cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.48577/jpl.ofx0gk
title: Passive Positioning, Navigation, and Timing (PPNT) in Cislunar Space using Earth-based Transmitters

description: We study the feasibility of a passive system for Positioning,Navigation, and Timing (PPNT) in the cislunar environment.The signal structure and position estimation procedureare inspired by the Global Positioning System (GPS), with themain difference being the makeup and location of the transmitters.Cislunar PNT utilizing sidelobe transmissions fromGPS satellites, i.e., “weak GPS”, was studied in prior work andit was shown to achieve a one-shot estimation error between200 and 300 meters under the assumption that the individualpseudorange errors do not exceed 5cm.In contrast, we consider a system in which a set of Earth-basedtransmitters continuously transmit a PN ranging signal similarin structure to the GPS signals, but in a dedicated frequencyband. A receiver in cislunar space must acquire and tracksignals from four separate transmitters before solving for itsposition and time offset via multilateration. Similar to theweak GPS concept, this system provides a passive PNT solutionfor vehicles in cislunar space. We assume that the receiver isderived from state-of-the-art GPS receivers and is modified tooperate in a dedicated frequency band. The main trade space forthis system consists of the location, output power, and antennagain of the ground transmitters. Intuitively, compared to theweak GPS concept, an Earth-based transmitter should allowfor increased output power and antenna gain when comparedto a GPS satellite, resulting in increased SNR and thus a lowerpositioning error. However, the decreased maximum distancebetween two transmitters in the PPNT scenario results in lessfavorable geometry and increased position dilution of precision(PDOP), causing an increase in the positioning error. In thispaper, we study these aspects of the trade space in detail, with aspecific focus on the impact of the transmitter-to-user geometry,i.e., PDOP, on the positioning error.The main findings of this study can be summarized as follows.First, due to the limited maximum inter-transmitter distanceof PPNT systems, the PDOP of PPNT systems is about oneorder of magnitude larger than the PDOP of weak GPS. Second,the performance of a PPNT system depends on the pointingstrategy used. If a receiver falls out of the main lobe of theground transmitters, performance is severely degraded. A weakGPS-based approach outperforms PPNT with naïve pointing,i.e., with all transmitters pointing their main lobes towardsthe moon, for most reasonable power levels. However, if thetransmitters can keep the receiver with their main lobes, PPNTsystems outperform weak GPS due to the advantage in SNR. Inthis case, a PPNT system is limited only by the decrease in PDOPand the combined effect of atmospheric and control segmenterrors; the SNR does not present a limit.
DOI: 10.48577/jpl.hr2ifp
title: Development of an Uplink Array Radar System for Cis-Lunar and Planetary Observations

description: Due to the monolithic antenna design of the Goldstone Solar System Radar (GSSR), the transmitter power of the GSSR can only be increased by installing higher power klystrons, which are likely reaching their limit around 250 kW. By contrast, the Phased Array Transmitter concept is a distributed system that coherently combines X-band signals from multiple 34 m antennas at the target, producing a reliable high power radar system that can serve as a viable backup to the GSSR. As described in this paper, our goal is to demonstrate a high-power wideband Phased Array Transmitter concept to meet requirements for planetary science, planetary defense, and cis-lunar space domain awareness, by configuring two of the Deep Space Network’s (DSN) 34 meter antennas, namely DSS-13 and DSS-26, as an Uplink Array Radar system.
DOI: 10.48577/jpl.f9zcgz
title: RELAY PLANNING IN THE PERSEVERANCE ROVER’S FIRST 600 SOLAR DAYS ON MARS

