Working the Martian
Night Shift
The MER Surface Operations Process
BY ANDREW H. MISHKIN, DANIEL LIMONADI,
SHARON L. LAUBACH, AND DEBORAH S. BASS
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process, the drivers that influenced its development, and how
the process has evolved over time.
Drivers on MER Operations Design
Operating two rovers on the surface of an alien planet millions of kilometers distant would present a number of
challenges for an Earthbound operations team:
◆ Communications time delay. The distances
between ground operators and the
rovers are so vast that “joysticking” or
teleoperation would be precluded
by the inherent speed-of-light
communications time delays. For
MER, the round-trip communications delays would range
from 6–44 min.
◆ Limited lifetime. Dust accumulation on the rovers’ solar
arrays was expected to significantly limit their performance
soon after completion of the
90-sol prime mission.
◆ Daytime operation. The solar-powered rovers’ prime active periods are
during peak daylight hours at each landing
site. The rovers must “sleep” each night (and
part of the day) to conserve energy.
◆ Execution uncertainty. The duration and success of activities involving rover-terrain interactions (for traverse,
instrument placement, and rock grinding) cannot always
be accurately modeled, resulting in significant latency in
the operations team’s knowledge of vehicle state.
Responding to these challenges meant that, unlike other
robotic deep space missions, most MER rover actions could
not be preplanned far in advance; instead, the plan for a given
Martian day (1 Martian day = 1 sol) would be dependent on
1070-9932/06/$20.00©2006 IEEE
JUNE 2006
MARS IMAGES: NASA/JPL/CORNELL/USGS, BINOCULAR IMAGE © PHOTODISC, INC.
O
n 3 January 2004, the Spirit rover successfully
landed on the surface of Mars, followed almost
exactly three weeks later by its twin Opportunity.
During each rover’s first several days after landing, the ground operations team directed the
rover through a carefully rehearsed and choreographed
set of deployments, unfolding the rover from its
compact in-flight configuration to its fully
stood-up surface exploration state [1].
This phase of the mission was performed largely as a series of go/nogo decisions, in which the
operations team located at the Jet
Propulsion Laboratory (JPL)
commanded a single deployment step, confirmed the success of that step, then
authorized execution of the
next step. After cutting its last
electrical umbilical connection,
the rover was directed to drive off
the lander and make its first tracks in
the Martian soil.
These tracks marked the rover’s transition from its deployment phase to mobile
exploration. Additionally, they signaled a change
in ground operations strategy to an approach merging science and engineering factors and capable of responding flexibly to discoveries made during the mission. Implementation
of this reactive strategy has required the development of specialized processes for telemetry analysis, activity planning,
visualization, and command sequence generation, integration,
and validation. As this is written, the Mars Exploration Rover
(MER) mission has operated the Spirit and Opportunity rovers
for a combined total of over 1,400 Martian days (or, sols) of
surface exploration. We describe the MER surface operations
the success in executing the prior day’s activities, requiring
daily commanding throughout the surface mission. Commanding a robotic mission this frequently was nearly unprecedented, having been achieved previously only during the
much less complex Mars Pathfinder mission.
Since issuing instructions to a spacecraft a single command
at a time and then waiting to assess the result before proceeding to the next command would be prohibitively slow and
preclude execution of time-critical activities, robotic
spacecraft are typically instructed via prepared sequences of
commands that are uploaded, stored, and then executed at designated times. For Spirit and Opportunity, such sequences govern the rovers’ science observations, motions, and engineering
housekeeping actions for a full day. The rovers are resourcelimited machines, with severely restricted available energy and
data storage capacity; they must also keep components within
specified temperature ranges to avoid equipment failure. The
operations team must manage all of these resources remotely,
without the benefit of real-time monitoring. Command errors
may potentially result in loss of some or all of the planned
activities for the sol, trap the vehicle in hazardous terrain, cause
unexpected resource usage, or damage hardware. Significant
errors can cause anomalies requiring multiple days of analysis
and recovery, loss of communications, or even loss of mission.
