The International Space Station. Credit: NASA
Friday, November 30, 2012
Thursday, November 29, 2012
Wednesday, November 28, 2012
LASAR COMMUNICATION IN SPACE
FROM: NASA
Laser Comm: That's a Bright Idea
Laser light made records obsolete. NASA is on the verge of doing the same thing with space based communications. Before the end of the decade, the Laser Communication Relay Demonstration (LCRD) mission will revolutionize the way we move tons of data from orbit to ground and all around the solar system.
Credit-NASA's Goddard Space Flight Center
Tuesday, November 27, 2012
Monday, November 26, 2012
Saturday, November 24, 2012
VAN ALLEN PROBES VIDEO
FROM: NASA
Van Allen Probes - The Instruments
Dr. David Sibeck explains the instruments on the twin Van Allen Probes (formerly the Radiation Belt Storm Probes, RBSP). The Van Allen Probes will explore the Van Allen Radiation Belts in the Earth's magnetosphere. The charged particles in these regions can be hazardous to both spacecraft and astronauts. The mission also will allow researchers to understand fundamental radiation and particle acceleration processes throughout the universe.
Friday, November 23, 2012
Wednesday, November 21, 2012
REBORN PLANETARY NEBULA
FROM: NASAA Reborn Planetary Nebula
These images of the planetary nebula Abell 30 show one of the clearest views ever obtained of a special phase of evolution for these objects. The inset image on the right is a close-up view of A30 showing X-ray data from NASA's Chandra X-ray Observatory in purple and Hubble Space Telescope data showing optical emission from oxygen ions in orange. On the left is a larger view showing optical and X-ray data from the Kitt Peak National Observatory and ESA's XMM-Newton, respectively. In this image the optical data show emission from oxygen (orange) and hydrogen (green and blue), and X-ray emission is colored purple.
A planetary nebula -- so called because it looks like a planet when viewed with a small telescope -- is formed in the late stage of the evolution of a sun-like star. After having steadily produced energy for several billion years through the nuclear fusion of hydrogen into helium in its central region, or core, the star undergoes a series of energy crises related to the depletion of hydrogen and subsequent contraction of the core. These crises culminate in the star expanding a hundred-fold to become a red giant.
Eventually the outer envelope of the red giant is ejected and moves away from the star at a relatively sedate speed of less than 100,000 miles per hour. The star meanwhile is transformed from a cool giant into a hot, compact star that produces intense ultraviolet radiation and a fast wind of particles moving at about 6 million miles per hour. The interaction of the UV radiation and the fast wind with the ejected red giant envelope creates the planetary nebula, shown by the large spherical shell in the bigger image.
In rare cases, nuclear fusion reactions in the region surrounding the star's core heat the outer envelope of the star so much that it temporarily becomes a red giant again. The sequence of events -- envelope ejection followed by a fast stellar wind -- is repeated on a much faster scale than before, and a small-scale planetary nebula is created inside the original one. In a sense, the planetary nebula is reborn.
Image Credit-NASA-ESA
Monday, November 19, 2012
Sunday, November 18, 2012
SPACEBOOK: THE INTERPLANETARY INTERNET
FROM: NASA
NASA, ESA Use Experimental Interplanetary Internet to Test Robot From International Space Station
WASHINGTON -- NASA and the European Space Agency (ESA) successfully have used an experimental version of interplanetary Internet to control an educational rover from the International Space Station. The experiment used NASA's Disruption Tolerant Networking (DTN) protocol to transmit messages and demonstrate technology that one day may enable Internet-like communications with space vehicles and support habitats or infrastructure on another planet.
Space station Expedition 33 commander Sunita Williams in late October used a NASA-developed laptop to remotely drive a small LEGO robot at the European Space Operations Centre in Darmstadt, Germany. The European-led experiment used NASA's DTN to simulate a scenario in which an astronaut in a vehicle orbiting a planetary body controls a robotic rover on the planet's surface.
"The demonstration showed the feasibility of using a new communications infrastructure to send commands to a surface robot from an orbiting spacecraft and receive images and data back from the robot," said Badri Younes, deputy associate administrator for space communications and navigation at NASA Headquarters in Washington. "The experimental DTN we've tested from the space station may one day be used by humans on a spacecraft in orbit around Mars to operate robots on the surface, or from Earth using orbiting satellites as relay stations."
