Mars Pathfinder Project
Science and Instrument Requirements
Revision 3
March 15, 1996
Jet Propulsion Laboratory
California Institute of Technology
Pasadena, California 91109-8099
Science and Instrument Requirements
Approved:
___________________________
Richard Cook
Mission Design Manager
___________________________
Matthew Golombek
Project Scientist
___________________________
Thanasis Economou
APXS Co-Investigator
___________________________
Jacob Matijevic
Rover Manager
___________________________
Henry Moore
Rover Scientist
___________________________
Brian Muirhead
Flight System Manager
___________________________
Rudolf Rieder
APXS Principal Investigator
___________________________
Allan Sacks
Ground Data System Manager
___________________________
Al Seiff
ASI/MET Science Adv. Team Leader
___________________________
Peter Smith
IMP Principal Investigator
___________________________
John B. Wellman
Science and Instruments Manager
___________________________
Anthony J. Spear
Mars Pathfinder Project Manager
CHANGE LOG
Revision no. Description Date
Revision 0 Initial signature version August 1, 1994
Revision 1 Incorporates numerous inputs from November 10, 1994
PSG and other Project personnel. Mission
success images changed and defined.
Desired capabilities that have been incorporated
are no longer listed as desires.
Revision 2 Corrections to describe IMP final flight Feb. 15, 1996
filter selections. Clarify number of APXS
samples for rover nominal mission
(7 sols) and lander nominal mission
(30 sols). Elimination of TBDs. Minor
editorial corrections.
Revision 3 Corrections to resolution of IMP images. March 15, 1996
Corrections to APXS/rover images.
Corrections to instrument health checks.
Revised IMP wind sock and radiometric
target observations. Minor editorial
corrections.
Table of Contents
1.0 Introduction 1
1.1 Imager for Mars Pathfinder (IMP) Characteristics 1
1.2 APXS Characteristics 3
1.3 ASI/MET Characteristics 3
2.0 Science Observation Requirements 4
2.1 Surface Morphology and Geology at the Meter Scale 4
2.2 Surface Mineralogy 5
2.3 Elemental Composition of Rocks, Soil and Surface Materials 6
2.4 Atmospheric Science 8
2.5 Astronomical Observations 10
3.0 Imaging Investigation Requirements 10
3.1 Mounting 10
3.2 Data Storage 10
3.3 Pointing 11
3.4 IMP Calibrations 11
3.5 Camera Operations 12
3.6 Onboard Software to Command the IMP 12
3.7 Onboard Software for Image Data Processing 12
4.0 Elementary Composition Investigation Requirements 12
4.1 Mounting Location 12
4.2 Deployment Mechanism 13
4.3 APXS Calibration 13
4.4 APXS Integration Times 14
5.0 Atmospheric Structure and Meteorology Investigation Requirements 14
5.1 Mounting Locations 14
5.2 ASI/MET Calibrations 15
6.0 Operational Requirements on Science Instruments 16
6.1 Operational Requirements on IMP 16
6.2 Operational Requirements on APXS 17
6.3 Operational Requirements on ASI/MET 17
6.4 Operational Requirements on the Science Accelerometers 17
7.0 Observation Priorities 18
7.1 Definition of Observation Priorities 18
7.2 Observation Priority Listing 19
8.0 Requested Requirements Not Accepted 19
8.1 IMP Requirements Not Accepted 19
8.2 APXS Requirements Not Accepted 19
8.3 ASI/MET Requirements Not Accepted 19
8.4 Science Accelerometer Requirements Not Accepted 20
1.0 Introduction
This document contains the top-level science and instrument requirements
for the Mars Pathfinder Mission. Section 2.0 contains the science
operational requirements, segregated by scientific discipline.
Those requirements that are essential to satisfying one or more
of the mission success criteria are so noted. Sections 3.0 to
5.0 contain science requirements imposed on the project by each
of the individual investigations. Section 6.0 contains requirements
placed on the science instruments to support operational objectives
(other than science), for example, imaging in support of rover
operations. Section 7.0 establishes the relative priorities
for all of the observational requirements, both science and operational.
Section 8.0 collects the requested requirements which the Pathfinder
Project has not accepted, along with the reasons for their non-acceptance.
Requirements and desires are listed in this document. Desires
are capabilities that will considerably enhance the science return
from the mission and that are thought to be achievable within
the baseline mission capabilities. Desires are clearly identified
as such, to distinguish them from requirements.
Observation frequencies assume that the lifetime requirement of
30 days for the lander (including the IMP) is met and that after
the nominal 30-day mission periodic measurements will be continued
indefinitely at the same frequency. The lifetime requirement
for the rover is 7 days.
