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NASA's Aerospace Safety Advisory Panel Releases 2021 Annual Report
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The SpaceX Dragon Freedom spacecraft carrying NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov approaches the International Space Station as it orbited 261 miles above Ontario, Canada, near James Bay. NASA published a new report Thursday highlighting 17 agency mechanisms that have directly and indirectly supported the development and growth of the U.S. commercial space sector for the benefit of humanity.
The report, titled Enabling America on the Space Frontier: The Evolution of NASA’s Commercial Space Development Toolkit, is available on the agency’s website.
“This is the most extensive and comprehensive historical analysis produced by NASA on how it has contributed to commercial space development over the decades,” said Alex MacDonald, NASA chief economist. “These efforts have given NASA regular access to space with companies, such as SpaceX and Rocket Lab, modernizing our communications infrastructure, and even led to the first private lunar lander thanks to Intuitive Machines. With commercial space growth accelerating, this report can help agency leaders and stakeholders assess the numerous mechanisms that the agency uses to support this growth, both now and in the future.”
Throughout its history, NASA has supported the development of the commercial space sector, not only leading the way in areas such as satellite communications, launch, and remote sensing, but also developing new contract and operational models to encourage commercial participation and growth. In the last three decades, NASA has seen the results of these efforts with commercial partners able to contribute more to missions across NASA domains, and increasingly innovative agency-led efforts to engage, nurture, and integrate these capabilities. These capabilities support the agency’s mission needs, and have seen a dramatic rise in importance, according to the report.
NASA has nurtured technology, companies, people, and ideas in the commercial space sector, contributing to the U.S. and global economies, across four distinct periods in the agency’s history:
1915–1960: NASA’s predecessor, the National Advisory Committee on Aeronautics (NACA), and NASA’s pre-Apollo years. 1961–1980: Apollo era. 1981–2010: Space shuttle era. 2011–present: Post-shuttle commercial era. Each of these time periods are defined by dominant technologies, programs, or economic trends further detailed in the report.
Though some of these mechanisms are relatively recent, others have been used throughout the history of NASA and NACA, leading to some overlap. The 17 mechanisms are as follows:
Contracts and Partnership Agreements Research and Technology Development (R&TD) Dissemination of Research and Scientific Data Education and Workforce Development Workforce External Engagement and Mobility Technology Transfer Technical Support Enabling Infrastructure Launch Direct In-Space Support Standards and Regulatory Framework Support Public Engagement Industry Engagement Venture Capital Engagement Market Stimulation Funding Economic Analysis and Due Diligence Capabilities Narrative Encouragement NASA supports commercial space development in everything from spaceflight to supply chains. Small satellite capabilities have inspired a new generation of space start-ups, while new, smaller rockets, as well as new programs are just starting. Examples include CLPS (Commercial Lunar Payload Services), commercial low Earth orbit destinations, human landing systems, commercial development of NASA spacesuits, and lunar terrain vehicles. The report also details many indirect ways the agency has contributed to the vibrance of commercial space, from economic analyses to student engagement.
The agency’s use of commercial capabilities has progressed from being the exception to the default method for many of its missions. The current post-shuttle era of NASA-supported commercial space development has seen a level of technical development comparable to the Apollo era’s Space Race. Deploying the 17 commercial space development mechanisms in the future are part of NASA’s mission to continue encouraging commercial space activities.
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https//:www.nasa.gov
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Last Updated Dec 19, 2024 EditorBill Keeter Related Terms
Office of Technology, Policy and Strategy (OTPS) View the full article
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By NASA
1 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s Office of Technology, Policy, and Strategy, shares highlights from the office in 2024, including key accomplishments and collaborations that support the NASA mission. Read the full report, NASA’s Office of Technology, Policy, and Strategy: A Year in Review 2024
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Last Updated Dec 18, 2024 EditorBill Keeter Related Terms
Office of Technology, Policy and Strategy (OTPS) View the full article
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By NASA
1 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The Airspace Operations and Safety Program (AOSP) enables safe, sustainable, and efficient aviation transportation operations to benefit the flying public and ensure the global competitiveness of the U.S. aviation industry. We are transforming the future of aviation into a digital, federated, and service-oriented architecture that fosters the growth of safe airspace for all users.
By partnering with FAA, academia, safety experts, operators, manufacturers, municipalities, and other government agencies, we facilitate the integration of new aviation technologies, ensure airspace access for new entrants, and champion the success of increasingly autonomous operations. At AOSP, safety is at the heart of everything we do. We stand firm in our unwavering commitment to the safe integration of these vehicles.