The DTN architecture is a new communications technology that enables standardized communications similar to the Internet to function over long distances and through time delays associated with on-orbit or deep space spacecraft or robotic systems. The core of the DTN suite is the Bundle Protocol (BP), which is roughly equivalent to the Internet Protocol (IP) that serves as the core of the Internet on Earth. While IP assumes a continuous end-to-end data path exists between the user and a remote space system, DTN accounts for disconnections and errors. In DTN, data move through the network "hop-by-hop." While waiting for the next link to become connected, bundles are temporarily stored and then forwarded to the next node when the link becomes available.
NASA's work on DTN is part of the agency's Space Communication and Navigation (SCaN) Program. SCaN coordinates multiple space communications networks and network support functions to regulate, maintain and grow NASA's space communications and navigation capabilities in support of the agency's space missions.
The space station also serves as a platform for research focused on human health and exploration, technology testing for enabling future exploration, research in basic life and physical sciences and Earth and space science.
NASA, ESA Use Experimental Interplanetary Internet to Test Robot From International Space Station
WASHINGTON -- NASA and the European Space Agency (ESA) successfully have used an experimental version of interplanetary Internet to control an educational rover from the International Space Station. The experiment used NASA's Disruption Tolerant Networking (DTN) protocol to transmit messages and demonstrate technology that one day may enable Internet-like communications with space vehicles and support habitats or infrastructure on another planet.
Space station Expedition 33 commander Sunita Williams in late October used a NASA-developed laptop to remotely drive a small LEGO robot at the European Space Operations Centre in Darmstadt, Germany. The European-led experiment used NASA's DTN to simulate a scenario in which an astronaut in a vehicle orbiting a planetary body controls a robotic rover on the planet's surface.
"The demonstration showed the feasibility of using a new communications infrastructure to send commands to a surface robot from an orbiting spacecraft and receive images and data back from the robot," said Badri Younes, deputy associate administrator for space communications and navigation at NASA Headquarters in Washington. "The experimental DTN we've tested from the space station may one day be used by humans on a spacecraft in orbit around Mars to operate robots on the surface, or from Earth using orbiting satellites as relay stations."
The DTN architecture is a new communications technology that enables standardized communications similar to the Internet to function over long distances and through time delays associated with on-orbit or deep space spacecraft or robotic systems. The core of the DTN suite is the Bundle Protocol (BP), which is roughly equivalent to the Internet Protocol (IP) that serves as the core of the Internet on Earth. While IP assumes a continuous end-to-end data path exists between the user and a remote space system, DTN accounts for disconnections and errors. In DTN, data move through the network "hop-by-hop." While waiting for the next link to become connected, bundles are temporarily stored and then forwarded to the next node when the link becomes available.
NASA's work on DTN is part of the agency's Space Communication and Navigation (SCaN) Program. SCaN coordinates multiple space communications networks and network support functions to regulate, maintain and grow NASA's space communications and navigation capabilities in support of the agency's space missions.
The space station also serves as a platform for research focused on human health and exploration, technology testing for enabling future exploration, research in basic life and physical sciences and Earth and space science.
Saturday, November 17, 2012
A PLACE WHERE STARS COME FROM
FROM: NASA
A Nearby Stellar Cradle
The Milky Way and other galaxies in the universe harbor many young star clusters and associations that each contain hundreds to thousands of hot, massive, young stars known as O and B stars. The star cluster Cygnus OB2 contains more than 60 O-type stars and about a thousand B-type stars. Deep observations with NASA’s Chandra X-ray Observatory have been used to detect the X-ray emission from the hot outer atmospheres, or coronas, of young stars in the cluster and to probe how these fascinating star factories form and evolve. About 1,700 X-ray sources were detected, including about 1,450 thought to be stars in the cluster. In this image, X-rays from Chandra (blue) have been combined with infrared data from NASA’s Spitzer Space Telescope (red) and optical data from the Isaac Newton Telescope (orange).
Image Credit: NASA
Friday, November 16, 2012
RADIATION AND WIND ON THE PLANET MARS
FROM: NASA
Wind and Radiation on Mars
Curiosity monitors radiation and spots elusive whirlwinds on Mars.
Credit: NASA/JPL-Caltech
Wind and Radiation on Mars
Curiosity monitors radiation and spots elusive whirlwinds on Mars.
