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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
This image shows about 1.5% of Euclid’s Deep Field South, one of three regions of the sky that the telescope will observe for more than 40 weeks over the course of its prime mission, spotting faint and distant galaxies. One galaxy cluster near the center is located almost 6 billion light-years away from Earth. ESA/Euclid/Euclid Consortium/NASA; image processing by J.-C. Cuillandre, E. Bertin, G. An-selmi With contributions from NASA, the mission is looking back into the universe’s history to understand how the universe’s expansion has changed.
The Euclid mission — led by ESA (European Space Agency) with contributions from NASA — aims to find out why our universe is expanding at an accelerating rate. Astronomers use the term “dark energy” to refer to the unknown cause of this phenomenon, and Euclid will take images of billions of galaxies to learn more about it. A portion of the mission’s data was released to the public by ESA released on Wednesday, March 19.
This new data has been analyzed by mission scientists and provides a glimpse of Euclid’s progress. Deemed a “quick” data release, this batch focuses on select areas of the sky to demonstrate what can be expected in the larger data releases to come and to allow scientists to sharpen their data analysis tools in preparation.
The data release contains observations of Euclid’s three “deep fields,” or areas of the sky where the space telescope will eventually make its farthest observations of the universe. Featuring one week’s worth of viewing, the Euclid images contain 26 million galaxies, the most distant being over 10.5 billion light-years away. Launched in July 2023, the space telescope is expected to observe more than 1.5 billion galaxies during its six-year prime mission.
The entirety of the Euclid mission’s Deep Field South region is shown here. It is about 28.1 square degrees on the sky. Euclid will observe this and two other deep field regions for a total of about 40 weeks during its 6-year primary mission. ESA/Euclid/Euclid Consortium/NASA; image processing by J.-C. Cuillandre, E. Bertin, G. An-selmi By the end of that prime mission, Euclid will have observed the deep fields for a total of about 40 weeks in order to gradually collect more light, revealing fainter and more distant galaxies. This approach is akin to keeping a camera shutter open to photograph a subject in low light.
The first deep field observations, taken by NASA’s Hubble Space Telescope in 1995, famously revealed the existence of many more galaxies in the universe than expected. Euclid’s ultimate goal is not to discover new galaxies but to use observations of them to investigate how dark energy’s influence has changed over the course of the universe’s history.
In particular, scientists want to know how much the rate of expansion has increased or slowed down over time. Whatever the answer, that information would provide new clues about the fundamental nature of this phenomenon. NASA’s Nancy Grace Roman Space Telescope, set to launch by 2027, will also observe large sections of the sky in order to study dark energy, complementing Euclid’s observations.
The location of the Euclid deep fields are shown marked in yellow on this all-sky view from ESA’s Gaia and Planck missions. The bright horizontal band is the plane of our Milky Way galaxy. Euclid’s Deep Field South is at bottom left.ESA/Euclid/Euclid Consortium/NASA; ESA/Gaia/DPAC; ESA/Planck Collaboration Looking Back in Time
To study dark energy’s effect throughout cosmic history, astronomers will use Euclid to create detailed, 3D maps of all the stuff in the universe. With those maps, they want to measure how quickly dark energy is causing galaxies and big clumps of matter to move away from one another. They also want to measure that rate of expansion at different points in the past. This is possible because light from distant objects takes time to travel across space. When astronomers look at distant galaxies, they see what those objects looked like in the past.
For example, an object 100 light-years away looks the way it did 100 years ago. It’s like receiving a letter that took 100 years to be delivered and thus contains information from when it was written. By creating a map of objects at a range of distances, scientists can see how the universe has changed over time, including how dark energy’s influence may have varied.
But stars, galaxies, and all the “normal” matter that emits and reflects light is only about one-fifth of all the matter in the universe. The rest is called “dark matter” — a material that neither emits nor reflects light. To measure dark energy’s influence on the universe, astronomers need to include dark matter in their maps.
Bending and Warping
Although dark matter is invisible, its influence can be measured through something called gravitational lensing. The mass of both normal and dark matter creates curves in space, and light traveling toward Earth bends or warps as it encounters those curves. In fact, the light from a distant galaxy can bend so much that it forms an arc, a full circle (called an Einstein ring), or even multiple images of the same galaxy, almost as though the light has passed through a glass lens.
