OVERCOMING THE CHALLENGES OF SOLAR ROVER AUTONOMY: ENABLING LONG-DURATION PLANETARY NAVIGATION

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OVERCOMING THE CHALLENGES OF SOLAR ROVER
                                              AUTONOMY: ENABLING LONG-DURATION PLANETARY
                                                              NAVIGATION
                                                                            Olivier Lamarre1 and Jonathan Kelly2
                                                1
                                                    STARS Laboratory, University of Toronto, Canada, E-mail: olivier.lamarre@robotics.utias.utoronto.ca
                                                          2
                                                            STARS Laboratory, University of Toronto, Canada, E-mail: jkelly@utias.utoronto.ca

                                         ABSTRACT                                                        Mars 2020 rover to cache samples and drop them
                                         The successes of previous and current Mars rovers               at a prespecified location [1]. The second phase
                                         have encouraged space agencies worldwide to                     will then land both a solar-powered rover and an
                                         pursue additional planetary exploration missions                ascent vehicle on the surface, to fetch the cache
arXiv:1805.05451v2 [cs.RO] 13 Jul 2018

                                         with more ambitious navigation goals. For exam-                 container and launch it into Martian orbit, respec-
                                         ple, NASA’s planned Mars Sample Return mis-                     tively. As part of the third and final phase, an or-
                                         sion will be a multi-year undertaking that will                 biter will capture the sample container and return
                                         require a solar-powered rover to drive over 150                 it to Earth.
                                         metres per sol for approximately three months.                  In 2011, it was reported that the “fetch” rover
                                         This paper reviews the mobility planning frame-                 for the MSR mission would be expected to drive
                                         work used by current rovers and surveys the major               up to fourteen kilometres in approximately three
                                         challenges involved in continuous long-distance                 months [2], corresponding to more than 150 me-
                                         navigation on the Red Planet. It also discusses                 tres per sol. Technically, Opportunity and Curios-
                                         recent work related to environment-aware and                    ity are already capable of driving such a distance
                                         energy-aware navigation, and provides a perspec-                during a single sol, but, in reality, this pace can-
                                         tive on how such work may eventually allow a                    not be maintained. In fact, since the beginning of
                                         solar-powered rover to achieve autonomous long-                 its mission, Curiosity has driven over 130 metres
                                         distance navigation on Mars.                                    during a single sol only four times [3]. This can
                                                                                                         be attributed to numerous factors, including op-
                                                                                                         erational restrictions, flight hardware limitations,
                                         1   INTRODUCTION
                                                                                                         and constraints related to the mission’s science-
                                         Surface mobility on Mars has tremendously accel-                driven goals. Nevertheless, such limitations raise
                                         erated the study of our solar system neighbour. In              questions about the ability of future solar-powered
                                         1997, the National Aeronautics and Space Admin-                 mobile robots, like the MSR fetch rover, to navi-
                                         istration (NASA) successfully delivered the So-                 gate long distances at a relatively fast pace across
                                         journer rover to the surface of the Red Planet, as              the diverse Martian terrain.
                                         part of the Mars Pathfinder mission. This little
                                         rover was the first robot to navigate on another                Numerous survey and review papers have already
                                         planet. Several years later, in 2004, the successful            discussed the future of mobile exploration of Mars
                                         landings of the Mars Exploration Rovers (MERs),                 (e.g., the authors of [4] review generic adaptive
                                         Spirit and Opportunity, marked the beginning of                 capabilities and behaviours of rovers operating
                                         an active and ongoing mobile presence on Mars,                  within a fully autonomous framework). How-
                                         which continues to the present day. In 2012, the                ever, to the best of our knowledge, no paper has
                                         Curiosity rover, part of the Mars Science Labora-               described the challenges of rover navigation in
                                         tory (MSL) mission, became the largest rover to                 energy-limited settings, considering the present
                                         date to explore the Martian surface.                            operational context and near-future mission goals.
                                                                                                         This paper surveys how the current operational
                                         Despite the very large amount of data collected by              and technological challenges of planetary mobil-
                                         rovers across different regions of Mars, the capa-              ity planning and execution can be addressed by
                                         bility of these rovers to conduct experiments on                recent research in the field. More specifically, we
                                         soil samples, for example, is very limited. This                identify work that could be applied in the context
                                         is why NASA is preparing a three-phase endeav-                  of long-distance navigation autonomy with solar-
                                         our, called the Mars Sample Return (MSR) mis-                   powered rovers, to meet the navigation require-
                                         sion, to return Martian soil samples to Earth. The              ments of the MSR mission and beyond.
