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By NASA
Download PDF: Statistical Analysis Using Random Forest Algorithm Provides Key Insights into Parachute Energy Modulator System
Energy modulators (EM), also known as energy absorbers, are safety-critical components that are used to control shocks and impulses in a load path. EMs are textile devices typically manufactured out of nylon, Kevlar® and other materials, and control loads by breaking rows of stitches that bind a strong base webbing together as shown in Figure 1. A familiar EM application is a fall-protection harness used by workers to prevent injury from shock loads when the harness arrests a fall. EMs are also widely used in parachute systems to control shock loads experienced during the various stages of parachute system deployment.
Random forest is an innovative algorithm for data classification used in statistics and machine learning. It is an easy to use and highly flexible ensemble learning method. The random forest algorithm is capable of modeling both categorical and continuous data and can handle large datasets, making it applicable in many situations. It also makes it easy to evaluate the relative importance of variables and maintains accuracy even when a dataset has missing values.
Random forests model the relationship between a response variable and a set of predictor or independent variables by creating a collection of decision trees. Each decision tree is built from a random sample of the data. The individual trees are then combined through methods such as averaging or voting to determine the final prediction (Figure 2). A decision tree is a non-parametric supervised learning algorithm that partitions the data using a series of branching binary decisions. Decision trees inherently identify key features of the data and provide a ranking of the contribution of each feature based on when it becomes relevant. This capability can be used to determine the relative importance of the input variables (Figure 3). Decision trees are useful for exploring relationships but can have poor accuracy unless they are combined into random forests or other tree-based models.
The performance of a random forest can be evaluated using out-of-bag error and cross-validation techniques. Random forests often use random sampling with replacement from the original dataset to create each decision tree. This is also known as bootstrap sampling and forms a bootstrap forest. The data included in the bootstrap sample are referred to as in-the-bag, while the data not selected are out-of-bag. Since the out-of-bag data were not used to generate the decision tree, they can be used as an internal measure of the accuracy of the model. Cross-validation can be used to assess how well the results of a random forest model will generalize to an independent dataset. In this approach, the data are split into a training dataset used to generate the decision trees and build the model and a validation dataset used to evaluate the model’s performance. Evaluating the model on the independent validation dataset provides an estimate of how accurately the model will perform in practice and helps avoid problems such as overfitting or sampling bias. A good model performs well on
both the training data and the validation data.
The complex nature of the EM system made it difficult for the team to identify how various parameters influenced EM behavior. A bootstrap forest analysis was applied to the test dataset and was able to identify five key variables associated with higher probability of damage and/or anomalous behavior. The identified key variables provided a basis for further testing and redesign of the EM system. These results also provided essential insight to the investigation and aided in development of flight rationale for future use cases.
For information, contact Dr. Sara R. Wilson. sara.r.wilson@nasa.gov
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By NASA
Northrop Grumman & NASA Digital Engineering SAA Kick-off meeting at Thompson Space Innovation Center. NASA’s Digital Engineering is paving the way for exciting new possibilities. Their latest Space Act Agreement with Northrop Grumman promises to accelerate progress in space exploration through innovative collaboration.
Under NASA’s HQ Office of the Chief Engineer, Terry Hill the Digital Engineering Program Manager, recently signed a Space Act Agreement with Northrop Grumman Space Sector to explore digital engineering approaches to sharing information between industry partners and NASA. This collaboration aims to support NASA’s mission by advancing engineering practices to reduce the time from concept to flight. By leveraging digital engineering tools, this collaboration could lead to improved design, testing, and simulation processes, It could also help improve how the government and industry write contracts, making it easier and more efficient for them to share information. This would help both sides work together better, handle more complicated missions, and speed up the development of new space technologies.
This collaboration between NASA and Northrop Grumman brings exciting possibilities for the future of space exploration. By embracing digital engineering, both organizations are working toward more efficient, cost-effective missions and solutions to greater challenges. Beyond accelerating mission timelines, the insights and technologies developed through this collaboration could pave the way for groundbreaking advancements in space capabilities.
