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All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Lessons Learned from Aerothermal Flight Data on NASA Mars Entry Vehicles

The NASA Mars Science Laboratory (MSL) and Mars 2020 entry vehicles included temperature measurements inside and direct heat flux on the surface of the thermal protection system (TPS) material. The instrumentation was included to begin addressing predictive capabilities for aerodynamic heating and ablative TPS material response. The MSL aeroshell included temperature measurements at seven heatshield locations, from which total aerodynamic heating was reconstructed. The Mars 2020 instrumentation suite included eleven heatshield measurement locations and new backshell measurements at nine locations: six with temperature sensors, two with sensors to directly measure total heat flux, and one to measure radiative heat flux. Both instrumentation suites returned full sets of data, with all temperature sensors nearest to the surface surviving entry, indicating minimal material recession. Heatshield boundary layer transition (BLT) was observed for both vehicles prior to the time of peak heating, with transition starting near the shoulder and progressing towards the stagnation area. MSL’s higher speed on approach to Mars resulted in higher total heating compared to Mars 2020, with the maximum occurring near the heatshield’s leeside shoulder. The Mars 2020 backshell heating data indicate significant contributions from shock layer radiation. Heating from Navier-Stokes flowfield calculations are in family with reconstructed heating. The paper covers the instrumentation, BLT and reconstructed heating on both heatshields, backshell heating for Mars 2020, TPS performance, and predicted versus reconstructed heat fluxes. Opportunities for improved design approaches for future Mars missions are discussed, especially for the upcoming Mars Sample Return mission.

Mars Science Laboratory↗
NASA NTRS2019

MEDLI2 Flight Heat Flux Sensor Environment and Planetary Protection Testing

Mars 2020 will fly the Mars Entry, Descent, and Landing Instrumentation II (MEDLI2) sensor suite consisting of a total of seventeen instrumented thermocouple sensor plugs, eight pressure transducers, two total heat flux sensors, and one radiometer embedded in the thermal protection system (TPS). Of the MEDLI2 instrumentation, eleven instrumented thermocouple plugs and seven pressure transducers will be installed on the heatshield of the Mars 2020 vehicle while the rest will be installed on the backshell. The goal of the MEDLI2 instrumentation is to directly inform the large performance uncertainties that contribute to the design and validation of a Mars entry system. A better understanding of the entry environment and TPS performance could lead to reduced design margins enabling greater payload mass-fraction and smaller landing ellipses. The MEDLI2 total heat flux sensors and radiometer are new instruments that were not flown on the Mars Science Laboratory mission. These sensors directly measure the surface heat flux and radiation at specific backshell locations. The total heat flux sensors use a Schmidt-Boelter sensing element. The radiometer version uses a sapphire window placed over the Schmidt-Boelter sensing element to separate the radiative component of the total heat flux. MEDLI2 recently planned and executed protoflight environmental testing as well planetary protection measures on the flight and flight-spare total heat flux sensors and radiometers. This testing is required to provide confidence in the performance of the flight-lot sensors when exposed to flight-like environments, and to reduce the risk of biological contamination on the planet of Mars with microbes from Earth.

MEDLI2 FLIGHT HEAT FLUX SENSOR ENVIRONMENT AND PLA↗
NASA NTRS2016

Martian Atmospheric Dust Mitigation for ISRU Intakes via Electrostatic Precipitation

The Mars 2020 and Mars Sample Return missions expected to fly to Mars within the next ten years will each include an In Situ Resource Utilization (ISRU) system. They convert carbon dioxide in the Martian atmosphere into consumable oxygen at 1% and 20% of the rate required by a full scale human exploration Mars mission, respectively. The ISRU systems will need to draw in the surrounding atmosphere at a rate of 110L/min and 550L/min, respectively, in order to meet their oxygen production goals. Over the duration of each respective mission, a total atmospheric dust mass of 4.86g and 243g will be drawn into each system, respectively. Ingestion of large quantities of dust may interfere with ISRU operations, so a dust mitigation device will be required. The atmospheric volume and dust mass flow rates above will be utilized to simulate Martian environmental conditions in a laboratory electrostatic precipitator being developed to provide active dust mitigation support for atmospheric ISRU systems such as these.