                                         first phase of the mission will involve using the
The remainder of the paper is structured as fol-        bilities [5]. On MSL, a single science campaign
lows: Section 2 describes the state of the art in       can last more than a week, due to both the large
navigation planning for Mars rovers, while Sec-         number of international researchers involved in
tion 3 highlights the current challenges related to     the process and the complexity of the numerous
mobility on Mars. Section 4 introduces promis-          sensors and analyzers on board the rover. This
ing work towards energy-aware navigation; Sec-          timeframe is too slow (fast) to be supported by
tion 5 discusses how the per-sol driving range          the tactical (strategic) planners. The supratac-
of solar-powered rovers may be substantially im-        tical cycle therefore serves as an intermediary
proved over the next few years.                         for multi-sol scientific campaigns, and acts as a
                                                        bridge between the international scientific teams
                                                        and the engineering personnel directly communi-
2     CURRENT ROVER                                     cating with the rover.
      NAVIGATION FRAMEWORK
Navigating on Mars is very challenging. In order
to understand the implications of the research pre-     2.2   Curiosity’s Navigation Modes
sented in the remainder of this paper, it is neces-     Curiosity was initially equipped with three pri-
sary to be familiar with the current rover naviga-      mary navigation modes, each with a different level
tion planning and execution process. This section       of autonomy [7]. Blind-drive (the first mode) in-
provides a very brief description of the operational    volves letting the tactical team assess the terrain
framework used to drive Curiosity and outlines the      around the rover and then prepare a sequence of
rover’s navigation capabilities.                        instructions for the exact manoeuvres to accom-
                                                        plish (e.g., drive 2 metres forward, turn 90 de-
2.1   Navigation Planning                               grees right, etc.). As the rover executes these
                                                        commands, it keeps track of its own motion using
The operational framework employed to control
                                                        wheel odometry. Since this is a dead-reckoning
Curiosity is composed of three distinct cycles:
                                                        technique (which causes the uncertainty of the
strategic, supratactical, and tactical. The strategic
                                                        state of the rover to increase with distance), blind-
cycle can vary from a few weeks to a few months,
                                                        drive can only be used over short distances in most
and involves high-level and long-term activity
                                                        situations.
planning; it heavily relies on input from the sci-
ence teams to select sites to investigate (based pri-   The second navigation mode, auto-navigation,
marily on orbital data), incorporates preliminary       employs a level of autonomy in order to reach a
traversability and activity assessment, and contin-     distant waypoint identified by the planning team.
uously ensures that the mission maintains focus         The rover frequently stops to survey the sur-
on its objectives while accounting for changes in       rounding terrain using stereo vision, assess the
the rover’s condition and capabilities [5]. The tac-    traversability of the local region, and select a safe
tical cycle, on the other hand, lies at the opposite    path to move closer to its goal. This process is
end of the planning spectrum, typically lasting a       accomplished using the Grid-based Estimation of
day (or a few days at most). The purpose of this        Surface Traversability Applied to Local Terrain
cycle is to ensure that daily mission goals, formu-     (GESTALT) algorithm, which is only able to de-
lated by the strategic and supratactical teams, are     tect and avoid geometric obstacles [8]. In auto-
fulfilled. Tactical mission planners mainly utilize     navigation mode, Curiosity can also use visual
surface data collected by Curiosity’s sensors (such     odometry (VO) at a very low frequency (roughly
as stereo imagery and telemetry). Tactical plan-        every 10 metres) to verify the rover’s egomotion
ning is highly reactive: on every cycle, the tactical   (by performing “slip checks”).
planners analyze the rover’s current state and ad-
                                                        The final navigation mode is the slowest, but ar-
just the next sequence of instructions accordingly
                                                        guably the safest. In addition to navigating using
before uplinking commands to the rover [6]. Both
                                                        obstacle detection and avoidance, Curiosity uses
the strategic and tactical cycle structures were in-
                                                        VO over short distances (1.5 metres or so) as an
herited from the MER planning framework.
                                                        additional source of relative motion information.
