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In this paper we will examine NASA's strategy for relay communications support of missions planned for this decade, and discuss options for longer-term relay network evolution in support of second-decade missions.
After receiving global admiration for the Mars Science Laboratory (MSL) Curiosity rover, the Jet Propulsion Laboratory (JPL) is planning to embark upon another mobile mission to the red planet in the year 2020. Currently, the working name given to this sophisticated next-generation rover is Mars 2020. Mars 2020 will boast a multitude of newly developed instruments to aid in the scientific study of Mars. This paper will describe the process of testing one of the Mars 2020 instruments in the 25 ft. Space Simulator. The testing was performed at Mars CO2 atmospheric pressure of 7 Torr and consisted of multiple chamber evacuations and backfills. The Programmable Logic Control (PLC) system for the chamber was in the middle of a major overhaul that resulted in utilizing the manual Hand/Off/Auto switches to operate the chamber. Accomplishing this challenging task required the meticulous development of new operating procedures and thorough training of the chamber’s operators.
Major objectives of the Perseverance rover mission include identifying past habitable environments, collecting rocks that are likely to preserve biosignatures and using the rover’s instruments to look for potential biosignatures in these rocks. The recognition of the > 3.5 billion-year old habitable environments in Jezero crater, Mars (Fig. 1); promised that the mission could achieve these objectives. The western sedimentary fan deposit, the hydrated minerals therein and the carbonate minerals at the margin of this fan were identified as particularly compelling areas in which to search for the signs of past life and collect the oldest aqueously deposited rocks from another planet.
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Graphical data necessary for the analysis of planetary exploration missions to Mars are presented. Positional and geometric information spanning the time period from 1990 through 2020 is provided. The data and usage are explained.
NASA is developing a long‐term strategy for achieving extended human missions to Mars in support of the policies outlined in the 2010 NASA Authorization Act and National Space Policy. The Authorization Act states that "A long term objective for human exploration of space should be the eventual international exploration of Mars." Echoing this is the National Space Policy, which directs that NASA should, "By 2025, begin crewed missions beyond the moon, including sending humans to an asteroid. By the mid‐2030s, send humans to orbit Mars and return them safely to Earth." Further defining this goal, NASA's 2014 Strategic Plan identifies that "Our long‐term goal is to send humans to Mars. Over the next two decades, we will develop and demonstrate the technologies and capabilities needed to send humans to explore the red planet and safely return them to Earth." Over the past several decades numerous assessments regarding human exploration of Mars have indicated that landing humans on the surface of Mars remains one of the key critical challenges. In 2015 NASA initiated an Agency‐wide assessment of the challenges associated with Entry, Descent, and Landing (EDL) of large payloads necessary for supporting human exploration of Mars. Due to the criticality and long‐lead nature of advancing EDL techniques, it is necessary to determine an appropriate strategy to improve the capability to land large payloads. This paper provides an overview of NASA's 2015 EDL assessment on understanding the key EDL risks with a focus on determining what "must" be tested at Mars. This process identified the various risks and potential risk mitigation strategies, that is, benefits of flight demonstration at Mars relative to terrestrial test, modeling, and analysis. The goal of the activity was to determine if a subscale demonstrator is necessary, or if NASA should take a direct path to a human‐scale lander. This assessment also provided insight into how EDL advancements align with other Agency Mars lander activities such as the technology portfolio investments and post‐2020 robotic Mars Exploration Program missions.
During the summer of 2020, the NASA Mars Architecture Team (MAT) conducted a functional volume assessment of the Transit Habitat (TH). The TH has evolved substantially since that time and the current TH does not share the same internal configuration, but the insights gained from the assessment remain relevant. In virtually all architectures involving chemical, electric, or nuclear propulsion, the majority of the crew mission is spent aboard the TH. The Earth to Mars transit durations may vary from architecture to architecture, but all are on the order of hundreds of days, regardless of whether an opposition or conjunction class trajectory is selected, and regardless of whether the propulsion system is chemical, electric, or nuclear. Thus, the TH must provide capabilities appropriate to a very long duration. So, despite significant changes in the current Mars architecture over the past few years, this evaluation still provides useful recommendations in the form of habitability guidance that can be applied to current and future TH concepts. This assessment had six primary objectives: provide a sanity check to the BOC-derived TH layout; understand if we can fit the hardware and functional tasks in the volume; provide a high-level assessment of how aggressive the layout is; generate a list of challenges or assumptions necessary to make it work; generate a list of future work to refine understanding; and identify proposed requirements. All of this information is critical to drive habitat sizing studies and key architecture decisions. It was clear that a human-in-the-loop (HITL) evaluation of some kind would be necessary, but several challenges were immediately identified. The most information could be gleaned from a Desert Research and Technology Studies (DRATS) type of mission operations test (MOT), but the TH concept was too low fidelity to construct the type of prototype necessary to conduct a MOT, nor were their financial resources to do so. The next best option – and really the one most appropriate for the BOC’s stage of maturity – is a Virtual Reality (VR) walk-through evaluation. However, NASA was in a shutdown state due to the COVID-19 pandemic and the VR labs were inaccessible. As a result, a tabletop evaluation was created, using .jpg imagery from the ECM CAD model along with Excel-based datasheets. High-level crew living and working functions within the habitat were identified for evaluation. Questionnaires using Likert scales assessed acceptability of habitat functions and sim quality – the degree to which the function was represented in CAD. This enabled the evaluation to be conducted by personnel working remotely. Each function was evaluated individually along with several overarching habitability parameters and vehicle subsystems. The results of this evaluation are discussed, including methodological challenges and rating challenges. Acceptability results are discussed for functions that the participants were able to rate and participant comments for functions that could not be related are also described. Final conclusions are described, including challenges or assumptions needed to make the TH design acceptable, future work needed to refine understanding of the TH, and proposed habitat requirements based on test data.