In-situ resource utilization↗
NASA NTRSDate not supplied

Comparison of Mars Entry Performance Using Bank-Angle and Alpha-Beta Steering Systems

State-of-the-art Mars entry systems havemodulated the bank angle (σ) on blunt-body entry capsulesto steer, providing hypersonic trajectory control. These bank-angle steering vehicles have provided successful entries forboth the Mars 2020 and Mars Science Laboratory missions, achieving landing accuracy on the order of several kilometers. Conventional guidance algorithms for these vehicles choose the bank magnitude to control the longitudinal motionand periodically change the sign of the bank angle to managethe lateral error through open-loop bank reversals. While these bank reversals are relatively simple to implement, they can inject error into the trajectory. More sophisticated steering commands simultaneously considering the lateral and longitudinal motion can potentially obtain higher entry performance, although the high coupling over the lateral and longitudinal motion remains. Bank-angle steering systemsfor Mars entries have achieved a trim angle of attack (α) for steering by offseting the center-of-gravity (CG) usinginert ballast mass and payload packaging. This ballast mass can be a significant, relative to the mass of the payload, reducing the payload mass. Lastly bank-angle steering vehicles typically modulate the bank angle using reactioncontrol system (RCS) thrusters, which can interfere with thehypersonic wake behind the entry vehicle, potentially limitingcontrollability.

Mars↗
NASA NTRS2006

Mars: 2010 - 2020

This slide presentation reviews the Mars Exploration program for the current decade and beyond. The potential items for procurements for the Mars Science Laboratory (MSL) are discussed, as well as future technology investments to enable to continued development of exploration of Mars by rovers and orbiters that are planned and envisioned for future missions.

Mars exploration↗
NASA NTRSDate not supplied

Aerothermal Analysis and Thermal Protection System Design of the Mars Sample Retrieval Lander [SRL].

Mars Sample Retrieval Lander, part of the Mars Sample Return (MSR) mission, is being designed to land the heaviest payload yet, to the surface of Mars. SRL is being designed to carry the Lander, Sample Transfer System, Mars Acent Vehicle, and two Sample Recovery Helicopters. Compared to MSL and Mars 2020, SRL has a significantly higher ballistic coefficient, and flies at a higher lift/drag configuration. While the SRL heatshield is very similar to that of MSL and M2020, the backshell is very different, so as to accommode the payload. SRL is shielded by the same TPS materials as MSL and Mars 2020, with changes to design reflecting the SRL configuration and ConOPS. The aerothermal analysis and TPS design methodology of SRL relies on the successes of MSL and Mars 2020, and the lessons learned from MEDLI and MEDLI2. However, the constraints on mass require us to revisit all of our prediction models and analysis assumptions, in an attempt to reduce conservatism and TPS mass. MSL and Mars 2020 reconstruction, and detailed comparisons against MEDLI/MEDLI2 data are being used to justify our analysis approach and refine uncertainties and margins.

