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By European Space Agency
Less than two weeks after being launched into orbit, Sentinel-2C has delivered its first images. These spectacular views of Earth offer a sneak peek at the data that this new satellite will provide for Copernicus – Europe’s world-leading Earth observation programme.
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By NASA
Figure 1. An artist’s concept of the Van Allen belts with a cutaway section of the giant donuts of radiation that surround Earth. Image Credit: NASA Goddard Space Flight Center/Scientific Visualization Studio A new instrument is using advanced detection techniques and leveraging an orbit with specific characteristics to increase our understanding of the Van Allen belts—regions surrounding Earth that contain energetic particles that can endanger both robotic and human space missions. Recently, the instrument provided a unique view of changes to this region that were brought on by an intense magnetic storm in May 2024.
The discovery of the Van Allen radiation belts by the U.S. Explorer 1 mission in 1958 marked a prominent milestone in space physics and demonstrated that Earth’s magnetosphere efficiently accelerates and traps energetic particles. The inner belt contains protons in the MeV (million electric volt) to GeV (109 electric volt) range, and even higher concentrations of energetic electrons of 100s of keV (1000 electric volt) to MeV are found in both the inner belt and the outer belt.
The energetic electrons in these belts—also referred to as “killer electrons”—can have detrimental effects on spacecraft subsystems and are harmful to astronauts performing extravehicular activities. Understanding the source, loss, and varying concentrations of these electrons has been a longstanding research objective. High-energy resolution and clean measurements of these energetic electrons in space are required to further our understanding of their properties and enable more reliable prediction of their intensity.
Overcoming the challenges of measuring relativistic electrons in the inner belt
Measuring energetic electrons cleanly and accurately has been a challenge, especially in the inner belt, where MeV to GeV energy protons also exist. NASA’s Van Allen Probes, which operated from 2012 to 2019 in low inclination, geo-transfer-like orbits, showed that instruments traversing the heart of the inner radiation belt are subject to penetration by the highly energetic protons located in that region. The Relativistic Electron Proton Telescope (REPT) and the Magnetic Electron and Ion Spectrometer (MagEIS) instruments onboard the Van Allen Probes were heavily shielded but were still subject to inner-belt proton contamination.
To attempt to minimize these negative effects, a University of Colorado Boulder team led by Dr. Xinlin Li, designed the Relativistic Electron Proton Telescope integrated little experiment (REPTile)—a simplified and miniaturized version of REPT—to fly onboard the Colorado Student Space Weather Experiment (CSSWE). An effort supported by the National Science Foundation, the 3-Unit CSSWE CubeSat operated in a highly inclined low Earth orbit (LEO) from 2012 to 2014. In this highly inclined orbit, the spacecraft and the instruments it carried were only exposed to the inner-belt protons in the South Atlantic Anomaly (SAA) region where the Earth’s magnetic field is weaker, which greatly reduced the time that protons impacted the measurement of electrons.
REPTile’s success motivated a team, also led by Dr. Xinlin Li, to design REPTile-2—an advanced version of REPTile—to be hosted on the Colorado Inner Radiation Belt Experiment (CIRBE) mission. Like CSSWE, CIRBE operates in a highly inclined low-Earth orbit to ensure the exposure to damaging inner-belt protons is minimized. The team based the REPTile-2 design on REPTile but incorporated two additional technologies—guard rings and Pulse Height Analysis—to enable clean, high-energy-resolution measurements of energetic electrons, especially in the inner belt.
