Jump to content

Innovative Instrument Reveals Hidden Features Deep Inside the Van Allen Radiation Belts


Recommended Posts

  • Publishers
Posted
Van_Allen_Belts1-jpg.webp
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.

Two team members in blue lab coats at a desk working on a structure made of multiple flat black pieces, while another team member in a green lab coat looks on.
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.

Left: a striped rectangular platform with a pink cylinder on top. Middle: device constructed from multiple square, flat pieces. Right: a gold rectangular piece of equipment with multiple layers.
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.

four team members wearing lab coats and protective gloves standing next to a rectangular structure housed in a clear cube.
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.

reptile-5.png
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

Share

Details

Last Updated
Sep 17, 2024

View the full article

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By European Space Agency
      For decades, satellites have played a crucial role in our understanding of the remote polar regions. The ongoing loss of Antarctic ice, owing to the climate crisis, is, sadly, no longer surprising. However, satellites do more than just track the accelerating flow of glaciers towards the ocean and measure ice thickness.
      New research highlights how ESA’s CryoSat mission has been used to uncover the hidden impact of subglacial lakes – vast reservoirs of water buried deep under the ice – that can suddenly drain into the ocean in dramatic outbursts and affect ice loss.
      View the full article
    • By NASA
      NASA Men stand in front of turning vanes inside the Altitude Wind Tunnel (AWT) at the National Advisory Committee for Aeronautics Aircraft Engine Research Laboratory in this February 1944 publicity photo. The photo was taken just weeks after the tunnel became operational.
      The AWT was the only wind tunnel capable of testing full-size aircraft engines in simulated altitude conditions. A large wooden drive fan, located on the other side of these vanes, created wind speeds up to 500 miles per hour. Each corner of the rectangular tunnel had turning vanes, which straightened the airflow and directed it around the corners. This set of vanes was in the 31-foot-diameter southeast corner of the tunnel. These elliptical panels consisted of 36 to 42 vertical vanes that were supported by three horizontal supports. The individual vanes were 2.5 feet long and half-moon shaped. Each set of vanes took weeks to assemble before they were installed during the summer of 1943.
      The Aircraft Engine Research Laboratory went through several name updates and changes through NACA and NASA history; it is now NASA’s Glenn Research Center in Cleveland.
      Image credit: NASA
      View the full article
    • By NASA
      NASA The instrument enclosure of NASA’s Near-Earth Object Surveyor is prepared for critical environmental tests inside the historic Chamber A at the Space Environment Simulation Laboratory at NASA’s Johnson Space Center in Houston in December 2024. Wrapped in silver thermal blanketing, the 12-foot-long (3.7-meter-long) angular structure was subjected to the frigid, airless conditions that the spacecraft will experience when in deep space. The cavernous thermal-vacuum test facility is famous for testing the Apollo spacecraft that traveled to the Moon in the 1960s and ’70s.
      The instrument enclosure is designed to protect the spacecraft’s infrared telescope while also removing heat from it during operations. After environmental testing was completed, the enclosure returned to NASA’s Jet Propulsion Laboratory in Southern California for further work, after which it will ship to the Space Dynamics Laboratory (SDL) in Logan, Utah, and be joined to the telescope. Both the instrument enclosure and telescope were assembled at JPL.
      As NASA’s first space-based detection mission specifically designed for planetary defense, NEO Surveyor will seek out, measure, and characterize the hardest-to-find asteroids and comets that might pose a hazard to Earth. While many near-Earth objects don’t reflect much visible light, they glow brightly in infrared light due to heating by the Sun. The spacecraft’s telescope, which has an aperture of nearly 20 inches (50 centimeters), features detectors sensitive to two infrared wavelengths in which near-Earth objects re-radiate solar heat.
      More information about NEO Surveyor is available at: https://science.nasa.gov/mission/neo-surveyor/
      Image credit: NASA
      View the full article
    • By NASA
      Explore This Section RPS Home About About RPS About the Program About Plutonium-238 Safety and Reliability For Mission Planners Contact RPS Systems Overview Power Systems Thermal Systems Dynamic Radioisotope Power Missions Overview Timeline News Resources STEM Power to Explore Contest FAQ 4 min read
      NASA Reveals Semifinalists of Power to Explore Challenge
      A word cloud showing “superpowers” of the 45 semifinalists. NASA/David Lam NASA selected 45 student essays as semifinalists of its 2024-2025 Power to Explore Challenge, a national competition for K-12 students featuring the enabling power of radioisotopes. Contestants were challenged to explore how NASA has powered some of its most famous science missions and to dream up how their personal “superpower” would energize their success on their own radioisotope-powered science mission to explore one of the nearly 300 moons of our solar system.
      The competition asked students to learn about radioisotope power systems (RPS), a type of “nuclear battery” that NASA uses to explore the harshest, darkest, and dustiest parts of our solar system. RPS have enabled many spacecraft to explore a variety of these moons, some with active volcanoes, methane lakes, and intricate weather patterns similar to Earth. Many of these moons remain a mystery to us.
