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At least 109 records · Page 6

3D Material Response of the MSL Heatshield Using NuSil-Coated PICA

The Mars Science Laboratory (MSL) Entry, Descent and Landing Instrumentation (MEDLI) collected in-flight data largely used by the ablation community to verify and validate physics-based models for the response of the Phenolic Impregnated Carbon Ablator (PICA) material [1-4]. MEDLI data were recently used to guide the development of NASA’s high-fidelity material response models for PICA implemented in the Porous material Analysis Toolbox based on OpenFOAM (PATO) software [5-6]. A follow-up instrumentation suite, MEDLI2, was used for the Mars 2020 mission [7] after the large scientific impact of MEDLI. Recent analyses performed as part of MEDLI2 development drew the attention to significant effects of a protective coating to the aerothermal response of PICA. NuSil, a silicone-based overcoat sprayed onto the MSL heatshield, including the MEDLI plugs, as contamination control, is currently neglected in PICA ablation models. To mitigate the spread of phenolic dust from PICA, NuSil was applied to the entire MSL and Mars 2020 heatshields, including the MEDLI and MEDLI2 plugs. Ground testing of PICA-NuSil (PICA-N) models exhibited surface temperature jumps due to oxide scale formation and subsequent NuSil burn- off. It is therefore critical to include a model for the aerothermal response of the coating in ongoing code development and validation efforts. Figure 1 illustrates the PICA-N model implemented in PATO with a test case that shows a temperature jump and a change of recession rate at the wall after 20 seconds of simulation when the NuSil coating was fully removed.

Aerospace↗

Space Shuttle 750 psi Helium Regulator Application on Mars Science Laboratory Propulsion

The Mars Science Laboratory (MSL) is NASA's next major mission to Mars, to be launched in September 2009. It is a nuclear powered rover designed for a long duration mission, with an extensive suite of science instruments. The descent and landing uses a unique 'skycrane' concept, where a rocket-powered descent stage decelerates the vehicle, hovers over the ground, lowers the rover to the ground on a bridle, then flies a safe distance away for disposal. This descent stage uses a regulated hydrazine propulsion system. Performance requirements for the pressure regulator were very demanding, with a wide range of flow rates and tight regulated pressure band. These indicated that a piloted regulator would be needed, which are notoriously complex, and time available for development was short. Coincidentally, it was found that the helium regulator used in the Space Shuttle Orbiter main propulsion system came very close to meeting MSL requirements. However, the type was out of production, and fabricating new units would incur long lead times and technical risk. Therefore, the Space Shuttle program graciously furnished three units for use by MSL. Minor modifications were made, and the units were carefully tuned to MSL requirements. Some of the personnel involved had built and tested the original shuttle units. Delta qualification for MSL application was successfully conducted on one of the units. A pyrovalve slam start and shock test was conducted. Dynamic performance analyses for the new application were conducted, using sophisticated tools developed for Shuttle. Because the MSL regulator is a refurbished Shuttle flight regulator, it will be the only part of MSL which has physically already been in space.

Mizukami, Masashi↗

Collapsed Smectite in Gale Crater: Martian Clay Minerals May Have Been on Acid

The Mars Science Laboratory (MSL) rover Curiosity began investigating the layered deposits of Gale Crater, Mars, in August 2012. Among the many science instruments on the rover, the CheMin (Chemistry and Mineralogy) X-ray diffractometer (XRD) has been useful in definitively characterizing the mineralogy of samples collected by the rover.

Craig, P. I.↗

Relay Support for the Mars Science Laboratory Mission

The Mars Science Laboratory (MSL) mission landed the Curiosity Rover on the surface of Mars on August 6, 2012, beginning a one-Martian-year primary science mission. An international network of Mars relay orbiters, including NASA's 2001 Mars Odyssey Orbiter (ODY) and Mars Reconnaissance Orbiter (MRO), and ESA's Mars Express Orbiter (MEX), were positioned to provide critical event coverage of MSL's Entry, Descent, and Landing (EDL). The EDL communication plan took advantage of unique and complementary capabilities of each orbiter to provide robust information capture during this critical event while also providing low-latency information during the landing. Once on the surface, ODY and MRO have provided effectively all of Curiosity's data return from the Martian surface. The link from Curiosity to MRO incorporates a number of new features enabled by the Electra and Electra-Lite software-defined radios on MRO and Curiosity, respectively. Specifically, the Curiosity-MRO link has for the first time on Mars relay links utilized frequency-agile operations, data rates up to 2.048 Mb/s, suppressed carrier modulation, and a new Adaptive Data Rate algorithm in which the return link data rate is optimally varied throughout the relay pass based on the actual observed link channel characteristics. In addition to the baseline surface relay support by ODY and MRO, the MEX relay service has been verified in several successful surface relay passes, and MEX now stands ready to provide backup relay support should NASA's orbiters become unavailable for some period of time.

