Giant satellites outshining nearly all the stars
Five huge satellites – each blocking an area of the sky about the size of two city buses – unfurled their giant antennae in low Earth orbit this week. The spacecrafts’ enormous surface areas are expected to make them shine at up to magnitude 0.4. That’s brighter than nine of the 10 brightest stars.
AST SpaceMobile announced the craft – BlueBirds 1-5 – successfully unfolded their 639-square-foot (64-square-meter) antennae on Friday, October 25, 2024. Company founder and CEO Abel Avellan said plans to place 100 or more of the craft in space is quickly moving ahead:
These five satellites are the largest commercial communications arrays ever launched in low Earth orbit. It is a significant achievement to commission these satellites, and we are now accelerating our path to commercial activity.
The company says its satellites will benefit regions with little or no cellular telephone coverage. But the International Astronomical Union (IAU) believes the plan will further degrade the night sky.
Made in TX — size matters! #BlueWalker3's 693 sq ft array would be largest-ever commercial comms array in LEO. We're building the first & only cellular broadband network in space backed by 2,400 patent and patent-pending claims. Removing before-flight tags today!!! ???? #5G?? pic.twitter.com/Vx4oNVNYCK
— Abel Avellan (@AbelAvellan) August 31, 2022
BlueBird causes concern among professional astronomers
A peer-reviewed paper published in Nature in October of 2023 confirmed the astronomical community’s fears. The study tracked the brightness of BlueWalker 3, the prototype for the BlueBird, which matches it in size.
The peak brightness of the satellite reached an apparent magnitude of 0.4. This made the new satellite one of the brightest objects in the night sky.
BlueWalker 3 grew and dimmed in brightness. At its weakest, it shone at magnitude 6, the limit of human vision. But it retuned to its brightest level, especially when it passed high overhead. At magnitude 0.4, BlueBird will be visible in even the most light-polluted locations.
The BlueBird constellation could also pose a threat to radio astronomy. Broadcast frequencies used by AST SpaceMobile are of particular concern, the IAU said:
Frequencies allocated to cell phones are already challenging to observe even in radio quiet zones we have created for our facilities. New satellites such as BlueWalker 3 have the potential to worsen this situation and compromise our ability to do science if not properly mitigated.
The IAU also acknowledged the need for satellite constellations … as well as caution. And BlueBird will provide what appears to be a worthwhile service, according to the company’s marketing department:
Our engineers and space scientists are on a mission to eliminate the connectivity gaps faced by today’s five billion mobile subscribers and finally bring broadband to the billions who remain unconnected.
BlueBird constellation highlights crowding of low Earth orbit
AST SpaceMobile is far from the only company filling low Earth orbit with hundreds of new satellites. Or more. Projects such as SpaceX’s Starlink plan to fly tens of thousands of satellites. This rapid growth is raising the specter of catastrophic runaway satellite collisions, even outside the spaceflight community. The venerable publication Popular Science addressed the danger in its coverage of BlueBird:
In these scenarios, the untenable amount of human-made objects leads to ever-increasing collisions, causing debris to deorbit and pose a danger to anything in its path.
Experts have long feared this scenario, known as the Kessler syndrome. EarthSky reported on the danger in March 2024 after space junk from the ISS struck Earth:
As early as 1978, NASA scientist Donald Kessler was pondering what would happen as more satellites took up residence in orbit around Earth. Now known as the Kessler syndrome, the scenario imagines the density of objects in low-Earth orbit becoming high enough that it creates a cascade of collisions, with each collision generating space debris that increases the likelihood of further collisions.
Because of their large size, the AST SpaceMobile BlueBird constellation may be particularly at risk of collision.
Bottom line: BlueBird, the largest communications satellites ever, opened their antennae this week. Astronomers believe the bright craft will further degrade the night sky.