Figure 2: PI observing two engineers testing the interface between the CIRBE bus and REPTile-2 on September 29, 2021. Image Credit: Xinlin Li, University of Colorado Boulder As shown on the left in Figure 3, the field of view (FOV) of REPTile-2 is 51o. Electrons and protons enter the FOV and are measured when they reach a stack of silicon detectors where they deposit their energies. However, very energetic protons (energy greater than 60 MeV) could penetrate through the instrument’s tungsten and aluminum shielding and masquerade as valid particles, thus contaminating the intended measurements. To mitigate this contamination, the team designed guard rings that surround each detector. These guard rings are electronically separated from the inner active area of each detector and are connected by a separate electric channel. When the guard rings are triggered (i.e., hit by particles coming outside of the FOV), the coincident measurements are considered invalid and are discarded. This anti-coincidence technique enables cleaner measurements of particles coming through the FOV.
Figure 3. Left (adapted from Figure 1 of Khoo et al., 2022): Illustration of REPTile-2 front end with key features labeled; Right: REPTile-2 front end integrated with electronic boards and structures, a computer-aided design (CAD) model, and a photo of integrated REPTile-2. Image Credit: Xinlin Li, University of Colorado Boulder To achieve high energy resolution, the team also applied full Pulse Height Analysis (PHA) on REPTile-2. In PHA, the magnitude of measured charge in the detector is directly proportional to the energy deposited from the incident electrons. Unlike REPTile, which employed a simpler energy threshold discrimination method yielding three channels for the electrons, REPTile-2 offers enhanced precision with 60 energy channels for electron energies ranging from 0.25 – 6 MeV. The REPT instrument onboard the Van Allen Probes also employed PHA but while REPT worked very well in the outer belt, yielding fine energy resolution, it did not function as well in the inner belt since the instrument was fully exposed to penetrating energetic protons because it did not have the guard rings implemented.
Figure 4: The CIRBE team after a successful “plugs-out” test of the CIRBE spacecraft on July 21, 2022. During this test the CIRBE spacecraft successfully received commands from ground stations and completed various performance tests, including data transmission back to ground stations at LASP. Image Credit: Xinlin Li, University of Colorado Boulder CIRBE and REPTile-2 Results
CIRBE’s launch, secured through the NASA CubeSat Launch Initiative (CSLI), took place aboard SpaceX’s Falcon 9 rocket as part of the Transporter-7 mission on April 15, 2023. REPTile-2, activated on April 19, 2023, has been performing well, delivering valuable data about Earth’s radiation belt electrons. Many features of the energetic electrons in the Van Allen belts have been revealed for the first time, thanks to the high-resolution energy and time measurements REPTile-2 has provided.
Figure 5 shows a sample of CIRBE/REPTile-2 measurements from April 2024, and illustrates the intricate drift echoes or “zebra stripes” of energetic electrons, swirling around Earth in distinct bunches. These observations span a vast range across the inner and outer belts, encompassing a wide spectrum of energies and electron fluxes extending over six orders of magnitude. By leveraging advanced guard rings, Pulse Height Analysis (PHA), and a highly inclined LEO orbit, REPTile-2 is delivering unprecedented observations of radiation belt electrons.
Figure 5: Color-coded electron fluxes detrended between REPTile-2 measurements for a pass over the South Atlantic Anomaly region on April 24, 2023, and their average, i.e., the smoothed electron fluxes using a moving average window of ±19% in energy; Black curves plotted on top of the color-coded electron fluxes are contours of electron drift period in hr. The second horizontal-axis, L, represents the magnetic field line, which CIRBE crosses. The two radiation belts and a slot region in between are indicated by the red lines and arrow, respectively. Image Credit: Xinlin Li, University of Colorado Boulder In fact, the team recently announced that measurements from CIRBE/REPTile-2 have revealed a new temporary third radiation belt composed of electrons and sandwiched between the two permanent belts. This belt formed during the magnetic storm in May 2024, which was the largest in two decades. While such temporary belts have been seen after big storms previously, the data from CIRBE/REPTile-2 are providing a new viewpoint with higher energy resolution data than before. Scientists are currently studying the data to better understand the belt and how long it might stick around — which could be many months.
PROJECT LEAD
Dr. Xinlin Li, University of Colorado Laboratory for Atmospheric and Space Physics and Department of Aerospace Engineering Sciences.
