c and ø (and compensate for actuator losses) during the experiment:
A representative experiment procedure then was:
[repeat next two steps 23 times]
[completes 720° spin of front wheel]
[repeat next steps 2 more times with selected front wheel then 3 more times with other front wheel]
[repeat next two steps 24 times]
[completes 720° spin of front wheel]
[repeat next two steps 24 times]
[completes 720° spin of back wheel]
including the beginning and ending status data records and packet data records. For 7 experiments then this is 0.944Mbit of data.
At the beginning and at the end of soil mechanics experiment (at a minimum), health status data is collected. This represents an additional 688bits of data per check for a total of 1376bits for each of 7 experiments or about 0.01Mbit.
Each image from the rover cameras is a patch of 15° x 17° or a patch of 117x156 pixels (oversized by 50% in both horizontal and vertical) for a total of 146Kbits. At full resolution, 4 images are taken for a total of 0.584Mbit. An additional 232bits of engineering data, registering the image, is acquired with each image for a total of 928bits. The rover acquires an image at the rate of 50Kbps so that these images are acquired in about 11.7sec.
The traverses performed during the experiment amount to approximately 10 movements of approximately 20cm (not counting the repositioning of the vehicle to each data taking location). The traverse data set represents 408bits of status at the beginning each traverse and 400bits accumulated each wheel radius of travel. Hence, a total of:
is accumulated. During these traverses we may assume that the rover traverses over nominal terrain at the essentially no load speed of 1.2RPM or 49cm/min. The 10, 20cm movements then represent approximately 4min of traversing.
As an estimate of the time required to perform this experiment we may summarize the above as follows:
| 720° of wheel rotation for 7 experiments: | 1176sec | 19.6min |
| 10, 20cm traverses during the experiments: | 245sec | 4min |
| 4 images acquired: | 11.7sec | 0.2min |
| TOTAL: | 1432.7sec | 23.9min |
Rover image data is listed under the experiment entitled "Terrain Geometry Reconstruction and Imagery". Rover traverse data is listed under the experiment entitled "Dead Reckoning Sensor Performance". Health status data is listed under the experiment entitled "Logging/Trending". The data for a soil mechanics experiment is listed below.
Data collected during soil mechanics experiment: Engineering Data
| command code | 8bits (U) | soil exp = 12 |
| processed rover X position (mm) | 32bits (I) | lsb=1 mm |
| processed rover Y position (mm) | 32bits (I) | lsb=1 mm |
| processed rover heading (BAMs) | 16bits (U) | lsb=0.0055° |
| cycle number | 8bits (U) | 0-99 |
| time (short) | 2, 8bits (U) | lsb=1 sec |
| measured X,Y accelerometers | 2, 16bits (I) | lsb=0.0009765g |
| error state flags | 16bits (U) | |
| measured front motor temp. (in test) | 16bits (I) | lsb=0.381ohm |
| measured front steering pot | 16bits (I) | lsb=0.08° |
| time (short) | 2, 8bits (U) | lsb=1 sec |
| measured X,Y accelerometers | 2, 16bits (I) | lsb=0.0009765g |
| error state flags | 16bits (U) | |
| measured rear steering pot | 16bits (I) | lsb=0.08° |
| time (tiny) | 2, 8bits (U) | lsb=1 centon |
| measured bogie pots | 2, 16bits (I) | lsb=0.02° |
| measured differential pot | 16bits (I) | lsb=0.02° |
| motor drive encoder | 8bits (U) | lsb=1 count |
| measured motor drive current | 8bits (U) | lsb=1.46mA |
| time (short) | 2, 8bits (U) | lsb=1 sec |
| measured X,Y accelerometers | 2, 8bits (I) | lsb=0.0009765g |
| error state flags | 16bits (U) | |
| measured front motor temp. (in test) | 16bits (I) | lsb=0.381ohm |
| measured front steering pot | 16bits (I) | lsb=0.08° |
| time (short) | 2, 8bits (U) | lsb=1 sec |
| measured X,Y accelerometers | 2, 16bits (I) | lsb=0.0009765g |
| error state flags | 16bits (I) | |
| measured rear steering pot | 16bits (I) | lsb=0.08° |
| command code | 8bits (U) | soil exp = 12 |
| cycle number | 8bits (U) | 0-99 |
Data is taken as the result of a command. The header of the soil mechanics data telemetry packet contains the mission time (5bytes) and the unique command identified (2bytes). The 'soil mechanics' command is parameterized as follows:
| Soil mechanics test on wheel (w) at position (p), run for (n) counts, repeat (k) times | byte 0 (m) = motor ID (0-5) byte 1,2 (p) = steering pot position (ignored for center wheel) (-2048 to 2047) byte 3,4 (n) = encoder counts per cycle (1-1000) (up to 5 wheel revs) byte 5 (k) = repeat counts (1-1000) |
The rover position errors arise from using the dead reckoning (internal state) sensors (including 3-axis accelerometers and a heading gyro) to control mobility. Position error is also a function of distance over various Martian terrain types. The experiment involved traversing paths, noting vehicle behavior through engineering telemetry, and noting differences in visually perceived position versus that output from the dead-reckoning system. Also, visual sensing of terrain types was correlated with the behavior of the vehicle measured from telemetry and an array of several proximity sensors mounted on the rover. Proximity sensors would observe both the clearance between the rover and the ground and the detailed profile of the terrain.