Telecommunications↗

Transmission X-ray Diffraction (XRD) Patterns Relevant to the MSL Chemin Amorphous Component: Sulfates And Silicates

The Mars Science Laboratory (MSL) CheMin instrument on the Curiosity rover is a transmission X-ray diffractometer (Co-Kalpha radiation source and a approx.5deg to approx.52deg 2theta range) where the analyzed powder samples are constrained to have discrete particle diameters <150 microns by a sieve. To date, diffraction patterns have been obtained for one basaltic soil (Rocknest (RN)) and four drill fines of coherent rock (John Klein (JK), Cumberland (CB), Windjana (WJ), and Confidence Hills (CH)). The CheMin instrument has detected and quantified the abundance of both primary igneous (e.g., feldspar, olivine, and pyroxene) and secondary (e.g., Ca-sulfates, hematite, akaganeite, and Fe-saponite) minerals. The diffraction patterns of all CheMin samples are also characterized by a broad diffraction band centered near 30deg 2theta and by increasing diffraction intensity (scattering continuum) from approx.15deg to approx.5deg, the 2theta minimum. Both the broad band and the scattering continuum are attributed to the presence of an XRD amorphous component. Estimates of amorphous component abundance, based on the XRD data itself and on mass-balance calculations using APXS data crystalline component chemistry derived from XRD data, martian meteorites, and/or stoichiometry [e.g., 6-9], range from approx.20 wt.% to approx.50 wt.% of bulk sample. The APXSbased calculations show that the amorphous component is rich in volatile elements (esp. SO3) and is not simply primary basaltic glass, which was used as a surrogate to model the broad band in the RN CheMin pattern. For RN, the entire volatile inventory (except minor anhydrite) is assigned to the amorphous component because no volatile-bearing crystalline phases were reported within detection limits [2]. For JK and CB, Fesaponite, basanite, and akaganeite are volatile-bearing crystalline components. Here we report transmission XRD patterns for sulfate and silicate phases relevant to interpretation of MSL-CheMin XRD amorphous components.

Morris, R. V.↗

2011 Mars Science Laboratory Trajectory Reconstruction and Performance from Launch Through Landing

The Mars Science Laboratory (MSL) mission successfully launched on an Atlas V 541 Expendable Evolved Launch Vehicle (EELV) from the Eastern Test Range (ETR) at Cape Canaveral Air Force Station (CCAFS) in Florida at 15:02:00 UTC on November 26th, 2011. At 15:52:06 UTC, six minutes after the MSL spacecraft separated from the Centaur upper stage, the spacecraft transmitter was turned on and in less than 20 s spacecraft carrier lock was achieved at the Universal Space Network (USN) Dongara tracking station located in Western Australia. MSL, carrying the most sophisticated rover ever sent to Mars, entered the Martian atmosphere at 05:10:46 SpaceCraft Event Time (SCET) UTC, and landed inside Gale Crater at 05:17:57 SCET UTC on August 6th, 2012. Confirmation of nominal landing was received at the Deep Space Network (DSN) Canberra tracking station via the Mars Odyssey relay spacecraft at 05:31:45 Earth Received Time (ERT) UTC. This paper summarizes in detail the actual vs. predicted trajectory performance in terms of launch vehicle events, launch vehicle injection performance, actual DSN/USN spacecraft lockup, trajectory correction maneuver performance, Entry, Descent, and Landing events, and overall trajectory and geometry characteristics.