The instrument characteristics are summarized in the "Mars
Pathfinder Science and Instruments" brochure and are defined
in the individual instrument Functional Requirements. The implementation
of the instruments is described in the Science and Instruments
Implementation Plan (PF 100-1.4). Individual instrument characteristics
that are relevant to the science and instruments requirements
stated in this document are described below.
1.1 Imager for Mars Pathfinder (IMP) Characteristics
The IMP hardware consists of two cameras that are offset by a
stereo baseline distance of 15 cm. The cameras are mounted at
the top of a deployable mast that, when deployed, elevates the
cameras approximately 80 cm above their stowed position. The
camera can acquire images over a full range of azimuth and elevation
angles in both undeployed and deployed configurations. The obscuration
due to lander structure is different for the two elevations.
Each camera (or optical path) contains a filter wheel with 12
positions. The filters in the two sides are not identical except
for three positions intended explicitly for stereo use. There
are 4 pairs of solar filters, three pairs of stereo filters,
9 individual geologic filters (which, when combined with the
three pairs of stereo filters, result in 12 distinct geologic
filters) and one diopter or close-up lens, designed to acquire
images of magnetic wind-blown dust which adheres to a small
magnet located on the IMP tip plate (part of the camera). These
numbers total to 24.
The IMP experiment includes a magnetic properties investigation,
which includes a set of magnetic targets that are observed by
the camera. Two arrays of five magnets of differing strength
are positioned at two different locations on the lander structure.
An additional magnetic target is mounted on the camera baseplate
so that it can be viewed with a diopter (or close-up) lens in
the IMP filter wheel. A magnetic target is also included on each
rover deployment ramp such that an APXS analysis of a magnetically-segregated
sample may be acquired.
A set of three wind socks, mounted on the ASI/MET mast, are provided
as part of the IMP experiment. These wind socks may be imaged
in stereo to determine the wind speed and direction as a function
of height from the surface.
The IMP software provides a variety of ways to reduce the data
volume contained in a raw image, including lossless data compression,
lossy data compression, pixel averaging (which directly reduces
resolution) and segmenting frames into subframes so that only
the desired portion of a frame need be transmitted. Images containing
the wind sock are an example of a situation in which subframing
may be used to advantage. The stated requirements refer to these
several methods for reducing data volume; however, the reductions
in data volume are not stated quantitatively.
In describing data quality in this document, full resolution
implies lossless compression. A full panorama is a set of images
from one of the IMP cameras that covers 360 degrees in azimuth
and an elevation range that, as a minimum, covers from the edge
of the lander to above the local horizon at all azimuths. Note
that for some panoramas, it may be necessary to cover more of
the lander structure; for example, the rover deployment panorama,
in which it is desired to image the rover and both of its egress
ramps. This level of detail is more appropriately addressed in
the mission scenarios.
1.2 APXS Characteristics
The APXS will address the detailed and complete chemical composition
of multiple Martian rocks and soil samples. This information
will supplement the partial soil analyses of two sites obtained
by the Viking X-ray Fluorescence Experiment. The information
obtained by the APXS will help to better understand the history
and the evolution of the planet Mars.
The APXS consists of two parts: the sensor head and the main electronics
box. The sensor head contains the alpha, proton and x-ray detectors,
the Cm-244 radioactive alpha sources, the collimators, source
shutter and the preamplifier for the x-ray detector. The main
electronics box contains the rest of the analog, digital and
microcontroller electronics that handle the signals from the
three types of radiation detectors, and stores the data in the
form of three independent energy spectra. The chemical composition
of the measured samples is obtained by deconvolution of these
energy spectra in terms of an elemental library derived during
the extensive calibration of the instrument prior to launch.
The APXS Instrument on the Mars Pathfinder Mission is carried
aboard the Rover, which enables selection of multiple, interesting
samples for analysis. The ability to be positioned at a chosen
target location is provided both by the mobility characteristics
of the Rover and by the positioning capability of the APXS Deployment
Mechanism (ADM). In general, the selection of target locations
will be made using images from the IMP (target selection) and
from the Rover cameras (fine positioning). When potential target
sites are obscured or sufficiently remote from the IMP, target
selections may be made using Rover images alone.
It is expected that many rock and soil samples will be analyzed
for periods up to 10 hours each during the mission. Because
the APXS consumes relatively little energy per analysis, most
of the measurements can be done during the Martian night, when
there is little other activity aboard the rover. The amount
of data transmitted per analysis is sufficiently small that data
compression is unnecessary.