As mentioned above, the MSL mission introduced          This is useful when fine positioning of the rover is
a ‘supratactical’ cycle into the standard planning      required, or when driving on terrain with an ele-
framework. This is a direct consequence of Cu-          vated risk of slip. Since 2012, other drive modes
riosity’s advanced and extensive scientific capa-       have been uploaded to the rover (such as visual
target tracking) or derived from already-existing     on a regular basis must be detailed instructions
capabilities (e.g., combinations of blind-driving,    rather than more generic goals. Such detailed
VO, and geometric terrain assessment) [9].            command sequences necessitate an assumption of
                                                      the rover’s state and resources throughout the en-
Curiosity inherited its VO-based capabilities for
                                                      tire daily plan. Since such knowledge is uncertain
online slip detection and improved state estima-
                                                      (especially for long command sequences), highly
tion from the MER program [10]. Although rela-
                                                      conservative estimates are often made, resulting in
tively simple to measure once it is happening, slip
                                                      a recurrent under-use of the rover’s time and en-
is very hard to predict from vision data only. Mis-
                                                      ergy. On “traverse” sols (when driving is the main
sion planners have therefore largely relied upon
                                                      activity), these issues can be mitigated to some
empirical ‘slip versus slope’ curves, for bedrock,
                                                      extent by leveraging Curiosity’s navigation auton-
cohesive soil, and loose sand, derived from ter-
                                                      omy capabilities (which enable goal-driven driv-
restrial experiments in simulated Martian environ-
                                                      ing). On long traverses, it remains the case that
ments [11].
                                                      safety margins (for example attitude boundaries,
                                                      maximal slip, or wheel current draw) tend to be
3     LONG-DISTANCE NAVIGATION                        conservative and can slow the mission down.
      CHALLENGES                                      Another operational difficulty arises from the dif-
As with any robotic exploration mission in an         ference in the rotation periods of the Earth and
uncontrolled and partially unknown environment,       Mars (a day on Mars is 37 minutes longer than a
a number of unexpected factors may affect mis-        day on Earth). Because tactical planners normally
sion execution or lead to outcomes different from     operate during daytime hours on Earth, the contin-
those initially anticipated. In the case of MSL,      uously varying time difference between Pasadena
two key parameters for evaluating mission perfor-     (where the NASA Jet Propulsion Laboratory is lo-
mance are the number of soil samples success-         cated) and Gale Crater generates recurrent ineffi-
fully analyzed by the onboard laboratory and the      cient periods. For example, if the uplink window
total distance driven [7]. Initially, mission plan-   at the end of the day on Earth occurs near the end
ners anticipated that Curiosity should be capable     of the day on Mars, Curiosity will have to wait un-
of driving 18 kilometres and analyzing 11 sam-        til the following sol to execute the requested tasks.
ples within its warranty period (the first 687 sols   This leads to a “restricted sol,” during which few
of the mission). However, as of sol 1237, almost      or no activities can be scheduled (since the tacti-
twice the mission’s warranty period, the rover’s      cal planners have to wait for Curiosity to finish the
onboard laboratory had just analyzed its 12th sam-    assigned tasks and communicate with Earth).
ple, and it had traversed less than 12.9 kilometres
[3, 12]. Although there is no doubt that the MSL
mission has been highly successful, such a realiza-   3.2   Environmental Factors
tion raises questions about what factors, exactly,    The highly heterogeneous Martian terrain may be
may have contributed to slower overall navigation     the most significant element affecting the navi-
progress (besides those purely related to various     gation abilities of current rovers. Although Cu-
science campaigns), and how their impact can be       riosity was designed to handle sandy, hard, and
reduced in future missions. The following sub-        rocky terrains better than the MERs, it was not in-
sections provide an overview of contributing op-      tended to be driven over sharp embedded rocks
erational and Martian environmental factors.          (formed through wind erosion and called “ven-
                                                      tifacts”). Driving over such rocks early in the mis-
3.1   Operational Factors                             sion resulted in numerous punctures to Curiosity’s
                                                      wheels, which in turn has dramatically changed
In 2016, a study of the various mission aspects
                                                      how the rover is driven on Mars [14].
influencing the productivity of the MSL opera-
tions group was conducted, with the goal of reduc-    One resulting change involves driving more in
ing the quantity of labor-intensive planning tasks    sandy environments, to avoid concentrated loads
and improving current and future mission perfor-      on the wheels as much as possible—the gen-
mance levels [13]. A key element that stood out       eral result is lower driving distances per sol.
from the study is that, because Curiosity has very    This is particularly the case during the traverse
little computational power and limited general au-    of megaripples, which are aeolian sand accu-
tonomy [9], the commands uplinked to the rover        mulations covered by a coarser sand layer [15].
