Featured Image Source: Dr. John Barentine via Twitter / SpaceX
The founder and CEO of SpaceX, Elon Musk, was a guest at the National Academies of Sciences, Engineering, and Medicine, ‘Decadal Survey on Astronomy and Astrophysics 2020(Astro 2020) Optical Interference from Satellite Constellations Meeting.’ The meeting took place via a conference call with reporters and scientists on Monday, April 27. Musk addressed astronomers’ concerns over SpaceX’s Starlink satellite constellation appearing bright in the night sky.
Starlink, will be a constellation consisting of over 12,000 internet-beaming satellites. Offering broadband internet worldwide will help SpaceX fund missions to the moon and Mars. As of today, there is a total of 420 Starlink satellites in low Earth orbit (excludes two experimental satellites that will be deorbited).
According to astronomers and reporters who attended the conference call, Musk gave a short slide-presentation on how the company will decrease Starlink’s reflectivity. Starlink is deployed in clusters of 60 satellites; the fleet appears bright for several weeks until it reaches a higher orbit. During the conference, Musk said SpaceX aims to make Starlink satellites “invisible to the naked eye within a week of launch.” The satellites reflectivity is based on its orientation, on a slide, it details, that when each satellite is stationed - “brightness is driven by antennas since the satellite is in the ‘shark-fin’ configuration during sunset and sunrise.” As the satellites use ion thrusters to move into a higher operational orbit, the “brightness is driven by the ‘open book’ configuration for thrusting and drag and sunlight reflects off both the antenna and array.”
.@elonmusk: The goal of @SpaceX is to make Starlink satellites "invisible to the naked eye within a week of launch". Also notes that the brightness of the objects is directly related to their configuration/orientation on orbit, which they continue to work on. #Astro2020 pic.twitter.com/8EL2qX9JCG— Dr. John Barentine FRAS (@JohnBarentine) April 27, 2020
SpaceX’s ‘key solutions’ to reduce Starlink’s reflectivity are to “reduce reflection on antenna during sunset and sunrise” when each satellite is stationed. And as fleets of satellites raise into operational orbit, SpaceX aims to change their orientation by rolling each satellite to reduce reflection. A SpaceX slide reads:
“Rolling satellite makes sunlight bounce off smaller ‘knife-edge’ of array reducing reflection."
@elonmusk: Soon all Starlink objects launched will be modeled on "Visorsat", which uses a radio-transparent foam material as a sun shade. They should be less visible from the ground. How we roll them during orbit raise may also reduce visibility. #Astro2020 pic.twitter.com/qBXYKicG3a— Dr. John Barentine FRAS (@JohnBarentine) April 27, 2020
In January, SpaceX deployed an experimental satellite, known as ‘DarkSat,’ which features an anti-reflective coating. The dark coating was placed on the antenna, at bottom of the satellite. Musk says, soon all Starlink satellites deployed will feature a sunshade, he called it ‘VisorSat.’ Stating, VisorSats will be made up of a radio-transparent foam material. This would work kind of like an umbrella to shield from the suns rays and minimize the potential for reflection.
He also stated, all current satellites in orbit will be deorbited within 3 to 4 years, to burn up into Earth’s atmosphere, in order to be replaced by an upgraded version, with “far greater throughput.”
During the conference, Musk assured scientists SpaceX will not interfere with space-based research – “We will take further steps as needed," adding that the darkening Starlink is "quite simple" and "we'll feel a bit silly in hindsight."
In addition, Musk shared his interest in collaborating with the astronomy community to launch and build a “planet-imaging observatory” that could orbit Earth above the fleet of Starlink satellites, "I'm very excited about a future of space-based telescopes that could be very large,” he said. Adding that the new Starship SpaceX is developing will be capable of deploying very large space telescopes, larger than NASA’s Hubble, "Starship will be able to launch telescopes over 3X [times] diameter of Hubble."