Saturday, February 11, 2023

3871 - GAMMA RAY BURSTERS - and tiny satellites?

 

-  3871  -   GAMMA  RAY  BURSTERS  -   and tiny satellites? -  Tiny satellites could revolutionize the study of the most energetic explosion in the cosmos and help astronomers untangle the mysteries of colliding stellar remnants, Gamma Ray Bursters, that produce powerful gravitational waves.


-----------  3871  -  GAMMA  RAY  BURSTERS  -   and tiny satellites?

-   With tiny budgets and a lot of resourcefulness nd energized in the early 2000s that had given birth to “cubesats”, perhaps the space industry's most game-changing innovation of recent decades.  Cubesats are one cubic foot in volume and can be lunched in bunches as cheap, easy-to-build space gadgets.

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-    Gamma-ray bursts are really bright and all you need is a relatively small detector to spot them.   Gamma-ray bursts are the highest-energy explosions known to take place in the universe. Astronomers believe that only the Big Bang produced more energy than these mysterious flashes of super-energetic photons that come from distant galaxies.

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-    Accidentally discovered in the 1960s by American satellites keeping an eye on Russia's testing of nuclear weapons (which too produce the dangerous, penetrating gamma radiation), gamma-ray bursts had long puzzled astronomers. While some last a fraction of a second, others can brighten up the sky for several minutes.

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-    It took until the 1990s for astronomers to find that short gamma-ray bursts are likely caused by collisions of neutron stars, super-dense remnants of giant stars that prior to their death were over ten times more massive than our sun.

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-    The long-lasting bursts, astronomers believe, occur when even larger stars explode into supernovas at the end of their lives and then turn into black holes. Both of these events emit jets of super energetic material that illuminate the surrounding universe like the beam of a flashlight.

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-    Satellites orbiting Earth only detect a gamma-ray burst when this flashlight is directed toward our part of the cosmos, but detecting a gamma-ray burst is not a rare event. Almost every day, one flashes briefly at our planet from somewhere in the universe. Many more are believed to take place throughout the cosmos that go undetected because the "flashlight" is not aimed at us.

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-    Because gamma-ray bursts are so fleeting, astronomers don't always manage to locate their source. In fact, only about 30% of detected gamma-ray bursts get tracked to their origins.

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-     NASA's nearly 15-year-old “Fermi” satellite are the current flagship gamma-ray burst spotters. Optimized to detect super high energy gamma radiation, which is billions of times more energetic than what human eyes can see, these two spacecraft together detect the vast majority of gamma-ray bursts aimed at Earth.

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-    Another NASA spacecraft, 'Swift”, just a year and a half short of its 20th birthday, is equipped to find the source of gamma-ray bursts. Swift, however, only sees about one ninth of the sky. And since gamma-ray bursts are distributed evenly all over the universe, Swift only detects a small fraction of them.

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-    Astronomers want to know where gamma-ray bursts come from so that they can point other types of telescope toward those sources, and study the aftermath of the cataclysmic events that produced them.

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-    A constellation of cubesats can cover the whole sky.  That's a big advantage compared to the big monolithic missions. The second advantage is that you can measure the difference in time between when the different cubesats detect the gamma-ray burst and you can triangulate the position of the gamma-ray burst on the sky.

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-   By 2018 a new detector was developed that would fit on a “1U cubesat”, the smallest type of cubesat measuring only 3.9 by 3.9 by 3.9 inches (10 by 10 by 10 centimeters) in size.

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-     In March 2021, the world's first gamma-ray burst-detecting cubesat, called “GRBAlpha”, shot off to space.   GRBAlpha, the smallest astrophysical satellite ever, has been orbiting Earth 340 miles above the planet's surface. The innovative detector bolted to the tiny satellite's surface has been exceeding the team's expectations from the start.

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-    The first burst was detected in August 2021. Since then, GRBAlpha has detected 22 gamma-ray bursts.  Three times larger than GRBAlpha, the “VZLUSAT-2” has been orbiting Earth since January 2022, having scored 12 gamma-ray bursts since then.

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-   Gravitational waves were first predicted by Albert Einstein in 1916, gravitational waves are ripples in spacetime that arise from the interplay of gravitational forces of two or more supermassive objects, such as neutron stars and black holes.

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-    Across the universe, these objects frequently get pulled into each other's sphere of gravitational influence and start orbiting each other. Gradually, they spiral closer and closer to each other and eventually collide, the collision producing a gravitational tsunami that can be detected from Earth by gravitational wave detectors such as the American LIGO (The Laser Interferometer Gravitational-Wave Observatory) and the European Gravitational Observatory Virgo.

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-    Teams from all over the world working on cubesat missions to detect gamma-ray bursts met at a conference in Brno, the Czech Republic, in 2022.

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-     An Italian project called “HERMES” to be a constellation of six gamma-ray burst-detecting 3U cubesats. The first of these spacecraft is expected to launch in 2024.   Prior to that, the HERMES project team will fly a hosted payload on a cubesat built by the University of Melbourne, Australia, which is set for launch at the end of 2023.

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-    The HERMES satellites are quite a bit more sophisticated than GRBAlpha, featuring a detector sensitive to gamma-rays but also the slightly less energetic X-rays.

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-   The satellites are also equipped with a set of high-tech sensors including GPS receivers and accelerometers that will be able to report the spacecraft's positions with an accuracy of a few meters.

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-   Since there will be six of these satellites astronomers will be able, for the first time, to use the minuscule time difference in the arrival of the gamma-ray burst at the individual satellites, to calculate the location of the burst's source.  The time resolution is of about 300 nanoseconds.

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-    NASA is also working on a gamma-ray burst-detecting cubesat. The “BurstCube” twice as big as the HERMES satellites, is expected to launch by the end of 2023.

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-   GRBAlpha's somewhat larger and more complex successor 'GRBBeta” has its ride to space booked on the debut flight of Europe's new Ariane 6 heavy-lift rocket, which is expected to take place by the end of this year,2022.

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-   Astreonomers can all coordinate their efforts and build the constellation together. Most of these cubesats are built by small teams that have limited funding, but by working together, we can do it easier with the funding that we have.

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            February11, 2023    GAMMA  RAY  BURSTERS  - tiny satellites?         3871                                                                                                                          

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--------------------- ---  Saturday, February 11, 2023  ---------------------------

 

 

 

 

         

 

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