Read more: Confirmed! BlueWalker 3 satellite outshines 99% of stars
The post Enormous BlueBird satellites unfurled in low Earth orbit first appeared on EarthSky.
from EarthSky https://ift.tt/TQ6dPtA
Giant satellites outshining nearly all the stars
Five huge satellites – each blocking an area of the sky about the size of two city buses – unfurled their giant antennae in low Earth orbit this week. The spacecrafts’ enormous surface areas are expected to make them shine at up to magnitude 0.4. That’s brighter than nine of the 10 brightest stars.
AST SpaceMobile announced the craft – BlueBirds 1-5 – successfully unfolded their 639-square-foot (64-square-meter) antennae on Friday, October 25, 2024. Company founder and CEO Abel Avellan said plans to place 100 or more of the craft in space is quickly moving ahead:
These five satellites are the largest commercial communications arrays ever launched in low Earth orbit. It is a significant achievement to commission these satellites, and we are now accelerating our path to commercial activity.
The company says its satellites will benefit regions with little or no cellular telephone coverage. But the International Astronomical Union (IAU) believes the plan will further degrade the night sky.
Made in TX — size matters! #BlueWalker3's 693 sq ft array would be largest-ever commercial comms array in LEO. We're building the first & only cellular broadband network in space backed by 2,400 patent and patent-pending claims. Removing before-flight tags today!!! ???? #5G?? pic.twitter.com/Vx4oNVNYCK
— Abel Avellan (@AbelAvellan) August 31, 2022
BlueBird causes concern among professional astronomers
A peer-reviewed paper published in Nature in October of 2023 confirmed the astronomical community’s fears. The study tracked the brightness of BlueWalker 3, the prototype for the BlueBird, which matches it in size.
The peak brightness of the satellite reached an apparent magnitude of 0.4. This made the new satellite one of the brightest objects in the night sky.
BlueWalker 3 grew and dimmed in brightness. At its weakest, it shone at magnitude 6, the limit of human vision. But it retuned to its brightest level, especially when it passed high overhead. At magnitude 0.4, BlueBird will be visible in even the most light-polluted locations.
The BlueBird constellation could also pose a threat to radio astronomy. Broadcast frequencies used by AST SpaceMobile are of particular concern, the IAU said:
Frequencies allocated to cell phones are already challenging to observe even in radio quiet zones we have created for our facilities. New satellites such as BlueWalker 3 have the potential to worsen this situation and compromise our ability to do science if not properly mitigated.
The IAU also acknowledged the need for satellite constellations … as well as caution. And BlueBird will provide what appears to be a worthwhile service, according to the company’s marketing department:
Our engineers and space scientists are on a mission to eliminate the connectivity gaps faced by today’s five billion mobile subscribers and finally bring broadband to the billions who remain unconnected.
BlueBird constellation highlights crowding of low Earth orbit
AST SpaceMobile is far from the only company filling low Earth orbit with hundreds of new satellites. Or more. Projects such as SpaceX’s Starlink plan to fly tens of thousands of satellites. This rapid growth is raising the specter of catastrophic runaway satellite collisions, even outside the spaceflight community. The venerable publication Popular Science addressed the danger in its coverage of BlueBird:
In these scenarios, the untenable amount of human-made objects leads to ever-increasing collisions, causing debris to deorbit and pose a danger to anything in its path.
Experts have long feared this scenario, known as the Kessler syndrome. EarthSky reported on the danger in March 2024 after space junk from the ISS struck Earth:
As early as 1978, NASA scientist Donald Kessler was pondering what would happen as more satellites took up residence in orbit around Earth. Now known as the Kessler syndrome, the scenario imagines the density of objects in low-Earth orbit becoming high enough that it creates a cascade of collisions, with each collision generating space debris that increases the likelihood of further collisions.
Because of their large size, the AST SpaceMobile BlueBird constellation may be particularly at risk of collision.
Bottom line: BlueBird, the largest communications satellites ever, opened their antennae this week. Astronomers believe the bright craft will further degrade the night sky.
Read more: Confirmed! BlueWalker 3 satellite outshines 99% of stars
The post Enormous BlueBird satellites unfurled in low Earth orbit first appeared on EarthSky.
from EarthSky https://ift.tt/TQ6dPtA
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