Mars↗
NASA NTRS2018

Maximum Sample Temperature for Mars Sample Return: A Historical Perspective

Since the first Mars Sample Return (MSR) report published by the Jet Propulsion Laboratory (JPL) in 1974 [1], a series of panels, reports, and white papers have recognized the importance of sample temperature and offered an informed sample maximum temperature (henceforth SMT) limit for returning martian samples to Earth. The Mars Sample Handling and Requirements Panel (MSHARP, 1999) stated that "[t]he main issue in sample preservation is temperature" [2]. More recently, the Mars Exploration Program Analysis Group (MEPAG)'s "Science Priorities for Mars Sample Return" report (2008), declared that "[s]ignificant loss, particularly to biological studies, occurs if samples reach +50C for three hours", whereby "scientific objectives related to life goals could be seriously compromised" [3]. By contrast, the Mars 2020 mission has adopted a SMT of +60C as spelled out in Beaty et al., 2016 [4]. Samples will be collected and then deposited on the surface in sealed tubes for possible retrieval and return to Earth. Beaty et al. [4] calculates that the samples will experience maximum temperatures of ~+30 to +60C, depending on latitude. At present, there is no mission requirement for the measurement/data logging of sample temperature during this period. We will explore the history of martian SMTs, as they have been recorded since 1974 [1], effectively representing input across multiple generations of Mars scientists. Ten separate publications present SMTs for MSR samples [1-10]. One report [10] is for a mission concept specifically designed to exclude life detection investigations, and recommended an SMT of 50C. Another did not specify a temperature, recommending "Mars ambient temperature" [5]. Of the remaining eight, SMTs are given as: -30C [1], -20C [3], 60C [4], -73 to 41C depending on sample type [6], -40C [7], -43 to 13C depending on type [2,8], and -33C [9]. If we restrict the temperatures to samples highlighted in the Mars 2020 mission goals, i.e. organics-bearing and sedimentary rocks, then the average SMT is -28+/-39C (n=8). Applying a Dixon's Q Test at P=0.05 (two-tailed), the 60C SMT [4] fails with Q=0.602 versus Qcrit=0.526. Excluding the outlier produces an average SMT of -40+/-17C (n=7). Therefore, the average SMT expressed by the Mars science community over the past 44 years (two generations) is a sample temperature no greater than -40C. The difference in chemical reaction rates between this average SMT and Beaty et al [4] can be estimated using the Arrhenius equation. Assuming a generic chemical reaction with an activation energy of 50 kJ/mol and a pre-exponential factor invariant with temperature, this reaction will proceed 2300x faster at 60C than at -40C. To illustrate the effects of the increased reaction rate, consider 10 ppb of alanine in a Mars 2020 cache, and assume that it becomes unmeasurable if it degrades to 1 ppb, as per the Mars 2020 Organic Contamination Panel contamination limits [11]. If we illustrate the effect with an arbitrary degradation rate such that the alanine will become undetectable in ten years at -40C, then the same 10 ppb alanine degrades beyond detectability in only 38 days at 60C. Further research is required to quantify expected analyte losses in the cached samples due to thermal processing.

Fries, Marc↗
NASA NTRS2019

Charactarization of Thermal Protection Systems

In 2012, NASA's mission of landing the Mars Science Laboratory (MSL) on Mars was successful. MSL was protected by an ablative heatshield of tiled low density material known as PICA (phenolic impregnated carbon ablator). The heatshield was instrumented with MEDLI (MSL Entry Descent Landing Instrument) a suite of sensors & thermocouples at discrete locations in order to monitor the in-depth ablator temperature response and surface pressure. MEDLI was designed and developed by NASA Langley, in partnership with NASA Ames Research Center for the purposes of probing Mars and evaluating the performance of the spacecraft upon entry into the Martian atmosphere. The flight data reduces the uncertainty in engineer models for predicting the response of a spacecraft towards the extreme heating environment of an entry into the Martian atmosphere. MEDLI2 is a part of the Mars 2020 mission and is the next-generation sensor suite for entry, descent, and landing. This data will again help engineers validate their flight models. Additionally, the atmospheric data, can help us understand atmospheric density and winds. This is a critical study for reducing risks to both robotic and future human missions to Mars. Engineered models for Mars 2020 are dependent upon parameters related to the materials response to heating and radiation. In this work, the thermal properties and other measurements of various ablative materials are analyzed to achieve greater utility of the 2012 MEDLI flight data and more accurately determine the parameters being used in Mars 2020. The purpose of this study was to measure specific heat, thermal conductivity, char yield, reflectance as a function of wavelength, and other thermal parameters and optical properties of various ablative materials. CO2(g) at extreme temperatures emits radiation impacting MEDLI2 flight predictions. Emissivity & absorptivity as a function of temperature were calculated from FTIR and UV-Vis data as a means of investigating whether these materials might absorb CO2 radiation upon entry into the Mars atmosphere.