During the summer of 2020, the NASA Mars Architecture Team (MAT) assessed the Enhanced Habitation Capability (EHC), the transit spacecraft that was part of what was then the current Mars human exploration architecture, the Basis of Comparison (BOC). This assessment had six primary objectives: provide a sanity check to the BOC-derived EHC layout; understand if we can fit the hardware and functional tasks in the volume; provide a high-level assessment of how aggressive the layout is; generate a list of challenges or assumptions necessary to make it work; generate a list of future work to refine understanding; and identify proposed requirements. The results of this evaluation are discussed, including methodological challenges and rating challenges. Acceptability results are discussed for functions that the participants were able to rate and participant comments for functions that could not be evaluated are also described. Final conclusions are described, including challenges or assumptions needed to make the EHC design acceptable, future work needed to refine understanding of the EHC, and proposed habitat requirements based on test data. While NASA has since moved away from the BOC architecture, this assessment is still useful to inform the design of future Transit Habitats.
NASA will launch a rover to Mars in 2020 to collect and cache samples of Martian rocks and regolith for potential return to Earth on a future mission. The collected samples will be placed in tubes, hermetically sealed, and deposited on the surface of Mars for a period of up to 10 years. Preventing the deposited samples from overheating is an important consideration in order to ensure their scientific integrity. The samples are required to remain below 60 °C, however there is a goal to keep them below 40 °C. This temperature requirement is challenging, considering that the maximum surface temperature of Mars is 38 °C and the tube must be thermally controlled through only passive means. As a result, a significant effort has been made to design a tube to contain the samples and investigate innovative tube surface treatments that maintain proper sample temperatures without significant adverse effects of sample contamination. The tube uses a specialized aluminum oxide coating to prevent overheating on the Martian surface. The maximum predicted tube temperature is relatively insensitive to local thermal inertia, ground contact, and ground slope, but is very sensitive to landing site latitude and dust deposition. The maximum predicted sample temperature in the +/- 30° landing latitude range with worst case assumptions is 54 °C, but many of the potential landing sites have significantly cooler maximum predicted sample temperatures. This paper describes the thermal design, analysis, and sensitivity studies performed on the sample tubes and also discusses operational considerations.
The SuperCam instrument on the PerseveranceMars 2020 rover uses a pulsed 1064 nm laser to ablate targets at a distance and conduct laser induced breakdown spectroscopy (LIBS) by analyzing the light from the resulting plasma. SuperCam LIBS spectra are preprocessed to remove ambient light, noise, and the continuum signal present in LIBS observations. Prior to quantification, spectra are masked to remove noisier spectrometer regions andspectra are normalized to minimize signal fluctuations and effectsof target distance.In some cases, the spectra are also standardized or binned prior to quantification. To determine quantitative elemental compositionsof diverse geologic materials at Jezero crater, Mars, we use a suite of 1198 laboratory spectra of 334 well-characterized reference samples. The samples were selected to span a wide range of compositions and include typical silicate rocks, pure minerals (e.g.,silicates, sulfates, carbonates, oxides),more unusual compositions (e.g.,Mn oreand sodalite), andreplicates of the sintered SuperCam calibration targets (SCCTs) onboardthe rover. For each major element (SiO2, TiO2, Al2O3, FeOT, MgO, CaO, Na2O, K2O), the database was subdivided into five“folds” with similar distributions of the element of interest. One fold was held out as an independent test set, and the remaining fourfolds were used to optimize multivariate regression models relating the spectrum to the composition. We considered a variety of models, and selected several for further investigation for each element, based primarily on the root mean squared error of prediction (RMSEP) on the test set, when analyzed at 3m. In cases with several models of comparable performance at 3 m, we incorporated the SCCT performance at different distances to choose the preferred model. Shortly after landing on Mars and collecting initial spectra of geologic targets, we selected one model per element. Subsequently, with additional data from geologic targets, some models were revised to ensure results that are more consistent with geochemical constraints. The calibration discussed here is a snapshot of an ongoing effort to deliver the most accurate chemical compositions with SuperCam LIBS.