Credit: NASA/JPL-Caltech
Thursday, November 15, 2012
Wednesday, November 14, 2012
Tuesday, November 13, 2012
Sunday, November 11, 2012
COLLISION OF A GALACTIC PROPORTION
FROM: NASASpacecraft Image Mashup Shows Galactic Collision
This new composite image from the Chandra X-ray Observatory, the Hubble Space Telescope, and the Spitzer Space Telescope shows two colliding galaxies more than a 100 million years after they first impacted each other. The continuing collision of the Antennae galaxies, located about 62 million light years from Earth, has triggered the formation of millions of stars in clouds of dusts and gas
This new composite image from the Chandra X-ray Observatory, the Hubble Space Telescope, and the Spitzer Space Telescope shows two colliding galaxies more than a 100 million years after they first impacted each other. The continuing collision of the Antennae galaxies, located about 62 million light years from Earth, has triggered the formation of millions of stars in clouds of dusts and gas
Saturday, November 10, 2012
THE U.S. AIR FORCE AND THE NEAR SPACE JUMP
FROM: U.S. AIR FORCE
AFRL played major role in historic near-space jump
11/2/2012 - KIRTLAND AFB, N.M (AFNS) -- For more than nine minutes Oct. 14, an international audience watched as Austrian daredevil Felix Baumgartner egressed from a capsule 128,000 feet above the earth and fell toward the planet reaching speeds of 834 miles per hour, to become the first person to break the sound barrier outside of a vehicle.
When Baumgartner safely touched down 33 miles east of Roswell, N.M., shortly before noon, he had also achieved another milestone, topping Air Force Col. Joe Kittinger's 52-year-old record of the highest free fall by 25,200 feet.
The historic event would not have occurred without the significant participation of the Air Force Research Laboratory's Space Vehicles Directorate and one of its contractors, ATA Aerospace.
Five years ago, Red Bull Stratos, which sponsored Baumgartner's near-space jump, approached the directorate about supporting the mission, but the Kirtland-based organization's officials did not believe the activity had enough of a science and technology perspective, so they passed on it. About 18 months later, the directorate decided to assist the proposed mission, with the reversal attributable to a cooperative research and development agreement signed between the agency and ATA Aerospace.
"The agreement with ATA Aerospace allows a commercial company to use our facilities, evaluate equipment and conduct testing. It is a good way to offset costs and take advantage of excess capacity of both the facilities and equipment," said Harold "Vern" Baker, chief, Space and Integration Test Branch, Integrated Experiments and Evaluation Division, AFRL's Space Vehicles Directorate. "We realized that under the CRADA, we should be able to assist Baumgartner's jump and allow ATA to use our launch equipment for our high-altitude balloon program."
For Red Bull Stratos' two unmanned flights and the three manned missions (Baumgartner's two test jumps and his record-breaking decent), on-site ATA Aerospace staff performed liftoff and capsule-retrieval functions with the support and expertise of AFRL staff members Ed Coca, balloon launch director, and Baker, who ensured pre-and post-operations procedures had been conducted safely and properly. A 20-plus year veteran of the Air Force high-altitude balloon program, Baker watched Baumgartner's historic jump from mission control at the Roswell International Air Center.
"The balloon, which took Felix's capsule to 128,000 feet, was filled with 30 million cubic feet of helium," Baker said. "After about an hour delay due to winds, the balloon lifted off shortly after 9:30 a.m., for a two-and-a-half hour journey to the egress point. During that time, Felix's visor was not defrosting and there was concern the mission would have to be aborted."
Despite the defrost problem, the flight was not aborted and in-flight troubleshooting was attempted instead.
"The visor eventually defrosted from power in his suit, so after about 15-20 minutes, Baumgartner leapt from the capsule," Baker recalled."Several seconds into the free fall, he began to flat spin and there was a lot of concern in mission control, but he suddenly stabilized. He was also close to blacking out, but if that would have occurred, a drogue parachute would have been deployed. Those of us in Mission Control roared when Felix landed on the ground safe and sound."
ATA Aerospace employee Tracy Gerber, who has worked at the directorate since 1995 and has participated in many high-altitude balloon launches, said the opportunity to play a significant role in, and witness Baumgartner's leap into the history books, has been a career highlight.
