Credit: NASA’s Goddard Space Flight Center
Machine-readable PDF copy", "items": [ { "id": 204564, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857249, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Infographic_Final.jpg", "filename": "ComPair_Infographic_Final.jpg", "media_type": "Image", "alt_text": "Explore this infographic to learn more about ComPair and scientific ballooning.Credit: NASA’s Goddard Space Flight CenterMachine-readable PDF copy", "width": 5100, "height": 6600, "pixels": 33660000 } }, { "id": 204565, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857250, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Infographic_Final.png", "filename": "ComPair_Infographic_Final.png", "media_type": "Image", "alt_text": "Explore this infographic to learn more about ComPair and scientific ballooning.Credit: NASA’s Goddard Space Flight CenterMachine-readable PDF copy", "width": 5100, "height": 6600, "pixels": 33660000 } }, { "id": 204566, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857251, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Infographic_Final-half.jpg", "filename": "ComPair_Infographic_Final-half.jpg", "media_type": "Image", "alt_text": "Explore this infographic to learn more about ComPair and scientific ballooning.Credit: NASA’s Goddard Space Flight CenterMachine-readable PDF copy", "width": 2550, "height": 3300, "pixels": 8415000 } }, { "id": 204567, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857252, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Infographic_Final-half.png", "filename": "ComPair_Infographic_Final-half.png", "media_type": "Image", "alt_text": "Explore this infographic to learn more about ComPair and scientific ballooning.Credit: NASA’s Goddard Space Flight CenterMachine-readable PDF copy", "width": 2550, "height": 3300, "pixels": 8415000 } } ], "extra_data": {} }, { "id": 311801, "url": "https://svs.gsfc.nasa.gov/14373/#media_group_311801", "widget": "Basic text with HTML", "title": "", "caption": "", "description": "ComPair is a balloon-borne science instrument designed to detect gamma rays with energies between 200,000 and 20 million electron volts. Visible light’s energy falls between 2 and 3 electron volts, for comparison.
Supernovae and powerful explosions called gamma-ray bursts shine the brightest in this energy range. It’s also where astronomers expect to see the strongest glow from the most massive and distant active galaxies, which are powered by monster black holes. Current missions don’t cover this range well, however, so future ComPair-inspired instruments could fill in important gaps in astronomers' knowledge.
Earth’s atmosphere filters out most of the high-energy radiation coming from space – which is good for humans but makes testing new gamma-ray technologies challenging. ComPair's solution is to fly to about 133,000 feet (40,000 meters) on a scientific balloon, which brings it above 99.5% of the atmosphere.
ComPair gets its name from two methods it uses to study gamma rays: Compton scattering and pair production. In Compton scattering, light hits a particle, such as an electron, and transfers some energy to it. Pair production occurs when a gamma ray grazes the nucleus of an atom and converts into a pair of particles – an electron and its antimatter counterpart, a positron.
The instrument has four major components:
1. A tracker containing 10 layers of silicon detectors that determines the position of incoming gamma rays.
2. A high-resolution calorimeter made of cadmium, zinc, and telluride that precisely measures lower-energy Compton-scattered gamma rays and some converted into electron-positron pairs.
3. A high-energy calorimeter made of cesium iodide that mostly measures electron-positron pairs as well as some Compton-scattered gamma rays.
4. An anticoincidence detector that notes the entry of high-energy charged particles called cosmic rays.
ComPair is a collaboration among Goddard, NRL, Brookhaven National Laboratory in Upton, New York, and Los Alamos National Laboratory in New Mexico.", "items": [], "extra_data": {} }, { "id": 311803, "url": "https://svs.gsfc.nasa.gov/14373/#media_group_311803", "widget": "Single image", "title": "", "caption": "", "description": "These elements from the infographic above show the ComPair instrument on the left and its location on the gondola on the right.
