Elon Musk’s Starlink Satellites Concern Star Watchers

The new satellites will fly lower than many of the traditional ones and will more than double the approximately 5,000 satellites that currently surround the Earth.

Two days after Spaceon, of Elon Musk, launched 60 satellites in May as part of a mission to provide fast Internet service to people around the world, astronomers noticed something different.

When some of the satellites passed quickly through the Lowell Observatory in Flagstaff, Arizona, telescopes trained in the night sky captured rays of reflected sunlight that tarnished their vision of a distant star system.

Astronomers are now concerned that the large number of planned communication devices, including the nearly 12.00 of Musk’s Starlink fleet, shine with such intensity that they interfere with research that relies on delicate visual observations of distant galaxies and nearby asteroids. .

The new satellites will fly lower than many of the traditional artifacts and will arrive in unprecedented numbers: in total, more than double the approximately 5,000 satellites that currently surround the Earth.

“We were aiming in the right direction, and Starlink flew through it” on May 25, two days after launch, says Jeffrey Hall, director of the Lowell Observatory. The unexpected appearance helped point out that, in Hall’s words, “this is potentially a problem”.

Space Exploration Technologies Corp., of Musk, is authorized to launch 11,943 satellites of its Starlink fleet, which makes it a leader by far in a total of almost 13,000 satellites in low Earth orbit currently approved by the Federal Communications Commission, which coordinates trajectories and the use of radio frequencies.

In addition, Jeff Bezos, of Amazon.com Inc, on Thursday requested authorization to place 3,236 satellites of Internet transmission in low Earth orbit.

The lower trajectories offer a minimum delay time for data to bounce between the ground and the ship, overcoming the lethargy of the signal that has limited Internet schemes from space that depend on traditional communications satellites. The oldest artifacts are stationed at 36,000 kilometers above the Earth, an altitude that allows them to appear to float in one place.

In low Earth orbit-altitudes between 160 and 2,000 kilometers-satellites must rotate around the planet to stay suspended, completing orbits in just 90 minutes. As one advances toward the horizon, he hands over the task of signaling the next.

Many satellites are needed if the objective is a continuous and widespread coverage, which explains the constellations planned by Musk and others.

Currently, there are 1,338 satellites in low Earth orbit, according to a database compiled by the Union of Concerned Scientists. NASA, the United States space agency, accounted for 4,972 satellites in its most recent count of active and inactive payloads.

The number of stars visible to the unaided human eye is not much more than 1,628, which is the number of stars recorded in the fifth magnitude of a scale of brightness used by scientists, explains Robert Zinn, an astronomer at Yale University. , in an email. Abnormally favorable conditions (exceptional view, total darkness without light pollution and without moonlight) could produce more.

Plans for low-flying satellite fleets have existed for years. The finding that they could alarm the sky watchers seems novel. A video of the Starlink satellites floating online across the sky has attracted more than 1-3 million views on the Vimeo video sharing site. And Musk’s public statements have varied.

“The satellites will be in the dark when the stars are visible,” Musk tweeted on May 25, in response to solar system researcher Alex Parker, who said on Twitter that the view of SpaceX satellites launched two days earlier “gives me a pause “because” they are bright and there will be many “.

Two days later, Musk tweeted that “Starlink will not be seen by anyone unless you look very carefully and will have an impact of ~ 0% on advances in astronomy.”

He followed with a tweet that said: “We will make sure that Starlink does not have any material effect on discoveries in astronomy.” Musk said he had sent a note to the Starlink team about “albedo reduction,” or the reduction in the proportion of light reflected by the spacecraft.

Astronomers are studying the magnitude of the problem, says Pat Seitzer, former chairman of the Committee on light pollution, radio interference and space debris in American Astronomical Society, which represents professional astronomers in North America.

Satellites may be less bright once they move into the higher planned orbits, and their visibility may vary with the seasons: their altitude implies that they will stay out of Earth’s shadow and remain in sunlight even after dark during a longer period in summer than in winter.

“Our concern is how bright they can be,” says Seitzer, an astronomer at the University of Michigan.

Astronomers using radio telescopes that rely on non – visible spectrum may also be affected. They will have to adapt to a sky full of low-orbiting satellites, says Harvey Liszt, spectrum manager of the National Radio Astronomy Observatory based in Charlottesville, Virginia.

The spacecraft in orbit will communicate through the radio, which will generate a celestial background noise that astronomers must take into account when listening to weak signals from the ends of the universe.

“We will have to learn to operate our electronics to detect weak cosmic signals in the presence of satellite signals at other frequencies that will be millions of times stronger,” Liszt said by email.

Trustees of the American Astronomical Society quickly approved a resolution expressing concern after Starlink stormed its scene, and the centennial International Astronomical Union also commented.

“Reflections of the sun in the hours after sunset and before dawn make them appear as points of slow movement in the night sky,” the union said in a June 3 statement. Although they are difficult to distinguish with the naked eye, “they can be detrimental to the sensitive capabilities of large terrestrial astronomical telescopes.”

NASA does not regulate the orbits or the spacecraft that enter them, said JD Harrington, a spokesman for the US space agency. The Federal Aviation Administration regulates the security of commercial launches and does not regulate satellites, said Greg Martin, a spokesman.

The concern extends to the purely aesthetic level, since some contemplate the visual plague carried to the heavens without touching for millennia, but now marked by the age of the satellite.

“The darkness and inspiration that the natural sky of the night brings to humanity has resulted in great works of art, literature and music,” says Barentine. “The possibility of losing all that is the possibility of breaking a key link between the humanity and the natural world.”



Source: Gestion