Data Collected:
Each time the rover is commanded to perform a movement a set of elemental move or waypoint commands is given to the rover. At execution of each movement the rover:
During waypoint traverses, the rover :
During traverses arising from move or turn commands the rover:
At end of sol's traverses,
During the primary mission, (nominally) the rover traverses in the vicinity of the lander, achieving the objectives of:
Closed loop paths or other TBD paths specifically designed for collecting data for this experiment were expected to be conducted during extended mission. No special experiments were performed during the mission.
Waypoint traverses are decomposed into the execution of a series of waypoint commands. During the execution of a waypoint command, data is taken every wheel radius of travel as measured from an average of the wheel encoders. This corresponds to the rate at which proximity detection is performed using the rover laser stripers. The traverse data set represents 408bits of status at the beginning and end of each traverse and 400bits accumulated each wheel radius of travel If there are 10 waypoint commands per traverse,
accumulated data per waypoint.
At the beginning and at the end of each waypoint command execution (as a worse case), health status data is collected.
An estimate of the time required to conduct this experiment is a function of terrain traversed by the rover. We may bound the traversing time between so called nominal terrain, where the rover wheels are driven at the essentially no load speed of 1.2RPM or 49cm/min, and extreme terrain, where the wheels are driven at the high working load speed of 0.6RPM or 24.5cm/min. Hence for a 10m traverse:
| Terrain Type | Time | Bit Rate |
|---|---|---|
| nominal terrain | 20.4min | 4.4 Kbit/min |
| extreme terrain | 40.8min | 2.2 Kbit/min |
It should be noted that the above are times are for driving of the vehicle alone. Driving is interrupted at each wheel radius of travel with proximity detection and at each vehicle length of travel with the generation of a 'heartbeat' transmission to the lander. Proximity detection requires approximately 5sec to complete while 'heartbeat' transmissions can be conducted in under 1sec (primarily modem power up time). This adds approximately a 37% overhead factor to the time given for nominal terrain traversing and a 26% overhead factor to the time given for extreme terrain traversing.
Rover image data is listed under the experiment entitled "Terrain Geometry Reconstruction and Imagery". Health status data is listed under the experiment entitled "Logging/Trending". The data for a traverse is listed below.