"We've done a number of launches over the years, but none of them, in my opinion, compare to the one we did Oct. 14 with Red Bull Stratos and Sage Cheshire Aerospace, who built the capsule, and also the David Clark Company, which makes all the balloon suits for the NASA program did the one for Felix as well," said Gerber, Space Technology Research and Integrated Vehicle Experiments deputy program manager, in support of the Space Vehicles Directorate's Space Integration and Test Branch. "Getting to work with all these organizations was an incredible experience. Finally, from Oct. 23 to 28, I had the unique opportunity to attend a post-mission event in Salzburg, Austria, sponsored by Red Bull Stratos, to recognize all those involved in Felix's record-breaking jump."
In preparation for the big day, Baker arrived on scene late Saturday and then after discussions with three operations managers, including Gerber, he and Coca directed the helium inflation of the balloon at about 3 a.m. Shortly before 6 a.m., Baumgartner entered the 2,900-pound capsule. Three and half hours later, he began his ascent at a rate of about 1,000 feet per minute. The rest is history.
"Our expertise, our contract support and the contractor expertise we've developed played a huge part in Felix's successful mission," said Baker. "ATA Aerospace spent a lot of time, effort and money putting together all the procedures, processes and countdowns, and deserves much of the credit in making the record-shattering event happen. Although Felix was the main focus and rightly so, it took a team of dedicated and determined individuals to ensure it was mission possible."
AFRL played major role in historic near-space jump
11/2/2012 - KIRTLAND AFB, N.M (AFNS) -- For more than nine minutes Oct. 14, an international audience watched as Austrian daredevil Felix Baumgartner egressed from a capsule 128,000 feet above the earth and fell toward the planet reaching speeds of 834 miles per hour, to become the first person to break the sound barrier outside of a vehicle.
When Baumgartner safely touched down 33 miles east of Roswell, N.M., shortly before noon, he had also achieved another milestone, topping Air Force Col. Joe Kittinger's 52-year-old record of the highest free fall by 25,200 feet.
The historic event would not have occurred without the significant participation of the Air Force Research Laboratory's Space Vehicles Directorate and one of its contractors, ATA Aerospace.
Five years ago, Red Bull Stratos, which sponsored Baumgartner's near-space jump, approached the directorate about supporting the mission, but the Kirtland-based organization's officials did not believe the activity had enough of a science and technology perspective, so they passed on it. About 18 months later, the directorate decided to assist the proposed mission, with the reversal attributable to a cooperative research and development agreement signed between the agency and ATA Aerospace.
"The agreement with ATA Aerospace allows a commercial company to use our facilities, evaluate equipment and conduct testing. It is a good way to offset costs and take advantage of excess capacity of both the facilities and equipment," said Harold "Vern" Baker, chief, Space and Integration Test Branch, Integrated Experiments and Evaluation Division, AFRL's Space Vehicles Directorate. "We realized that under the CRADA, we should be able to assist Baumgartner's jump and allow ATA to use our launch equipment for our high-altitude balloon program."
For Red Bull Stratos' two unmanned flights and the three manned missions (Baumgartner's two test jumps and his record-breaking decent), on-site ATA Aerospace staff performed liftoff and capsule-retrieval functions with the support and expertise of AFRL staff members Ed Coca, balloon launch director, and Baker, who ensured pre-and post-operations procedures had been conducted safely and properly. A 20-plus year veteran of the Air Force high-altitude balloon program, Baker watched Baumgartner's historic jump from mission control at the Roswell International Air Center.
"The balloon, which took Felix's capsule to 128,000 feet, was filled with 30 million cubic feet of helium," Baker said. "After about an hour delay due to winds, the balloon lifted off shortly after 9:30 a.m., for a two-and-a-half hour journey to the egress point. During that time, Felix's visor was not defrosting and there was concern the mission would have to be aborted."
Despite the defrost problem, the flight was not aborted and in-flight troubleshooting was attempted instead.
"The visor eventually defrosted from power in his suit, so after about 15-20 minutes, Baumgartner leapt from the capsule," Baker recalled."Several seconds into the free fall, he began to flat spin and there was a lot of concern in mission control, but he suddenly stabilized. He was also close to blacking out, but if that would have occurred, a drogue parachute would have been deployed. Those of us in Mission Control roared when Felix landed on the ground safe and sound."
ATA Aerospace employee Tracy Gerber, who has worked at the directorate since 1995 and has participated in many high-altitude balloon launches, said the opportunity to play a significant role in, and witness Baumgartner's leap into the history books, has been a career highlight.