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s Stennis Space Center enjoyed an active 2024, marking several milestones and engaging in frontline activities in several key areas. A compilation video offers a look at 2024 highlights in such areas of work as propulsion testing, autonomous systems, range operations, community outreach, and STEM engagement. NASA’s Stennis Space Center near Bay St. Louis, Mississippi, celebrated propulsion testing and site operations milestones in 2024, all while inspiring the Artemis Generation and welcoming new leadership that will help NASA Stennis innovate and grow into the future.
Featured highlights show a year of progress and vision, as NASA Stennis accelerates the exploration and commercialization of space, innovates to benefit NASA and industry, and leverages assets to grow as an impactful aerospace and technology hub.
“These highlights are just a small snapshot of 2024 at NASA Stennis that show the future is bright,” Bailey said. “We have an incredibly talented and committed team of employees – and all of Mississippi can be proud of the work they do here at NASA Stennis. Together, with the Artemis Generation leading the way, we are returning to the Moon. Together, we are a part of something great.”
New Center Leadership
NASA Stennis Director John Bailey, right, and NASA Stennis Deputy Director Christine Powell stand near the United States Capitol during a visit to Washington, D.C. on Sept. 18. It marked the first visit to Capitol Hill for the center leaders since being named to their current roles. NASA/Stennis NASA Administrator Bill Nelson named John Bailey as director of NASA Stennis in April. Bailey had been serving as acting director since January 2024. “So much of NASA runs through Stennis,” said Nelson. “It is where we hone new and exciting capabilities in aerospace, technology, and deep space exploration. I am confident that John will lead the nation’s largest and premier propulsion test site to even greater success.”
Four months later in August, Bailey announced that longtime propulsion engineer/manager Christine Powell had been selected as deputy director of NASA Stennis.
Powell, the first woman selected as NASA Stennis deputy director, began her 33-year agency career as an intern at the center in 1991. She previously worked in multiple Engineering and Test Directorate roles, and most recently served as manager of the NASA Rocket Propulsion Test Program Office.
Propulsion Activity
NASA achieves a major milestone for future Artemis missions with successful completion of the second – and final – RS-25 engine certification test series April 3 on the Fred Haise Test Stand at NASA’s Stennis Space Center. NASA/Danny Nowlin NASA achieved major milestones for future Artemis missions at NASA Stennis in 2024. The NASA Stennis test team successfully completed a second – and final – RS-25 engine certification test series in April. The mission-critical series verified engine upgrades designed to enhance efficiency and reliability for future SLS (Space Launch System) missions.
NASA Stennis crews also completed a safe lift and installation of the interstage simulator component in October needed for future testing of NASA’s exploration upper stage in the B-2 position of the Thad Cochran Test Stand. The component will function during Green Run testing like the SLS interstage section that helps protect the upper stage during Artemis launches.
The test complex milestones support NASA’s goal of returning humans to the Moon and paving the way for future Mars exploration through Artemis missions.
Commercial Testing
NASA Stennis commercial tenant Rocket Lab completes a successful hot fire test of its Archimedes engine in its onsite test complex in the second half of 2024. Rocket Lab is one of numerous customers conducting test campaigns at NASA Stennis during the most recent year. Rocket Lab Already the nation’s largest multiuser propulsion test site, NASA Stennis aims to continue fueling growth of the commercial space market even further by working with aerospace companies to support a range of testing needs. In 2024, NASA Stennis supported work conducted by commercial companies such as Boeing, Blue Origin, Evolution Space, Launcher (a Vast company), Relativity Space, Rocket Lab, and Rolls-Royce.
Officials from NASA Stennis and Roll-Royce also broke ground in June for a test pad located in the NASA Stennis E Test Complex. Rolls-Royce will conduct hydrogen testing for the Pearl 15 engine, which helps power the Bombardier Global 5500 & 6500 aircraft.