The successful crossing of megaripples including        the environment. This type of sensing is used ex-
Dingo Gap and Moon Light Valley, and the fail-          tensively by Curiosity whenever it arrives at a new
ures experienced in Hidden Valley, revealed that        site: imagery provides dense details about the spa-
the traversability of such formations is influenced     tial content around the rover. As such, efforts to
by both their geometry (shape, wavelength and           extract useful information from these data involve
amplitude) and their material properties. The ex-       vision-based terrain classification. At present, due
act material properties cannot be determined by         to the low processing power on board Curiosity,
the rover itself and are very difficult for mission     dense image processing must happen on Earth.
planners to infer remotely.
                                                        One of the solutions to the accelerated wheel dam-
Similar traversability issues were encountered          age issue on MSL was the development of a risk-
several times by the MERs on sandy terrain. For         aware navigation planning tool to assist tactical
example, Opportunity remained stuck in the Pur-         operations and reduce risks associated with hu-
gatory dunes for 38 sols and took six sols to           man errors [20]. The goal of this work was to
leave the Jammerbugt ripple [16]. Orbital im-           easily distinguish safe and hazardous terrain (es-
agery was later used to identify additional fields of   pecially embedded sharp rocks), and plan safe
large ripples, requiring the rover to make several      paths based on the physical configuration of the
detours. Unforeseen terrain properties, in fact,        surrounding ground and the detected local ter-
brought Spirit’s mission to an end: in April 2009,      rain types. A random forest-based algorithm was
the rover broke through a poorly cemented thin          used to classify NAVCAM (navigation camera)
crust and embedded itself into unconsolidated soil      images, categorizing each pixel as belonging to
[17], where it remained trapped.                        one of five terrain types. These terrain types were
                                                        determined using a set of meaningful intensity and
Operating a solar powered-rover on the Red
                                                        gradient-based features extracted from the spatial
Planet adds another source of vulnerability. En-
                                                        context around each pixel in each image. The ran-
ergy availability became a major constraint when
                                                        dom forest architecture was suitable for this task,
planning activities for the MERs [18] after their
                                                        primarily because of its speed of execution, in-
missions extended beyond their warranty periods.
                                                        herent robustness to irrelevant or noisy data, and
Energy generation rates are heavily influenced by
                                                        ability to capture nonlinear relationships between
the opacity of the atmosphere, the amount of dust
                                                        features (which are common in planetary environ-
covering the solar panels, and the frequency of
                                                        ments). The classified image data were finally
natural cleaning events caused by the wind [19].
                                                        combined with more traditional attitude-related
In addition, as the seasons change, the paths uti-
                                                        constraints in a random geometric graph frame-
lized by the MERs must be adjusted due to the
                                                        work, to find optimal, safe paths that considered
change in the maximal elevation of the sun in the
                                                        the placement of the rover’s wheels.
sky. The typically lower energy levels limit the
activities that can be accomplished in a single sol,    A more modern terrain classification approach
while also decreasing the amount of data that can       was employed as part of the Mars 2020 landing
be downlinked to Earth [6].                             site selection campaign. The Mars Reconnais-
                                                        sance Orbiter is equipped with the High Resolu-
4     RECENT RELEVANT WORK                              tion Imaging Science Experiment (HiRISE) cam-
                                                        era, which is able to capture images of the Mar-
Based on the issues raised in the previous section,     tian surface with a resolution of 25 centimetres
it is clear that increased situational awareness and    per pixel. Although downsampled or cropped
effective energy modelling would allow for bet-         HiRISE images are used on a regular basis by mis-
ter predictions of the behaviour of a rover as it       sion planning teams, it is impossible for humans
is navigating; in turn, a more productive use of        to thoroughly inspect large areas (i.e., Mars 2020
battery resources would be possible. This section       landing site candidates) at the full resolution. The
presents a selection of recent research that could      Soil Property and Object Classifier (SPOC) sys-
potentially contribute to an increase of navigation     tem, built on a convolutional neural network, was
autonomy under energy constraints.                      trained to assign one of 17 terrain classes to each
                                                        HiRISE pixel. SPOC was able to achieve high ac-
4.1   Increased Situational Awareness                   curacy with only very sparse training labels sup-
Passive exteroceptive sensors, such as cameras,         plied by humans experts [21].
perceive natural electromagnetic radiation from
A separate SPOC deep classifier with a similar ar-       velocity profiles using a virtual rover model on
chitecture was trained with MSL NAVCAM data,             simulated terrains [23]. An estimate of energy
and then used to annotate images taken on sols           consumption can easily be computed from these
0 to 938. The results were correlated with thou-         values. Such simulations are however computa-
sands of previously-recorded MSL slip events, for        tionally expensive and are not suitable for use in
each terrain type, and compared to the empiri-           an optimization framework. More ‘convenient’
cal Earth-based slip versus slope curves used by         energy models are required for long-distance nav-
tactical planners. As expected, the slip versus          igation planning.
slope data retrieved from Martian traverses were
                                                         Sakayori et al. have suggested a deep learning-
slightly different from the Earth-calibrated mod-
                                                         based approximation [24] to the terramechanics
els, except for the case of sand, where the differ-
                                                         simulations for rovers driving on sandy inclines.
ences were dramatic. Once again, this is mainly
                                                         The authors used the Wong-Reece wheel-soil in-
due to the failure of vision-based methods to fully
                                                         teraction equations and the dynamic model of a 4-
characterize sandy soil.
