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By European Space Agency
Last night a crucial step in the European Space Agency’s eclipse-making Proba-3 mission was completed: the two spacecraft, flying jointly since launch, have successfully separated. This leaves them ready to begin their cosmic dance in the world’s first-ever precision formation-flying mission.
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By NASA
5 min read
NASA’s LEXI Will Provide X-Ray Vision of Earth’s Magnetosphere
A NASA X-ray imager is heading to the Moon as part of NASA’s Artemis campaign, where it will capture the first global images of the magnetic field that shields Earth from solar radiation.
The Lunar Environment Heliospheric X-ray Imager, or LEXI, instrument is one of 10 payloads aboard the next lunar delivery through NASA’s CLPS (Commercial Lunar Payload Services) initiative, set to launch from the agency’s Kennedy Space Center in Florida no earlier than mid-January, with Firefly Aerospace’s Blue Ghost Lander. The instrument will support NASA’s goal to understand how our home planet responds to space weather, the conditions in space driven by the Sun.
NASA’s next mission to the Moon will carry an instrument called LEXI (the Lunar Environment Heliospheric X-ray Imager), which will provide the first-ever global view of the magnetic environment that shields Earth from solar radiation. This video can be freely shared and downloaded at https://svs.gsfc.nasa.gov/14739.
Credits: NASA’s Goddard Space Flight Center Once the dust clears from its lunar landing, LEXI will power on, warm up, and direct its focus back toward Earth. For six days, it will collect images of the X-rays emanating from the edges of our planet’s vast magnetosphere. This comprehensive view could illustrate how this protective boundary responds to space weather and other cosmic forces, as well as how it can open to allow streams of charged solar particles in, creating aurora and potentially damaging infrastructure.
“We’re trying to get this big picture of Earth’s space environment,” said Brian Walsh, a space physicist at Boston University and LEXI’s principal investigator. “A lot of physics can be esoteric or difficult to follow without years of specific training, but this will be science that you can see.”
What LEXI will see is the low-energy X-rays that form when a stream of particles from the Sun, called the solar wind, slams into Earth’s magnetic field. This happens at the edge of the magnetosphere, called the magnetopause. Researchers have recently been able to detect these X-rays in a patchwork of observations from other satellites and instruments. From the vantage point of the Moon, however, the whole magnetopause will be in LEXI’s field of view.
In this visualization, the LEXI instrument is shown onboard Firefly Aerospace’s Blue Ghost Mission 1, which will deliver 10 Commercial Lunar Payload Services (CLPS) payloads to the Moon. Firefly Aerospace The team back on Earth will be working around the clock to track how the magnetosphere expands, contracts, and changes shape in response to the strength of the solar wind.
“We expect to see the magnetosphere breathing out and breathing in, for the first time,” said Hyunju Connor, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the NASA lead for LEXI. “When the solar wind is very strong, the magnetosphere will shrink and push backward toward Earth, and then expand when the solar wind weakens.”
The LEXI instrument will also be poised to capture magnetic reconnection, which is when the magnetosphere’s field lines merge with those in the solar wind and release energetic particles that rain down on Earth’s poles. This could help researchers answer lingering questions about these events, including whether they happen at multiple sites simultaneously, whether they occur steadily or in bursts, and more.
These solar particles streaming into Earth’s atmosphere can cause brilliant auroras, but they can also damage satellites orbiting the planet or interfere with power grids on the ground.
“We want to understand how nature behaves,” Connor said, “and by understanding this we can help protect our infrastructure in space.”
The LEXI team packs the instrument at Boston University. Michael Spencer/Boston University The CLPS delivery won’t be LEXI’s first trip to space. A team at Goddard, including Walsh, built the instrument (then called STORM) to test technology to detect low-energy X-rays over a wide field of view. In 2012, STORM launched into space on a sounding rocket, collected X-ray images, and then fell back to Earth.
It ended up in a display case at Goddard, where it sat for a decade. When NASA put out a call for CLPS projects that could be done quickly and with a limited budget, Walsh thought of the instrument and the potential for what it could see from the lunar surface.
“We’d break the glass — not literally — but remove it, restore it, and refurbish it, and that would allow us to look back and get this global picture that we’ve never had before,” he said. Some old optics and other components were replaced, but the instrument was overall in good shape and is now ready to fly again. “There’s a lot of really rich science we can get from this.”
Under the CLPS model, NASA is investing in commercial delivery services to the Moon to enable industry growth and support long-term lunar exploration. As a primary customer for CLPS deliveries, NASA aims to be one of many customers on future flights. NASA Goddard is a lead science collaborator on LEXI. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the development of seven of the 10 CLPS payloads carried on Firefly’s Blue Ghost lunar lander, including LEXI.