      This year’s submissions to NASA’s Power to Explore Challenge were immensely enthralling, and we’re thrilled that the number of entries reached a record high.
      Carl Sandifer II
      Program Manager, NASA Radioisotope Power Systems Program
      In 275 words or less, students wrote about a mission of their own that would use these space power systems to explore any moon in our solar system and described their own power to achieve their mission goals.
      The Power to Explore Challenge offered students the opportunity to learn more about these reliable power systems, celebrate their own strengths, and interact with NASA’s diverse workforce. This year’s contest set a record, receiving 2,051 submitted entries from all 50 states, Guam, U.S. Virgin Islands, American Samoa, Northern Mariana Islands, Puerto Rico, and the Department of Defense Education Activity (DoDEA) Overseas.
      “This year’s submissions to NASA’s Power to Explore Challenge were immensely enthralling, and we’re thrilled that the number of entries reached a record high,” said Carl Sandifer II, program manager of the Radioisotope Power Systems Program at NASA’s Glenn Research Center in Cleveland. “It was particularly interesting to see which moons the students selected for their individual essays, and the mysteries they hope to unravel. Their RPS-powered mission concepts always prove to be innovative, and it’s a joy to learn about their ‘superpowers’ that exemplify their path forward as the next generation of explorers.” 
      Entries were split into three categories: grades K-4, 5-8, and 9-12. Every student who submitted an entry received a digital certificate, and over 4,859 participants who signed up received an invitation to the Power Up with NASA virtual event. Students learned about what powers the NASA workforce utilizes to dream big and work together to explore. Speakers included Carl Sandifer II, Dr. Wanda Peters, NASA’s deputy associate administrator for programs in the Science Mission Directorate and Dr. Zibi Turtle, principal investigator for NASA’s Dragonfly mission from the John Hopkins Applied Physics Laboratory.
      Fifteen national semifinalists in each grade category (45 semifinalists total) have been selected. These participants also will receive a NASA RPS prize pack. Finalists for this challenge will be announced on April 23.
      Grades K-4
      Vihaan Akhoury, Roseland, NJ Ada Brolan, Somerville, MA Ashwin Cohen, Washington D.C Unnathi Chandra Devavarapu, San Marcos, CA Levi Fisher, Portland, OR Tamanna Ghosh, Orlando, FL Ava Goodison, Arnold, MD Anika Lal, Pflugerville, TX Diya Loganathan, Secaucus, NJ Mini M, Ann Arbor, MI Mark Porter, Temple Hills, MD Rohith Thiruppathy, Canton, MI Zachary Tolchin, Guilford CT Kavin Vairavan, West Windsor Township, NJ Terry Xu, Arcadia, CA Grades 5-8
      Chowdhury Wareesha Ali, Solon OH Caydin Brandes, Los Angeles, CA Caleb Braswell, Crestview, FL Lilah Coyan, Spokane, WA Ashwin Dhondi Kubeer, Phoenix, AZ Jonathan Gigi, Cypress, TX Gagan Girish, Portland, OR Maggie Hou, Snohomish, WA Sanjay Koripelli, Louisville, KY Isaiah Muniz, South Orange, NJ Sarabhesh Saravanakumar, Bothell, WA Eliya Schubert, Katonah, NY Gabriel Traska, Fort Woth, TX Jaxon Verbeck, Riggins, ID Krish Vinodhkumar, Monrovia, MD Grades 9-12
      Samaria Berry, Kinder, LA David Cai, Saipan, MP Reggie Castro, Saipan, MP Ryan Danyow, Rutland City, VT Faiz Karim, Jericho, NY Sakethram Kuncha, Chantilly, VA Katerina Morin, Miami, FL Emilio Olivares, Edmond, OK Kairat Otorov, Trumbull, CT Dev Rai, Herndon, VA Shaurya Saxena, Irving, TX Saanvi Shah, Bothell, WA Niyant Sithamraju, San Ramon, CA Anna Swenson, Henderson, NV Alejandro Valdez, Orlando, FL About the Challenge
      The Power to Explore Student Challenge is funded by the NASA Science Mission Directorate’s Radioisotope Power Systems Program Office and managed and administered by Future Engineers under the direction of the NASA Tournament Lab, a part of the Prizes, Challenges, and Crowdsourcing Program in NASA’s Space Technology Mission Directorate.
      Kristin Jansen
      NASA’s Glenn Research Center
      View the full article
    • By USH
      Researchers utilizing publicly available Synthetic Aperture Radar (SAR) data from Capella Space and Umbra have uncovered significant hidden structures within and beneath the CFR Pyramid on the Giza Plateau. The study reveals five distinct "Zed" structures located above what was previously believed to be the pharaoh’s burial chamber, resembling similar formations found in the Khufu Pyramid. These structures are connected by geometric pathways, with additional secondary formations identified through satellite imaging. 
      Source and credit images: The Reese report / The Kafre Research Project.
      Most notably, eight vertically aligned cylindrical structures, arranged in two parallel rows from north to south, extend 648 meters underground. These formations merge into two massive cubic structures, each approximately 80 meters per side. Tomographical analysis indicates that the cylindrical structures function as hollow wells surrounded by descending spiral pathways. 
      Further research suggests that these subterranean formations are not limited to the CFR Pyramid but extend beneath the Khufu and Menkaure pyramids as well, reaching depths of approximately two kilometers. The study marks a groundbreaking advancement in the understanding of the Giza Plateau’s underground complexity, 
      The discoveries surrounding the CFR Pyramid represent just the tip of a vast and complex structure beneath the Giza Plateau.If confirmed, this discovery could challenge mainstream Egyptology’s belief that the pyramids were simply royal tombs. 
        View the full article
  • Check out these Videos

×
×
  • Create New...