To avoid such a fate, command sequences are carefully constructed, reviewed, and validated. For most missions, ensuring
the integrity of complex sets of sequences totaling hundreds or
thousands of commands is commonly an iterative, time-consuming process taking place over days or weeks. MER was
required to compress this process to hours.
To enable simultaneous operation of two rovers, surface
operations personnel would be divided into two independent tactical teams, one for each rover. While team members might periodically move from one tactical team to the
other, any individual on a tactical team would be responsible for only a single rover during a workshift. Coordination between the two rovers, as well as between the MER
mission and other organizations, would be handled by a
distinct strategic team.
Critical and noncritical data would be carefully distinguished and appropriately prioritized for downlink. For
ground operators to evaluate the success of a sol’s worth of
activities and plan the rover’s next move, they would need
imagery, engineering telemetry, and selected instrument data
sets. “Critical” data was defined as that data required for planning the next sol’s worth of activities. For energy and thermal
reasons, this critical data would need to fit within a volume of
about 20 Mb per sol, consistent with the data volume available via an X-band direct-to-Earth communications session.
Any plan for a given sol that generated more critical data than
could be downlinked via that sol’s X-band session would be
simplified to fit.
Ultrahigh-frequency (UHF) relays would also be
employed for downlink of science telemetry. Two NASA
spacecraft—Mars Odyssey and Mars Global Surveyor—would
be in orbit over Mars when Spirit and Opportunity arrived.
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The combination of these two orbiters could potentially supply each rover with up to four additional communications
opportunities per sol, providing as much or more data volume as the direct-to-Earth link. However, due to concerns
over the inherent latency in these relay links, the mission
architecture presumed that only noncritical data would be
downlinked via the orbiters.
As the landings approached,
wristwatches adjusted to keep
Mars-time became popular among
team members.
Prime Mission: Living on Mars Time
Mars Time
Since the Mars day is about 40 min longer than an Earth day,
the solar-powered rovers would be waking up 40 min later
each morning, accepting commands 40 min later, and downlinking their telemetry 40 min later. To stay synchronized
with our rovers, the operations teams would start their work
shifts 40 min later each day as well. Since the two rovers’
selected landing sites were literally on opposite sides of the
planet from each other, the tactical teams for Spirit and Opportunity would not just be living on Mars time, they would be
living in two distinct Martian time zones. In addition, to
maximize the science retur n given the presumed
90-sol lifetimes of the two rovers, we would execute the tactical process seven days a week.
Why is it so important for the team to work on Marstime? During the MER development phase, several alternative operations staffing schemes were assessed. None were
found to be nearly as effective overall as having the operations
team work a rotating schedule tied to the Mars clock. First,
working on a Mars-time schedule provided the maximum
number of workhours between receipt of downlinked rover
telemetry and the next uplink of commands. Second, since
the steps of the operations process required specialized skills,
keeping the team synchronized with the rovers’ schedules
minimized the number of personnel requiring cross-training,
while maximizing the level of personnel experience given the
limited number of training opportunities prior to landing.
Finally, the Mars-time schedule kept key spacecraft and
ground events tightly coordinated, contributing to the team’s
situational awareness of what was likely to be happening on
board the rovers at any given time.
To facilitate working this unique schedule, fatigue countermeasure techniques were implemented; blackout curtains
were installed in the operations areas; and the team was sized
to permit personnel to work schedules that allowed ample
recovery time between shifts (e.g., four days on/three days
off). As the landings approached, wristwatches adjusted to
keep Mars-time became popular among team members.
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47
◆
For MER, the round-trip
communications delays
would range between
6–44 min.
Tactical Process Overview
Strategic Processes
MER operations processes were partitioned into those that
must be tied to the Mars clock (designated as tactical) and
those that could be performed per a more leisurely timeline
(strategic). The primary benefit of the partitioning was to
enable the tactical team to focus solely on those tasks that
contributed directly to achieving the strict deadlines of commanding the rovers each sol. In addition, it facilitated key
interactions with other organizations that were not working a
Mars time schedule. Strategic processes included:
◆ generation of strategic activity plans, with time horizons of about two weeks
◆ negotiation of communications allocations with the
Deep Space Network, and delivering the associated
communications windows to load into rover memory
◆ negotiation of orbiter relay passes with Odyssey and
Mars Global Surveyor
◆ maintenance of the mission “scorecard” tracking
progress toward mission goals
◆ design, evaluation, and testing of first-time rover activities
◆ resource model updates
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11
12
13
long-range traversability analysis in support of science
objectives.