description: Since landing in Jezero Crater on Mars on February 18, 2021, the Mars 2020 mission’s Perseverance rover has been performing daily operations on the Martian surface and has been collecting samples that may one day be returned to Earth. The majority of science and engineering data from the Perseverance rover is returned through the Mars orbiters operated by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) that make up the Mars Relay Network: Mars Reconnaissance Orbiter (MRO), Mars Odyssey (ODY), Mars Atmosphere and Volatile Evolution (MAVEN), and Trace Gas Orbiter (TGO). Prior to the rover’s landing, the Mars 2020 team joined the Mars Relay Network to begin planning relay through the coordinated, multi-mission process that is the cornerstone of relay planning. The Perseverance rover has now been on the Martian surface for more than 600 Martian solar days (“sols”) with several UHF relay sessions planned and executed per sol. The Mars 2020 relay planning team has established and improved upon the recurring process and tool suite to enable both data return and forward link of rover uplink products, and continues to coordinate and negotiate relay asset usages and constraints with the Mars Science Laboratory and Insight relay planning teams. Among many accomplishments, the relay planning team has supported checkouts and commissioning of Low-Density Parity-Check (LDPC) relay link configurations, the mission’s first solar conjunction period, and several rover flight software transitions.The Mars 2020 team has also been performing a checkout and commissioning campaign for the use of bitstream, or “unreliable”, relay sessions. Nominal use of bitstream relay is a new operational capability intended for the Perseverance rover that will allow specific science or engineering activities to run in parallel with the relay session, rather than pausing all other activities during relay, enabling additional and more timely data return. Pending the completion of the checkout and commissioning campaign, the operations team plans to approve and begin regular scheduling and use of bitstream UHF relay sessions beginning in 2023. This paper describes the Mars 2020 relay planning processes and tool architecture, key accomplishments (including progress for the bitstream checkout and commissioning campaign), and lessons learned and ongoing challenges during the first 600 sols of the Mars 2020 surface mission.
DOI: 10.48577/jpl.7qgsmp
title: Europa Clipper Payload Verification and Validation: Instrument Delivery into System Integration

description: NASA’s Europa Clipper mission is designed to investigate the habitability of the Jovian moon Europa with a suite of 10 science instruments. The project is now past its project system integration review and in the middle of instrument deliveries to Assembly, Test, and Launch Operations (ATLO). The payload verification and validation (V&V) program is thus in the process of receiving and auditing instrument-provided verification evidence, executing the payload-level software interface testing campaign, and beginning a series of checkouts on the flight instruments in ATLO. Previous work described the set of planned verification activities that we developed to ensure consistent V&V coverage across all of the instruments, at the instrument, payload, and ATLO levels. This paper describes the implementation of that plan, including statistics on scope of the work and its execution, adjustments/additions to the original plans, how the team managed priorities with limited resources, and other lessons learned. We first describe the payload V&V oversight of instrument-level verification item closures. We describe the assessments performed to determine V&V status at instrument deliveries, and how we managed shortfalls and workload. We then describe the software interface V&V campaigns that the payload team is executing, summarizing the verification work and resources required to perform it. Finally, we describe the V&V role in post-delivery activities for the instruments include a summary of pre-ATLO (PATLO) testing and early ATLO activities. We conclude the paper by reflecting on how the executed V&V program compared to the planned program, and what strengths and challenges the program as designed offered in the execution phase. We then briefly summarize the work remaining as the payload V&V program enters its final phases prior to launch.
DOI: 10.48577/jpl.wc6foo
title: Preparing for a Productive Low Power Future on the Curiosity Rover

description: Power operations are crucial to the efficiency of the Mars Science Laboratory (MSL) Curiosity rover. The rover’s ability to perform experiments and make progress along the drive path is directly limited by the available energy. The degrading power source required a change to operations to ensure a productive future. The team updated modeling of expected energy consumption of nominal rover activities and increased the modeled battery capacity by 15\% points. On board the rover the team reduced daily energy consumption of communications hardware by 3\% state of charge, and reduced cell spread on the battery by over 100 mV. From these improvements, the team saw an average decrease of 50 Whrs of wasted energy per sol, and an average improvement of 10\% in modeled state of charge. Modeling of the next extended mission proved that MSL can continue productive science operations for the next two Martian years.
DOI: 10.48577/jpl.6n0aoj
title: M2020 Rover Heater Energy Correction Factors for Improving Mission Operations