                                                         wheeled rover to generate a set of predetermined
In order to resolve the inability to predict slip        terrain and robot configurations and the corre-
on sandy terrain, a different exteroceptive sensing      sponding theoretical energy consumption values.
technique has recently been suggested: thermal           These data were used to train a feedforward neu-
measurements of the ground, from which thermal           ral network to output power consumption based
inertia can be derived. The thermal inertia of a         on three input parameters: the rover’s target ve-
sandy terrain describes the rate at which the ter-       locity, its heading angle, and the slope angle of the
rain gains or loses heat relative to the surrounding     local terrain. The high accuracy achieved by the
environment. This property is strongly character-        network was heavily influenced by the assump-
ized by the physical characteristics of the sand,        tion that the simulated sandy environment was
such as density, particle size distribution, cemen-      uniform; however, this network concept could be
tation and others. Cunningham et al. [22] re-            readily extended to incorporate soil mechanical
cently demonstrated that considering thermal iner-       properties as inputs.
tia can increase slip prediction accuracy on sandy
                                                         A similar idea for reducing computations related
terrain. Although thermal inertia estimates from
                                                         to energy consumption is presented in [25]. In-
orbital data have already been used to assess gen-
                                                         stead of direct calculation, a series of lookup ta-
eral traversability, work in [22] represents the first
                                                         bles store energy consumption values for differ-
use of in-situ measurements for this purpose. The
                                                         ent ‘bins’ of slope angle and terrain type, ob-
intuition behind the correlation between thermal
                                                         tained from dynamic and terramechanics simula-
inertia and traversability is that, at Martian at-
                                                         tions. The bin reference values are used in con-
mospheric pressure, the physical factors affecting
                                                         cert with solar energy generation predictions (de-
thermal inertia are also key factors influencing the
                                                         pendent on the alignment of the rover’s top plate
amount of slip experienced by a rover on gran-
                                                         normal with respect to the sun) to provide an en-
ular terrain. The work in [22] presented a two-
                                                         ergy profile for a given, discretized path. In this
experts model approach (considering both thermal
                                                         case, the optimality of a path depends on the net
inertia and terrain slope) for in-situ thermal mea-
                                                         energy balance, path length, and a risk factor (re-
surement (using Curiosity’s ground temperature
                                                         lated to the terrain configuration). Similar to [24],
sensor) and orbital measurement (using the Mars
                                                         this framework can also be applied to real-world
Odyssey spacecraft’s thermal imager). For each
                                                         platforms.
case, a threshold value separating low from high
thermal inertia sand and a slip versus slope curve       A great deal of work to date has focused on pro-
for each regime were learned. This model exhib-          ducing energy models and maps from empirical
ited a lower error than the traditional single-expert    data collected by proprioceptive sensors on board
model, which only considers terrain slope.               planetary rovers. Although such models are typ-
                                                         ically biased towards simple terrain types in the
                                                         context of real missions because of safety con-
4.2   Energy Models                                      cerns, they generally offer accurate terrain rep-
Existing wheel-soil interaction simulators such as       resentations and mobility predictions. Research
the Adams-based Rover Terramechanics and Mo-             by Martin et al. [26] has examined methods to
bility Interaction Simulator (Artemis) can already       generate energy-optimal paths by driving through
provide an estimate of required wheel torques and
an unknown environment several times and post-          tactical planners in the context of the MSR mis-
processing the gathered data. The energy cost of        sion. Better integration of the strategic and tac-
a path is represented as a function of parameters       tical teams during long-distance optimal naviga-
related to mobility (rover velocity, terrain config-    tion planning would reduce reactivity and improve
uration) and includes a constant energy sink defin-     predictability.