ASTRA Mission Success
Members of the NASA Stennis Autonomous Systems Laboratory team monitor the center’s in-space satellite payload from the onsite ASTRA (Autonomous Satellite Technology for Resilient Applications) Payload Operation Command Center. The ASTRA payload launched aboard the Sidus Space LizzieSat-1 small satellite in March 2024, with the NASA Stennis team announcing in July that it had achieved primary mission objectives. In September, the team announced the ASTRA mission would continue during the satellite’s planned four-year mission.NASA/Danny Nowlin In July, NASA Stennis and commercial partner Sidus Space Inc. announced primary mission success for the center’s historic in-space mission – an autonomous systems payload aboard an orbiting satellite.
ASTRA (Autonomous Satellite Technology for Resilient Applications) is the on-orbit payload mission developed by NASA Stennis. The NASA Stennis ASTRA technology demonstrator is a payload rider aboard the Sidus Space premier satellite, LizzieSat-1 (LS-1) small satellite. Partner Sidus Space is responsible for all LS-1 mission operations, including launch and satellite activation, which allowed the NASA Stennis ASTRA team to complete its primary mission objectives.
NASA Stennis announced in September it will continue the center’s in-space autonomous systems payload mission through a follow-on agreement with Sidus Space Inc.
Range Operations
The Skydweller Aero solar-powered, autonomous aircraft flies above the Thad Cochran Test Stand (B-1/B-2) at NASA’s Stennis Space Center during a September 2024 test operation. Skydweller Aero has an ongoing airspace agreement with NASA Stennis to conduct test flights of its aircraft in the area. Skydweller Aero During 2024, NASA Stennis entered into an agreement with Skydweller Aero Inc. for the company to operate its solar-powered autonomous aircraft in the site’s restricted airspace, a step towards achieving a strategic center goal.
The agreement marked the first Reimbursable Space Act agreement between NASA Stennis and a commercial company to utilize the south Mississippi center’s unique capabilities to support testing and operation of uncrewed systems.
The company announced in October it had completed an initial test flight campaign of the aircraft, including two test excursions totaling 16 and 22.5 hours.
NASA Engagement
NASA Stennis representatives inspire the Artemis Generation at the NAS Pensacola Blue Angels Homecoming Air Show on Nov. 1-2. NASA’s exhibits at the air show honored 55th anniversary of the Apollo 11 lunar landing and showcased the agency’s mission to inspire the world through discovery. NASA/Stennis NASA representatives participated in a variety of outreach activities during the past year to create meaningful connections with the Artemis Generation.
The NASA ASTRO CAMP® Community Partners program, which originated at the south Mississippi NASA center, surpassed previous milestone marks in fiscal year 2024 by partnering with 373 community sites, including 50 outside the United States, to inspire youth, families, and educators.
NASA Stennis also supported STEM (science, technology, engineering, and mathematics) engagement during the year. It once again joined with NASA’s Robotics Alliance Project and co-sponsor Mississippi Power to support the second annual For the Inspiration and Recognition of Science and Technology (FIRST) Robotics Magnolia Regional Competition in Laurel, Mississippi. The event attracted 37 high school teams from eight states and one from Mexico.
The center also supported NASA activities during the 2024 total solar eclipse. In addition, it hosted informational efforts and exhibits at high-visibility events such as the 51st Annual Bayou Classic, and Essence Fest in New Orleans.
For information about NASA’s Stennis Space Center, visit:
Stennis Space Center – NASA
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Last Updated Dec 16, 2024 EditorNASA Stennis CommunicationsContactC. Lacy Thompsoncalvin.l.thompson@nasa.gov / (228) 688-3333LocationStennis Space Center 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 Space Force
The Space Force senior leader highlighted the ever-changing landscape of developing partnerships in the space domain.
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