14
15
16
17
18
The tactical operations process was designed to provide a sol’s
worth of instructions to each rover each sol, thereby fully utilizing the rovers and maximizing the science return of the
overall mission. If one considers a rover command and its
specified arguments to be comparable to a line of software
code, then the tactical process is daily producing approximately
500 validated lines of code to control a robotic system, code
that must work the first time it is executed on the target system, with no real-time human monitoring.
The major steps of the tactical process are:
◆ receipt of downlink
◆ engineering downlink assessment
◆ science downlink assessment and science activity planning
◆ activity plan refinement and validation
◆ activity plan review
◆ command sequence generation
◆ sequence integration and validation
◆ command review
◆ transmission of commands to the spacecraft.
During the early prime surface mission, the execution of
the tactical process, from end of downlink to transmission
of the next sol’s commands, was executed in about 18 h
(see Figure 1).
On a typical sol, the rover completes its critical activities
(i.e., those activities generating critical data required to plan
19
20
21
22
23
0
1
Odyssey
UHF Passes
2
3
4
MGS
5
6
7
8
9
8
9
Odyssey
Direct-to-Earth Communications
Periods
Sleep
Nighttime Rover Operations
Nighttime Rover Operation
Wakeup
Real-Time Monitoring
Downlink Product Generation
Science Sol n Context Meeting
Science Sol n Context Meeting
Tactical Science
Assessment/Observation Planning
Science DL Assessment Meeting
Science DL Assessment Meeting
Tactical End-of-Sol Engineering
Assessment
SOWG Meeting
SOWG Meeting
Activity Plan Integration and
Validation
Activity Plan Approval Meeting
Activity Plan Approval Meeting
Sequence Development
Master/Submaster Walkthrough
Master/Submaster Walkthru
Integrate Sequences
Command Product Generation,
Yalidation, and Review
Command Approval Meeting
Command Approval Meeting
Margin
Sol n Radiation
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12
13
14
15
16
17
18
19
20
21
22
23
0
1
2
3
4
5
6
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Figure 1. Generic timeline for the MER tactical operations process as performed during the early prime mission. Note that the
hour labels at top and bottom of the chart represent Mars local time at the rover’s landing site.
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Figure 2. Science Activity Planner (SAP) displays. This planning tool, developed specifically for MER, was based on the
preexisting WITS (Web Interface for Telescience) application. Science team members use this tool to define rover science
activities, specify science targets, and estimate resource usage.
the next sol’s set of activities) by midafternoon, Mars local
time (LST). Via a prescheduled X-band communications session, the rover then transmits this data to Earth. The data
received at the Deep Space Network station is forwarded to
JPL, and key data products (including images) are derived
within 30 min or so of the end of the downlink.
Engineering Downlink Assessment
With the downlinked telemetry in hand, the spacecraft rover
engineering team (SRET) begins its review, assessing the state
of the vehicle and verifying that planned activities occurred as
expected, verifying the health of all subsystems, and identifying any constraints on future sols as needed.
While these analysis tasks are not conceptually different
from those performed for other deep space missions, the
MER rovers are operating in the variable Martian surface
environment, resulting in heightened uncertainty in commanded action versus actual action. Sources of uncertainty are
present in the following areas:
◆ Energy. The rovers are solar-powered vehicles with
body-fixed arrays, and hence anything that affects solar
flux on the array is a factor in total available energy for
a given sol: rover pitch/roll, atmospheric opacity
changes (see reference [2]), and seasonal variations.
Because of the strong influence of tilt on available energy,
energy can have large day-to-day variations if the terrain the rover is moving on is highly irregular.
