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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 European Space Agency
A multi-orbit constellation of about 300 satellites that will deliver resilient, secure and fast communications for EU governments, European companies and citizens will be put in orbit after two contracts were confirmed today in Brussels.
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By NASA
3 Min Read Matt Dominick’s X Account: A Visual Journey from Space
We are lucky to have had the opportunity to fly in space and feel a responsibility to share with humanity the incredible views of the Earth and the cosmos.
Matt dominick
NASA Astronaut
NASA astronaut and Expedition 72 Flight Engineer Matthew Dominick launched to the International Space Station on March 3, 2024 as the commander of NASA’s SpaceX Crew-8 mission. As a flight engineer aboard the orbiting laboratory, Dominick conducted scientific research while capturing breathtaking views of Earth and beyond from the ultimate vantage point—250 miles above the planet.
Dominick’s X account (@dominickmatthew) has become a visual diary, showcasing the beauty of our planet captured from low Earth orbit during his 235 days in space. From the ethereal glow of auroras dancing across the atmosphere to comets rising up over the horizon during an orbital sunrise, each meticulously captured image reflects his dedication to sharing the wonders of space exploration through social media. He goes beyond simply posting pictures; he reveals the techniques behind his astrophotography, including camera settings and insights into his creative process, inviting followers to appreciate the artistry involved.
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Matt Dominick shared this timelapse video to his X account in August 2024, showing the Moon setting into streams of red and green aurora.Matt Dominick See the full X post here.
Amid his daily astronaut duties, Dominick dedicated personal time to this endeavor, amassing nearly 500,000 captivating photos of Earth and snapshots of life aboard the International Space Station, while having traveled 99,708,603 total statue miles around our home planet. Through his lens(es), he invited us to experience the awe of space while highlighting the realities of life in orbit, fostering an authentic connection with those who engage with his work.
Building on this commitment to connect, Dominick participated in the first-ever live X Spaces event from space, marking a new way for NASA astronauts to connect personally with followers. He shared insider tips on astrophotography from orbit and discussed the challenges and joys of capturing stunning images in microgravity. Concluding the event, he vividly narrated his live experience floating into the Cupola at sunset while orbiting over Paris just days before the 2024 Summer Olympic Games.
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A screen recording of the first X Spaces event from space featuring NASA astronaut Matt Dominick.NASA Dominick’s journey as an astronaut unfolds in real-time on his X account. He has captured the arrivals and departures of various spacecraft, documented dynamic weather events, and even participated in Olympic festivities. His stunning timelapses and behind-the-scenes videos offer an intimate look at life aboard the space station, beautifully illustrating the intricate interplay between science and wonder.
What sets Dominick’s account apart is his playful perspective. He invites his audience into lighthearted moments—whether he’s cleaning his retainer in microgravity, relishing the arrival of fresh fruit, or sharing insights from the ISS toolbox. By documenting and sharing these experiences, he demystifies the complexities of space travel, making it an accessible and relatable journey for all. Through his engaging posts, Dominick cultivates a deeper connection with his followers, encouraging them to share in the beauty and reality of life beyond our planet.
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Matt Dominick shared this video video to his X account in August 2024 after receiving fresh fruit aboard the International Space Station.Matt Dominick See the full X post here.
Visit Dominick’s X account (@dominickmatthew) to experience the wonders of space through his eyes, enriched by his remarkable journey of orbiting the Earth 3,760 times.
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Last Updated Dec 05, 2024 Related Terms
International Space Station (ISS) Astronauts Expedition 72 Humans in Space View the full article
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By NASA
4 min read
NASA, JAXA XRISM Mission Looks Deeply Into ‘Hidden’ Stellar System
The Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) observatory has captured the most detailed portrait yet of gases flowing within Cygnus X-3, one of the most studied sources in the X-ray sky.
Cygnus X-3 is a binary that pairs a rare type of high-mass star with a compact companion — likely a black hole.
Cygnus X-3 is a high-mass binary consisting of a compact object (likely a black hole) and a hot Wolf-Rayet star. This artist’s concept shows one interpretation of the system. High-resolution X-ray spectroscopy indicates two gas components: a heavy background outflow, or wind, emanating from the massive star and a turbulent structure — perhaps a wake carved into the wind — located close to the orbiting companion. As shown here, a black hole’s gravity captures some of the wind into an accretion disk around it, and the disk’s orbital motion sculpts a path (yellow arc) through the streaming gas. During strong outbursts, the companion emits jets of particles moving near the speed of light, seen here extending above and below the black hole. NASA’s Goddard Space Flight Center “The nature of the massive star is one factor that makes Cygnus X-3 so intriguing,” said Ralf Ballhausen, a postdoctoral associate at the University of Maryland, College Park, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s a Wolf-Rayet star, a type that has evolved to the point where strong outflows called stellar winds strip gas from the star’s surface and drive it outward. The compact object sweeps up and heats some of this gas, causing it to emit X-rays.”