description: In the year since NASA’s Perseverance Rover landedon Mars, it reached many noteworthy milestones despite theharsh thermal environment where ambient temperatures oftendip below -80°C. Perseverance’s accomplishments includesurpassing the record distance driven on Mars within a MartianSol, successfully acquiring multiple rock samples, collectingthousands of images, and enabling the first powered flight onanother planet. In order to successfully execute these activitiesand ensure hardware safety in this frigid environment,Perseverance’s instruments and actuators must be heated suchthat the components reach and remain within operationalallowable flight temperatures (AFTs). To bring temperatures tooperational AFTs, a prescribed preheat is applied prior to thestart of the planned activity. The prescribed preheat includes aheating duration and the target temperatures necessary for thecomponent, including the internal parts not monitored bytemperature sensors, to reach operational AFTs. Should thecomponent not reach its target temperature within theprescribed preheat duration, Perseverance cannot perform thevaluable science activity planned for that Sol. Therefore, thepreheat command arguments are based off of a conservativethermal model that assumes a worst-case cold environment toguarantee a successful preheat regardless of the roverorientation with respect to the sun, high wind speeds, andvarying dust coverage. By adopting this conservative stance onpreheats, the rover planners also consequently allocate moreenergy to preheats than what is actually used. On certain Sols,this over-allocation can exceed 100Whr; all of which could haveinstead been allocated to other rover activities. To address thechallenge of balancing accurate preheat energy estimates withthe requirement to ensure successful preheats, the thermalsubsystem has developed energy correction factors based onPerseverance’s actual preheat energy usage. By focusing oncorrecting the energy estimates rather than adjusting thesequenced preheat duration or target temperature, the thermalteam balances a strict mission risk posture with the need tomaximize mission science return and efficiently allocate energy.This paper focuses on how the energy correction factors weredeveloped; the verification and validation of these energyfactors with flight data; and the energy correction factors'impact on rover planning.
DOI: 10.48577/jpl.ec7goh
title: Leveraging Ingenuity Software and Avionics to Enable Robotic Arm Sampling for COLDArm

description: The Cold Operable Lunar Deployable Arm (COLDArm)project is developing an experimental robotic arm with the goalof demonstrating cold-operable actuators and sensors in a lunartechnology demonstration, saving energy and mass over con-ventionally heated systems. To support this goal, the JPL teamdeveloped new flight software and avionics to demonstrate keyfunctional manipulation capabilities. Drawing on the successfulIngenuity Mars Helicopter, significant avionics and softwareelements were leveraged as a starting point and modified to suitthe needs of COLDArm.
DOI: 10.48577/jpl.j5mnjc
title: MySQL-Based Automation for Checking Mars Science Laboratory Communications Windows

description: The Mars Science Laboratory (MSL) Telecom OperationsTeam at the Jet Propulsion Laboratory (JPL) has implementedan automated system for checking Comm BehaviorManager (CBM) window load sequences. CBM manages MSL’sTelecommunications subsystem, and CBM windows are definedperiods of time when the MSL spacecraft communicates eitherwith Mars orbital assets via UHF or directly with Earth via XBand.CBM windows must be verified against a long list of flightrules in order to enforce proper configuration of the Telecomsubsystem and to ensure the spacecraft is operated in a safeway throughout the pass. In addition, the windows are verifiedagainst corresponding orbiter Telecom configurations for UHFpasses or ground station configurations for X-Band passes inorder to confirm agreement on both sides of the link. Errorsin timing, geometry, or hardware configuration will result in afailed communication session, potentially preventing uplink ofcommands to the rover or delaying the return of critical data tothe ground. Due to the complexity of the process in which dozensof windows must each be individually checked against manyflight rules and against corresponding Earth station or orbiterconfigurations and timings, manual verification is an arduoustask and highly susceptible to errors.The CBM window checking tool makes extensive use of aMySQL relational database to keep track of communicationswindows and to check their correctness in an automated andreliable way, eliminating many sources of error. Additionally,since CBM sequences must often be verified with a shortturnaround when real-time changes to parameters, configuration,and timing are required during operations, it is importantfor the checking process to be swift in addition to reliable.
DOI: 10.48577/jpl.agcifc
title: Investigating the Double-ITCZ Bias in CMIP6 Models

