ALBERT

Description: The Compass Final Report: Europa Tunnelbot, is a summary of three Compass concurrent engineering team designs for penetrating the ice of Europa and reaching the ocean, while sampling for biomarkers and communicating back to the surface. These conceptual designs, while providing complete conceptual layouts for these penetrators, or 'Tunnelbots' along with the associated communication 'Repeaters' primarily focused on the power and thermal systems needed for these devices. Trades for these systems will provide advantages and challenges for each option. These results will be used to guide power technology development.

Description: In 2012 during the entry, descent, and landing of the Mars Science Laboratory (MSL), the MSL Entry, Descent, and Landing Instrumentation (MEDLI) sensor suite was collecting in-flight heatshield pressure and temperature data. The data collected by the MEDLI instruments has since been used for reconstruction of vehicle aerodynamics, atmospheric conditions, aerothermal heating, and Thermal Protection System (TPS) performance as well as material response model validation and refinement. The Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) sensor suite for the Mars 2020 heatshield and backshell is being designed to expand on the measurements and knowledge gained from MEDLI. Similar to MEDLI, MEDLI2 will measure the pressure and temperature of the heatshield. MEDLI2 will additionally measure the temperature, pressure, total heat flux, and radiative heat flux on the backshell.Since the backshell instrumentation is new to MEDLI2, Do No Harm (DNH) testing was conducted on instrumented backshell TPS (SLA-561V) panels. The panels consisted of four pressure port holes, one Mars Entry Atmospheric Data System (MEADS) pressure port plug, one MEDLI2 Integrated Sensor Plug (MISP) thermal plug, and one heat flux sensor. DNH testing was conducted to ensure the performance of the TPS was not degraded due to sensor integration and to characterize any TPS performance changes. The testing consisted of environmental testing vibration, shock, thermal vacuum (TVAC) cycling and bounding aerothermal (arc jet) testing. During arc jet testing, the heat flux sensors embedded in the SLA-561V panels exhibited an unexpected temporary reduction in the heat flux sensor temperature and response. After review of the test results, it was determined that this unexpected response was confined to the two heat flux sensors that experienced the greatest thermal shock condition. This condition consisted of a liquid nitrogen (LN2) bath that induced temperatures of approximately -190C, and then a transition (thermal shock) to an arc jet test at a heat rate of approximately 21 W/cm2. Both heat flux sensors that were exposed to this thermal shock experienced a blister in the thermal coating during the arc jet test.Two heat flux sensor thermal shock test series were performed to investigate the cause of the blistering and subsequent energy release. In these tests, the heat flux sensor was first cold soaked in either a dry ice or LN2 bath to induce temperatures of approximately -78C or -190C, respectively. Then the sensors were thermally shocked using two propane torches with a heat rate of either approximately 8 W/cm2 or 21 W/cm2. The key findings indicated that there is a correlation between thermal shock and the blistering observed in the DNH test series, and that the cause appeared to be rooted in the heat flux sensor epoxy that encapsulates the sensor thermopile.Since the heat flux sensors are required to measure heat fluxes up to 15 W/cm2 during the Mars 2020 entry, a third test series was designed to determine if blistering is an issue at this maximum expected flight heat flux. Results from all three thermal shock test series and a discussion about whether or not blistering of the heat flux sensor thermal coating could be an issue for the Mars 2020 mission will be presented.

Description: Seeker is an automated extravehicular free-flying inspector CubeSat designed and built in-house at the Johnson Space Center (JSC). As a Class 1E project funded by the International Space Station (ISS) Program, Seeker had a streamlined process to flight certification, but the vehicle had to be designed, developed, tested, and delivered within approximately one year after authority to pro-ceed (ATP) and within a $1.8 million budget. These constraints necessitated an expedited Guidance, Navigation, and Control (GNC) development schedule, development began with a navigation sensor trade study using Linear Covariance (LinCov) analysis and a rapid sensor downselection process, resulting in the use of commercial off-the-shelf (COTS) sensors which could be procured quickly and subjected to in-house environmental testing to qualify them for flight. A neural network was used to enable a COTS camera to provide bearing measurements for visual navigation. The GNC flight software (FSW) algorithms utilized lean development practices and leveraged the Core Flight Software (CFS) architecture to rapidly develop the GNC system, tune the system parameters, and verify performance in simulation. This pace was anchored by several Hardware-Software Integration (HSI) milestones, which forced the Seeker GNC team to develop the interfaces both between hardware and software and between the GNC domains early in the project and to enable a timely delivery.

Description: No abstract available

Description: OuroboroSat (also known as MRMSS: the Modular Rapidly Manufactured Spacecraft System) is a modular instrumentation platform consisting of multiple 3 inch (7.5 centimeter) square printed circuit boards that are mechanically and electrically connected to one another in order to produce a fully- functioning payload facility system. Each OuroboroSat module consists of a microcontroller, a battery, conditioning and monitoring circuitry for the battery, optional space for solar panels, and an expansion area where an experimental payload or specialized functionality (such as wireless communication submodules) can be attached.