A paper describing the findings, led by Ballhausen, will appear in a future edition of The Astrophysical Journal.
“For XRISM, Cygnus X-3 is a Goldilocks target — its brightness is ‘just right’ in the energy range where XRISM is especially sensitive,” said co-author Timothy Kallman, an astrophysicist at NASA Goddard. “This unusual source has been studied by every X-ray satellite ever flown, so observing it is a kind of rite of passage for new X-ray missions.”
XRISM (pronounced “crism”) is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency). NASA and JAXA developed the mission’s microcalorimeter spectrometer instrument, named Resolve.
Observing Cygnus X-3 for 18 hours in late March, Resolve acquired a high-resolution spectrum that allows astronomers to better understand the complex gas dynamics operating there. These include outflowing gas produced by a hot, massive star, its interaction with the compact companion, and a turbulent region that may represent a wake produced by the companion as it orbits through the outrushing gas.
XRISM’s Resolve instrument has captured the most detailed X-ray spectrum yet acquired of Cygnus X-3. Peaks indicate X-rays emitted by ionized gases, and valleys form where the gases absorb X-rays; many lines are also shifted to both higher and lower energies by gas motions. Top: The full Resolve spectrum, from 2 to 8 keV (kiloelectron volts), tracks X-rays with thousands of times the energy of visible light. Some lines are labeled with the names of the elements that produced them, such as sulfur, argon, and calcium, along with Roman numerals that refer to the number of electrons these atoms have lost. Bottom: A zoom into a region of the spectrum often dominated by features produced by transitions in the innermost electron shell (K shell) of iron atoms. These features form when the atoms interact with high-energy X-rays or electrons and respond by emitting a photon at energies between 6.4 and 7 keV. These details, clearly visible for the first time with XRISM’s Resolve instrument, will help astronomers refine their understanding of this unusual system. JAXA/NASA/XRISM Collaboration In Cygnus X-3, the star and compact object are so close they complete an orbit in just 4.8 hours. The binary is thought to lie about 32,000 light-years away in the direction of the northern constellation Cygnus.
While thick dust clouds in our galaxy’s central plane obscure any visible light from Cygnus X-3, the binary has been studied in radio, infrared, and gamma-ray light, as well as in X-rays.
The system is immersed in the star’s streaming gas, which is illuminated and ionized by X-rays from the compact companion. The gas both emits and absorbs X-rays, and many of the spectrum’s prominent peaks and valleys incorporate both aspects. Yet a simple attempt at understanding the spectrum comes up short because some of the features appear to be in the wrong place.
That’s because the rapid motion of the gas displaces these features from their normal laboratory energies due to the Doppler effect. Absorption valleys typically shift up to higher energies, indicating gas moving toward us at speeds of up to 930,000 mph (1.5 million kph). Emission peaks shift down to lower energies, indicating gas moving away from us at slower speeds.
Some spectral features displayed much stronger absorption valleys than emission peaks. The reason for this imbalance, the team concludes, is that the dynamics of the stellar wind allow the moving gas to absorb a broader range of X-ray energies emitted by the companion. The detail of the XRISM spectrum, particularly at higher energies rich in features produced by ionized iron atoms, allowed the scientists to disentangle these effects.
“A key to acquiring this detail was XRISM’s ability to monitor the system over the course of several orbits,” said Brian Williams, NASA’s project scientist for the mission at Goddard. “There’s much more to explore in this spectrum, and ultimately we hope it will help us determine if Cygnus X-3’s compact object is indeed a black hole.”
XRISM is a collaborative mission between JAXA and NASA, with participation by ESA. NASA’s contribution includes science participation from CSA (Canadian Space Agency).
Download additional images from NASA’s Scientific Visualization Studio
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Nov 25, 2024 Related Terms
Black Holes Electromagnetic Spectrum Galaxies, Stars, & Black Holes Research Goddard Space Flight Center Stars Stellar-mass Black Holes The Universe X-ray Binaries XRISM (X-Ray Imaging and Spectroscopy Mission) Facebook logo @NASAUniverse @NASAUniverse Instagram logo @NASAUniverse Keep Exploring Discover Related Topics
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