description: No abstract available.
DOI: 10.48577/jpl.etynqt
title: Electrospray Mass Spectrometry for In-Orbit Biomolecule Analysis

description: Here we describe a suite of experiments probing the ability of ESI propulsion sources to serve as TOF-MS ionization stages in pure vacuum operation. The goals of the study are to assess the operational parameter space which may result in biomolecules entrained in an ion spray, detectable by traditional mass spectrometry techniques. The variables explored in this work include working solvents EMI-BF4 and EMI-Am, and biomolecules arginine and cellulose. A laboratory ESI source is coupled with a TOF-MS capable of providing a mass resolution (m/dm) between 200 and 1000 for the ion range of interest (100-500 amu). Optimal methods of ionization and preliminary results measuring organics will be presented. Initial experiments indicate that cellulose may be detectable at high concentrations in EMI-BF4 while operation with EMI-Am may require heating above room temperature.
DOI: 10.48577/jpl.lrhct0
title: Ground Software to Support Autonomous Onboard Scheduling for Mars Perseverance Rover

description: The flight software for the Mars Perseverance Rover is capable of autonomous onboard scheduling. The goal of this capability is to reduce spacecraft idle time and unnecessary heating to leave more resources for science observations. Enabling this first-of-its-kind onboard scheduling requires tight coordination between the Mission Operations team, ground software, and flight software.This paper will focus on the ground software tools that have been created or enhanced by the Mars 2020 mission in support of autonomous onboard scheduling. The following challenges were encountered: automating the creation of planning constraints to reduce tedious and error-prone manual work, while providing enough flexibility for the team to handle unique scenarios; providing visibility to allow the Operations team to build trust in a variable execution system in a way that is digestible within a tight planning timeline; using flight software simulation to validate the files that will be sent to the spacecraft in a realistic manner, even though we cannot truly predict what will happen on the rover; after plan execution on the rover, analyzing the data returned from the spacecraft to understand what did happen, and being able to use that information to predict initial conditions for the next planning cycle.
DOI: 10.48577/jpl.mzgmxr
title: Playing Telephone Through Martian Rock: Assessing Terrain Occlusions to Enhance Telecom Predictions

description: As the Curiosity Mars rover has traversed through Gale Crater, a wide variety of terrain and rock formations have been observed. Earlier in the mission, the rover experienced relatively flat local terrain, with few hills or buttes in its immediate vicinity. As the rover traversed into the “clay-sulfate transition region,” the terrain changed dramatically to include higher elevation features. Despite the intrigue and beauty of these formations, their proximity to the rover can impact performance of both Ultra-High Frequency (UHF) and X-Band communication by physically occluding some or all of the link. This paper will describe and demonstrate a tool developed to assess the risk of terrain occlusions, enabling more accurate telecom predictions in addition to providing advanced knowledge of hardware visibility, both from Earth and from the orbiters at Mars. By utilizing Digital Elevation Models (DEMs) derived from images taken by the High Resolution Imaging Science Experiment (HiRISE) onboard the Mars Reconnaissance Orbiter (MRO), in addition to images from the High Resolution Stereo Camera (HRSC) onboard the Mars Express (MEX) orbiter, a horizon map of the surrounding terrain elevation can be produced at a localized rover position on the surface. The horizon map can then be compared to predicted Earth positions and predicted orbiter geometry during scheduled communication windows to assess the impact of terrain occlusions on those upcoming windows. During nominal operations, the rover utilizes its UHF radio to transmit telemetry to Mars-orbiting relay assets, which then return that data back to Earth. In addition, the rover utilizes its X-Band radio to receive commands directly from Earth via the Deep Space Network (DSN). However, occlusions of either antenna directly impact the planning timeline by delaying the return of critical data required for planning and/or forcing the team to relay commands to the rover via the orbiters. These deviations from the standard procedure almost always result in loss of one or more planning days and present uncommonly encountered risks. By providing invaluable situational awareness of the telecom subsystem in advance of daily planning, this terrain occlusion checking tool reduces the number of lost planning cycles, directly increasing science return.
DOI: 10.48577/jpl.sep8tn
title: Systems Test Strategies for the Psyche Orbital Operations Phase