AOSP Approach:
Efficient, Sustainable Aviation Operations Seamless Integration of Heterogeneous and Emergent Aviation Prognostic In-Time Aviation Safety Management System of Future Operations System Level Autonomy for Aviation Operations, Vehicle Command and Control Systems, and Safety Meet the diversity, density, and complexity challenges of future aviation AOSP Projects
Advanced Capabilities for Emergency Response Operations Project
Air Mobility Pathfinders
Air Traffic Management—Exploration (ATM-X)
System-Wide Safety (SWS)
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Last Updated Dec 17, 2024 EditorLillian GipsonContactJim Bankejim.banke@nasa.gov Related Terms
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By NASA
This article is from the 2024 Technical Update.
Multiple human spaceflight programs are underway at NASA including Orion, Space Launch System, Gateway, Human Landing System, and EVA and Lunar Surface Mobility programs. Achieving success in these programs requires NASA to collaborate with a variety of commercial partners, including both new spaceflight companies and robotic spaceflight companies pursuing crewed spaceflight for the first time. It is not always clear to these organizations how to show their systems are safe for human spaceflight. This is particularly true for avionics systems, which are responsible for performing some of a crewed spacecraft’s most critical functions. NASA recently published guidance describing how to show the design of an avionic system meets safety requirements for crewed missions.
Background
The avionics in a crewed spacecraft perform many safety critical functions, including controlling the position and attitude of the spacecraft, activating onboard abort systems, and firing pyrotechnics. The incorrect operation of any of these functions can be catastrophic, causing loss of the crew. NASA’s human rating requirements describe the need for “additional rigor and scrutiny” when designing safety-critical systems beyond that done
for uncrewed spacecraft [2]. Unfortunately, it is not always clear how to interpret this guidance and show an avionics architecture is sufficiently safe. To address this problem, NASA recently published NASA/TM−20240009366 [1]. It outlines best practices for designing safety-critical avionics, as well as describes key artifacts or evidence NASA needs to assess the safety of an avionics architecture.
Failure Hypothesis
One of the most important steps to designing an avionics architecture for crewed spacecraft is specification of the failure hypothesis (FH). In short, the FH summarizes any assumptions the designers make about the type, number, and persistence of component failures (e.g., of onboard computers, network switches). It divides the space of all possible failures into two parts – failures the system is designed to tolerate and failures it is not.
One key part of the FH is a description of failure modes the system can tolerate – i.e., the behavior exhibited by a failed component. Failure modes are categorized using a failure model. A typical failure model for avionics splits failures into two broad categories:
Value failures, where data produced by a component is missing (i.e., an omissive failure) or incorrect (i.e., a transmissive failure). Timing failures, where data is produced by a component at the wrong time.
Timing failures can be further divided into many sub-categories, including:
Inadvertent activation, where data is produced by a component without the necessary preconditions. Out-of-order failures, where data is produced by a component in an incorrect sequence. Marginal timing failures, where data is produced by a component slightly too early or late.
In addition to occurring when data is produced by a component, these failure modes can also occur when data enters a component. (e.g., a faulty component can corrupt a message it receives). Moreover, all failure modes can manifest in one of two ways:
Symmetrically, where all observers see the same faulty behavior. Asymmetrically, where some observers see different faulty behavior.
Importantly, NASA’s human-rating process requires that each of these failure modes be mitigated if it can result in catastrophic effects [2]. Any exceptions must be explicitly documented and strongly justified. In addition to specifying the failure modes a system can tolerate, the FH must specify any limiting assumptions about the relative arrival times of permanent failures and radiation-induced upsets/ errors or the ability for ground operator to intervene to safe the system or take recovery actions. For more information on specifying a FH and other artifacts needed to evaluate the safety of an avionics architecture for human spaceflight, see the full report [1].
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By NASA
This article is from the 2024 Technical Update.