This paper describes how the Mars ScienceLaboratory (MSL) project prepared for and successfully beganCuriosity rover Mars operations from their homes in responseto the COVID-19 work-from-home orders. In a very shortperiod, the team developed procedures and executed a remoteoperations readiness test in parallel with the team's support fornominal operations. Continuing regular rover operations withan entirely remote team had not previously been consideredfeasible due to a variety of factors. These included both thehuman factors, such as multiple concurrent person-to-personinteractions of the uplink planning team, as well as technicalfactors, such as reliance on powerful workstations dedicated tographically intensive software tools used for planning. The testwas conducted on March 12th, with both the downlink anduplink teams successfully simulating a near full planning day.The JPL administration announced the transition to mandatorytelework on Monday, March 16th. MSL stood down the uplinkplanning originally scheduled for the next day while downlinkcontinued monitoring the rover. Full operations then resumedper schedule with nearly the entire operations team teleworkingon Friday, March 20th, during which the team planned roveractivities for three Martian days (sols). These activities includedthe successful drilling of the "Edinburgh" rock target, a highlycomplex contact science activity.As of October 1st, 2020, the Mars Science Laboratory missionoperations team has conducted 88 remote tactical uplink shiftsfor a total of 190 sols of planned rover activity, which accountsfor more than 6% of the mission to date. In this period the roverhas completed four drilling campaigns and driven over 1150meters towards its next major science target – a sulfate bearinggeologic unit at the foot of Mount Sharp. Success has not beenwithout its challenges. Many of these have been addressed whileothers will remain in some form until the team can safely returnto JPL, which in turn is the largest challenge for the future.
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NASAs exploration and technology roadmaps call for capability advancements in Mars entry, descent, and landing (EDL) systems to enable increased landed mass, a higher landing precision, and a wider planetary access. It is also recognized that these ambitious EDL performance goals must be met while maintaining a low mission risk in order to pave the way for future human missions. As NASA is engaged in developing new EDL systems and technologies via testing at Earth, instrumentation of existing Mars missions is providing valuable engineering data for performance improvement, risk reduction, and an improved definition of entry loads and environment. The most notable recent example is the Mars Entry, Descent and Landing Instrument (MEDLI) suite hosted by Mars Science Laboratory for its entry in Aug 2012. The MEDLI suite provided a comprehensive dataset for Mars entry aerodynamics, aerothermodynamics and thermal protection system (TPS) performance. MEDLI data has since been used for unprecedented reconstruction of aerodynamic drag, vehicle attitude, in-situ atmospheric density, aerothermal heating, and transition to turbulence, in-depth TPS performance and TPS ablation. [1,2] In addition to validating predictive models, MEDLI data has demonstrated extra margin available in the MSL forebody TPS, which can potentially be used to reduce vehicle parasitic mass. The presentation will introduce a follow-on MEDLI instrumentation suite (called MEDLI2) that is being developed for Mars-2020 mission. MEDLI2 has an enhanced scope that includes backshell instrumentation, a wider forebody coverage, and instruments that specifically target supersonic aerodynamics. Similar to MEDLI, MEDLI2 uses thermal plugs with embedded thermocouples and ports through the TPS to measure surface pressure. MEDLI2, however, also includes heat flux sensors in the backshell and a low range pressure transducer to measure afterbody pressure.
Terrain Relative Navigation (TRN) is an on-board GN&C function that generates a position estimate of a spacecraft relative to a map of a planetary surface. When coupled with a divert, the position estimate enables access to more challenging landing sites through pin-point landing or large hazard avoidance. The Lander Vision System (LVS) is a smart sensor system that performs terrain relative navigation by matching descent camera imagery to a map of the landing site and then fusing this with inertial measurements to obtain high rate map relative position, velocity and attitude estimates. A prototype of the LVS was recently tested in a helicopter field test over Mars analog terrain at altitudes representative of Mars Entry Descent and Landing conditions. TRN ran in real-time on the LVS during the flights without human intervention or tuning. The system was able to compute estimates accurate to 40m (3 sigma) in 10 seconds on a flight like processing system. This paper describes the Mars operational test space definition, how the field test was designed to cover that operational envelope, the resulting TRN performance across the envelope and an assessment of test space coverage.
In 2020, the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) will fly to Mars as part of the Mars-2020 “Perseverance” rover’s experiment package, and for the first time will demonstrate the use of in-situ resources of another planet, by using the carbon dioxide atmosphere of Mars as a feedstock to produce oxygen. MOXIE, however, was not the first flight experiment proposed to test in-situ resource utilization (ISRU). The Mars ISPP Precursor, “MIP”, was a flight experiment on the 2001 Mars Surveyor Lander that was designed to demonstrate In-situ Propellant Production--ISPP--for the first time on Mars. The experiment was designed to show that it was possible to produce oxygen from the carbon dioxide atmosphere, and to demonstrate the individual technology components that would go into a full-scale production plant. The aim point of the oxygen production was to showcase the possibility of producing oxygen for use as rocket fuel, ultimately as an enabling technology for a future human expedition to Mars.
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