In most cases, gravitational lensing warps the apparent shape of a galaxy so subtly that researchers need special tools and computer software to see it. Spotting those subtle changes across billions of galaxies enables scientists to do two things: create a detailed map of the presence of dark matter and observe how dark energy influenced it over cosmic history.
It is only with a very large sample of galaxies that researchers can be confident they are seeing the effects of dark matter. The newly released Euclid data covers 63 square degrees of the sky, an area equivalent to an array of 300 full Moons. To date, Euclid has observed about 2,000 square degrees, which is approximately 14% of its total survey area of 14,000 square degrees. By the end of its mission, Euclid will have observed a third of the entire sky.
The dataset released this month is described in several preprint papers available today. The mission’s first cosmology data will be released in October 2026. Data accumulated over additional, multiple passes of the deep field locations will also be included in the 2026 release.
More About Euclid
Euclid is a European mission, built and operated by ESA, with contributions from NASA. The Euclid Consortium — consisting of more than 2,000 scientists from 300 institutes in 15 European countries, the United States, Canada, and Japan — is responsible for providing the scientific instruments and scientific data analysis. ESA selected Thales Alenia Space as prime contractor for the construction of the satellite and its service module, with Airbus Defence and Space chosen to develop the payload module, including the telescope. Euclid is a medium-class mission in ESA’s Cosmic Vision Programme.
Three NASA-supported science teams contribute to the Euclid mission. In addition to designing and fabricating the sensor-chip electronics for Euclid’s Near Infrared Spectrometer and Photometer (NISP) instrument, JPL led the procurement and delivery of the NISP detectors as well. Those detectors, along with the sensor chip electronics, were tested at NASA’s Detector Characterization Lab at Goddard Space Flight Center in Greenbelt, Maryland. The Euclid NASA Science Center at IPAC (ENSCI), at Caltech in Pasadena, California, supports U.S.-based science investigations, and science data is archived at the NASA / IPAC Infrared Science Archive (IRSA). JPL is a division of Caltech.
For more information about Euclid go to:
science.nasa.gov/mission/euclid/
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ESA Media Relations
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Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
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Last Updated Mar 19, 2025 Related Terms
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By NASA
This video sparkles with synthetic supernovae from the OpenUniverse project, which simulates observations from NASA’s upcoming Nancy Grace Roman Space Telescope. More than a million exploding stars flare into visibility and then slowly fade away. The true brightness of each transient event has been magnified by a factor of 10,000 for visibility, and no background light has been added to the simulated images. The pattern of squares shows Roman’s full field of view.Credit: NASA’s Goddard Space Flight Center and M. Troxel The universe is ballooning outward at an ever-faster clip under the power of an unknown force dubbed dark energy. One of the major goals for NASA’s upcoming Nancy Grace Roman Space Telescope is to help astronomers gather clues to the mystery. One team is setting the stage now to help astronomers prepare for this exciting science.
“Roman will scan the cosmos a thousand times faster than NASA’s Hubble Space Telescope can while offering Hubble-like image quality,” said Rebekah Hounsell, an assistant research scientist at the University of Maryland-Baltimore county working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a co-principal investigator of the Supernova Cosmology Project Infrastructure Team preparing for the mission’s High-Latitude Time-Domain Survey. “We’re going to have an overwhelming amount of data, and we want to make it so scientists can use it from day one.”
Roman will repeatedly look at wide, deep regions of the sky in near-infrared light, opening up a whole new view of the universe and revealing all sorts of things going bump in the night. That includes stars being shredded as they pass too close to a black hole, intense emissions from galaxy centers, and a variety of stellar explosions called supernovae.
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This data sonification transforms a vast simulation of a cosmic survey from NASA’s upcoming Nancy Grace Roman Space Telescope into a symphony of stellar explosions. Each supernova’s brightness controls its volume, while its color sets its pitch –– redder, more distant supernovae correspond to deep, low tones while bluer, nearer ones correspond to higher frequencies. The sound in stereo mirrors their locations in the sky. The result sounds like celestial wind chimes, offering a way to “listen” to cosmic fireworks. Credit: NASA’s Goddard Space Flight Center, M. Troxel, SYSTEM Sounds (M. Russo, A. Santaguida) Cosmic Radar Guns
Scientists estimate around half a dozen stars explode somewhere in the observable universe every minute. On average, one of them will be a special variety called type Ia that can help astronomers measure the universe.
