SpaceX's VisorSat will use sunshades modeled on sun visors in a car windshield to keep sunlight from reflecting off the satellite's antennas, reducing its brightness as seen from the ground. Credit: SpaceX

WASHINGTON — SpaceX has decided to add sunshades to future Starlink satellites to reduce their impact on astronomy, having opted for constellation-wide implementation of the reflective hardware. 

Patricia Cooper, SpaceX’s vice president of satellite government relations, said May 26 that SpaceX has another 80 or so Starlink satellites it is preparing to launch based on their current design before regularly incorporating sunshades that block sunlight from hitting reflective parts of each satellite. 

“We would have about 500 satellites at their current brightness, and then all satellites beyond that would have these sunshades,” Cooper said during a webinar hosted by the American Astronomical Society and the Satellite Industry Association. “That is the ratio we would be looking at.”

SpaceX has launched 422 Starlink satellites, including two prototypes, since 2018. The company is building and launching an initial constellation of roughly 4,400 satellites, though regulatory filings indicate the company could grow Starlink to 12,000 or even 42,000 satellites. 

SpaceX’s first visor-equipped satellite, dubbed VisorSat, was expected to launch May 17, but was delayed because of Tropical Storm Arthur until after the company’s highly anticipated Crew Demo 2 mission, scheduled for May 27 at 4:33 p.m. Eastern. Cooper said SpaceX has yet to announce a date for its next Starlink mission. 

SpaceX typically launches Starlink satellites in batches of 60 on Falcon 9 rockets, a rate that would suggest one or two more launches would occur without Starlink satellites routinely equipped with sunshades. Cooper said SpaceX will likely retire early Starlink satellites more quickly to reduce their impact on astronomy. 

“The earlier version of our satellites that we’ve launched, we don’t expect them to have a complete five-year life span,” she said. “We are expecting to cut in the VisorSat mitigation at the point that we are launching still in the 500s of satellites.”

Tony Tyson, chief scientist for the Vera Rubin Observatory, said Starlink satellites need to be dimmed to an apparent magnitude of seven so that astronomers can work around them using image processing. Recent observations show Starlink satellites at around magnitude five. DarkSat, a Starlink satellite treated with an experimental darkening coating, was observed at roughly magnitude six, he said. 

“Progress is being made, [but] we still have to get to seventh magnitude somehow,” Tyson said. SpaceX is working with astronomers on reducing the impact of Starlink, he said.

Cooper, when asked if SpaceX had the same goal of lowering Starlink’s brightness to magnitude seven, said it is an “interesting threshold,” but did not commit to meeting that target. 

Caleb Henry is a former SpaceNews staff writer covering satellites, telecom and launch. He previously worked for Via Satellite and NewSpace Global.He earned a bachelor’s degree in political science along with a minor in astronomy from...