"We've done a number of launches over the years, but none of them, in my opinion, compare to the one we did Oct. 14 with Red Bull Stratos and Sage Cheshire Aerospace, who built the capsule, and also the David Clark Company, which makes all the balloon suits for the NASA program did the one for Felix as well," said Gerber, Space Technology Research and Integrated Vehicle Experiments deputy program manager, in support of the Space Vehicles Directorate's Space Integration and Test Branch. "Getting to work with all these organizations was an incredible experience. Finally, from Oct. 23 to 28, I had the unique opportunity to attend a post-mission event in Salzburg, Austria, sponsored by Red Bull Stratos, to recognize all those involved in Felix's record-breaking jump."
In preparation for the big day, Baker arrived on scene late Saturday and then after discussions with three operations managers, including Gerber, he and Coca directed the helium inflation of the balloon at about 3 a.m. Shortly before 6 a.m., Baumgartner entered the 2,900-pound capsule. Three and half hours later, he began his ascent at a rate of about 1,000 feet per minute. The rest is history.
"Our expertise, our contract support and the contractor expertise we've developed played a huge part in Felix's successful mission," said Baker. "ATA Aerospace spent a lot of time, effort and money putting together all the procedures, processes and countdowns, and deserves much of the credit in making the record-shattering event happen. Although Felix was the main focus and rightly so, it took a team of dedicated and determined individuals to ensure it was mission possible."
Friday, November 9, 2012
Thursday, November 8, 2012
Wednesday, November 7, 2012
Sunday, November 4, 2012
NASA'S CURIOSITY ROVER LANDING VIDEO
FROM: NASA
Red Planet: Landing
Adam Steltzner, Mars Science Laboratory Entry, Descent and Landing Lead, guides viewers through the landing process for the NASA Mars rover Curiosity.
Red Planet: Landing
Saturday, November 3, 2012
SPACEX TRASITIONS
FROM: NASA, SLPACEX
SpaceX Transitions to Third Commercial Crew Phase with NASA
WASHINGTON -- Space Exploration Technologies (SpaceX) has completed its first three performance milestones for NASA's Commercial Crew Integrated Capability (CCiCap) initiative, which is intended to lead to the availability of commercial human spaceflight services for government and commercial customers.
During the company's first milestone, a technical baseline review, NASA and SpaceX reviewed the Dragon spacecraft and Falcon 9 rocket for crew transportation to low-Earth orbit and discussed future plans for ground operations for crewed flights. The second milestone included a review of the company's plan to achieve the CCiCap milestones established during SpaceX's $440 million Space Act Agreement. SpaceX also presented the company's financial resources to support its co-investment in CCiCap.
At the company's headquarters in Hawthorne, Calif., on Oct. 29, SpaceX presented techniques it will use to design, build and test its integrated system during the third milestone, called an integrated systems requirements review. The company also provided NASA with the initial plans it would use for managing ground operations, launch, ascent, in-orbit operations, re-entry and landing should they begin transporting crews.
"These initial milestones are just the beginning of a very exciting endeavor with SpaceX." said Ed Mango, NASA's Commercial Crew Program manager. "We expect to see significant progress from our three CCiCap partners in a fairly short amount of time."
SpaceX also has completed its Space Act Agreement with NASA for the Commercial Crew Development Round 2 (CCDev2) initiative, the development phase that preceded CCiCap. During CCDev2, the company designed, developed and tested components of a launch abort system. A large hypergolic engine named SuperDraco would propel the Dragon spacecraft away from its rocket to save the crew from a disastrous event during launch or ascent. SpaceX also built a rocket engine test stand for developing an abort system. Engineers from NASA and SpaceX analyzed the trajectories, loads and dynamics the spacecraft would experience as it separates from a failing rocket.
"Our NASA team brought years of experience to the table and shared with SpaceX what components, systems, techniques and processes have worked for the agency's human space transportation systems in the past and why they've worked," said Jon Cowart, NASA's SpaceX partner manager during CCDev2. "This sharing of experience benefitted both NASA and the company, and is creating a more dependable system at an accelerated pace."
SpaceX is one of three U.S. companies NASA is working with during CCiCap to set the stage for a crewed orbital demonstration mission around the middle of the decade. SpaceX already is executing a contract with NASA for 12 cargo resupply missions to the International Space Station.
"The Dragon spacecraft has successfully delivered cargo to the space station twice this year, and SpaceX is well under way toward upgrading Dragon to transport astronauts as well," said SpaceX President Gwynne Shotwell.