◆ Component temperature. Use of mechanisms and cameras
in early morning, late afternoon, or nighttime often
requires warm-up heating. These component temperatures are heavily influenced on sol-to-sol and multisol
timescales by Martian seasonal atmospheric mean temperature swings, winds, atmospheric opacity variances,
and differences in surface thermal inertia and albedo
from location to location. Reference [3] summarizes
some of the long-term thermal trends seen by the
MER rovers through Sol 400.
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Mobility efficiency and predictability. Terrain type, e.g.,
unconsolidated sand versus soft bedrock versus a mix of
bedrock and loose sand, etc., combined with terrain tilt
has a large effect on the correlation of actual vehicle
motion to commanded vehicle motion. In addition,
vehicle traverse through terrain will sometimes markedly
change the properties of the terrain (e.g., local failure of
the material that changes its load bearing or friction
properties) so that driving over the same patch of
ground a second time will result in very different
behavior or even change the topography of the terrain.
◆ Downlink bandwidth. UHF pass volume is often difficult
to predict accurately due to changes in rover attitude
and orientation. The achieved accuracy was no better
than +/ − 20 Mb to +/ − 50 Mb, depending on the
downlink data rate used for the pass. Later in the mission, the team began to rely on Odyssey for downlink of
critical telemetry; in order to properly plan for maximum allowable “critical” data volume the predicted pass
volumes were derated by the latter uncertainty values.
See [4] for a description of the MER UHF system and
its early flight performance.
Examples of key downlink data assessment focus points for
the team are comparing predictions to “as run” spacecraft
actions, energy assessment and predictions for next sol, thermal assessment and confirmation of execution of proper heating sequences, telecommunications link performance and
trending, assessment of rover attitude knowledge performance, and identification of any solar panel shadowing or
antenna occultation issues for next sol.
◆
Tactical Science Downlink Assessment
and Initial Activity Planning
Each sol, in parallel with the SRET engineering downlink
assessment, the science team assesses newly arriving data and
decides what to plan for the next sol. At the Science Context
Meeting, science team members discuss the plan, and suggest
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Figure 3. Sample MAPGEN display. This tool combines activity
planning and resource modeling capabilities developed at JPL
with an automated scheduling component provided by Ames
Research Center.
and receive assignments on portions of the plan. For example,
one scientist might wish to examine the detailed morphology
of a particular rock. Alternatively, another scientist might
work to request monitoring of atmospheric dust.
Midway through the science planning process, the science
team reconvenes at the Science Assessment Meeting to make
adjustments to the structure of the sol being planned based on
a review of the updated telemetry from the previous sol and
past sols. Science subgroups continue to develop possible science requests as defined by their assignments.
The science team uses a software tool called the Science
Activity Planner (SAP) [5] to specify their requests, called
Observations (see Figure 2). Observations describe a set of
actions the rover would accomplish for a particular scientific
rationale. The actions are called Activities, and a single Observation might be composed of one to many Activities. Activity
types range from individual images to panoramas, spectrometer
integrations, and rover traverse. Activities, along with their
parameters, were defined in a construct known as the Activity
Dictionary. To improve efficiency, some often-used Activities
are kept as templates with their particular parameters filled out.
After defining their Observations in SAP, members of the
science team meet again in the science operations working
group (SOWG) meeting to discuss and finalize the complete
set of requested Observations and rover actions for the next
sol. An SRET representative provides the engineering assessment of the current state of the rover, the resources available
for that sol, and any necessary engineering activities (e.g., attitude updates) that will consume some of these resources. The
team resolves competing requests, prioritizes the observations
and ensures that the plan achieves the objectives for the day,
and identifies a rough activity timeline, checking the resources
against a resource model.
Members of the integrated sequence team (IST), which has
responsibility for delivery of the final command load for
uplink, are present to assess the feasibility of the science team’s
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Figure 4. RoSE (Rover Sequence Editor) command editing
display.
plan from two perspectives: the plan must be executable by the
rover given the time and resources available, and secondly, the
team must be able to implement the plan in the hours remaining before the next uplink. Typically, overly complex plans will
be pruned before the end of the SOWG meeting. To stay on
track for the next Mars morning uplink, the SOWG meeting
must deliver its prioritized activity plan by 2000 LST.