HEEET↗
NASA NTRS2020

Advanced Supersonic Parachute Inflation Research Experiment Preflight Trajectory Modeling and Postflight Reconstruction

The Advanced Supersonic Parachute Inflation Research and Experiments (ASPIRE) was a series of sounding rocket flights aimed at understanding the dynamics of supersonic parachutes that are used for Mars robotic applications. The 2012 Mars Science Laboratory (MSL) had a successful deployment of a supersonic parachute, but based on post-flight analysis of parachute margins, the ASPIRE project was created as a risk-reduction program to improve quantification of these margins and qualify a supersonic parachute for Mars 2020, the follow-on mission to MSL. The first sounding rocket (SR01) flight of ASPIRE occurred near Wallops Island, Virginia on Oct. 4, 2017 and demonstrated the successful deployment and inflation of a MSL build-to-print parachute in flight conditions similar to the 2012 MSL mission. The ASPIRE SR02 and SR03 were successful follow-on flights on Mar. 31, 2018 and Sep. 7, 2018 that demonstrated the new, strengthened supersonic parachute designed for the Mars 2020 project. The SR02 and SR03 parachuteswere targeted to 100% and 140% of the expected flight limit load for Mars 2020 to confirm new margins expected from the strengthened parachute. Prior to all flights, a multi-body flight dynamics simulation was developed to predict the parachute dynamics and was used, in conjunction with other tools, to target Mars-relevant flight conditions. After each flight, the on-board data were used to reconstruct the flight trajectory and to validate the pre-flight dynamics simulation. Post-flight analysis showed that all three tests achieved their targeted conditions and pre-flight modeling bounded the key performance metrics for the parachute. This paper describes the flight mechanics simulation, post-flight reconstruction, and the reconciliation process used to validate the flight models.

Soumyo Dutta↗
NASA NTRS2019

Mission analysis for a potential Mars Sample Return campaign in the 2020's

The Mars 2020 mission, currently under development by NASA, plans to acquire and cache carefully-selected rock and regolith samples from the surface of Mars for potential future return. NASA and ESA are jointly studying options for returning those samples to Earth with missions launching in the 2020s. This paper demonstrates a method for modeling the various campaign elements, synthesizing coordinated campaign timelines, and assuring trajectory feasibility in the presence of many constraints, and finally optimizing towards mission success. Options for complete sample return campaigns in multiple launch and arrival opportunities are explored and compared.

Huesing, Jakob↗
NASA NTRS2022

Perseverance Rover Collision Model for a range of Autonomous Behaviors

The NASA Mars 2020 Perseverance rover landed in Jezero crater on Mars on 18 February 2021. It is a science mission to collect and cache sample cores for possible return to Earth in the future. Robot collision modeling is traditionally used in robotics for hardware safety for manipulation and sampling. The Mars 2020 Rover Collision Model (RCM) optimizes and extends collision checking in innovative ways to provide a range of onboard autonomous capability on a computationally constrained system. It provides an example of the benefit of systems and operations cognizant software design and development of autonomous systems.

Klein, Douglas↗
NASA NTRS2024

The Scientific Value of Collecting Samples From the Jezero Crater Rim

The Mars 2020 mission has been conducting ground-based investigation of the geology, habitability, and biosignature preservation potential and collecting samples for return to Earth in Jezero crater, Mars for nearly 3 years. Analysis of these samples will address outstanding questions in Mars science including potential habitability and how and why the climate the interior of the planet evolved through time. As of December 2023, samples of 4 igneous rocks of the Jezero crater floor and 9 sedimentary rocks of the Jezero fan and inner margin, remain on the rover. 15 tubes remain to be filled to enhance the diversity of the cache and broaden the scope of the science questions that can be addressed with returned sample studies. The next step in the mission is to explore the Jezero crater rim. It will be imperative to investigate and sample the diversity of crater rim rocks because they represent materials from Mars’ most ancient crust older than those sampled in Jezero crater, a diversity of geologic processes, and potential ancient habitable environments that have not yet been investigated or sampled. Ongoing mapping efforts are using orbiter data and long-distance images from Perseverance to identify and interpret the geologic context of the crater rim. Building on this effort and the broader geologic context for the crater rim put forward by previous studies, we identify diverse targets for in situ investigation and potential sampling by Mars 2020.