These explosions peak at a similar intrinsic brightness, allowing scientists to find their distances simply by measuring how bright they appear.
Scientists can also study the light of these supernovae to find out how quickly they are moving away from us. By comparing how fast they’re receding at different distances, scientists will trace cosmic expansion over time.
Using dozens of type Ia supernovae, scientists discovered that the universe’s expansion is accelerating. Roman will find tens of thousands, including very distant ones, offering more clues about the nature of dark energy and how it may have changed throughout the history of the universe.
“Roman’s near-infrared view will help us peer farther because more distant light is stretched, or reddened, as it travels across expanding space,” said Benjamin Rose, an assistant professor at Baylor University in Waco, Texas, and a co-principal investigator of the infrastructure team. “And opening a bigger window, so to speak, will help us get a better understanding of these objects as a whole,” which would allow scientists to learn more about dark energy. That could include discovering new physics, or figuring out the universe’s fate.
The People’s Telescope
Members of the planning team have been part of the community process to seek input from scientists worldwide on how the survey should be designed and how the analysis pipeline should work. Gathering public input in this way is unusual for a space telescope, but it’s essential for Roman because each large, deep observation will enable a wealth of science in addition to fulfilling the survey’s main goal of probing dark energy.
Rather than requiring that many individual scientists submit proposals to reserve their own slice of space telescope time, Roman’s major surveys will be coordinated openly, and all the data will become public right away.
“Instead of a single team pursuing one science goal, everyone will be able to comb through Roman’s data for a wide variety of purposes,” Rose said. “Everyone will get to play right away.”
This animation shows a possible tiling pattern of part of NASA’s Nancy Grace Roman Space Telescope’s High Latitude Time-Domain Survey. The observing program, which is being designed by a community process, is expected to have two components: wide (covering 18 square degrees, a region of sky as large as about 90 full moons) and deep (covering about 5.5 square degrees, about as large as 25 full moons). This animation shows the deeper portion, which would peer back to when the universe was about 500 million years old, less than 4 percent of its current age of 13.8 billion years.Credit: NASA’s Goddard Space Flight Center This Is a Drill
NASA plans to announce the survey design for Roman’s three core surveys, including the High-Latitude Time-Domain Survey, this spring. Then the planning team will simulate it in its entirety.
“It’s kind of like a recipe,” Hounsell said. “You put in your observing strategy — how many days, which filters — and add in ‘spices’ like uncertainties, calibration effects, and the things we don’t know so well about the instrument or supernovae themselves that would affect our results. We can inject supernovae into the synthetic images and develop the tools we’ll need to analyze and evaluate the data.”
Scientists will continue using the synthetic data even after Roman begins observing, tweaking all aspects of the simulation and correcting unknowns to see which resulting images best match real observations. Scientists can then fine-tune our understanding of the universe’s underlying physics.
“We assume that all supernovae are the same regardless of when they occurred in the history of the universe, but that might not be the case,” Hounsell said. “We’re going to look further back in time than we’ve ever done with type Ia supernovae, and we’re not completely sure if the physics we understand now will hold up.”
There are reasons to suspect they may not. The very first stars were made almost exclusively of hydrogen and helium, compared to stars today which contain several dozen elements. Those ancient stars also lived in very different environments than stars today. Galaxies were growing and merging, and stars were forming at a furious pace before things began calming down between about 8 and 10 billion years ago.
“Roman will very dramatically add to our understanding of this cosmic era,” Rose said. “We’ll learn more about cosmic evolution and dark energy, and thanks to Roman’s large deep view, we’ll get to do much more science too with the same data. Our work will help everyone hit the ground running after Roman launches.”
For more information about the Roman Space Telescope visit www.nasa.gov/roman.
The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Mar 11, 2025 EditorAshley BalzerContactAshley Balzerashley.m.balzer@nasa.govLocationGoddard Space Flight Center 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 NASA
NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; Even matter ejected by black holes can run into objects in the dark. Using NASA’s Chandra X-ray Observatory, astronomers have found an unusual mark from a giant black hole’s powerful jet striking an unidentified object in its path.
The discovery was made in a galaxy called Centaurus A (Cen A), located about 12 million light-years from Earth. Astronomers have long studied Cen A because it has a supermassive black hole in its center sending out spectacular jets that stretch out across the entire galaxy. The black hole launches this jet of high-energy particles not from inside the black hole, but from intense gravitational and magnetic fields around it.