SPONSORING ORGANIZATIONS
Heliophysics Flight Opportunities for Research & Technology (H-FORT) program, National Science Foundation
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Last Updated Sep 17, 2024 Related Terms
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By European Space Agency
The Global Methane Budget 2024 paints a troubling picture of the current state of global methane emissions. The new report, which uses data from the Copernicus Sentinel-5P satellite, reveals that human activities are now responsible for at least two-thirds of global methane emissions.
This marks a significant increase in human-produced methane sources over the past two decades, with emissions rising by 20%, with the fastest rise occurring over the last five years.
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By NASA
5 Min Read NASA’s Webb Reveals Distorted Galaxy Forming Cosmic Question Mark
The galaxy cluster MACS-J0417.5-1154. Full image below. Credits:
NASA, ESA, CSA, STScI, V. Estrada-Carpenter (Saint Mary’s University). It’s 7 billion years ago, and the universe’s heyday of star formation is beginning to slow. What might our Milky Way galaxy have looked like at that time? Astronomers using NASA’s James Webb Space Telescope have found clues in the form of a cosmic question mark, the result of a rare alignment across light-years of space.
“We know of only three or four occurrences of similar gravitational lens configurations in the observable universe, which makes this find exciting, as it demonstrates the power of Webb and suggests maybe now we will find more of these,” said astronomer Guillaume Desprez of Saint Mary’s University in Halifax, Nova Scotia, a member of the team presenting the Webb results.
Image A: Lensed Question Mark (NIRCam)
The galaxy cluster MACS-J0417.5-1154 is so massive it is warping the fabric of space-time and distorting the appearance of galaxies behind it, an effect known as gravitational lensing. This natural phenomenon magnifies distant galaxies and can also make them appear in an image multiple times, as NASA’s James Webb Space Telescope saw here. Two distant, interacting galaxies — a face-on spiral and a dusty red galaxy seen from the side — appear multiple times, tracing a familiar shape across the sky. Active star formation, and the face-on galaxy’s remarkably intact spiral shape, indicate that these galaxies’ interaction is just beginning. NASA, ESA, CSA, STScI, V. Estrada-Carpenter (Saint Mary’s University). While this region has been observed previously with NASA’s Hubble Space Telescope, the dusty red galaxy that forms the intriguing question-mark shape only came into view with Webb. This is a result of the wavelengths of light that Hubble detects getting trapped in cosmic dust, while longer wavelengths of infrared light are able to pass through and be detected by Webb’s instruments.
Astronomers used both telescopes to observe the galaxy cluster MACS-J0417.5-1154, which acts like a magnifying glass because the cluster is so massive it warps the fabric of space-time. This allows astronomers to see enhanced detail in much more distant galaxies behind the cluster. However, the same gravitational effects that magnify the galaxies also cause distortion, resulting in galaxies that appear smeared across the sky in arcs and even appear multiple times. These optical illusions in space are called gravitational lensing.
The red galaxy revealed by Webb, along with a spiral galaxy it is interacting with that was previously detected by Hubble, are being magnified and distorted in an unusual way, which requires a particular, rare alignment between the distant galaxies, the lens, and the observer — something astronomers call a hyperbolic umbilic gravitational lens. This accounts for the five images of the galaxy pair seen in Webb’s image, four of which trace the top of the question mark. The dot of the question mark is an unrelated galaxy that happens to be in the right place and space-time, from our perspective.
Image B: Hubble and Webb Side by Side
Image Before/After In addition to producing a case study of the Webb NIRISS (Near-Infrared Imager and Slitless Spectrograph) instrument’s ability to detect star formation locations within a galaxy billions of light-years away, the research team also couldn’t resist highlighting the question mark shape. “This is just cool looking. Amazing images like this are why I got into astronomy when I was young,” said astronomer Marcin Sawicki of Saint Mary’s University, one of the lead researchers on the team.
