Starlink Satellites Get Upgrades To Prevent Interference With Astronomy

SpaceX is working on several upgrades to the company’s Starlink satellites in an effort to prevent them from bothering astronomers. 

The upgrades try to address how Starlink satellites can reflect sunlight as they orbit the Earth. This same light can accidentally photo-bomb astronomical observations, which has sparked concerns within the scientific community. 

In response, SpaceX has been working with astronomers to develop ways to reduce the amount of sunlight Starlink satellites will reflect over the night sky. On Thursday, the company published a document(Opens in a new window) that outlines the upgrades, which involve altering some design elements to the Starlink satellites. 

(SpaceX)

According to SpaceX, Starlink satellites can reflect sunlight when their orbit reaches the dark side of the “terminator,” the boundary between day and night. As a result, the satellites can be seen from the ground usually in the first several hours after dusk, or in the first several hours before dawn. This sunlight can pose a problem for astronomical research on comets and near-Earth asteroids, since these observations are often done during twilight hours. 

One of SpaceX’s early attempts to solve the problem was to install a “sun visor” on the Starlink satellites capable of blocking the incoming sunlight from causing reflections. However, the company now says it’s dumping the sun visors solution. One reason is because the visors can also block the “laser links” on Starlink satellites. The other is how the visors generate too much atmospheric drag, forcing the satellites to spend more fuel maintaining their orbits. 

(SpaceX)

The company’s alternative solution involves using a mirror film on the satellites, which can scatter most of the reflected sunlight away from the planet. “A new and improved version of this film” is slated to arrive for the company’s second-generation satellites, which have yet to launch. According to SpaceX, the new film can reduce the brightness by over 10 times compared to the first-generation mirror film. 

(Spacex)

The other measure involves using darker materials on the SpaceX satellites to make the surfaces less reflective. On the first-generation satellites, the company is now employing a “dark red” pigmentation on the solar cells instead of a white-colored material. For the second-gen Starlink satellites, SpaceX has developed a “low reflectivity black” color. It’ll be used to paint over various components on the satellites, which can’t be covered by the mirror film.  

The final mitigation step involves the solar cell arrays on the second-gen Starlink satellites. The company plans on pointing the solar arrays away from the Sun as they cross the terminator boundary, dampening their ability to reflect light down to the Earth’s surface. 

(SpaceX)

“This off-pointing maneuver results in a 25% reduction in available power for the satellites,” the company said. “Despite this cost, SpaceX has specifically designed the second-generation satellites to be able to accommodate this significant power reduction.”

According to SpaceX, the mitigation measures promise to make the Starlink satellites “invisible to the naked eye when at their standard operational altitude.” However, the company says it’s still working to reduce the amount of sunlight the satellites can reflect when they’re launched into space, enter into orbit, or when they eventually retire and burn up in the atmosphere. 

SpaceX also points out other companies are working on their own satellite constellations to rival the Starlink network. This could generate even more light pollution in the night sky, unless the satellite industry responds accordingly. SpaceX itself plans on launching tens of thousands of second-generation Starlink satellites in the future, pending approval from regulators.

In response, SpaceX plans on selling the mirror film it developed to third-parties “at cost” so that all satellite operators can use it. “While SpaceX has spent considerable engineering effort on mitigating satellite brightness from the ground, no engineering model is perfect,” the company added. “For that reason, SpaceX expects to continue to find and implement technologies and operational techniques that further reduce the brightness of its second generation satellites.”

The company has currently launched almost 3,000 satellites for the first-generation Starlink network.