Learn more about CLPS and Artemis at:
https://www.nasa.gov/clps
By Kate Ramsayer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jan 03, 2025 Editor Abbey Interrante Related Terms
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By NASA
NASA’s Dawn spacecraft captured this image of Vesta as it left the giant asteroid’s orbit in 2012. The framing camera was looking down at the north pole, which is in the middle of the image.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA Known as flow formations, these channels could be etched on bodies that would seem inhospitable to liquid because they are exposed to the extreme vacuum conditions of space.
Pocked with craters, the surfaces of many celestial bodies in our solar system provide clear evidence of a 4.6-billion-year battering by meteoroids and other space debris. But on some worlds, including the giant asteroid Vesta that NASA’s Dawn mission explored, the surfaces also contain deep channels, or gullies, whose origins are not fully understood.
A prime hypothesis holds that they formed from dry debris flows driven by geophysical processes, such as meteoroid impacts, and changes in temperature due to Sun exposure. A recent NASA-funded study, however, provides some evidence that impacts on Vesta may have triggered a less-obvious geologic process: sudden and brief flows of water that carved gullies and deposited fans of sediment. By using lab equipment to mimic conditions on Vesta, the study, which appeared in Planetary Science Journal, detailed for the first time what the liquid could be made of and how long it would flow before freezing.
Although the existence of frozen brine deposits on Vesta is unconfirmed, scientists have previously hypothesized that meteoroid impacts could have exposed and melted ice that lay under the surface of worlds like Vesta. In that scenario, flows resulting from this process could have etched gullies and other surface features that resemble those on Earth.
To explore potential explanations for deep channels, or gullies, seen on Vesta, scientists used JPL’s Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE, to simulate conditions on the giant asteroid that would occur after meteoroids strike the surface.NASA/JPL-Caltech But how could airless worlds — celestial bodies without atmospheres and exposed to the intense vacuum of space — host liquids on the surface long enough for them to flow? Such a process would run contrary to the understanding that liquids quickly destabilize in a vacuum, changing to a gas when the pressure drops.
“Not only do impacts trigger a flow of liquid on the surface, the liquids are active long enough to create specific surface features,” said project leader and planetary scientist Jennifer Scully of NASA’s Jet Propulsion Laboratory in Southern California, where the experiments were conducted. “But for how long? Most liquids become unstable quickly on these airless bodies, where the vacuum of space is unyielding.”
The critical component turns out to be sodium chloride — table salt. The experiments found that in conditions like those on Vesta, pure water froze almost instantly, while briny liquids stayed fluid for at least an hour. “That’s long enough to form the flow-associated features identified on Vesta, which were estimated to require up to a half-hour,” said lead author Michael J. Poston of the Southwest Research Institute in San Antonio.
Launched in 2007, the Dawn spacecraft traveled to the main asteroid belt between Mars and Jupiter to orbit Vesta for 14 months and Ceres for almost four years. Before ending in 2018, the mission uncovered evidence that Ceres had been home to a subsurface reservoir of brine and may still be transferring brines from its interior to the surface. The recent research offers insights into processes on Ceres but focuses on Vesta, where ice and salts may produce briny liquid when heated by an impact, scientists said.
Re-creating Vesta
To re-create Vesta-like conditions that would occur after a meteoroid impact, the scientists relied on a test chamber at JPL called the Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE. By rapidly reducing the air pressure surrounding samples of liquid, they mimicked the environment around fluid that comes to the surface. Exposed to vacuum conditions, pure water froze instantly. But salty fluids hung around longer, continuing to flow before freezing.
The brines they experimented with were a little over an inch (a few centimeters) deep; scientists concluded the flows on Vesta that are yards to tens of yards deep would take even longer to refreeze.
The researchers were also able to re-create the “lids” of frozen material thought to form on brines. Essentially a frozen top layer, the lids stabilize the liquid beneath them, protecting it from being exposed to the vacuum of space — or, in this case the vacuum of the DUSTIE chamber — and helping the liquid flow longer before freezing again.
This phenomenon is similar to how on Earth lava flows farther in lava tubes than when exposed to cool surface temperatures. It also matches up with modeling research conducted around potential mud volcanoes on Mars and volcanoes that may have spewed icy material from volcanoes on Jupiter’s moon Europa.
“Our results contribute to a growing body of work that uses lab experiments to understand how long liquids last on a variety of worlds,” Scully said.
Find more information about NASA’s Dawn mission here:
https://science.nasa.gov/mission/dawn/
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Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
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NASA Headquarters, Washington
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2024-178
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Last Updated Dec 20, 2024 Related Terms
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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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