The image shows low-energy X-rays seen by Chandra represented in pink, medium-energy X-rays in purple, and the highest-energy X-rays in blue.
In this latest study, researchers determined that the jet is — at least in certain spots — moving at close to the speed of light. Using the deepest X-ray image ever made of Cen A, they also found a patch of V-shaped emission connected to a bright source of X-rays, something that had not been seen before in this galaxy.
Called C4, this source is located close to the path of the jet from the supermassive black hole and is highlighted in the inset. The arms of the “V” are at least about 700 light-years long. For context, the nearest star to Earth is about 4 light-years away.
Source C4 in the Centaurus A galaxy.NASA/CXC/SAO/D. Bogensberger et al; Image Processing: NASA/CXC/SAO/N. Wolk; While the researchers have ideas about what is happening, the identity of the object being blasted is a mystery because it is too distant for its details to be seen, even in images from the current most powerful telescopes.
The incognito object being rammed may be a massive star, either by itself or with a companion star. The X-rays from C4 could be caused by the collision between the particles in the jet and the gas in a wind blowing away from the star. This collision can generate turbulence, causing a rise in the density of the gas in the jet. This, in turn, ignites the X-ray emission seen with Chandra.
The shape of the “V,” however, is not completely understood. The stream of X-rays trailing behind the source in the bottom arm of the “V” is roughly parallel to the jet, matching the picture of turbulence causing enhanced X-ray emission behind an obstacle in the path of the jet. The other arm of the “V” is harder to explain because it has a large angle to the jet, and astronomers are unsure what could explain that.
This is not the first time astronomers have seen a black hole jet running into other objects in Cen A. There are several other examples where a jet appears to be striking objects — possibly massive stars or gas clouds. However, C4 stands out from these by having the V-shape in X-rays, while other obstacles in the jet’s path produce elliptical blobs in the X-ray image. Chandra is the only X-ray observatory capable of seeing this feature. Astronomers are trying to determine why C4 has this different post-contact appearance, but it could be related to the type of object that the jet is striking or how directly the jet is striking it.
A paper describing these results appears in a recent issue of The Astrophysical Journal. The authors of the study are David Bogensberger (University of Michigan), Jon M. Miller (University of Michigan), Richard Mushotsky (University of Maryland), Niel Brandt (Penn State University), Elias Kammoun (University of Toulouse, France), Abderahmen Zogbhi (University of Maryland), and Ehud Behar (Israel Institute of Technology).
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
Read more from NASA’s Chandra X-ray Observatory.
Learn more about the Chandra X-ray Observatory and its mission here:
https://www.nasa.gov/chandra
https://chandra.si.edu
Visual Description
This release features a series of images focusing on a collision between a jet of matter blasting out of a distant black hole, and a mysterious, incognito object.
At the center of the primary image is a bright white dot, encircled by a hazy purple blue ring tinged with neon blue. This is the black hole at the heart of the galaxy called Centaurus A. Shooting out of the black hole is a stream of ejected matter. This stream, or jet, shoots in two opposite directions. It shoots toward us, widening as it reaches our upper left, and away from us, growing thinner and more faint as it recedes toward the lower right. In the primary image, the jet resembles a trail of hot pink smoke. Other pockets of granular, hot pink gas can be found throughout the image. Here, pink represents low energy X-rays observed by Chandra, purple represents medium energy X-rays, and blue represents high energy X-rays.
Near our lower right, where the jet is at its thinnest, is a distinct pink “V”, its arms opening toward our lower right. This mark is understood to be the result of the jet striking an unidentified object that lay in its path. A labeled version of the image highlights this region, and names the point of the V-shape, the incognito object, C4. A wide view version of the image is composited with optical data.
At the distance of Cen A, the arms of the V-shape appear rather small. In fact, each arm is at least 700 light-years long. The jet itself is 30,000 light-years long. For context, the nearest star to the Sun is about 4 light-years away.
News Media Contact
Megan Watzke
Chandra X-ray Center
Cambridge, Mass.
617-496-7998
mwatzke@cfa.harvard.edu
Lane Figueroa
Marshall Space Flight Center, Huntsville, Alabama
256-544-0034
lane.e.figueroa@nasa.gov
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