1.3 ASI/MET Characteristics
The ASI/MET Investigation addresses the profile of the atmosphere,
as sensed during the entry and descent phases; and the local
meteorologic conditions at the landing site after landing. During
the entry and descent phases measurements are provided by both
the ASI/MET Instrument and the Science Accelerometers (contained
within the AIM Subsystem). After landing the meteorological
measurements are provided by the ASI/MET instrument, which consists
of a pressure sensor, a set of thermocouples at varying heights
above the surface, and a wind sensor that detects wind direction
and speed. During entry, the ASI/MET also supports the engineering
function of the Aeroshell Instrumentation Package -- a set of
thermocouples mounted in the aeroshell to determine its heating
and ablation rates. Requirements in this document specifically
address the ASI/MET Investigation (which includes the Science
Accelerometers) or the ASI/MET Instrument (which excludes the
Science Accelerometers).
The ASI/MET Instrument data-taking sequence start and stop cycles are controlled by the AIMS. There is complete flexibility in the times and durations of observational sequences (limited by power, data storage and telemetry constraints). For the purposes of these requirements two data taking modes are defined -- an observation and a continuous observation -- defined as follows. ASI/MET post-landed observations of temperature, pressure, wind speed and wind direction consist of samples taken 8 times per second for each sensor for a five minute period. Post-landed continuous observations of these sensors consist of samples taken eight times per second for each sensor for a specified duration in excess of five minutes.
2.0 Science Observation Requirements
2.1 Surface Morphology and Geology at the Meter Scale
2.1.1 Pre-deployment Panorama
A full, monoscopic, monochrome panorama shall be acquired prior
to deployment of the IMP mast. This panorama shall be returned
at full resolution.
2.1.2 Post-deployment Panorama
A full panorama in three colors for one camera and one color
for the other (stereo) camera shall be acquired after IMP mast
deployment and at high sun elevation angle. This panorama shall
be returned at full resolution.
2.1.3 Panoramas for Change Detection
Monoscopic, single color (750 nm) panoramas shall be acquired
monthly over the life of the mission, at the same local time
of day (either at high sun elevation or in late afternoon), and
returned at full resolution. The second panorama shall be scheduled
to be acquired and returned before the end of the nominal (30-day)
mission.
2.1.4 Photoclinometric Images
Images of eight (8) selected features shall be acquired at four
(4) different solar elevation angles to permit topographic analysis
by shadow length and photoclinometry.
2.1.5 Use of Rover Images for Surface Morphology and Geology
Images acquired by the rover cameras for operational purposes
shall be made available for science data analysis.
2.2 Surface Mineralogy
2.2.1 Multispectral Panorama
A full monoscopic panorama at full resolution in each of the
geology spectral filters shall be acquired at high sun elevation
angles at least once during the landed mission.
2.2.2 Multispectral Observations of Selected Targets
Multispectral observations in each of the geology filters of at
least 6 selected features shall be acquired at low phase angles.
(Note: these observations may be combined with those in requirement
2.2.1 to reduce the number of frames acquired).
2.2.3 High Resolution Soil Images
Images shall be acquired at low phase angle in each of the geology
filters at three locations closest to the lander to provide the
highest resolution IMP images of the local soil. Preferably
these images shall be acquired from the undeployed IMP location.
2.2.4 Observations of Magnetic Properties Targets
Subframe images of the two magnetic properties target arrays shall
be acquired in as many of the geology filters as possible, at
least six times during the mission (more frequently at first,
then less frequently; i.e. on sols 1, 2, 4, 8, 16 and 30).
2.2.5 Observations of Near-Field Magnet
A close-up image of the near-field magnetic target shall be acquired
in the close-up (diopter) filter position at least six times
during the mission at the same times as the magnetic properties
target array observations.
2.2.6 Observations of Magnetic Targets Attached to Rover Ramps
The magnetic and the nonmagnetic reference targets attached to
the rover ramps shall be imaged in each of the geology filters
at least six times during the mission (at the same times as the
magnetic properties target array observations). It is highly
desirable to acquire the first set of images before the rover
is deployed.
2.2.7 Search for Surface Frosts
At least 30 surface images (one complete 360 degree rotation in
azimuth) in the blue filter and at high compression shall be
acquired within one hour after sunrise to search for evidence
of surface frost formation. These images shall be acquired on
at least 4 separate sols, equally spaced throughout the nominal
landed mission.
2.3 Elemental Composition of Rocks, Soil and Surface Materials
2.3.1 APXS Analysis of Rock
The APXS shall be employed to analyze a rock sample (mission success
criterion)
2.3.2 APXS Analysis of Soil
The APXS shall be employed to analyze a soil sample (mission success
criterion)
2.3.3 Documentation of APXS Samples (Rover Imager)
The rover shall acquire images of the rock and soil samples at
close range in conjunction with performing an APXS measurement.