Credit: NASA's Goddard Space Flight Center", "items": [ { "id": 204569, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857254, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Thumbnail_print.jpg", "filename": "ComPair_Thumbnail_print.jpg", "media_type": "Image", "alt_text": "These elements from the infographic above show the ComPair instrument on the left and its location on the gondola on the right.Credit: NASA's Goddard Space Flight Center", "width": 1024, "height": 576, "pixels": 589824 } }, { "id": 204568, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857253, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Thumbnail.jpg", "filename": "ComPair_Thumbnail.jpg", "media_type": "Image", "alt_text": "These elements from the infographic above show the ComPair instrument on the left and its location on the gondola on the right.Credit: NASA's Goddard Space Flight Center", "width": 3840, "height": 2160, "pixels": 8294400 } }, { "id": 204570, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857255, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Thumbnail_searchweb.png", "filename": "ComPair_Thumbnail_searchweb.png", "media_type": "Image", "alt_text": "These elements from the infographic above show the ComPair instrument on the left and its location on the gondola on the right.Credit: NASA's Goddard Space Flight Center", "width": 320, "height": 180, "pixels": 57600 } }, { "id": 204571, "type": "media", "extra_data": null, "title": null, "caption": null, "instance": { "id": 857256, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014373/ComPair_Thumbnail_thm.png", "filename": "ComPair_Thumbnail_thm.png", "media_type": "Image", "alt_text": "These elements from the infographic above show the ComPair instrument on the left and its location on the gondola on the right.Credit: NASA's Goddard Space Flight Center", "width": 80, "height": 40, "pixels": 3200 } } ], "extra_data": {} }, { "id": 311804, "url": "https://svs.gsfc.nasa.gov/14373/#media_group_311804", "widget": "Basic text", "title": "For More Information", "caption": "", "description": "See [https://nasa.gov/feature/goddard/2023/nasa-s-compair-balloon-mission-readies-for-flight](https://nasa.gov/feature/goddard/2023/nasa-s-compair-balloon-mission-readies-for-flight)", "items": [], "extra_data": {} } ], "studio": "gms", "funding_sources": [ "NASA Astrophysics" ], "credits": [ { "role": "Producer", "people": [ { "name": "Scott Wiessinger", "employer": "KBR Wyle Services, LLC" } ] }, { "role": "Science writer", "people": [ { "name": "Jeanette Kazmierczak", "employer": "University of Maryland College Park" } ] }, { "role": "Graphic designer", "people": [ { "name": "Scott Wiessinger", "employer": "KBR Wyle Services, LLC" } ] }, { "role": "Scientist", "people": [ { "name": "Regina Caputo", "employer": "NASA/GSFC" } ] }, { "role": "Project support", "people": [ { "name": "Francis Reddy", "employer": "University of Maryland College Park" } ] } ], "missions": [], "series": [ "Astrophysics Stills" ], "tapes": [], "papers": [], "datasets": [], "nasa_science_categories": [ "Universe" ], "keywords": [ "Antimatter", "Ast", "Astrophysics", "Black Hole", "Blazar", "Gamma Ray", "Infographic", "Neutron Star", "Space", "Supernova" ], "recommended_pages": [], "related": [ { "id": 14980, "url": "https://svs.gsfc.nasa.gov/14980/", "page_type": "Produced Video", "title": "Prototype ComPair-2 Gamma-Ray Detectors Complete Thermal Vacuum Testing", "description": "Prototype gamma-ray detectors for the ComPair-2 mission rests in a thermal vacuum chamber after testing in June 2025 at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The ComPair-2 team tested the detectors’ performance at hot and cold temperatures over the course of a week and the overall survivability of the layer itself. Credit: NASA/Sophia RobertsAlt text: A piece of equipment sits inside a chamber in a lab. Image description: A cylindrical metal chamber at the center of the image has its door swung all the way open. Inside are silver-wrapped ComPair-2 detectors attached to many copper-colored wires. The chamber is in a lab with white walls and has tubes, wires, and other pieces of equipment attached. || ComPair2_TVAC-1-small.jpg (4096x2732) [3.2 MB] || ComPair2_TVAC-1.jpg (8192x5464) [30.6 MB] || ", "release_date": "2026-02-26T12:00:00-05:00", "update_date": "2026-02-26T12:02:25-05:00", "main_image": { "id": 1202201, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014900/a014980/ComPair2_TVAC-2-small_searchweb.png", "filename": "ComPair2_TVAC-2-small_searchweb.png", "media_type": "Image", "alt_text": "Iker Liceaga-Indart, a mechanical engineer at NASA Goddard, peers into the thermal vacuum chamber to evaluate the prototype after testing. \rCredit: NASA/Sophia Roberts\rAlt text: A man investigates a chamber in a lab.