Activity Plan Integration,
Validation, and Approval
Immediately after the SOWG meeting, the bulk of the science team drops off the critical path, and the focus of the tactical operations process shifts to a smaller colocated group of
engineers and instrument sequencing experts. The SOWG
lead remains present to ensure that the original science intent
of the submitted plan is maintained and to make any science
tradeoffs that may arise as the process proceeds. At this point,
the operations team has roughly 12 h to complete planning,
implementation, and validation before uplink.
A sampling of logistical questions addressed by the operations team every sol includes:
◆ Will the critical data needed to plan the following sol’s
activities be ready early enough for afternoon downlink, and will it fit within the expected downlink data
volume?
◆ Should the team opt to trade a communications opportunity with Earth for the time and energy to do more
science or driving?
◆ Is there enough room in the onboard memory to store
the new data generated by the current sol’s activities?
◆ Is it feasible to position the rover to maximize solar
energy or maximize data return?
◆ Will the current sol’s planned activities fit within the
rover’s resources?
◆ Does this sol’s plan leave enough energy stored in the
battery for the next sol’s plans?
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Use of UHF communications interferes with the use of
many of the science instruments. Are there any such
conflicts to resolve?
Activity planning and sequencing proceed in parallel over
the next few hours. Science constraints that apply to the
proposed activities (e.g., ordering of activities, time of day,
etc.) are formally entered into the planning tools. Using
MAPGEN [6] activity planning and scheduling software (see
Figure 3), IST members schedule both science and engineering activities, juggling rover wakeup and shutdown times,
communications windows, and proposed science Observations. Science activities are planned in priority order so that
the highest priority items are included in the event that the
team runs out of time. Modeling and flight rule checking
software ensures that no resource budgets are exceeded and
that no cross-activity conflicts remain. The validated Activity
Plan for the upcoming sol must be ready for review before
midnight LST.
Other team members are generating the sequences of
commands that will implement the individual activities, using
the Rover Sequence Editor (RoSE) [7], Figure 4. Effectively,
the sequencers are creating the building blocks of the sol plan,
while the activity planning process is putting each of the
building blocks in the right place. At the risk that some effort
will be expended on sequences that will ultimately be rejected
from the activity plan, this parallel approach results in a
streamlined overall process, hours shorter than would otherwise be possible.
The Rover Sequencing and Visualization Program
(RSVP) provides the capability to visualize the terrain and
plan and simulate rover motions in three dimensions (see
Figure 5). The team uses RSVP to assess the feasibility of
the rover motions requested by the science team. For example, given a chosen rock, engineers must determine whether
the traverse to the rock is safe, what method of traverse will
be used, and whether the rover can safely gather the
required workspace imagery for its robotic arm, the instrument deployment device (IDD). If the rover is already positioned near a rock target, the team must determine whether
the rock is within the useable workspace of each of the
desired IDD-mounted instruments and whether it is safe to
unstow the IDD. Duration estimates must also be provided
to MAPGEN.
The SRET systems engineer also works to make sure all
required engineering activities are included in the plan and to
build and test any new engineering sequences required for the
sol. Among the engineering maintenance activities are periodic attitude knowledge updates, high gain antenna gimbal
calibration, and various actuator calibrations.
At the Activity Plan Approval meeting, the operations
team reviews the overall Activity Plan and the detailed rover
motion simulation, double-checking resource consumption,
activity conflicts, and spacecraft safety. Only minor changes
that would not require remodeling are permitted at this point.
Any major issues with the delivered Activity Plan would result
in the rejection of the plan and in no creation of a command
◆
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Unlike other robotic deep space
missions, most MER rover actions
could not be preplanned
far in advance.
load. In practice, careful management of the process prior to
this decision gate has always produced an approved plan.