Description: NASA's Determination of Offgassed Products (Test 7) from materials and assembled articles for spaceflight has evolved since the Apollo program for over 50 years to meet various habitable spacecraft nonmetallic programmatic requirements. Now mandated by NASA STD-6016A, Standard Materials and Processes Requirements for Spacecraft, all nonmetallic materials used in habitable flight compartments, with the exception of ceramics, metal oxides, inorganic glasses, and materials used in sealed containers, must meet the offgassing requirements in NASA-STD-6001B Test 7. This manuscript presents the history of Test 7, beginning with the Apollo spacecraft nonmetallic materials selection guidelines and test requirements in 1967, in which tests were performed in mostly oxygen atmospheres. It progresses through Skylab, Space Shuttle, International Space Station nonmetals testing, and acceptance requirements with milder test environments. This review of the history of Test 7 presents the reader with a perspective on the development and changes undergone since inception to the present. Related NASA standard tests (some now former, discontinued, combined, or supplemental) including Test 6, Odor Assessment, Test 16, Determination of Offgassed Products from Assembled Articles, and Test 12, Total Spacecraft Cabin Offgassing, are discussed in context

Description: The Lunar Reconnaissance Orbiter (LRO) was launched in 2009 and, with itsseven science instruments, has made numerous contributions to our understandingof the moon. LRO is in an elliptical, polar lunar orbit and nominally maintainsa nadir orientation. There are frequent slews off nadir to observe various sciencetargets. LRO attitude control system (ACS) has two star trackers and a gyro forattitude estimation in an extended Kalman filter (EKF) and four reaction wheelsused in a proportional-integral-derivative (PID) controller. LRO is equipped withthrusters for orbit adjustments and momentum management. In early 2018, thegyro was powered off following a fairly rapid decline in the laser intensity on theX axis. Without the gyro, the EKF has been disabled. Attitude is provided by asingle star tracker and a coarse rate estimate is computed by a back differencingof the star tracker quaternions. Slews have also been disabled. A new rate estimationapproach makes use of a complementary filter, combining the quaterniondifferentiated rates and the integrated PID limited control torque (with reactionwheel drag and feedforward torque removed). The filtered rate estimate replacesthe MIMU rate in the EKF, resulting in minimal flight software changes. The paperwill cover the preparation and testing of the new gyroless algorithm, both inground simulations and inflight.

Description: The Orion European Service Module - Structural Test Article (E-STA) underwent sine vibration testing in 2016 using the Mechanical Vibration Facility (MVF) multi-axis shaker system at NASA Glenn Research Centers (GRC) Plum Brook Station (PBS) Space Power Facility (SPF). The main objective was to verify the structural integrity of the European Service Module (ESM) under sine sweep dynamic qualification vibration testing. A secondary objective was to perform a fixed-base modal survey, while E-STA was still mounted to MVF, in order to achieve a test correlate the finite element model (FEM). To facilitate the E-STA system level correlation effort, a building block test approach was implemented. Modal tests were performed on two major subassemblies, the crew module/launch abort structure (CM/LAS) and the crew module adapter (CMA) mass simulators. These subassembly FEMs were individually correlated and then integrated into the E-STA FEM prior to the start of the E-STA sine vibration test. This paper summarizes the modal testing and model correlation efforts of both of these subassemblies and how the building block approach assisted in the overall correlation of the E-STA FEM. This paper will also cover modeling practices that should be avoided, recommended instrumentation positioning on complex structures, and the importance of the FEM geometrically matching CAD in sufficient detail in order to adequately replicate internal load paths. The goal of this paper is to inform the reader of the hard earned lessons learned and pitfalls to avoid when applying a building block test approach.

Description: Advances in Entry Systems Technologies -- Continuing the Ames' Innovation Heritage" will provide an overview of recent accomplishments in the areas of entry systems, TPS materials, arcjet testing, etc.Hypervelocity Entry is a Hard Problem !Use of atmospheric drag is the most efficient way to slow down. Protection fromthe entry heating demands comprehensive understanding of the hypervelocity,reacting flow (aero-thermodynamics), and selection, design, testing and verificationof the integrated entry system, especially thermal protection system.

Description: Atomic oxygen erosion of polymers in low Earth orbit (LEO) poses a serious threat to spacecraft performance and durability. Forty thin film polymer and pyrolytic graphite samples, collectively called the PEACE (Polymer Erosion and Contamination Experiment) Polymers, were exposed to the LEO space environment on the exterior of the ISS for nearly four years as part of the Materials International Space Station Experiment 1 & 2 (MISSE 1 & 2) mission. The purpose of the MISSE 2 PEACE Polymers experiment was to determine the atomic oxygen (AO) erosion yield (E(sub y), volume loss per incident oxygen atom) of a wide variety of polymers exposed to the LEO space environment. The Ey values were determined based on mass loss measurements. Because many polymeric materials are hygroscopic, the pre-flight and post-flight mass measurements were obtained using dehydrated samples. To maximize the accuracy of the mass measurements, obtaining dehydration data for each of the polymers was desired to ensure that the samples were fully dehydrated before weighing. A comparison of dehydration and rehydration data showed that rehydration data mirrors dehydration data, and is easier and more reliable to obtain. Tests were also conducted to see if multiple samples could be dehydrated and weighed sequentially. Rehydration curves of 43 polymers and pyrolytic graphite were obtained. This information was used to determine the best pre-flight, and post-flight, mass measurement procedures for the MISSE 2 PEACE Polymers experiment, and for subsequent NASA Glenn Research Center MISSE polymer flight experiments.