“Knowing when, where, and how star formation occurs within galaxies is crucial to understanding how galaxies have evolved over the history of the universe,” said astronomer Vicente Estrada-Carpenter of Saint Mary’s University, who used both Hubble’s ultraviolet and Webb’s infrared data to show where new stars are forming in the galaxies. The results show that star formation is widespread in both. The spectral data also confirmed that the newfound dusty galaxy is located at the same distance as the face-on spiral galaxy, and they are likely beginning to interact.
“Both galaxies in the Question Mark Pair show active star formation in several compact regions, likely a result of gas from the two galaxies colliding,” said Estrada-Carpenter. “However, neither galaxy’s shape appears too disrupted, so we are probably seeing the beginning of their interaction with each other.”
“These galaxies, seen billions of years ago when star formation was at its peak, are similar to the mass that the Milky Way galaxy would have been at that time. Webb is allowing us to study what the teenage years of our own galaxy would have been like,” said Sawicki.
The Webb images and spectra in this research came from the Canadian NIRISS Unbiased Cluster Survey (CANUCS). The research paper is published in the Monthly Notices of the Royal Astronomical Society.
Image C: Wide Field – Lensed Question Mark (NIRCam)
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).
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Media Contacts
Laura Betz – laura.e.betz@nasa.gov, Rob Gutro – rob.gutro@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Christine Pulliam – cpulliam@stsci.edu , Leah Ramsey – lramsey@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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Last Updated Sep 04, 2024 Editor Stephen Sabia Contact Laura Betz laura.e.betz@nasa.gov Related Terms
Astrophysics Galaxies Galaxies, Stars, & Black Holes Galaxy clusters Goddard Space Flight Center Gravitational Lensing James Webb Space Telescope (JWST) Science & Research The Universe View the full article
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By NASA
2 min read
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The National Aeronautics and Space Administration (NASA) seeks applicants interested in six to twelve month reimbursable details with the Office of General Counsel (OGC). Applicants must be current Federal Employees. Applicants should receive the approval of their supervisor before applying. Consisting of a Headquarters Office and nine Center-level legal offices, NASA OGC provides advice and legal support on cutting edge issues in support of NASA’s mission of research and exploration on behalf of the United States. Ideal candidates will be experienced legal practitioners ready to make an immediate contribution in one of the following areas.
Artificial Intelligence and Cybersecurity. Candidates for this detail area are prepared to offer insight in interpreting rapidly changing regulatory requirements, drafting guidance, anticipating future use cases, and working with various stakeholders and technical experts to define agency needs. Because of overlapping regulatory requirements and related governance schemes, familiarity with cyber-security requirements would also be highly valued in this detail. Employment Law. Candidates for this detail area have experience in providing high impact litigation services to the federal government. Experience with EEOC, MSPB, and federal court proceedings are highly desired. Ethics. Candidates for this detail area are experienced ethics attorneys capable of training and advising agency personnel on ethics matters in connection with NASA’s challenging mission and diverse ecosystem of partners and stakeholders. Procurement. Candidates for this detail area are experienced procurement attorneys interested in providing short term assistance for the coming fiscal year as NASA’s dynamic team of lawyers supports major acquisitions of technology and space capabilities. NASA prefers that these details be in person, with telework available consistent with Agency policy, but would consider a remote detail in some circumstances. In addition to Headquarters in Washington, D.C., NASA has locations in Alabama, California, Florida, Maryland, Mississippi, Ohio, Texas, and Virginia.
All applicants must possess a Juris Doctor (J.D.) or equivalent and be a member in good standing of a state bar (any jurisdiction). To apply, please email a cover letter, resume, and recent writing sample of no more than five (5) pages to hq-ogc-legalops@mail.nasa.gov. In your cover letter please indicate which detail area(s) interest you. Interested applicants may indicate more than one area of interest.
Please submit your application by September 9, 2024.
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