Images of the APXS target location shall be acquired both before
and after the APXS ADM deployment to allow confirmation of the
actual sensor head location relative to the target surface.
2.3.4 Documentation of APXS Samples (IMP)
The IMP shall acquire multispectral images in each of the geology
filters and at a minimum of three different illumination geometries
of the area immediately surrounding the APXS sample sites within
±1 sol of the APXS analysis. For APXS sample sites consisting
of disturbed soil (desire) or abraded rock (desire) IMP images
shall be acquired both before and after the APXS analysis (desire).
2.3.5 Number of APXS Samples
The APXS shall be employed to analyze a minimum of 3 samples (of
rocks and of soil) during the nominal (7 sol) rover mission.
If the rover operates a total of 30 sols (nominal lander mission)
then a total of 6 rock and 4 soil analyses shall be acquired.
2.3.6 APXS Analysis of Disturbed Soil (Desire)
It is desired that the APXS be employed to analyze the soil in
a trench dug by the rover wheels at least twice during the landed
mission.
2.3.7 APXS Analysis of Abraded Rock (Desire)
It is desired that the APXS be employed to analyze a rock sample
before and after an abrasion attempt using one of the rover wheels.
Rover images of the site shall be acquired both before and after
the abrasion attempt.
2.3.8 APXS Analysis of Material on Rover Ramp Magnetic Targets
(Desire)
It is desired that the APXS be employed to analyze a sample of
dust collected on at least one of the magnetic targets attached
to the rover ramps. (Note: this sample should be acquired at
a time late in the nominal mission when data from the other magnetic
targets indicates that a sufficient sample has been acquired).
It is desired to image the magnetic targets on the rover ramp
within one hour prior to the APXS analysis with both the rover
camera and the IMP.
2.3.9 APXS Analysis of Material on Rover Ramp Non-Magnetic Targets
(Desire)
( Deleted)
2.3.10 APXS Analysis of Relatively Unoxidized Rock (Desire)
It is desired that the APXS be employed to analyze at least one
relatively dust-free and unoxidized (low red:blue reflectance
ratio) rock surface, if there is such a rock available and the
rover can reach it.
2.4 Atmospheric Science
2.4.1 Measurement of Vehicle Accelerations During Entry
The accelerations of the entry vehicle in three axes shall be
obtained as a function of time during the entry phase and transmitted
to earth after landing (mission success criterion).
2.4.2 Measurement of Temperature and Pressure During Descent
The free stream temperature and pressure of the atmosphere as
a function of time shall be obtained during the descent phase
(from parachute deployment until landing) and transmitted to
earth after landing (mission success criterion).
2.4.3 Post-landed Temperature Measurements
Temperatures of the ambient atmosphere shall be obtained by observations
performed hourly at three heights above the Martian surface after
landing. It is desired to obtain these measurements more frequently,
at least once every half-hour. Continuous measurements shall
be acquired for one hour each day. The particular hour shall
be selectable by command.
2.4.4 Post-landed Wind Speed and Direction Measurements
Wind speed and direction observations shall be obtained concurrently
with the temperature data using the ASI/MET sensors after landing.
Continuous measurements shall be acquired for one hour each day.
The particular hour shall be selectable by command.
2.4.5 Post-landed Atmospheric Pressure Measurements
Ambient atmospheric pressure measurements shall be obtained hourly
after landing. It is desired to obtain these measurements more
frequently, at least once every half-hour. Continuous measurements
shall be acquired for one hour each day. The particular hour
shall be selectable by command.
2.4.6 Wind Sock Observations
During daylight hours, monoscopic observations (10 frames in each
of two positions) of the wind socks shall be acquired hourly
by the IMP, concurrent with the ASI/MET observations. These
images may be transmitted as subframes of 100 wide x 256 high
pixels, compressed 25:1.
2.4.7 Aerosol Opacity Measurements (Sun Images)
Aerosol opacity shall be measured by imaging the sun through two
narrow band filters, once every 10 minutes for the first two
hours after sunrise and for the last two hours prior to sunset,
and hourly in between. Full resolution subframes of the images
will be transmitted to minimize the data volume.
2.4.8 Aerosol Opacity Measurements (Phobos and Star Images)
Images of Phobos (when visible) and at least four (4) bright stars
shall be acquired in four (4) filter positions, hourly at night.
These images shall be transmitted at full resolution as subframes.
2.4.9 Dust Particle Characterization (Sky Images)
Dust particle characterization shall be performed by making IMP
observations through 4 spectral filters of the sky at sunrise
and sunset at least once every 3 days. Observations shall be
made every 10 minutes for the two hours preceding sunrise and
for the two hours following sunset. Images of the flat field
calibration target shall be acquired at full resolution in conjunction
with these observations.
