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Planet-Sized Brown Dwarf May Yield Smallest Known Solar System
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By NASA
Illustration of the main asteroid belt, orbiting the Sun between Mars and JupiterNASA NASA’s powerful James Webb Space Telescope includes asteroids on its list of objects studied and secrets revealed.
A team led by researchers at the Massachusetts Institute of Technology (MIT) in Cambridge repurposed Webb’s observations of a distant star to reveal a population of small asteroids — smaller than astronomers had ever detected orbiting the Sun in the main asteroid belt between Mars and Jupiter.
The 138 new asteroids range from the size of a bus to the size of a stadium — a size range in the main belt that has not been observable with ground-based telescopes. Knowing how many main belt asteroids are in different size ranges can tell us something about how asteroids have been changed over time by collisions. That process is related to how some of them have escaped the main belt over the solar system’s history, and even how meteorites end up on Earth.
“We now understand more about how small objects in the asteroid belt are formed and how many there could be,” said Tom Greene, an astrophysicist at NASA’s Ames Research Center in California’s Silicon Valley and co-author on the paper presenting the results. “Asteroids this size likely formed from collisions between larger ones in the main belt and are likely to drift towards the vicinity of Earth and the Sun.”
Insights from this research could inform the work of the Asteroid Threat Assessment Project at Ames. ATAP works across disciplines to support NASA’s Planetary Defense Coordination Office by studying what would happen in the case of an Earth impact and modeling the associated risks.
“It’s exciting that Webb’s capabilities can be used to glean insights into asteroids,” said Jessie Dotson, an astrophysicist at Ames and member of ATAP. “Understanding the sizes, numbers, and evolutionary history of smaller main belt asteroids provides important background about the near-Earth asteroids we study for planetary defense.”
Illustration of the James Webb Space TelescopeNASA The team that made the asteroid detections, led by research scientist Artem Burdanov and professor of planetary science Julien de Wit, both of MIT, developed a method to analyze existing Webb images for the presence of asteroids that may have been inadvertently “caught on film” as they passed in front of the telescope. Using the new image processing technique, they studied more than 10,000 images of the star TRAPPIST-1, originally taken to search for atmospheres around planets orbiting the star, in the search for life beyond Earth.
Asteroids shine more brightly in infrared light, the wavelength Webb is tuned to detect, than in visible light, helping reveal the population of main belt asteroids that had gone unnoticed until now. NASA will also take advantage of that infrared glow with an upcoming mission, the Near-Earth Object (NEO) Surveyor. NEO Surveyor is the first space telescope specifically designed to hunt for near-Earth asteroids and comets that may be potential hazards to Earth.
The paper presenting this research, “Detections of decameter main-belt asteroids with JWST,” was published Dec. 9 in Nature.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
For news media:
Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.
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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
5 Min Read Scientists Share Early Results from NASA’s Solar Eclipse Experiments
On April 8, 2024, a total solar eclipse swept across a narrow portion of the North American continent from Mexico’s Pacific coast to the Atlantic coast of Newfoundland, Canada. This photo was taken from Dallas, Texas. Credits:
NASA/Keegan Barber On April 8, 2024, a total solar eclipse swept across North America, from the western shores of Mexico, through the United States, and into northeastern Canada. For the eclipse, NASA helped fund numerous research projects and called upon citizen scientists in support of NASA’s goal to understand how our home planet is affected by the Sun – including, for example, how our star interacts with Earth’s atmosphere and affects radio communications.
At a press briefing on Tuesday, Dec. 10, scientists attending the annual meeting of the American Geophysical Union in Washington, D.C., reported some early results from a few of these eclipse experiments.
“Scientists and tens of thousands of volunteer observers were stationed throughout the Moon’s shadow,” said Kelly Korreck, eclipse program manager at NASA Headquarters in Washington. “Their efforts were a crucial part of the Heliophysics Big Year – helping us to learn more about the Sun and how it affects Earth’s atmosphere when our star’s light temporarily disappears from view.”
Changes in the Corona
On April 8, the Citizen CATE 2024 (Continental-America Telescopic Eclipse) project stationed 35 observing teams from local communities from Texas to Maine to capture images of the Sun’s outer atmosphere, or corona, during totality. Their goal is to see how the corona changed as totality swept across the continent.
On Dec. 10, Sarah Kovac, the CATE project manager at the Southwest Research Institute in Boulder, Colorado, reported that, while a few teams were stymied by clouds, most observed totality successfully — collecting over 47,000 images in all.