Sequence Development and Integration
With the approved Activity Plan in hand, the team’s emphasis
shifts to completing the command sequences that will carry it
out. The command load for a sol is organized as a hierarchical
multisequence structure. This facilitates partitioning the design
of the command load among multiple sequencers, each of
which has a different domain of expertise. “Master” and “submaster” sequences sit at the top of the hierarchy, providing a
modular structure that embodies the activity plan in a few
sequences. The master sequence triggers the submaster
Figure 5. Sample RSVP visualization display. (Image courtesy
of Frank Hartman, JPL.)
sequences at the times specified by the Activity Plan; the submasters in turn trigger the subsequences implementing individual activities. The master also governs when the rover wakes up
and shuts down, ensures that no conflicting activities will be
executing during communications sessions, cleans up loose
ends left by failed/incomplete execution of other sequences,
accepts control from prior masters, and transfers control to succeeding masters. The master sequence must be adapted each sol
to the timing of communications sessions, rover waking periods, and the specifics of the observations for the sol.
At 0200 LST, the full team reviews the master, submaster,
and rover motion sequences. Integration of sequence files
provided by six or more sequence developers then begins. For
a given sol, there may be 30 or more individual sequences, to
be hierarchically structured per the Activity Plan. Between
0400 LST and 0700 LST, final products are produced and
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The tactical teams for
Spirit and Opportunity would not
just be living on Mars time, they
would be living in two distinct
Martian time zones.
◆
validated. The team generates the binary command files and
human-readable sequence reports for review. Multimission
tools perform resource and flight rule checks on the entire
command load, identifying issues that cannot be captured at
the individual sequence level. SRET team members validate
the full set of command files by loading them into a flight
software simulator and verifying the proper activation of key
sequences in this set.
The final review and decision gate for the tactical process is
the Command Approval Meeting, scheduled at 0700 LST.
Deviations are noted and evaluated to determine whether
they can be accepted or require a command load modification
(e.g., removal of a flawed sequence). At the conclusion of the
meeting, signed-off approval forms and uplink instructions are
delivered to the command radiation console, in time for the
0900 LST uplink. All team members document their part of
the overall process in an online sol report, which becomes
immediately available to the entire MER team. This report
provides key information for the next shift’s downlink analysis
as well as the activity planning for the next sol.
And then of course, on the next sol, the whole process
repeats.
◆
Extended Mission: Returning to Earth
By the end of February 2004, it had become clear that the
MER rovers were likely to survive significantly beyond their
promised 90-sol lifetimes. This presented a new operations
challenge: The operations process would need to transition
from the high-intensity approach geared to wringing every
possible bit of science out of the rovers in their presumed
short lives to an approach that could be sustained indefinitely.
For cost reasons, the size of the operations team would need
to shrink as well.
How to Stop Working on Mars-Time
The key to getting the operations team off of the Mars-time
schedule (while the rovers continued to live on Mars-time)
was shortening the duration of the tactical process. Reduction
in cycle time translates directly into time margin between
receipt of critical telemetry and the next Mars morning
uplink. This margin can then be spent to release the team
from working night shifts.
By April 2004, the mean overall tactical cycle was down to
about ten hours. How was this achieved? There was no single
magic bullet, but a combination of factors together reduced
the time to produce a command load by nearly 50%:
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◆
◆
◆
Incremental automation of previously manual steps,
both for sequence integration and downlink assessment,
had begun even prior to landing. The tools continued
to evolve as the surface mission progressed, saving time
and reducing the possibility of human error.
The key functions performed by each team role were
refined through experience during early prime mission,
leading to elimination of nonessential tasks, better
focused communications within the team, and fully
trained personnel.
Libraries of reusable instrument sequences evolved during the prime mission.
The one factor that could be modulated tactically was
the complexity of a sol’s plan. By eliminating certain
parallel rover activities that would otherwise necessitate
intricate planning to prevent onboard resource conflicts,
fewer hours were needed to plan and sequence a sol.
Finally, the implementation of the above measures
reduced the overall process duration to the point that it
could be completed in one workshift, eliminating the
overhead associated with shift handover.
