As our world gets more and more connected through telecommunications, the impact caused by the satellites launched for this feat are getting more and more serious. Large collections of satellite-constellations of placed in low earth orbit pose difficulty to visual based astronomy.
A study coordinated by aerospace engineer Siegfried Eggl, University of Illinois Urbana-Champaign showed that the BlueWalker 3 – recently launched by AST Mobile – appears brighter than the brightest stars to the naked eye, and has hence become the brightest objects in the night sky. A video taken by Marco Langbroek, Delft Technical University shows the AST Mobile satellite – being much brighter and bigger than stars to the naked eye, showing it in comparison to starlink satellites Starlink-4781, and Starlink-4016.
Challenges Posed By Bright Satellites
With so many bright stars in the night sky as well as planets like Venus and Mars on the brighter side as well, why would a few more bright satellites make a difference? Well this report is only about one satellite-constellation, while SpaceEx has a schedule full of launches for thousands of such constellations, possibly soon to be hundreds of thousands.
Countries like China and Russia also want their own communications satellites, and so does Europe. Just the launches by the US are estimated to be in the ballpark of about 400,000. This would completely change the appearance of the night sky – typically you can only see about a 1000 stars with just the human eye, even at areas with minimal to no light pollution and thousands of bright objects streaking past constantly might not be the most ideal.
There are methods in place to track and can compensate for the movement of planets – as their movements are predictable – in order to factor them out of visual astronomy. Tracking hundreds of thousands of satellites however will prove to be challenging. “BlueWalker 3 is so bright that most of the big telescopes such as the Rubin Observatory believe it could obliterate large parts of exposures,” Siegfried Eggl said.
Even though these satellites wouldn’t necessarily damage telescopes at observatories, cruising around would cause streaking in the captured data, and hence could cause significant data loss to observatories that have cost millions of dollars to set up.
Solutions Being Explored
Several solutions to these problems that satellites pose to visual astronomy are being explored in collaboration with the Laboratory for Advanced Space Systems at Illinois and satellite operators such as SpaceX.
One possible solution that Starlink is looking at is making their satellites’ surfaces darker, which would mean that these satellites would absorb more and reflect less sunlight. However, the absorption would generate heat causing the satellites to emit infrared light instead, which would mean observations in optical wavelengths wouldn’t be as affected, but infrared observations might. Heat is also one of the biggest engineering problems that is constantly being looked into in the context of space. Painting everything black comes with repercussions.
Another proposed solution from SpaceX involves making solar panels more reflective by using dielectric mirrors. These mirrors would change the direction of the reflection so that it’s not pointing directly at Earth, thereby avoiding glints or reflection by using mirror tricks. This might solve a lot of the problems with optical flaring of Starlink satellites.
It’s not quite as easy with all types of satellites though, as AST has gigantic satellites with hundreds of square feet of electronic phased arrays that they need to efficiently communicate with cell phones on the ground without causing radio leaks. Starlink solutions may not easily translate to AST satellites, which need to be pointed at the ground for maximum efficiency, which creates the need for new solutions for these problems. Solutions can only be achieved through collaborative efforts as space is a shared resource, that can only be exploited so much.