ing the power needs of the internal rover com-
                                                        An efficient use of the resources on board the
ponents. Since power consumption data points
                                                        MSR fetch rover will be vital to the success of the
are collected along discrete paths in a continu-
                                                        mission. To achieve this, more accurate empirical
ous space, gaussian process regression is used for
                                                        energy models for predicting energy consumption
interpolation purposes and to provide an under-
                                                        and generation will need to be employed. More
standing of where detail is lacking in the path
                                                        efficient use of the rover’s time will also be highly
map. This information is used incrementally dur-
                                                        valuable—this may be accomplished by carrying
ing the exploration phase until optimal planning
                                                        out navigation planning for multiple sols in a row,
across the whole space is possible. The approach
                                                        lessening the impact of restricted sols, solar con-
has been demonstrated (statistically) on simulated
                                                        junctions, reduced planning efforts during week-
flat terrains and through simplified tests in natural
                                                        ends or holidays, and other inefficiencies. Multi-
environments [27].
                                                        sol navigation with solar-powered rovers will re-
Otsu et al. [28] have also analyzed ways to ex-         quire a dynamic activity planner to prioritize dif-
ploit proprioceptive measurements, developing a         ferent tasks (driving along energy-optimal paths,
self-supervised learning framework that uses vi-        stopping to replenish batteries, selecting a proper
bration data to train a system to associate visual      location to “sleep” for the night, etc.) and to main-
information with energy consumption. A SVM-             tain robustness against varying energy generation
based terrain classifier is first trained on features   rates. Goal-driven planning and online task prior-
extracted from processed time-series acceleration       itization has recently been investigated in [29].
signals (in a supervised manner) to identify dif-
                                                        It is also important to note that greater levels
ferent terrain types. Separately, linear regression
                                                        of autonomy, through improved online situational
(with two parameters only) is applied to fit em-
                                                        awareness (via exteroceptive sensing) and/or in-
pirical energy versus slope data for each terrain
                                                        cremental energy model learning, may be possi-
type. The linear relationship is based on several
                                                        ble over the next decade with the development of
assumptions: the rover drives at constant veloc-
                                                        space-qualified Field Programmable Gate Arrays
ity and the traversable slope is limited and de-
                                                        (FPGAs). These co-processors are expected to ac-
forms linearly. A vision-based classifier is then
                                                        celerate image processing through parallel com-
trained with the output of the vibration terrain
                                                        puting on board the Mars 2020 rover [30].
classifier, to identify visible soil types. Combined
with the corresponding terrain slope information,       Lastly, our laboratory is currently developing
energy consumption can then be predicted. This          methods to improve solar rover autonomy in
approach has been successfully tested using a real      Martian environments by incorporating empirical
rover platform on three different soil types across     rover energy consumption information with or-
multiple terrains with different slope angles.          bital data, including thermal inertia maps, digi-
                                                        tal elevation models, and imagery pre-categorized
                                                        with identified terrain classes. These techniques
5   DISCUSSION                                          will be tested on real rover platforms and will
The recent research presented in the last sec-          be validated in several Martian analogue environ-
tion may lead to new opportunities for sustain-         ments on Earth.
able long-distance navigation planning with solar-
powered rovers such as the MSR fetch rover. In
the past, detailed navigation planning at the strate-   6   CONCLUSION
gic level has been very restricted due to the limited   In summary, long-distance planetary navigation
amount of information provided by orbital data.         involving solar-powered rovers will be critically
Now, with the ability of algorithms such as SPOC        important in the next decade, especially for
to provide richer information about the Martian         NASA’s upcoming Mars Sample Return mission.
terrain, more reliable planning is possible from        This paper highlighted the operational and ex-
orbital imagery. Identifying preliminary and then       traterrestrial environmental factors limiting the
global energy-optimal paths could better inform         current mobility planning framework, and re-
viewed recent work tackling issues related to situ-        the MER Tactical Uplink Process. In: Proc.
ational awareness and improved energy models.              AIAA SpaceOps Conf., Rome, Italy.
A more detailed analysis of energy-efficient and       [7] Grotzinger JP, Crisp J, Vasavada AR, Ander-
long-distance navigation in a completely au-               son RC, Baker CJ, Barry R, Blake DF, Con-
tonomous manner could extend the current survey.           rad P, Edgett KS, Ferdowski B et al. (2012)
The present paper did not report on this specific          Mars Science Laboratory Mission and Sci-
research area, in order to keep the discussion fo-         ence Investigation. In: Space Science Re-
cussed on existing operational processes and flight        views, 170(1–4):pp.5–56.
hardware limitations.