Future development and certification initiatives eventually will lead to the availability of human spaceflight services for NASA to send its astronauts to the International Space Station, where critical research is taking place daily.
For more information about NASA's Commercial Crew Program, visit:
SpaceX Transitions to Third Commercial Crew Phase with NASA
WASHINGTON -- Space Exploration Technologies (SpaceX) has completed its first three performance milestones for NASA's Commercial Crew Integrated Capability (CCiCap) initiative, which is intended to lead to the availability of commercial human spaceflight services for government and commercial customers.
During the company's first milestone, a technical baseline review, NASA and SpaceX reviewed the Dragon spacecraft and Falcon 9 rocket for crew transportation to low-Earth orbit and discussed future plans for ground operations for crewed flights. The second milestone included a review of the company's plan to achieve the CCiCap milestones established during SpaceX's $440 million Space Act Agreement. SpaceX also presented the company's financial resources to support its co-investment in CCiCap.
At the company's headquarters in Hawthorne, Calif., on Oct. 29, SpaceX presented techniques it will use to design, build and test its integrated system during the third milestone, called an integrated systems requirements review. The company also provided NASA with the initial plans it would use for managing ground operations, launch, ascent, in-orbit operations, re-entry and landing should they begin transporting crews.
"These initial milestones are just the beginning of a very exciting endeavor with SpaceX." said Ed Mango, NASA's Commercial Crew Program manager. "We expect to see significant progress from our three CCiCap partners in a fairly short amount of time."
SpaceX also has completed its Space Act Agreement with NASA for the Commercial Crew Development Round 2 (CCDev2) initiative, the development phase that preceded CCiCap. During CCDev2, the company designed, developed and tested components of a launch abort system. A large hypergolic engine named SuperDraco would propel the Dragon spacecraft away from its rocket to save the crew from a disastrous event during launch or ascent. SpaceX also built a rocket engine test stand for developing an abort system. Engineers from NASA and SpaceX analyzed the trajectories, loads and dynamics the spacecraft would experience as it separates from a failing rocket.
"Our NASA team brought years of experience to the table and shared with SpaceX what components, systems, techniques and processes have worked for the agency's human space transportation systems in the past and why they've worked," said Jon Cowart, NASA's SpaceX partner manager during CCDev2. "This sharing of experience benefitted both NASA and the company, and is creating a more dependable system at an accelerated pace."
SpaceX is one of three U.S. companies NASA is working with during CCiCap to set the stage for a crewed orbital demonstration mission around the middle of the decade. SpaceX already is executing a contract with NASA for 12 cargo resupply missions to the International Space Station.
"The Dragon spacecraft has successfully delivered cargo to the space station twice this year, and SpaceX is well under way toward upgrading Dragon to transport astronauts as well," said SpaceX President Gwynne Shotwell.
Future development and certification initiatives eventually will lead to the availability of human spaceflight services for NASA to send its astronauts to the International Space Station, where critical research is taking place daily.
For more information about NASA's Commercial Crew Program, visit:
Thursday, November 1, 2012
NASA EXPLORES THE EARLY UNIVERSE
FROM: NASA
NASA's Fermi Explores the Early Universe
This animation tracks several gamma rays through space and time, from their emission in the jet of a distant blazar to their arrival in Fermi's Large Area Telescope (LAT). During their journey, the number of randomly moving ultraviolet and optical photons (blue) increases as more and more stars are born in the universe. Eventually, one of the gamma rays encounters a photon of starlight and the gamma ray transforms into an electron and a positron. The remaining gamma-ray photons arrive at Fermi, interact with tungsten plates in the LAT, and produce the electrons and positrons whose paths through the detector allows astronomers to backtrack the gamma rays to their source.
Credit: NASA's Goddard Space Flight Center/Cruz ...
NASA's Fermi Explores the Early Universe
This animation tracks several gamma rays through space and time, from their emission in the jet of a distant blazar to their arrival in Fermi's Large Area Telescope (LAT). During their journey, the number of randomly moving ultraviolet and optical photons (blue) increases as more and more stars are born in the universe. Eventually, one of the gamma rays encounters a photon of starlight and the gamma ray transforms into an electron and a positron. The remaining gamma-ray photons arrive at Fermi, interact with tungsten plates in the LAT, and produce the electrons and positrons whose paths through the detector allows astronomers to backtrack the gamma rays to their source.
Credit: NASA's Goddard Space Flight Center/Cruz ...
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