Data collected during traverses:
| command code | 8bits (U) | go to waypoint=8 and turn=10 |
| processed rover X position (start) | 32bits (I) | lsb=1 mm |
| processed rover Y position (start) | 32bits (I) | lsb=1 mm |
| processed rover heading (BAM's) | 16bits (U) | lsb=0.0055° |
| error state flags (start) | 16bits (U) | |
| accumulated average odometer counts (start) | 32bits (U) | lsb=1 count |
| contact sensor state (start) | 16bits (U) | bit pattern |
| measured temperature sensors (start) | 13, 8bits (I) | |
| measured power supply current sensors (start) | 9, 8bits (I) | lsb=2.03mA to 5.47mA (sensor dependent) |
| measured power supply voltage sensors (start) | 10, 8bits (I) | lsb=19.52mV to 78.08mV (sensor dependent) |
| time (tiny) | 16bits (U) | lsb=1 sec |
| processed rover X position ls word | 16bits (I) | lsb=1 mm |
| processed rover Y position ls word | 16bits (I) | lsb=1 mm |
| processed rover heading lsbs | 8bits (U) | lsb=0.0055° |
| measured steering pots | 4, 8bits (I) | lsb=1.3° |
| measured linear accelerometers | 3, 8bits (I) | lsb=0.015625g |
| measured motor temperature | 2, 8bits (I) | lsb=6.1ohm |
| measured motor encoder counts | 6, 8bits (U) | lsb=1 count |
| measured bogie pots | 2, 16bits (I) | lsb=0.02° |
| measured differential pots | 16bits (I) | lsb=0.02° |
| measured motor currents | 6, 8bits (I) | lsb=1.46mA |
| reading laser spot offsets from nominal: 6 lines by 5 stripes | 15, 8bits (I) | 3 lines by 5 stripes |
| proximity hazard indicator | 8bits (I) | 0 - 4 |
| command code | 8bits (U) | go to waypoint=8 and turn=10 |
| error state flags (final) | 16bits (U) |
Data is taken as the result of 'go to waypoint' and 'turn' commands. The header of the traverse data telemetry packet contains the mission time (5bytes) and the unique command identified (2bytes). The 'go to waypoint', 'turn', 'move' commands are parameterized as follows:
| Go to waypoint at (x) (y) within (m) minutes | byte 0-3 (x) = destination X (mm N of lander) byte 4-7 (y) = destination Y (mm E of lander) byte 8 (m) = time limit in minutes (1 - 255) |
| Turn left (n) BAMs, Turn rt (n) BAMs | byte 0-1 = relative heading in BAMs (+ = rt, - = left) |
| Move forward (n) counts with steering (l) (r), Move backward (n) counts with steering (l) (r) | byte 0-1 = encoder counts (+ = fwd, - = back) byte 2-3 = left front/left rear offset from straight byte 4-5 = right front/right rear offset from straight |
Wheel tracks shall be viewed with the rover camera(s) and lander camera to estimate sinkage. During soil mechanics experiments, after driving a single wheel into the soil, the rover and lander images the track pattern produced by this wheel. The bogey angles before and after the single wheel motion is recorded.
Data Collected:
During the soil mechanics experiment an image from the rear camera of the rover and also an image from the lander camera, if possible, is taken showing a rear wheel in soil. Also during portions of a soil mechanics experiment a front wheel driven into soil is imaged by the lander or (after the rover has moved out of the wheel track) imaged by the rover cameras. This is correlated with the other measurements taken during the soil mechanics experiments to determine sinkage. The rear camera is in a position to obtain an image of wheel and track together.
During the soil mechanics experiment, additional measurement data includes other images of rover wheel patches and portions of tracks, bogey angle measurements and inertial reference.
Rover image data is listed under the experiment entitled "Terrain Geometry Reconstruction and Imagery". The data taken during soil mechanics experiments is listed under the experiment entitled "Soil Mechanics".
All measurable engineering parameters (drive torques/current, position, voltage, etc) shall be logged and time tagged. Analysis of the logged data shall determine performance, degradation, etc.
Data Collected:
During each commanded action, the rover records data. In addition, during each sol (nominally, every 10min during day, every hour during the night) the rover records health status data.
This data set, augmented by data accumulated during traverses, contains information which allows monitoring of:
Power
Thermal
Communication
Mobility (during traverses)
Navigation: (during traverses)
Data recorded for the health status check is a function of level. Routine scheduled health checks are at level 0 and amount to 688bits of data. During a typical sol the data accumulated for 10hrs of daytime and 14hrs of nighttime operation is:
During traverses, health checks of level 2 are conducted at the end of each segment of travel (i.e., at the end of each command) to record odometry and performance data. During a typical sol, we may assume about 4 additional level 2 health checks are commanded with each check amounting to 1944bits of data or 0.007Mbit of data per sol.
Rover traverse data is listed under the experiment entitled "Dead Reckoning Sensor Performance".