The NESC evaluated material compatibility of some common aerospace metals in monomethylhydrazine (MMH) and nitrogen tetroxide (MON-3). Previous work had identified a lack of quantitative compatibility data for nickel alloy 718, 300 series stainless steel, and titanium Ti-6Al-4V in MMH and MON-3 to support the use of zero-failure-tolerant, thin-walled pressure barriers in these propellants. Static (i.e., not flowing) general corrosion and electrochemistry testing was conducted, evaluating varied processing forms and heat treatment of the metals, water content of propellant, and exposure duration. Corrosion-rate data for all tested product forms, fluids, and durations were on the order of 1 x 10–6 inch per year rather than the previously documented “less than 1 x 10–3 inch per year”. The majority of the corrosion products were seen in the first 20 days of exposure, with an overall corrosion rate decreasing with time due to the increased divisor (time). It is therefore recommended that corrosion testing be performed at multiple short-term durations to inform the need for longer-duration testing.
Background
Nickel alloy 718, 300 series stainless steel, and Ti-6Al-4V are commonly used in storable propulsion systems (i.e., MMH/MON-3), but a concern was raised regarding what quantitative compatibility data were available for proposed zero-failure-tolerant, thin-walled (~0.005 to 0.010 inch thickness) pressure barrier designs. A literature search found that limited and conflicting data were available for commonly used aerospace metals in MMH and MON-3. For example, corrosion behavior was listed qualitatively (e.g., “A” rating), data on materials and fluids tested were imprecise, fluids were identified as contaminated without describing how they were contaminated, no compatibility data were found on relevant geometry specimens (i.e., very thin-walled or convoluted), and limited data were available to quantify differences between tested materials and flight components. When corrosion data were quantified, documented sensitivity was “1 x 10–3 inch per year or less”, which is insufficient for assessing long-duration, thin-walled, flight-weight applications.
Discussion
General corrosion testing was performed with a static/non-flowing configuration based on NASA-STD-6001, Test 15 [1]. Design of experiments methods were used to develop a test matrix varying material, propellant, propellant water content, and tested duration. Materials tested were nickel alloy 718 (solution annealed sheet, aged sheet, aged/welded sheet, and hydroformed bellows), 300 series stainless steel (low carbon sheet, titanium stabilized sheet, and hydroformed bellows), and Ti 6Al-4V sheet. Samples were tested in sealed test tubes in MMH and MON-3 with water content ranging from as-received (“dry”) up to specification allowable limits [2,3]. Tested durations ranged from 20 to 365 days. Measurements included inductively coupled plasma mass spectrometry (ICPMS) to identify corrosion products and their concentrations in test fluid, gravimetric (i.e., scale) measurements pre- and post-exposure, and visual inspection. Bimetallic pairs (titanium stabilized 300 series stainless steel: Ti 6Al-4V and nickel alloy 718: Ti 6Al-4V) were tested for up to 65 days in both MMH and MON-3. The test setup incorporated important features of the test standard (e.g., electrode spacing and finish) and adapted the configuration for MMH/MON-3 operation. Measurements included potential difference and current flow between samples. Figure 1 shows images of the general corrosion and bimetallic pair test setups.
Test Results
For all tested materials and product forms, corrosion rates were on the order of 1 x 10–6 inch per year in MMH or MON-3, three orders of magnitude lower than historically reported. Corrosion products were generated in the first 20 days of exposure, and corrosion rate decreased with time due to the increase in divisor (i.e., time). Corrosion products increased as the water content of the propellants increased but remained in the same order of magnitude between the as-received dry propellant and propellant containing the maximum water content allowed by specification. Figure 2 illustrates test results for corrosion rate, mass loss with duration, and mass loss with water content. It is important to note that water has been demonstrated to contribute to flow decay even when water is within the specification allowable limit, and previous NASA-STD-6001 Test 15 data have demonstrated susceptibility of some nickel alloys to crevice-type corrosion attack [4]. Therefore, these results do not reduce the importance of considering the system impact of water content and evaluating for crevice corrosion behavior. Finally, in the bimetallic pair testing, tested materials did not measurably corrode in MON-3 and MMH within specification-allowable water content, as evidenced by no visual indications of corrosion and very low electrical interaction (i.e., corrosion rates derived to be less than 1 microinch per year from electrical interaction).
Recommendations
It is recommended that corrosion testing be performed at multiple shortterm durations to inform the need for longer-duration testing.
References
NASA-STD-6001 Flammability, Odor, Offgassing, and Compatibility Requirements
and Test Procedures for Materials In Environments that Support Combustion MIL-PRF-27404 Performance Specification: Propellant, Monomethylhydrazine MIL-PRF-26539 Performance Specification: Propellants, Dinitrogen Tetroxide WSTF Test 15 Report 12-45708 and WSTF Test 15 Report 13-46207 View the full article
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