2.4.10 Water Vapor Abundance Measurements
Water vapor abundance shall be measured every three days by making
IMP observations of the sun through 4 filters, 12 times a day
( sampled nonuniformly in time such that the greatest sampling
frequency occurs when the sun is within 15 degrees of the dawn
or dusk horizons). Full resolution, 25 x 25 pixel, subframes
of the images will be transmitted to minimize the data volume.
Images of the flat field calibration target shall be acquired
in conjunction with these observations.
2.5 Astronomical Observations
2.5.1 Phobos and Deimos Radiometry
Images of Phobos and Deimos through eight filters shall be acquired
at least once during the mission to establish their photometric
properties.
2.5.2 Jupiter, Saturn and Earth Radiometry
If these objects are visible from the lander at night, the images
of Jupiter, Saturn and the Earth through eight filters shall
be acquired at least once during the mission to establish their
photometric properties.
2.5.3 Star Images
Images of bright stars shall be acquired through eight spectral
filters in conjunction with the Phobos, Deimos, Jupiter, Saturn
and Earth images to standardize the radiometric observations.
3.0 Imaging Investigation Requirements
3.1 Mounting
The Flight System shall supply mounting surfaces for the camera
assembly, for two radiometric calibration targets, and for two
sets of two each magnetic target arrays. Mounting for three
wind socks shall be provided by the ASI/MET meteorology boom.
Mounting surfaces for two additional magnetic plaques, one each
on the two rover deployment ramps shall be provided so that the
APXS can analyze a magnetically sorted sample of wind-blown dust.
3.2 Data Storage
The Flight System shall provide long term (30 days minimum after
landing) data storage capability for IMP calibration files, image
files and data compression parameter files.
3.3 Pointing
3.3.1 Local Target Pointing
The project shall calculate the pointing angles needed to point
the camera at features located within the Flight System-referenced
coordinate system (calibration targets, lander structure and
rover for both undeployed and deployed IMP locations).
3.3.2 Celestial Object Pointing
The project shall calculate the pointing angles needed to point
the camera at the sun, earth, Jupiter, Saturn, Phobos, Deimos
and selected bright stars.
3.3.3 Field of Regard
It shall be possible to point the IMP such that the field of view
covers the range of 360 degrees in azimuth and from -66 to +90
degrees in elevation. Portions of this field of regard will
be obscured by spacecraft structure and portions cannot be imaged
in stereo because of these obstructions.
3.4 IMP Calibrations
3.4.1 IMP In-flight Health Checks
Two IMP health checks shall be made during the cruise phase of
the mission, the first within approximately 30 days following
launch, the second within 30 days prior to arrival at Mars.
The health check consists of pairs of dark current frames acquired
at three different integration times and two different CCD temperatures,
totalling 12 frames. These data shall be losslessly compressed
and transmitted with accompanying engineering data. At the end
of the health check the filter wheel shall be commanded to rotate
to its limit switch position.
3.4.2 Dark Current Calibration Images
Dark current calibration images at full resolution are required
for each of the stereo optical paths at least three times per
day or once per major imaging sequence, whichever is less.
3.4.3 Flat Field Calibration Images (Full Frame)
Images of the flat field calibration target shall be acquired
for both of the stereo optical paths in all filter positions.
These images shall be acquired on the day of landing and at
5 day intervals thereafter. They shall be returned at full resolution.
3.4.4 Radiometric Calibration Images (Partial Frame)
Images of the radiometric calibration targets shall be acquired
in each filter position used that sol at three different solar
elevation angles to permit spectral correction of sky brightness.
These images shall be returned as full resolution subframes.
3.5 Camera Operations
The IMP shall be operable at any time during the landed mission
(day and night)
3.6 Onboard Software to Command the IMP
The Flight System Computer shall contain and execute the software
needed to command the camera operations, including heater control,
pointing of the camera, stepping of the filter wheel and the
execution of data taking sequences.
3.7 Onboard Software for Image Data Processing
The Flight System Computer shall contain and execute the software
needed to perform image data compression, data storage, packetization
and queuing of the telemetry packets.
4.0 Elementary Composition Investigation Requirements
4.1 Mounting Location
The APXS shall be mounted aboard the rover so that it can be transported
to sampling sites within the operating range of the rover
4.2 Deployment Mechanism
4.2.1 Orientation
It shall be possible to orient the APXS sensor head with its axis
of symmetry (look angle) at any angle between horizontal (parallel
to the ground) and vertical (downward).