description: Psyche, “Journey to a Metal World”, is a NASA Discovery-class mission led by principal investigator Dr. Lindy Elkins-Tanton of Arizona State University. The Maxar solar electric propulsion (SEP) chassis will carry Jet Propulsion Laboratory (JPL) avionics and a magnetometer from the Danish Technical University (DTU), multispectral imagers from Malin Space Science Systems (MSSS), and gamma ray and neutron spectrometers (GRNS) from the Johns Hopkins Applied Physics Laboratory (APL) to the presumed metallic asteroid 16 Psyche in the asteroid belt. The Deep Space Optical Communications (DSOC) tech demo will additionally be accommodated in the early mission.The spacecraft will fly through four progressively lower orbits once at the asteroid, utilizing the electric propulsion system to transfer between orbits. Each science orbit is designed such that it enables specific science goals, including global mapping, while operating all payloads concurrently. A testing strategy was developed to provide adequate verification and validation of science scenarios and capabilities while appropriately prioritizing testing based on the need date in the mission. The testing of payload-heavy scenarios is planned to be covered functionally by a blend of unit and functional testing on flight hardware and engineering models, and scenario testing on the flight hardware and system testbed. This paper will focus on the systems engineering process and explore how this strategy was both implemented and is evolving as testing continues. It will additionally discuss work to go in preparation for launch.
DOI: 10.48577/jpl.0qcuhb
title: Seasonal time-scale evolution of the sub-surface structure in the nucleus of comet 67P/Churyumov-Gerasimenko constrained with Rosetta

description: No abstract available.
DOI: 10.48577/jpl.3giv8f
title: Mars Science Laboratory R13 Mobility Regression Testing

description: Now in its 10th year of Operation on Mars, NASA’sCuriosity Rover is preparing to undergo a software update, onethat has been six years in the making. In order to qualify thisupdate for use on Mars, the flight software first needs to be runthrough a regression test campaign here on Earth. This paperdetails the regression testing efforts of the Mobility team as theyevaluated the performance of the rover’s driving capabilitiesunder this new Flight Software Upgrade - known as R13. Thistest campaign was conducted to ensure that all of the rover’smobility capabilities behave as expected, especially to check theparts that are “untouched” by R13 have not regressed inperformance, hence the term regression testing. Of 75 mobilitycommands, Curiosity has 18 commands that initiate motion andeach has a number of arguments and options that cancompletely change the rover’s traverse behavior. This leads to avast and complex problem space that is impossible toexhaustively explore, necessitating a regression test campaignthat targets key subsets of commands and arguments in orderto create the confidence needed to approve R13 for flight. Toconduct this testing, the Mobility Team spent 10 days in the JetPropulsion Laboratory’s (JPL) Mars Yard commanding theVehicle System Test Bed (VSTB) – Curiosity’s Earthboundtwin. The nominal performance for 11 of Curiosity’s motioninducingcommands was evaluated in addition to the FaultProtection behavior for 29 off-nominal cases that could occur inrelation to mobility activities. The off-nominal testing requiredcommanding the rover in a way that the Operations Team neverintentionally would on Mars, purposefully stalling motors,shutting down the rover mid-drive, and exceeding limits that arehopefully never reached in flight. The Mobility team’s 10 shifts,the most of any subsystem, created two significant challengesconsisting of staffing and data management. Unlike most otherspacecraft testbeds that spend their days in clean rooms,Curiosity’s drives around the Mars Yard and requires at leasttwo testers to operate. One of which commands the rover, andthe other who moves the umbilical cable that provides powerand communication between the command station and vehicle –a physically demanding task in the Southern California summerheat – leading to the often addition of a third tester to lightenthe load. After testing concluded, data from the tests wasanalyzed to confirm that the rover behaved as expected, and ifnot, what further testing or documentation would be requiredto proceed with approval for R13. Finally, the Mobility Teampresented their test results to the regression review board andthe test campaign was approved, bringing R13 one step closer torunning on Mars.