trajectory↗

Mars 2020: Mission, Science Objectives and Build

If all goes according to plan, in February 2021, NASA will land the Mars 2020 Rover on the surface of Mars. Mars 2020 is the latest in a series of unmanned Martian robotic rover missions that are part of NASA’s Mars Exploration Program, a long-term effort of robotic exploration of the planet. The mission seeks to address high-priority goals for Mars exploration, including answering questions about the potential for past life on Mars. Mars 2020 will look for evidence of habitable conditions on Mars in the ancient past, as well as look for signs of past microbial life itself. The mission also seeks to understanding the geological history and evolution of the planet, and to prepare for future robotic and human exploration. The Mars 2020 spacecraft and rover borrow heavily from the Mars Science Laboratory (MSL) mission and Curiosity rover which landed on Mars in 2012. This reliance on proven technology helps reduce mission risk and cost. Mars 2020 does contain new technology, including a drill for coring samples from Martian rock and soil and a Sample Caching System for gathering, storing and preserving samples for possible future return to Earth. In this paper, we will review the primary goals of the Mars 2020 Mission and look at the reasons for choosing Jezero Crater as the landing site. We will discuss the design and build of the Mars 2020 Spacecraft system and its similarities and differences with Mars Science Laboratory and the Curiosity Rover. We will also review the Mars 2020 Scientific Instrument Suite and their goals. Finally, we will review the Return Sample Contamination Control requirements and the design choices that were made to facilitate meeting these requirements.

Soares, Carlos E.↗

Attitude Controller for the Atmospheric Entry of the Mars Science Laboratory

This paper describes the attitude controller for the atmospheric entry of the Mars Science Laboratory (MSL). The controller will command 8 RCS thrusters to control the 3- axis attitude of the entry capsule. The Entry Controller is formulated as three independent channels in the control frame, which is nominally aligned with the stability frame. Each channel has a feedfoward and a feedback path. The feedforward path enables fast response to large bank commands. The feedback path stabilizes the vehicle angle of attack and sideslip around its trim position, and tracks bank commands. The feedback path has a PD/D control structure with deadbands that minimizes fuel usage. The performance of this design is demonstrated via computer simulations.

attitude controller↗

Filter Strategies for Mars Science Laboratory Orbit Determination

The Mars Science Laboratory (MSL) spacecraft had ambitious navigation delivery and knowledge accuracy requirements for landing inside Gale Crater. Confidence in the orbit determination (OD) solutions was increased by investigating numerous filter strategies for solving the orbit determination problem. We will discuss the strategy for the different types of variations: for example, data types, data weights, solar pressure model covariance, and estimating versus considering model parameters. This process generated a set of plausible OD solutions that were compared to the baseline OD strategy. Even implausible or unrealistic results were helpful in isolating sensitivities in the OD solutions to certain model parameterizations or data types.

Mars Science Laboratory (MSL)↗

Vertical and Horizontal Heterogeneity of Atmospheric Dust Loading in Northern Gale Crater, Mars

This paper updates the record of atmospheric dust loading within northern Gale Crater, Mars, by providing line-of-sight extinction (LOS-Ext) measurements of the intervening dust between the rover and the crater rim. These measurements are derived from images taken with the Navigation Cameras (Navcam) onboard the Mars Science Laboratory (MSL) rover, Curiosity. The observations span 2.44 Mars years, from Mars Year (MY) 31 at a solar longitude (L(sub s)) of 208° to t L(sub s) = 7° of MY34, sols 100–1701 of the MSL surface mission. This work examines the dataset for seasonal trends of the LOS-Ext in addition to horizontal variations and the vertical structure of LOS-Ext. The LOS-Ext has a repetitive pattern with a single peak in the latter half of the Mars year. The atmosphere in the crater is well mixed horizontally but not vertically as larger LOS-Ext is seen nearer the crater floor than at higher altitudes within the crater. The results allow a discussion on whether or not Gale Crater is a sink for atmospheric dust or a source of atmospheric dust in the current era.

Casey A. Moore↗

Multi-Mission Radioisotope Thermoelectric Generator Experience on Mars

The Mars Science Laboratory (MSL) Curiosity rover has been operating on Mars using the F1 Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) for over one and one-half Mars years (over three Earth years). During this extended period, Curiosity has provided a wealth of information about operating with a MMRTG in the Mars surface environment. This paper discusses MMRTG performance over the life of the mission as affected not only by expected radioisotope degradation, but also by the thermal environment, including seasonal, wind, and time-of-sol effects. Additionally, issues related to MMRTG internal shorts will be discussed including detection, impacts on operations, and clearing the shorts.