4.2.2 Alignment with Rock or Soil Surface (Angular)
It shall be possible to align the APXS sensor head to within 20
degrees of normal to a tangent plane at the intersection of the
APXS sensor head axis of symmetry with the sample surface.
4.2.3 Alignment with Rock or Soil Surface (Spatial)
It shall be possible to align the APXS sensor head center line
within 5 cm of a preselected target location (using rover images)
for horizontal surfaces and for inclined surfaces within the
range of motion of the APXS Deployment Mechanism.
4.2.4 Elevation Above Soil Surface
It shall be possible to place the APXS sensor head in contact
with soil or rock samples within the range of motion of the APXS
Deployment Mechanism.
4.3 APXS Calibration
4.3.1 APXS In-flight Health Checks
Two APXS health checks shall be made during the cruise phase of
the mission, the first within approximately 30 days following
launch, the second within 30 days prior to arrival at Mars. Each
health check shall consist of powering on the APXS instrument,
followed by an abbreviated set of commands sent to the APXS from
the rover. Telemetry containing the appropriate command acknowledgements
from the APXS instrument shall confirm its operational status.
4.3.2 APXS Background Calibration
Prior to the first acquisition of data from soil or rock samples,
a calibration data take of three hours duration shall be acquired
with the APXS shutter in the closed position, followed by the
transmission of a complete APXS spectrum.
4.4 APXS Integration Times
Integration times of up to ten hours duration shall be provided
for APXS observations (the integration time need not be continuous).
The APXS shall be held in a single, fixed position until data
have been acquired.
5.0 Atmospheric Structure and Meteorology Investigation Requirements
5.1 Mounting Locations
5.1.1 Science Accelerometer Mounting
The science x-, y-, and z-axis accelerometers shall be mounted
in a plane (the Lander x-y plane) perpendicular to the Lander
spin, or z-axis. The z-axis accelerometer shall be positioned
on the z-axis. As a goal the plane containing the three accelerometers
shall pass through the Lander center of mass. Should this goal
not be achievable, then the positions of the effective centers
of the x-, y- and z-axis sensors shall be known to an accuracy
of 5 mm. (The center of mass is that of the entry vehicle, at
entry into the atmosphere).
5.1.2 Pressure Sensor Mounting
The pressure sensor head shall be mounted inside the thermal enclosure.
It shall be coupled via tubing to an inlet port location mounted
near the opening between two solar panels and the base plate
such that it can measure stagnation or total pressure. The response
time of the pressure in the pressure sensor to pressure changes
in the outside atmosphere shall be less than 0.1 s.
5.1.3 Descent Temperature Sensor Mounting
The descent temperature sensor shall be mounted near the opening between two solar panels and the base plate where the atmospheric flow velocities are high. The intent is to achieve good thermal coupling to the atmosphere and to avoid thermal contamination of the measurements by the Lander thermal boundary layer.
5.1.4 Post-landed Temperature Sensor Mounting
The temperature sensors used for post-landed meteorology shall
be mounted so that they sample the ambient temperature at three
different heights above the surface and are unperturbed by
the thermal influences of the lander for most wind directions.
The temperature sensors shall be mounted below the wind sensor
to avoid thermal contamination by wind sensor natural convection,
and shall be shielded from a direct view of the wind sensor heaters.
The post-landed temperature sensors shall be mounted to the meteorology
boom. The three heights are nominally 0.25, 0.5 and 1.0 m above
the lander attachment point. The three temperature sensors each
consist of a single electrical element containing three thermocouples
connected in parallel.
5.1.5 Wind Sensor Mounting
The wind sensor will be mounted on the meteorology boom and will
be deployed as high above the surface as possible. It shall
be positioned so as to avoid the disturbance in the flow caused
by the lander for most wind directions.
5.2 ASI/MET Calibrations
5.2.1 ASI/MET In-flight Health Check
Two ASI/MET health checks shall be made during the cruise phase
of the mission, the first within approximately 30 days following
launch, the second within 30 days prior to arrival at Mars.
5.2.2 Pre-entry Calibration of the ASI/MET Pressure Sensor
The ASI/MET Instrument shall be turned on prior to entry so that
at least fifteen (15) minutes of pressure measurements can be
made after the instrument has stabilized and before the sensible
atmosphere is reached, so that the zero offset of the pressure
sensor can be established.
5.2.3 Pre-entry Calibration of the Science Accelerometers
The Science Accelerometers shall be turned on prior to entry so
that at least fifteen (15) minutes of acceleration measurements
can be made after the sensors have stabilized and before the
sensible atmosphere is reached, so that the zero offset of the
accelerometers can be established.