Some MER Acronyms
IDD
IST
LST
MER
RoSE
RSVP
SAP
SOWG
SRET
Instrument Deployment Device
Integrated Sequence Team
Local Solar Time
Mars Exploration Rover
Rover Sequence Editor
Rover Sequencing and Visualization Program
Science Activity Planner
Science Operations Working Group
Spacecraft Rover Engineering Team
The “Earth-time” schedule must still slide to ensure the
availability of critical telemetry for planning. While team
workshifts generally start at 8 a.m., as the Mars afternoon
downlink inevitably marches into the Earth day, the team
workshifts slide later. Once the downlink time passes
1 p.m., the team no longer tracks the downlink, and the
schedule reverts to an 8 a.m. start time, entering the realm
of “restricted sols.” During restricted sols, the tactical team
plans a new sol before the results of the prior sol are known;
the team instead relies on “stale” data from two sols earlier.
Since many rover actions, such as driving and instrument
placement, require knowledge of the current rover position
to be planned safely, rover drives during restricted periods
can be planned only every other sol. After about ten days,
Earth-Mars time phasing again permits the planning process
to rely on data from the current sol. This workshift pattern
repeats every 37 Earth-days, the time required for Earth and
Mars clocks to achieve the same relative phasing.
This sliding Earth-time schedule has been maintained
for nearly two years. Further software tool enhancements
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have reduced the average tactical cycle time to 8 h, while
other tool improvements have enabled multisol planning
during a single workshift, eliminating weekend and holiday tactical cycles.
Conclusions
The Mars Exploration Rover mission has conducted continuous Mars surface operations for over 24 months to
date. The operations processes and tools put in place
before landing have continued to develop throughout the
surface mission, evolving from a capability intended to
operate for less than four months to one capable of continuing indefinitely. The MER operations design has been
accepted as baseline for the Mars Science Laboratory mission, scheduled for launch in 2009. Our experiences during MER’s exciting and unexpectedly extensive surface
exploration phase may provide useful insights for other
future long duration surface missions.
Acknowledgments
The work described in this article was performed at the
Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics
and Space Administration (NASA). Reference herein to
any specific commercial product, process, or service by
trade name, trademark, manufacturer, or otherwise, does
not constitute or imply its endorsement by the United
States Government or the Jet Propulsion Laboratory, California Institute of Technology.
Keywords
Space, Mars, mission operations, Mars Exploration Rover,
MER, Spirit, Opportunity.
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Andrew H. Mishkin has held systems engineering positions
on both autonomous vehicle technology efforts and flight projects at the NASA Jet Propulsion Laboratory. He was the principal architect of the operations process for the Spirit and
Opportunity rovers and has been both a Mars Exploration Rover
mission manager and sequencing team chief. He is the author
of the book Sojourner: An Insider’s View of the Mars Pathfinder
Mission. He received B.S. and M.S. degrees in systems engineering from the University of California at Los Angeles.
Daniel Limonadi was the system engineer with end-toend responsibility for rover mobility system deployments
during the impact-to-egress mission phase and was also the
team lead for the surface operations systems engineering
team. He is currently the flight system engineer responsible
for payload accommodation on the 2009 Mars Science
Laboratory rover mission. He received his B.S. degree in
aerospace engineering from the University of California at
Los Angeles.
Sharon L. Laubach was the Mars Exploration Rover
(MER) uplink systems engineer and architect of the commanding and sequencing process for MER. She is currently the MER sequencing team chief. She received her
Ph.D. from the California Institute of Technology in
autonomous robot control.
Deborah S. Bass currently works at the NASA Jet Propulsion Laboratory, where she was the deputy science team
chief for the Mars Exploration Rover (MER) Project. She is
now the project science systems engineer for the 2007 Mars
lander Phoenix. She received her Ph.D. from the University
of California at Los Angeles, and her science expertise
focuses on Mars polar geology, with an emphasis on water
transport in and out of the polar regions.
Address for Correspondence: Andrew H. Mishkin, Jet
Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 USA.
Phone: +1 818 354 0986. Fax: +1 818 354 5074. E-mail:
[email protected].
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