These images were taken in polarized light, or light oriented in different directions, to help scientists better understand the processes that shape the corona.
This preliminary movie from the Citizen CATE 2024 project stitches together polarized images of the solar corona taken from different sites during the total solar eclipse on April 8, 2024. SwRI/Citizen CATE 2024/Dan Seaton/Derek Lamb Kovac shared the first cut of a movie created from these images. The project is still stitching together all the images into the final, hour-long movie, for release at a later time.
“The beauty of CATE 2024 is that we blend cutting-edge professional science with community participants from all walks of life,” Kovac said. “The dedication of every participant made this project possible.”
Meanwhile, 50,000 feet above the ground, two NASA WB-57 aircraft chased the eclipse shadow as it raced across the continent, observing above the clouds and extending their time in totality to approximately 6 minutes and 20 seconds.
On board were cameras and spectrometers (instruments that analyze different wavelengths of light) built by multiple research teams to study the corona.
This image of the total solar eclipse is a combination of 30 50-millisecond exposures taken with a camera mounted on one of NASA’s WB-57 aircraft on April 8, 2024. It was captured in a wavelength of light emitted by ionized iron atoms called Fe XIV. This emission highlights electrified gas, called plasma, at a specific temperature (around 3.2 million degrees Fahrenheit) that often reveals arch-like structures in the corona. B. Justen, O. Mayer, M. Justen, S. Habbal, and M. Druckmuller On Dec. 10, Shadia Habbal of the University of Hawaii, who led one of the teams, reported that their instruments collected valuable data, despite one challenge. Cameras they had mounted on the aircraft’s wings experienced unexpected vibrations, which caused some of the images to be slightly blurred.
However, all the cameras captured detailed images of the corona, and the spectrometers, which were located in the nose of the aircraft, were not affected. The results were so successful, scientists are already planning to fly similar experiments on the aircraft again.
“The WB-57 is a remarkable platform for eclipse observations that we will try to capitalize on for future eclipses,” Habbal said.
Affecting the Atmosphere
On April 8, amateur or “ham” radio operators sent and received signals to one another before, during, and after the eclipse as part of the Ham Radio Science Citizen Investigation (HamSCI) Festivals of Eclipse Ionospheric Science. More than 6,350 amateur radio operators generated over 52 million data points to observe how the sudden loss of sunlight during totality affects their radio signals and the ionosphere, an electrified region of Earth’s upper atmosphere.
Students from Case Western Reserve University operate radios during the 2024 total solar eclipse. HamSCI/Case Western Reserve University Radio communications inside and outside the path of totality improved at some frequencies (from 1-7 MHz), showing there was a reduction in ionospheric absorption. At higher frequencies (10 MHz and above), communications worsened.
Results using another technique, which bounced high-frequency radio waves (3-30 MHz) off the ionosphere, suggests that the ionosphere ascended in altitude during the eclipse and then descended to its normal height afterward.
“The project brings ham radio operators into the science community,” said Nathaniel Frissell, a professor at the University of Scranton in Pennsylvania and lead of HamSCI. “Their dedication to their craft made this research possible.”
Also looking at the atmosphere, the Nationwide Eclipse Ballooning Project organized student groups across the U.S. to launch balloons into the shadow of the Moon as it crossed the country in April 2024 and during a solar eclipse in October 2023. Teams flew weather sensors and other instruments to study the atmospheric response to the cold, dark shadow.
The eclipse’s shadow was captured from a camera aboard Virginia Tech’s balloon as part of the Nationwide Eclipse Ballooning Project on April 8, 2024. Nationwide Eclipse Ballooning Project/Virginia Tech This research, conducted by over 800 students, confirmed that eclipses can generate ripples in Earth’s atmosphere called atmospheric gravity waves. Just as waves form in a lake when water is disturbed, these waves also form in the atmosphere when air is disturbed. This project, led by Angela Des Jardins of Montana State University in Bozeman, also confirmed the presence of these waves during previous solar eclipses. Scientists think the trigger for these waves is a “hiccup” in the tropopause, a layer in Earth’s atmosphere, similar to an atmospheric effect that is observed during sunset.
“Half of the teams had little to no experience ballooning before the project,” said Jie Gong, a team science expert and atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But their hard work and research was vital in this finding.”
By Abbey Interrante and Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Dec 10, 2024 Related Terms
2024 Solar Eclipse Citizen Science Goddard Space Flight Center Heliophysics Solar Eclipses The Sun Uncategorized Explore More
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