\rImage description: A man in a navy-blue polo shirt kneels to look into a cylindrical metal chamber in a lab. The chamber door is fully open and inside are silver-wrapped ComPair-2 detectors attached to many copper-colored wires.", "width": 320, "height": 180, "pixels": 57600 } }, { "id": 14794, "url": "https://svs.gsfc.nasa.gov/14794/", "page_type": "Produced Video", "title": "Developing NASA’s ComPair-2 Detectors", "description": "ComPair-2 will host a gamma-ray tracker with 10 layers, each with 380 silicon detectors, like the engineering test unit shown here. This trial version allows the mission team to test the electronics, measure how well the detectors work together, and develop assembly procedures for each layer. Credit: NASA/Sophia RobertsAlt text: Scientific hardware on a table Image description: A square piece of scientific hardware rests on a table on top of a silver cover. The hardware has a white board on the bottom with a silver peg at each corner. Inside the pegs is a black square with orange and green electronic components. The green runs along the bottom of the square and takes up the left corner of the black square. The orange electronic components run in 20 stripes along the black square. The orange is interspersed with black. || ComPair2-3_print.jpg (1024x683) [631.9 KB] || ComPair2-3.jpg (8192x5464) [29.1 MB] || ComPair2-3_searchweb.png (320x180) [124.5 KB] || ComPair2-3_web.png (320x213) [137.6 KB] || ComPair2-3_thm.png [28.0 KB] || ", "release_date": "2025-03-11T00:00:00-04:00", "update_date": "2025-03-11T12:44:33-04:00", "main_image": { "id": 1153310, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014700/a014794/Daniel_Violette_ComPair2-1_print.jpg", "filename": "Daniel_Violette_ComPair2-1_print.jpg", "media_type": "Image", "alt_text": "Dan Violette, a postdoctoral fellow at NASA Goddard, tips the engineering test unit toward the camera in the ComPair-2 lab. The black carbon fiber frame was fabricated at NASA’s Marshall Space Flight Center in Huntsville, Alabama, and machined and assembled at Goddard.\rCredit: NASA/Sophia Roberts\rAlt text: A man holds a square piece of electronic equipment\rImage description: A man in a long-sleeved blue lab coat tips a square piece of electronic equipment toward the camera. The square has a white base, with a slightly smaller black square on top. Orange and black rows cover the black square, with green along the right side and covering the bottom right corner. The square rests on a lab bench covered in silver material.", "width": 1024, "height": 712, "pixels": 729088 } }, { "id": 14372, "url": "https://svs.gsfc.nasa.gov/14372/", "page_type": "B-Roll", "title": "ComPair Thermal Vacuum Photos", "description": "Team members work on the ComPair balloon instrument before it begins testing in a thermal vacuum chamber at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. ComPair project manager Regina Caputo (front right), graduate student Nicholas Kirschner (George Washington University, left), and research scientist Nicholas Cannady (University of Maryland Baltimore County, rear) examine ComPair's various components to determine what needs to be “harnessed,” or connected via cable to power systems and the onboard computer.Credit: NASA/Scott Wiessinger || ComPair_TVac_IMG_2141.png (5319x3546) [30.9 MB] || ComPair_TVac_IMG_2141.jpg (5319x3546) [6.0 MB] || ComPair_TVac_IMG_2141_half.jpg (2659x1773) [1.4 MB] || ", "release_date": "2023-07-20T10:00:00-04:00", "update_date": "2023-07-25T08:45:11-04:00", "main_image": { "id": 