Data recorded during health status checks
| health check level | 8bits (U) | 0 - 5 |
| processed rover X position (mm) | 32bits (I) | lsb=1 mm |
| processed rover Y position (mm) | 32bits (I) | lsb=1 mm |
| processed rover heading (BAM's) | 16bits (U) | lsb=0.0055° |
| error state flags (start of health check) | 16bits (U) | |
| error state flags (end of health check) | 16bits (U) | |
| derived mission phase | 8bits (U) | |
| time at last startup (long) | 32bits (U) | lsb=1 sec |
| cause of last startup | 8bits (U) | 0 - 6 |
| averaged accumulated odometer | 32bits (U) | lsb=1 count |
| measured linear accelerometers | 3, 8bits (I) | lsb=0.015625g |
| turn sensor integrator drift | 8bits (I) | |
| measured steering pots | 4, 8bits (I) | lsb=1.3° |
| measured bogie pots | 2, 16bits (I) | lsb=0.02° |
| measured differential pot | 16bits (I) | lsb=0.02° |
| measured APXS deployment pot | 8bits (I) | lsb=1.3° |
| contact sensor state | 16bits (U) | bit pattern |
| measured temperature sensors | 13, 8bits (I) | lsb=6.1ohm |
| measured power supply current sensors | 9, 8bits (I) | lsb=2.03mA to 5.47mA (sensor dependent) |
| measured power supply voltage sensors | 10, 8bits (I) | lsb=19.52mV to 78.08mV (sensor dependent) |
| transmitted comm frame count | 16bits (U) | lsb=1 count |
| received comm frame count | 16bits (U) | lsb=1 count |
| received comm error counts | 16bits (U) | lsb=1 count |
| battery power used | 3, 16bits (U) |
| A/D reference levels | 3, 8bits (U) | ground lsb=9.76mV -5V lsb=78.08m +5V lsb=39.08mV |
| individual wheel odometer counts | 6, 32bits (U) | lsb=1 count |
| detected comm error counts (by error type) | 13, 16bits (U) | lsb=1 count |
| failure counts for all devices | 62, 8bits (U) | 0 - 6 |
| linear accelerometers | 3, 8bits (I) | lsb=0.015625g |
| bogey pots | 2, 16bits (I) | lsb=0.02° |
| differential pot | 16bits (U) | lsb=0.02° |
| front wheel motor temperatures | 2, 8bits (U) | lsb=6.1ohm |
| linear accelerometers | 3, 8bits (I) | lsb=0.015625g |
| bogey pots | 2, 16bits (I) | lsb=0.02° |
| differential pot | 16bits (U) | lsb=0.02° |
| front wheel motor temperatures | 2, 8bits (U) | lsb=6.1ohm |
| drive/steer motor current (average during last traverse) | 10, 8bits (U) | lsb=1.46mA |
| drive/steer motor current (maximum during last traverse) | 10, 8bits (U) | lsb=1.46mA |
| modem current/transmit 9V | 8bits (U) | lsb=2.03mA |
| APXS electronics current (9V) | 8bits (U) | lsb=2.03mA |
| laser current (direct) | 5, 8bits (U) | lsb=2.85mA |
| CCD current (+/-12V) | 8bits (U) | lsb=2.03mA |
| accelerometer current (+/-12V) | 8bits (U) | lsb=2.03mA |
| gyro current (5V regulator) | 8bits (U) | lsb=5.47mA |
| MAE electronics current (5V regulator) | 8bits (U) | lsb=5.47mA |
| LED current (contact/encoder) (5V regulator) | 8bits (U) | lsb=5.47mA |
| WEB heater (motor/heater bus current) | 8bits (U) | lsb=4.88mA |
| motor heaters (each set, motor/heater bus current) | 4, 8bits (U) | lsb=4.88mA |
| modem heater (motor/heater bus current) | 8bits (U) | lsb=4.88mA |
| MAE dust cover current (5V regulator) | 8bits (U) | lsb=5.47mA |
Data is taken as the result of a health check command. The header of the health check data telemetry packet contains the mission time (5bytes) and the unique command identified (2bytes). The 'health check' command is parameterized as follows:
| Health check at level (n) | byte 0 (n) = check level (0 - 4) |
Rover thermal behavior as a function of time and operating situation shall be monitored. The data shall be analyzed on the ground to characterize rover thermal behavior.
Data Collected:
As part of routine rover health checks, health status is logged, nominally, every 10min during day, and upon command during the night. 13 temperature measurements are collected:
| SENSOR LOCATION | NUMBER |
| External: | |
| CCD's | (3) one with each CCD |
| Front Wheels | (2) one with each motor |
| Solar Panel | (1) one at 'watch plate' |
| WEB: | |
| Battery Tray | (3) one on each string |
| WEB wall | 1 |
| Electronics Card | 2 |
| Modem | 1 |
Health check occurrence, particularly at night, is programmable. Night health checks are programmed at times giving approximately equal temperature steps of 8° on exterior equipment (based on predictions).
Rover health check data is listed under the experiment "Logging/Trending".
Images obtained from the lander of the rover tracks in the terrain can be correlated with data logs from the rover taken during driving to characterized the rover hazard avoidance capability.