RTG↗

EDL Simulation Results for the Mars 2020 Landing Site Safety Assessment

The Mars 2020 rover is NASA’s next flagship mission, set to explore Mars in search of scientific evidence of past microbial life. Importantly, the rover will also, for the first time, have the ability to collect and cache rock and soil samples for retrieval and return to laboratories here on Earth. A key step in the development of the Mars 2020 mission is the selection of a suitable landing site with the largest likelihood of meeting scientific goals. This decision is a complex and critical one that requires close interaction between the scientific and engineering communities. The chosen landing site must be both scientifically interesting — providing the project with the greatest possible chance of gathering credible and defendable scientific evidence — and also safe enough to attempt a landing in the first place. Thus, arguably one of the most important undertakings of the Entry, Descent, and Landing (EDL) team, is to effectively enumerate, quantify, and communicate the landing risks to all of the stakeholders. The culmination of this effort is the Landing Site Safety Assessment, which is a review commissioned by the project, presided over by the EDL Standing Review Board, and attended by management and science stakeholders, in which the EDL team communicates their assessment of the associated landing risks and the statistical probability of a successful landing at each of the final candidate landing sites. This paper summarizes the results of high-fidelity computer simulations of the Mars 2020 EDL sequence used in this assessment. From an EDL performance perspective, all four candidates offer similar level of robustness, which is in-family with Mars Science Laboratory (MSL). However, two new features of the Mars 2020 EDL sequence – range trigger and Terrain-Relative Navigation (TRN) – dramatically enhance the capability of the EDL system to safely land at landing sites with much more rugged terrain than ever before considered. This has allowed the landing site selection for Mars 2020 to proceed in a manner that has been unprecedentedly weighted more heavily toward scientific interest and less heavily on engineering constraints. With TRN, the overall probability of success is predicted to be approximately 99% for all of the candidates.

David Way↗

Overview of the Mars 2020 Parachute Risk Reduction Activity

In 2012, the Mars Science Laboratory (MSL) landed safely on the surface of Mars using a supersonic Disk-Gap-Band (DGB) parachute, which was structurally qualified for flight via a subsonic wind tunnel test program. Results of the Low Density Supersonic Decelerators (LDSD) program have called into question the methodology and principles that form the foundation of the MSL subsonic test program. LDSD discovered that quasi-static subsonic proof loading a parachute via ground testing may not provide canopy stresses that sufficiently bound the stresses experienced during a rapid supersonic inflation at Mars. Additionally, deeper scrutiny of the materials and structural margins present in previously successful supersonic DGBs indicated that the MSL parachute flew with lowest margins of any previous parachute. These factors have increased the perceived risk of reusing a heritage MSL DGB parachute design with a subsonic test program for Mars 2020. To reduce this risk,a series of risk reduction steps were initiated starting in 2016. First, two parachute assemblies have been pursued in parallel: a Build-to-Print (BTP) MSL parachute, designed and manufactured by Pioneer Aerospace Corporation, which maintains the heritage of the successful MSL parachute, and a strengthened parachute, designed and manufactured by Airborne Systems North America, which uses higher strength materials throughout the parachute assembly but maintains the same overall size as the MSL parachute. Second, each parachute system was tested in a subsonic wind tunnel to examine the canopies in their fully inflated state and assess the workmanship of each canopy. Finally, full-scale parachutes from each vendor will experience at least one supersonic inflation at Mars relevant Mach numbers and atmospheric densities at Earth via a supersonic sounding rocket test campaign. This paper presents high-level details regarding the risk reduction strategy, the two candidate parachute configurations, the ground test program, and the supersonic flight test program, and brief results from each of the test programs.

Chen, Allen↗

Post-flight Analysis of Atmospheric Properties from Mars 2020 Entry, Descent, and Landing

The Mars 2020 spacecraft landed the Perseverance rover and Ingenuity helicopter successfully in Jezero crater on Feb. 18, 2021. The entry, descent, and landing (EDL) sequence of the spacecraft largely leveraged the previous Mars Science Laboratory (MSL) mission. The atmospheric modeling approach for Mars 2020 was also borrowed from MSL, and consisted of utilizing two mesoscale atmospheric models of the landing site during the Martian season of landing, and using that data to create a statistical model of the pressure, density, temperature, and winds that Mars 2020 could have expected to encounter. Additionally, Mars 2020 contained an optical sensor - Landing Vision System (LVS) - that relied on taking pictures of the terrain, and was sensitive to the dust opacity of the atmosphere. This paper will briefly describe the pre-flight atmospheric models used for Mars 2020, but will focus on post-flight assessment of these models by comparing them to near-landing day orbiter sounder data and onboard atmospheric measurements. Suggestions for potential model changes will be also discussed.