6.0 Operational Requirements on Science Instruments
Requirements listed in this section describe uses of the science
instruments and instrument data for non-science operations and
for mission planning functions.
6.1 Operational Requirements on IMP
6.1.1 IMP Sun Locating Capability
Under control of the AIMS, the IMP shall execute a search for
the sun and return the most probable sun location coordinates
in the camera frame of reference to aid in positioning of the
high gain antenna. No returned images are required, however
diagnostic data generated during the search shall be transferred
to the AIMS.
6.1.2 Rover Deployment Images
Prior to deployment of the Rover and the deployment of IMP, a
set of stereo images shall be acquired which include the rover,
the egress ramps and an azimuthal segment of the Martian surface
in the vicinity of the lander. These images shall provide a minimum
of 1 cm ground pixel resolution (IFOV).
6.1.3 Pre-deployment Color Mosaic
A 3-color mosaic extending from the lander to the horizon and
including the rover (approximately 4 frames in elevation and
5 frames in azimuth for a total of 60 frames) shall be acquired
prior to deployment of the IMP mast. This color mosaic shall
be compressed only to the extent that its image quality does
not fall below that of the Viking Lander color images (mission
success criterion).
6.1.4 Rover Operations Support Images
Stereo images of the rover and its surrounding terrain shall be
acquired at the end of each sol during which the rover is operated.
These images shall provide a minimum of 1 cm ground resolution
(IFOV).
6.1.5 Images of the Rover Tracks
The IMP shall acquire full resolution, subframe images of the
rover tracks (disturbances of the soil caused by rover movement)
in the vicinity of the lander.
6.1.6 Images of the Lander
The IMP shall acquire a panorama of the lander hardware visible
within the pointing constraints of the camera to assess the post-landed
condition of the lander. These images may be highly compressed.
6.1.7 Images of Impact Sites
Panoramas acquired by the IMP in satisfaction of other requirements
listed herein shall be used to search for and characterize the
modification of the surface produced by the lander.
6.2 Operational Requirements on APXS
None
6.3 Operational Requirements on ASI/MET
6.3.1 Establishing the Landed Environment
ASI/MET post-landed data shall be used to establish the temperature,
pressure and wind conditions of the landing site, to aid in the
interpretation of engineering data and in the planning of surface
operations.
6.4 Operational Requirements on the Science Accelerometers
6.4.1 Science Accelerometers to provide Back-up to Engineering
Accelerometers
Science Accelerometer data acquired during the entry phase shall
be available for use by the AIMS as a back-up signal to be used
in deploying the parachute.
6.4.2 Lander Orientation with respect to Local Vertical
Following landing, the Science or Engineering Accelerometers shall
be reset to the highest on-scale gain state and shall be used
to determine the lander angular orientation with respect to local
vertical. These measurements shall be repeated at least hourly
during the first two sols and daily during the remaining sols
to determine the settling characteristics of the lander on the
surface.
7.0 Observation Priorities
The majority of the requirements contained in this document address
observations to be acquired by Mars Pathfinder. They are divided
between science requirements and operational requirements. Clearly,
some observations may satisfy both science and observational
objectives. Because the total list of required observations
may exceed the capabilities of the flight system and MFEX, a
set of priorities are given in this section, with the expectation
that they will be useful in constructing and evaluating scenarios.
At some risk, the priorities given in this document imply a
relative priority among the science and operational requirements.
While setting such priorities is controversial, it is also
necessary in order to provide a basis for the design of scenarios.
The priorities described below are tempered by the expectation
that the Flight System performance will be nominal or better.
For scenarios addressing partial failure modes, a finer division
of priorities may be needed.
As with any priority system some judgment must be exercised to
assure that the intent of the observation requirements is met,
not simply the letter of the requirement. For example, it may
be more desirable to satisfy 75% of a high priority requirement
and 25% of a lower priority requirement than to satisfy 100%
of the high priority requirement. With these provisos, the priorities
are established as described below.
7.1 Definition of Observation Priorities
Priority 1: An observation essential to meeting or verifying
a mission success criterion.
Priority 2: A fundamental part of a science investigation or
of a major technology or engineering investigation.
Priority 3: A significant part of a science investigation or
of a technology or engineering investigation.
Priority 4: An observation of value to a science investigation
or to a technology or engineering investigation, the loss
of which does not invalidate the investigation.
7.2 Observation Priority Listing
The observation priorities are given in Table 1.
8.0 Requested Requirements Not Accepted
The requirement statements listed below have not been accepted,
but are listed here to indicate that they have been considered.
The requester for each is identified. The reason for non-acceptance
is stated in each case.
