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SpaceX develops new sunshade to make Starlink satellites less visible from Earth

A launch in January carried one spacecraft, a so-called "Dark Sat," which had an experimental coating to make it less reflective and less visible to stargazers. The company later reported that the non-reflective coating made the satellite dimmer, but the sunshade experiment was expected to be more effective.


SpaceX plans to launch a Starlink satellite in May with a sunshade to make it less visible from Earth and mitigate interruptions to astronomical observations, company founder Elon Musk told a group of scientists.


The effort to make the satellites less visible is intended to placate astronomers, who have noted that Starlink's brightness can interrupt scientific observations of planets, stars and space phenomena.

If the company's so-called VisorSat is successful, it could become a regular component on Starlink spacecraft.
"I was pleased to see Elon himself make the presentation to us," said Constance Walker, an astronomer with the National Optical Astronomy Observatory, based in Tucson, Ariz.
"It just underlined their commitment to finding solutions to minimizing the brightness to something that the astronomical field can deal with," Walker said of his comments to scientists.

SpaceX faced protests from astronomers and other stargazers who have seen its satellites shining brightly in the night sky. Astronomy groups posted images showing how the satellites marred photos and interrupted observations of space objects.

Musk's address came during a teleconference Monday organized by the National Academies of Sciences, Engineering and Medicine. SpaceX did not respond to requests for more information about the VisorSat.

A launch in January carried one spacecraft, a so-called "Dark Sat," which had an experimental coating to make it less reflective and less visible to stargazers. The company later reported that the non-reflective coating made the satellite dimmer, but the sunshade experiment was expected to be more effective.

Starlink spacecraft are so bright at times that they can obliterate an image or leave lasting echoes and streaks on images, said Walker, who heads a panel with the International Astronomical Union to protect observatories.
"The number of satellites, the types of surfaces they have, their sizes, where they are in height and what orientation they are in all make a difference," Walker said. "It is hoped with the VisorSat that the brightness will be reduced by a factor of 10. It would not remove the streaking, but the residual [brightness] could be minimized."

SpaceX has 420 Starlink communications satellites in orbit, which is the largest constellation in history. The latest launch came April 22 from Kennedy Space Center in Florida.

The space firm previously launched 60 Starlink satellites at a time in May, November, on Jan. 6 and 29, Feb. 17, and March 18, with two test satellites sent aloft before that.

The biggest concern for astronomy is ensuring clear images from large survey telescopes charged with monitoring the skies - including surveys for asteroids that could collide with Earth and end life on the planet, said Yan Fernandez, an astronomer at the University of Central Florida.

"We're already living in an era when it's tough to get enough funding to do research, and having any additional problems could impede efforts to protect the planet," Fernandez said.

He said he hopes SpaceX and other satellite companies move quickly to address brightness concerns, because a number of firms plan to launch thousands of communication satellites in coming years for faster global Internet access.
Musk previously said that the sunshades would be made of "a special dark foam that's extremely radio transparent, so as not to affect the phased array antennas," and he compared them to car windshield visors.

A solution to brightness problems would "be to the mutual benefit of the astronomical community and satellite companies," Walker said.
"Hopefully other satellite companies will take a cue from SpaceX," she said.

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