During a virtual conference briefing this week, SpaceX founder and CEO Elon Musk provided more details about a new plan that his company has to mitigate the impact of their Starlink satellite constellation on night sky observation. Musk first revealed on Twitter the intent to build a "sun visor" to lower their visibility, but we didn't know much about how it would work or how it compared to the test dark paint job that SpaceX tried previously.
As reported by Space News, SpaceX's new "VisorSat" approach will essentially use sun visors to block inbound sunlight from hitting the reflective antennas on the spacecraft, stopping them from reflecting said light back to Earth, which is why they appear as bright lights in the night sky.
This new hardware addition to future Starlink satellites will supplement other measures, including making use of a new method for changing the orientation of the satellites as they raise into their target orbits after launch, which is a period during which they're especially visible. The overall goal, according to Musk, is to "make the satellites invisible to the naked eye within a week, and to minimize the impact on astronomy," with a specific focus on ensuring that whatever impact the constellation does have doesn't impeded the ability of scientists and researchers to make new discoveries.
SpaceX's first test for reducing the visiblity of its Starlink constellation focused on using a darkening treatment to cover reflective surfaces, and though that proved somewhat effective in early testing, Musk says that he believes the VisorSat alternative will be more effective, greatly reducing the satellites' brightness instead of just making a smaller reduction.
For now, SpaceX intends to test the VisorSat system on the next Starlink launch, which have been happening at about a pace of one per month so far in 2020. The system does involve some degree of mechanical difficulty, however, as it's a whole new part that has to extend during flight to block the inbound light. The company has also focused on using materials that are radio transparent for the shades, so they don't impact the primary mission of Starlink, which is to provide low-latency, high-broadband bandwidth to customers on the ground.
Should this work, future Starlink spacecraft will be equipped with VisorSat, and Musk notes that the existing satellites on orbit will have a relatively short lifespan, meaning while they won't have the treatment, they should only be in use for around three or four years before being deorbited, at which point they'll be replaced by hopefully optically improved versions.