8.1 IMP Requirements Not Accepted
8.1.1 IMP EEPROM Storage
In the event that volatile storage (DRAM) are to be powered off
to conserve energy, the flight system shall provide EEPROM storage
to enable the IMP to execute, process and store (afternoon) imaging
sequences acquired after the last preceding downlink and to
facilitate (morning) image acquisition and processing prior to
the next planned downlink.
Requester: Peter Smith
Reason for Rejection: The Flight System cannot commit to providing
more than the currently incorporated 2 Mbytes of EEPROM which
is completely consumed with software routines to sustain lander
operations.
8.2 APXS Requirements Not Accepted
None
8.3 ASI/MET Requirements Not Accepted
8.3.1 Second Wind Sensor (Desire)
Wind speed and direction at a second elevation shall be obtained
concur rently with the temperature data using ASI/MET sensors
after landing. The second wind sensor shall be mounted on the
meteorology boom just above the middle set of temperature sensors,
nominally 0.5 m above the surface.
Requester: Al Seiff
Reason for rejection: ASI/MET electronics channels and board
space are fully subscribed, thus additional sensor cannot be
accommodated within current instrument constraints.
8.4 Science Accelerometer Requirements Not Accepted
None
Table 1. Priorities of Mars Pathfinder Observational Requirements
Paragraph Requirement Priority Comments
2.1.1 Pre-deployment Panorama 1
2.1.2 Post-deployment Panorama 2
2.1.3 Panoramas for Change Detection 2
2.1.4 Photoclinometric Images 4
2.1.5 Use of Rover Images for Surface Morphology and
Geology 3
2.2.1 Multispectral Panorama 2
2.2.2 Multispectral Observations of Selected Targets 2
2.2.3 High Resolution Soil Images 3
2.2.4 Observations of Magnetic Properties Targets 3
2.2.5 Observations of Near-Field Magnet 4
2.2.6 Observations of Magnetic Targets Attached to
Rover Ramps 3
2.2.7 Search for Surface Frosts 4
2.3.1 APXS Analysis of Rock 1
2.3.2 APXS Analysis of Soil 1
2.3.3 Documentation of APXS Samples (Rover Imager) 3
2.3.4 Documentation of APXS Samples (IMP) 3
2.3.5 Number of APXS Samples 2
2.3.6 APXS Analysis of Disturbed Soil 3
2.3.7 APXS Analysis of Abraded Rock 3
2.3.8 APXS Analysis of Material on Rover Ramp
Magnetic Targets 3
2.3.10 APXS Analysis of Relatively Unoxidized Rock 3
2.4.1 Measurement of Vehicle Accelerations During Entry 1
2.4.2 Measurement of Temperature and Pressure During Descent 1
Table 1. Priorities of Mars Pathfinder Observational Requirements
- Continued
Paragraph Requirement Priority Comments
2.4.3 Post-landed Temperature and Pressure During
Descent 1
2.4.4 Post-landed Temperature Measurements 2
2.4.5 Post-landed Atmospheric Pressure Measurements 2
2.4.6 Wind Sock Observations 3
2.4.7 Aerosol Opacity Measurements (Sun Images) 3
2.4.8 Aerosol Opacity Measurements (Phobos and Star Images) 3
2.4.9 Dust Particle Characterization (Sky Images) 3
2.4.10 Water Vapor Abundance Measurements 3
2.5.1 Phobos and Deimos Radiometry 4
2.5.2 Jupiter, Saturn and Earth Radiometry 4
2.5.3 Star Images 4
3.4.1 IMP In-flight Health Checks 1
3.4.2 Dark Current Calibration Images 2 Generally, but priority 1 in conjunction with priority 1 imaging sequences
3.4.3 Flat Field Calibration Images (Full Frame) 2 Generally, but priority 1 on the day of landing
3.4.4 Radiometric Calibration Images (Partial Frame) 2
4.3.1 APXS In-flight Health Checks 1
4.3.2 APXS Background Calibration 1
5.2.1 ASI/MET In-flight Health Check 1
5.2.2 Pre-entry Calibration of the ASI/MET Pressure Sensor 1
5.2.3 Pre-entry Calibration of the Science Accelerometers 1
Table 1. Priorities of Mars Pathfinder Observational Requirements
- Continued
Paragraph Requirement Priority Comments
6.1.1 IMP Sun Locating Capacity 1
6.1.2 Rover Deployment Images 1
6.1.3 Pre-Deployment Color Mosaic 1
6.1.4 Rover Operations Support Images 1
6.1.5 Images of Rover Tracks 3
6.1.6 Images of the Lander 2
6.1.7 Images of Impact Sites 3
6.4.2 Lander Orientation with respect to Local Vertical 2