856273, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014372/ComPair_TVac_IMG_2159_searchweb.png", "filename": "ComPair_TVac_IMG_2159_searchweb.png", "media_type": "Image", "alt_text": "Kirschner (left), Caputo (right), and Cannady (rear) continue to harness ComPair's four main components: tracker, high-resolution low-energy calorimeter, high-energy calorimeter, and anticoincidence detector.Credit: NASA/Scott Wiessinger", "width": 320, "height": 180, "pixels": 57600 } }, { "id": 14354, "url": "https://svs.gsfc.nasa.gov/14354/", "page_type": "B-Roll", "title": "ComPair Gamma-Ray Balloon Mission", "description": "Carolyn Kierans, principal investigator for the ComPair balloon mission at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, works on the instrument in this video. First, she assembles a layer of the tracker, which is housed in an aluminum casing. Next, she shows one of the tracker’s silicon detectors. Then she takes the lid off the tracker.Credit: NASA/Sophia Roberts || Unassembled_Parts_of_ComPair.01740_print.jpg (1024x540) [148.3 KB] || Unassembled_Parts_of_ComPair.01740_searchweb.png (320x180) [94.0 KB] || Unassembled_Parts_of_ComPair.01740_thm.png (80x40) [7.0 KB] || Unassembled_Parts_of_ComPair.webm (4096x2160) [18.2 MB] || Unassembled_Parts_of_ComPair.mp4 (4096x2160) [570.8 MB] || ", "release_date": "2023-05-25T00:00:00-04:00", "update_date": "2023-07-20T12:46:13-04:00", "main_image": { "id": 855344, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014354/Unassembled_Parts_of_ComPair.01740_print.jpg", "filename": "Unassembled_Parts_of_ComPair.01740_print.jpg", "media_type": "Image", "alt_text": "Carolyn Kierans, principal investigator for the ComPair balloon mission at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, works on the instrument in this video. First, she assembles a layer of the tracker, which is housed in an aluminum casing. Next, she shows one of the tracker’s silicon detectors. Then she takes the lid off the tracker.Credit: NASA/Sophia Roberts", "width": 1024, "height": 540, "pixels": 552960 } }, { "id": 14317, "url": "https://svs.gsfc.nasa.gov/14317/", "page_type": "Produced Video", "title": "NASA Missions Probe What May Be a 1-In-10,000-Year Gamma-ray Burst", "description": "The Hubble Space Telescope’s Wide Field Camera 3 revealed the infrared afterglow (circled) of the BOAT GRB and its host galaxy, seen nearly edge-on as a sliver of light extending to the burst's upper left. This animation flips between images taken on Nov. 8 and Dec. 4, 2022, one and two months after the eruption. Given its brightness, the burst’s afterglow may remain detectable by telescopes for several years. Each picture combines three near-infrared images taken at wavelengths from 1 to 1.5 microns and is 34 arcseconds across. Credit: NASA, ESA, CSA, STScI, A. Levan (Radboud University); Image Processing: Gladys Kober || GRB_WFC3IR1108+1204_circled.gif (512x512) [3.5 MB] || ", "release_date": "2023-03-28T13:50:00-04:00", "update_date": "2023-05-03T11:43:38.257753-04:00", "main_image": { "id": 842157, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a014300/a014317/GRB_all_rings_XMM_2160_searchweb.png", "filename": "GRB_all_rings_XMM_2160_searchweb.png", "media_type": "Image", "alt_text": "XMM-Newton images recorded 20 dust rings, 19 of which are shown here in arbitrary colors. This composite merges observations made two and five days after GRB 221009A erupted. Dark stripes indicate gaps between the detectors. A detailed analysis shows that the widest ring visible here, comparable to the apparent size of a full moon, came from dust clouds located about 1,300 light-years away. The innermost ring arose from dust at a distance of 61,000 light-years on the other side of our galaxy. GRB221009A is only the seventh gamma-ray burst to display X-ray rings, and it triples the number previously seen around one.Credit: ESA/XMM-Newton/M. Rigoselli (INAF)", "width": 320, "height": 180, "pixels": 57600 } }, { "id": 11209, "url": "https://svs.gsfc.nasa.gov/11209/", "page_type": "Produced Video", "title": "Fermi Proves Supernova Remnants Produce Cosmic Rays", "description": "A new study using observations from NASA's Fermi Gamma-ray Space Telescope reveals the first clear-cut evidence that the expanding