                                                       [8] Goldberg SB, Maimone MW and Matthies
Acknowledgements                                           L (2002) Stereo Vision and Rover Navi-
This work was supported in part by the Natu-               gation Software for Planetary Exploration.
ral Sciences and Engineering Research Council              In: Proc. IEEE Aerospace Conf. (AERO’02),
(NSERC) of Canada. The authors wish to thank               volume 5, Big Sky, Montana, USA,
Dr. Masahiro Ono and Dr. Kyohei Otsu from the              pp.2025–2036.
NASA Jet Propulsion Laboratory for their invalu-       [9] Maimone M (2016) A Martian Vision: Im-
able advice regarding ongoing research, which              pact of JPL Robotics Vision and Mobil-
greatly assisted in the writing of this paper.             ity Research on the Mars Rovers.        In:
References                                                 JPL Robotics Section Senior Lecture Series,
                                                           NASA Jet Propulsion Laboratory, Pasadena,
 [1] Mars 2020 Mission Overview. Available                 California, USA.
     at: https://mars.nasa.gov/mars2020/
     mission/overview/. Accessed: 2018-04-            [10] Maimone M, Cheng Y and Matthies L
     10.                                                   (2007) Two Years of Visual Odometry on
                                                           the Mars Exploration Rovers. In: J. Field
 [2] Mattingly R and May L (2011) Mars Sam-                Robot., 24(3):pp.169–186.
     ple Return as a Campaign. In: Proc. IEEE         [11] Heverly M, Matthews J, Lin J, Fuller D,
     Aerospace Conf. (AERO’11), Big Sky, Mon-              Maimone M, Biesiadecki J and Leichty J
     tana, USA, pp.1–13.                                   (2013) Traverse Performance Characteriza-
                                                           tion for the Mars Science Laboratory Rover.
 [3] The Navigation and Ancillary Infor-                   In: J. Field Robot., 30(6):pp.835–846.
     mation Facility (NAIF). Mars Science
     Laboratory Project Kernel.  Available            [12] Sutter B, Mcadam AC, Mahaffy PR, Ming
     at:      https://naif.jpl.nasa.gov/                   DW, Edgett KS, Rampe EB, Eigenbrode JL,
     pub/naif/MSL/kernels/.      Accessed:                 Franz HB, Freissinet C, Grotzinger JP et al.
     2018-04-01.                                           (2017) Evolved gas analyses of sedimentary
                                                           rocks and eolian sediment in Gale Crater,
 [4] Wong C, Yang E, Yan XT and Gu D (2017)                Mars: results of the Curiosity Rover’s Sam-
     Adaptive and Intelligent Navigation of Au-            ple Analysis at Mars (SAM) instrument from
     tonomous Planetary Rovers – A Survey. In:             Yellowknife Bay to the Namib Dune. In: J.
     Proc. NASA/ESA Conf. Adaptive Hardware                Geophys. Res, 122(12):pp.2574–2609.
     and Systems (AHS’17), Pasadena, Califor-
                                                      [13] Gaines D, Anderson R, Doran G, Huff-
     nia, USA, pp.237–244.
                                                           man W, Justice H, Mackey R, Rabideau G,
                                                           Vasavada A, Verma V, Estlin T et al. (2016)
 [5] Chattopadhyay D, Mishkin A, Allbaugh
                                                           Productivity Challenges for Mars Rover Op-
     A, Cox ZN, Lee SW, Tan-Wang G and
                                                           erations. In: Proc. AAAI Int. Conf. Auto-
     Pyrzak G (2014) The Mars Science Lab-
                                                           mated Planning and Scheduling (ICAPS’16)
     oratory Supratactical Process. In: Proc.
                                                           Workshop on Planning and Robotics (Plan-
     AIAA SpaceOps Conf., Pasadena, California,
                                                           Rob), London, United Kingdom, pp.115–
     USA.
                                                           125.

 [6] Mishkin A and Laubach S (2006) From              [14] Lakdawalla E (2014) . Curiosity wheel
     Prime to Extended Mission: Evolution of               damage:    The problem and solutions.
Available at: http://www.planetary.              [22] Cunningham C, Whittaker WL and Nes-
     org/blogs/emily-lakdawalla/2014/                      nas IA (2017) Improving Slip Prediction on
     08190630-curiosity-wheel-damage.                      Mars Using Thermal Inertia Measurements.
     html. Accessed: 2018-04-12.                           In: Proc. Robotics: Science and Systems
                                                           (RSS’17), Cambridge, Massachusetts, USA.