Data collected:
Images from rover are taken (nominally) at "drive's end" (at the end of each traverse). Lander images taken once per sol are used in planning the next sol's rover traverse. Given the lander camera resolution and width of tracks on order of 10cm (where the wheel width is 6cm), track images within lander camera view are planned to be taken within approximately 7m of the lander. (At this distance, with the lander cameras about 1.5m above the surface, a wheel patch subtends an image of approximately 3pixels assuming flat terrain.) Lander camera images are compressed at 3:1. These images represent approximately 0.5Mbit to 1.0Mbit of data, depending on rover distance from the lander.
Engineering data is collected during traverses which can be correlated to the images of the tracks shown in the terrain.
Rover image data is listed under the experiment entitled "Terrain Geometry Reconstruction and Imagery". The data taken during traverse is listed under the experiment entitled "Dead Reckoning Sensor Performance". Rover health check data is listed under the experiment "Logging/Trending".
Using the statistics taken during communication sessions between the rover and lander, determine the effectiveness of the UHF link on Mars.
Data Collected:
Command and telemetry transmissions between lander and rover are collections of frames. Additional frames are transferred to establish/maintain transfer protocol. A typical frame appears as follows:
| --16-- | --8-- | --8-- | ------------0, 32, or 2000------------ | --16-- |
| SYNC | FID | FNUM | DATA FIELD | CRC |
Error checking during data transfer is conducted at several layers in the communication protocol. The errors that are logged in this experiment are those at the frame layer and are listed below:
| ERROR CODE | DIAGNOSTIC |
| 0 | No error |
| 1 | Timed out |
| 2 | Short frame received |
| 3 | CRC error |
| 4 | No sync code |
| 5 | Bad FID |
| 6 | Bad FNUM |
| 7 | No command data ready |
| 8 | Expected session start |
| 9 | Internal software error |
| 10 | Data overflow (too many frames) |
| 11 | Received abort |
| 12 | Modem latchup detected |
As part of each health check, the following data is transmitted:
| transmitted comm frame count | 16bits (U) | lsb=1count |
| received comm frame count | 16bits (U) | lsb=1count |
| received comm error counts | 16bits (U) | lsb=1count |
As a part of level 2 and higher health check, the following additional data is transmitted:
| detected comm error counts (by error type) | 13, 16bits (U) | lsb=1count |
During primary mission, rover traverses are in the vicinity of the lander (nominally ~10m radius).
In addition, lander proposes to collect telemetry TBD on rover/lander communications.
The abrasive qualities of Martian soil and dust can be derived from the wear observed on strips of material on one rover wheel.
Data Collected:
A center wheel of the rover is instrumented with a pattern of material strips and a solar cell. When this wheel is turned, the current from the solar cell is measured. The light impinging on the solar cell is ambient light reflection from the material strips on this wheel.
The variation in current from this cell measured during rotation of the center wheel correlates to the amount of material wear and therefore abrasion by the soil.
During the mission, a special experiment is conducted to collect a set of measurements from the cell while the center wheel is rotated (other wheels locked). This is similar to the soil mechanics experiment as follows:
720° (or 2 wheel turns) is the default rotation of the abraded wheel per each command. Additional, rotations can be commanded to enhance material wear either by commanding additional wheel abrasion experiments (data is taken) or by commanding the center wheel motor to run (no data is taken). Up to 16 revolutions of the center wheel can be executed by a single 'run motor' command. A health check is taken prior to conducting the wheel abrasion experiment.
The rover can rotate a wheel at a maximum (no load) rate of 1.2RPM. The full rotation of 720° per wheel in the experiment represents then 100sec of data taking. While the wheel is rotating, 32bits of data is taken every 16 encoder counts. Since the rover encoders are 2000 counts per wheel revolution, for 2 revolutions 250 samples of 32bits is accumulated. The amount of data accumulated during a given experiment is then:
including the rover status data record.
If the 'run motor' command is given, a 16bit parameter which is a part of the command allows the center wheel to be rotated forward up to 32000 counts of 16 revolutions. At the 1.2RPM maximum (no load) rate, a full 16 revolutions would take 800sec or 13min to complete. In the early stages of the rover mission to promote abrasion, a 'run motor' command may be commanded.
At the beginning of the wheel abrasion experiment, health status data is collected. This represents an additional 688bits of data.
Rover traverse data is listed under the experiment entitled "Dead Reckoning Sensor Performance". Health status data is listed under the experiment entitled "Logging/Trending". The data for a wheel abrasion experiment is listed below.