debris of exploded stars produces some of the fastest-moving matter in the universe. This discovery is a major step toward meeting one of Fermi's primary mission goals.Cosmic rays are subatomic particles that move through space at nearly the speed of light. About 90 percent of them are protons, with the remainder consisting of electrons and atomic nuclei. In their journey across the galaxy, the electrically charged particles become deflected by magnetic fields. This scrambles their paths and makes it impossible to trace their origins directly.Through a variety of mechanisms, these speedy particles can lead to the emission of gamma rays, the most powerful form of light and a signal that travels to us directly from its sources.Two supernova remnants, known as IC 443 and W44, are expanding into cold, dense clouds of interstellar gas. This material emits gamma rays when struck by high-speed particles escaping the remnants.Scientists have been unable to ascertain which particle is responsible for this emission because cosmic-ray protons and electrons give rise to gamma rays with similar energies. Now, after analyzing four years of data, Fermi scientists see a gamma-ray feature from both remnants that, like a fingerprint, proves the culprits are protons.When cosmic-ray protons smash into normal protons, they produce a short-lived particle called a neutral pion. The pion quickly decays into a pair of gamma rays. This emission falls within a specific band of energies associated with the rest mass of the neutral pion, and it declines steeply toward lower energies. Detecting this low-end cutoff is clear proof that the gamma rays arise from decaying pions formed by protons accelerated within the supernova remnants.In 1949, the Fermi telescope's namesake, physicist Enrico Fermi, suggested that the highest-energy cosmic rays were accelerated in the magnetic fields of interstellar gas clouds. In the decades that followed, astronomers showed that supernova remnants were the galaxy's best candidate sites for this process.?A charged particle trapped in a supernova remnant's magnetic field moves randomly throughout it and occasionally crosses through the explosion's leading shock wave. Each round trip through the shock ramps up the particle's speed by about 1 percent. After many crossings, the particle obtains enough energy to break free and escapes into the galaxy as a newborn cosmic ray. The Fermi discovery builds on a strong hint of neutral pion decay in W44 observed by the Italian Space Agency's AGILE gamma-ray observatory and published in late 2011.Watch this video on YouTube. || ", "release_date": "2013-02-14T14:00:00-05:00", "update_date": "2023-05-03T13:52:23.664601-04:00", "main_image": { "id": 468169, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a011200/a011209/Cas_A_Still.jpg", "filename": "Cas_A_Still.jpg", "media_type": "Image", "alt_text": "The husks of exploded stars produce some of the fastest particles in the cosmos. New findings by NASA's Fermi show that two supernova remnants accelerate protons to near the speed of light. The protons interact with nearby interstellar gas clouds, which then emit gamma rays. Short narrated video.For complete transcript, click here.", "width": 1280, "height": 720, "pixels": 921600 } }, { "id": 10690, "url": "https://svs.gsfc.nasa.gov/10690/", "page_type": "Produced Video", "title": "How to make a gamma ray", "description": "A series of animations showing how gamma rays can be created through various particle interactions. || ", "release_date": "2010-11-09T13:00:00-05:00", "update_date": "2023-05-03T13:53:57.665308-04:00", "main_image": { "id": 489082, "url": "https://svs.gsfc.nasa.gov/vis/a010000/a010600/a010690/Inverse_Compton278.jpg", "filename": "Inverse_Compton278.jpg", "media_type": "Image", "alt_text": "Inverse Compton scattering animation. An electron travelling at close the speed of light has a head-on collision with a lower-energy photon (from microwave to ultraviolet). The photon picks up energy from the electron and becomes a gamma ray.", "width": 1280, "height": 720, "pixels": 921600 } } ], "sources": [], "products": [], "newer_versions": [], "older_versions": [], "alternate_versions": [] }