[15] Arvidson RE, Iagnemma KD, Maimone M,
     Fraeman AA, Zhou F, Heverly MC, Bel-             [23] Zhou F, Arvidson RE, Bennett K, Trease
     lutta P, Rubin D, Stein NT, Grotzinger JP             B, Lindemann R, Bellutta P, Iagnemma K
     et al. (2017) Mars Science Laboratory Cu-             and Senatore C (2014) Simulations of Mars
     riosity Rover Megaripple Crossings up to              Rover Traverses.    In: J. Field Robot.,
     Sol 710 in Gale Crater. In: J. Field Robot.,          31(1):pp.141–160.
     34(3):pp.495–518.                                [24] Sakayori G and Ishigami G (2017) Energy
                                                           Efficient Slope Traversability Planning for
[16] Arvidson RE, Ashley JW, Bell J, Chojnacki             Mobile Robot in Loose Soil. In: Proc. IEEE
     M, Cohen J, Economou T, Farrand WH, Fer-              Int. Conf. Mechatronics (ICM’17)), Gipps-
     gason R, Fleischer I, Geissler P et al. (2011)        land, Victoria, Australia, pp.99–104.
     Opportunity Mars Rover mission: Overview
     and selected results from Purgatory ripple to    [25] Fallah S, Yue B, Vahid-Araghi O and Khaje-
     traverses to Endeavour crater. In: J. Geo-            pour A (2013) Energy Management of Plan-
     physical Res., 116(E7).                               etary Rovers Using a Fast Feature-Based
                                                           Path Planning and Hardware-in-the-Loop
[17] Arvidson RE, Bell J, Bellutta P, Cabrol               Experiments. In: IEEE Transactions on Ve-
     NA, Catalano J, Cohen J, Crumpler LS,                 hicular Technology, 62(6):pp.2389–2401.
     Des Marais D, Estlin T, Farrand W
                                                      [26] Martin S and Corke P (2014) Long-Term
     et al. (2010) Spirit Mars Rover Mission:
                                                           Exploration & Tours for Energy Con-
     Overview and selected results from the
                                                           strained Robots with Online Propriocep-
     northern Home Plate Winter Haven to the
                                                           tive Traversability Estimation. In: Proc.
     side of Scamander crater. In: J. Geophys.
                                                           IEEE Int. Conf. Robotics and Automation
     Res, 115(E7).
                                                           (ICRA’14), Hong Kong, China, pp.5778–
[18] Bresina JL, Jónsson AK, Morris PH and                5785.
     Rajan K (2005) Activity Planning for the         [27] Martin S and Corke P (2015) Long Term Op-
     Mars Exploration Rovers. In: Proc. AAAI               timisation of a Mobile Robot with Proprio-
     Int. Conf. Automated Planning and Schedul-            ceptive Perception. In: Proc. Australasian
     ing (ICAPS’05), Monterey, California, USA,            Conf. Robotics and Automation (ACRA’15),
     pp.40–49.                                             Canberra, Australia.

[19] Landis GA (2005) Exploring Mars with             [28] Otsu K and Kubota T (2016) Energy-aware
     Solar-powered Rovers. In: Proc. IEEE                  terrain analysis for mobile robot explo-
     Photovoltaic Specialists Conf., Lake Buena            ration. In: Field and Service Robotics, vol-
     Vista, Florida, USA, pp.858–861.                      ume 113 of Springer Tracts in Advanced
                                                           Robotics, pp.373–388.
[20] Ono M, Fuchs TJ, Steffy A, Maimone M and
                                                      [29] Gaines D, Rabideau G, Doran G, Schaffer
     Yen J (2015) Risk-aware Planetary Rover
                                                           S, Wong V, Vasavada A and Anderson R
     Operation: Autonomous Terrain Classifica-
                                                           (2017) Expressing Campaign Intent to In-
     tion and Path Planning. In: Proc. IEEE
                                                           crease Productivity of Planetary Exploration
     Aerospace Conf. (AERO’15), Big Sky, Mon-
                                                           Rovers. In: Proc. Int. Workshop on Plan-
     tana, USA, pp.1–10.
                                                           ning and Scheduling for Space (IWPSS’17),
[21] Rothrock B, Kennedy R, Cunningham C,                  Pittsburgh, Pennsylvania, USA.
     Papon J, Heverly M and Ono M (2016)              [30] Seablom MS (2016) Computing Advances
     SPOC: Deep Learning-based Terrain Classi-             to Enable Speedy New Rover on the Red
     fication for Mars Rover Missions. In: Proc.           Planet. In: 2015 Science Mission Direc-
     AIAA SPACE Forum, Long Beach, Califor-                torate Technology Highlights, pp.25–26.
     nia, USA.
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