Mars sample return↗
NASA NTRS2018

Introduction to the 2018 iMOST Study

The analysis in Earth laboratories of samples that could be returned from Mars is of extremely high interest to the Mars exploration community, and on an international basis. IMEWG (the International Mars Exploration Working Group) is currently exploring options to involve the international community in the planning for returned sample science, including the analysis of the returned samples. The Mars 2020 sample-caching rover mission is an essential component of the Mars Sample Return campaign, so its existence constitutes a critical opportunity-MSR is more real now than it has ever been. The Mars 2020 samples, when returned, would provide the basis for performing a variety of Earth-based experiments including ones related to the search for the signs of life.

Source record↗
NASA NTRS2018

A Comparison of Energy Conversion Technologies for Space Nuclear Power Systems

A key element of space nuclear power systems is the energy conversion subsystem that converts the nuclear heat into electrical power. Nuclear systems provide a favorable option for missions that require long-duration power in hostile space environments where sunlight for solar power is absent or limited. There are two primary nuclear power technology options. Radioisotope Power System (RPS) utilize the natural decay heat from Pu238 to generate electric power levels up to about one kilowatt. Fission Power System (FPS) rely on a sustained fission reaction of U235 and offer the potential to supply electric power from kilowatts to megawatts. Example missions for nuclear power include Mars science rovers (e.g. Curiosity, Mars 2020), lunar and Mars surface landers ? including crewed missions, deep space planetary orbiters, Ocean World science landers, and robotic space probes that utilize nuclear electric propulsion. This paper examines the energy conversion technology options that can be used with RPS and FPS, and provides an assessment of their relative performance and technology readiness.

Mason, Lee S.↗
NASA NTRS2019

Ready for Our Trip to Mars? Turning the Red Planet Blue

Mars exploration is one of the major current scientific breakthroughs. NASA is actively developing its Mars Exploration Program through several rovers and orbiters to better understand the origin and current conditions of the Red Planet. Since Mars is more Earth-like than any other planet, understanding its formation and evolution could enable to better understand our own origin. Mars is also considered as a future destination for survival of humankind, assuming our ability to face remaining technical challenges, such as radiation risks, extreme conditions, food and medicine supplies. The recent evidence of liquid water on Mars suggests that life could exist, and will be seeked by NASA Mars 2020 rover. Thus, Mars exploration opens remarkable perspectives towards the discovery of new resources and the humanity's expansion. But this tremendous potential also implies completely new questions: what will happen to the Earth if humans are able to escape from global warming and pollution? How will the Martian land be shared between Nations? Will it be impacted by political conflicts on the Earth? If life exists on Mars, will it be compatible with humans? As we get closer to Mars colonization every day, these questions should be addressed and considered as a new chance to envision a world that could benefit from the lessons of History. So, in addition to technical and scientific progress, Mars exploration gives us the chance to redefine our society as a whole.

societal impacts↗
NASA NTRS2019

Aerodynamic Performance of Supersonic Parachutes Behind Slender Bodies

NASA's ASPIRE (Advanced Supersonic Parachute Inflation Research Experiments) project was launched to investigate the supersonic deployment, inflation and aerodynamics of full-scale disk-gap-band (DGB) parachutes. Three flight tests (October 2017, March 2018 and July 2018) deployed and examined parachutes meant for the upcoming "Mars 2020" mission. Mars-relevant conditions were achieved by performing the tests at high altitudes over Earth on a sounding rocket platform, with the parachute deploying behind a slender body (roughly 1/6-th the diameter of the capsule that will use this parachute for descent at Mars). All three tests were successful and delivered valuable data and imagery on parachute deployment and performance. CFD simulations were used in designing the flight test, interpreting the flight data, and extrapolating the results obtained during the flight test to predict parachute behavior at Mars behind a blunt capsule. This presentation will provide a brief overview of the test program and flight test data, with emphasis on differences in parachute performance due to the leading body geometry.

Muppidi, Suman↗