Data collected during wheel abrasion experiment: Engineering Data
| command code | 8bits (U) | wheel abrasion =25 |
| processed rover X position (start) | 32bits (I) | lsb=1 mm |
| processed rover Y position (start) | 32bits (I) | lsb=1 mm |
| processed rover heading (BAM's) | 16bits (U) | lsb=0.0055° |
| measured X, Y accelerometers | 2, 16bits (I) | lsb=0.0009765g |
| measured bogie pots | 2, 16bits (I) | lsb=0.02° |
| measured differential pots | 16bits (I) | lsb=0.02° |
| WAE sensor gain | 8bits (U) | 16,32 |
| total odometer count for the abraded wheel (start) | 32bits (U) | lsb=1 count |
| error state flags (start) | 16bits (U) | |
| error state flags (end) | 16bits (U) |
| measured cell current sensor, abraded wheel | 16bits (I) | lsb=1.22mV |
| measured motor drive encoder | 8bits (U) | lsb=1 count |
| measured motor drive current | 8bits (I) | lsb=1.46mA |
Data is taken as the result of a command. The header of the wheel abrasion data telemetry packet contains the mission time (5bytes) and the unique command identified (2bytes). The 'wheel abrasion' command is parameterized as follows:
| Wheel abrasion with gain (a) | byte 0 (a) = 0, default 'high gain' setting of 32 1, 'low gain' setting of 16 |
When addition abrasion of the material on the center wheel is desired, the 'run motor' command can be used. It is parameterized as follows:
| Run motor (m) to (p) | byte 0 (m) = motor ID byte 1-2 (p) = encoder counts |
The 'run motor' command generates the 'command acknowledge' telemetry described as follows:
| command code | 8bits (U) | run motor=26 |
| error state flags | 16bits (U) |
The tendency of Martian dust to adhere to rover surfaces, especially solar arrays and detectors, shall be observed.
A test solar cell is situated below a dust cover on the solar panel. This cell was routinely measured for current production as part of the monitoring of the solar panel performance. As part of this separate experiment, the cell is measured both with the dust cover opened and closed. The performance degradation of the cell current due to adherence of dust to the cover can be determined. In addition, a quartz crystal monitor nearby was subject to the same dust adherence. A direct measurement of dust accumulation was made.
Data Collected:
The experiment was conducted nominally at least once each sol at the end of traverses, each noon, and at other times during the mission. This experiment is conducted after gathering data from a health check. The procedure is described below:
Data collected for this experiment amounts to 264bits. The experiment required approximately 1 minute to be performed. A health check is performed before the experiment begins and amounts to another 688bits of data collected.
Health status data is listed under the experiment entitled "Logging/Trending". The data for the material adherence experiment is listed below.
Data recorded for material adherence experiment
| command code | 8bits (U) | mat adh=23 |
| processed rover heading (BAM's) | 16bits (U) | lsb=0.0055° |
| measured X,Y accelerometers | 2, 16bits (I) | lsb=0.0009765g |
| error state flags (start) | 16bits (U) | |
| error state flags (final) | 16bits (U) | |
| measured temperature at watch plate (closed cover) | 16bits (I) | lsb=0.381ohm |
| measured temperature at watch plate (open cover) | 16bits (I) | lsb=0.381ohm |
| measured current from shorted cell (closed cover start) | 16bits (I) | lsb=0.15mV |
| measured current from shorted cell (open cover) | 16bits (I) | lsb=0.15mV |
| measured current from shorted cell (closed cover final) | 16bits (I) | lsb=0.15mV |
| measured open cell voltage | 16bits (I) | lsb=1.22mV |
| QCM reading | 16bits (U) |
Note that shorted cell implemented with ground return to electronics (not common external ground) to increase resolution. Only 12 bits of the 16 bits assigned above are a part of the measurement. The remaining bits to align packets on byte boundaries.
Data is taken as the result of a command. The header of the material adherence data telemetry packet contains the mission time (5bytes) and the unique command identified (2bytes). The 'material adherence' command has no parameters. The 'on-time' for the actuation of the dust cover is an adjustable parameter. The default value is 0.5sec, consistent with an 'on-time' for a mid-sol Martian day (0°C ambient temperature). This parameter can be adjusted through the issuance of a 'set parameter command. This command and its parameters is described as follows :
| Set parameter (p) = (value) | byte 0 (p) = parameter index byte 1-2 (value) = parameter value |
MATIJEVICETAL1997B
MOOREETAL1999
Abrasion:
Adherence:
JENKINSETAL1997
LANDISETAL1997