Soumyo Dutta↗

Post-flight Analysis of Atmospheric Properties from Mars 2020 Entry, Descent, and Landing

The Mars 2020 spacecraft landed the Perseverance rover and Ingenuity helicopter successfully in Jezero crater on Feb. 18, 2021. The entry, descent, and landing (EDL) sequence of the spacecraft largely leveraged the previous Mars Science Laboratory (MSL) mission. The atmospheric modeling approach for Mars 2020 was also borrowed from MSL, and consisted of utilizing two mesoscale atmospheric models of the landing site during the Martian season of landing, and using that data to create a statistical model of the pressure, density, temperature, and winds that Mars 2020 could have expected to encounter. Additionally, Mars 2020 contained an optical sensor - Landing Vision System (LVS) - that relied on taking pictures of the terrain, and was sensitive to the dust opacity of the atmosphere. This paper will briefly describe the pre-flight atmospheric models used for Mars 2020, but will focus on post-flight assessment of these models by comparing them to near-landing day orbiter sounder data and onboard atmospheric measurements. Suggestions for potential model changes will be also discussed.

Soumyo Dutta↗

Driving Curiosity: Mars Rover Mobility Trends During the First Seven Years

NASA’s Mars Science Laboratory (MSL) mission landed the Curiosity rover on Mars on August 6, 2012. As of August 6, 2019 (sol 2488), Curiosity has driven 21,318.5 meters over a variety of terrain types and slopes, employing multiple drive modes with varying amounts of onboard autonomy. Curiosity’s drive distances each sol have ranged from its shortest drive of 2.6 centimeters to its longest drive of 142.5 meters, with an average drive distance of 28.9 meters. Real-time human intervention during Curiosity drives on Mars is not possible due to the latency in uplinking commands and downlinking telemetry, so the operations team relies on the rover’s flight software to prevent an unsafe state during driving. Over the first seven years of the mission, Curiosity has attempted 738 drives. While 622 drives have completed successfully, 116 drives were prevented or stopped early by the rover’s fault protection software. The primary risks to mobility success have been wheel wear, wheel entrapment, progressive wheel sinkage (which can lead to rover embedding), and terrain interactions or hardware or cabling failures that result in an inability to command one or more steer or drive actuators. In this paper, we describe mobility trends over the first 21.3km of the mission, operational aspects of the mobility fault protection, and risk mitigation strategies that will support continued mobility success for the remainder of the mission.

Rankin, Arturo↗

Post-flight Analysis of Atmospheric Properties from Mars 2020 Entry, Descent, and Landing

The Mars 2020 spacecraft landed the Perseverance rover and Ingenuity helicopter successfully in Jezero crater on Feb. 18, 2021. The entry, descent, and landing (EDL) sequence of the spacecraft largely leveraged the previous 2012 Mars Science Laboratory (MSL) mission. The atmospheric modeling approach for Mars 2020 was also borrowed from MSL. It consisted of two mesoscale atmospheric models of the target site during the Martian season of landing, and a statistical model of the pressure, density, temperature, and winds based on the mesoscale model data. This paper briefly describes the pre-flight atmospheric models used for Mars 2020, but focuses on the post-flight assessment of these models and comparison to near-landing day orbiter sounder and other onboard atmospheric measurements. Observations from post-flight analysis showed that density was under-predicted in the upper atmosphere, but within the altitudes covered by the mesoscale models, the pre-flight modeling matched post-flight results, including for quantities like wind velocities. Potential improvements to address the upper atmosphere and other deficiencies of the Mars 2020 pre-flight model are also discussed.

Villar, Gregorio↗

Preliminary Surface Thermal Design of the Mars 2020 Rover

The Mars 2020 rover, scheduled for launch in July 2020, is currently being designed at NASA's Jet Propulsion Laboratory. The Mars 2020 rover design is derived from the Mars Science Laboratory (MSL) rover, Curiosity, which has been exploring the surface of Mars in Gale Crater for over 2.5 years. The Mars 2020 rover will carry a new science payload made up of 7 instruments. In addition, the Mars 2020 rover is responsible for collecting a sample cache of Mars regolith and rock core samples that could be returned to Earth in a future mission. Accommodation of the new payload and the Sampling Caching System (SCS) has driven significant thermal design changes from the original MSL rover design. This paper describes the similarities and differences between the heritage MSL rover thermal design and the new Mars 2020 thermal design. Modifications to the MSL rover thermal design that were made to accommodate the new payload and SCS are discussed. Conclusions about thermal design flexibility are derived from the Mars 2020 preliminary thermal design experience.

Novak, Keith S.↗