Chinese satellites shine brighter than cosmic objects, threatening astronomy

China’s new broadband constellation has become a significant threat to astronomical observations due to its exceptional brightness.

The first batch of Qianfan megaconstellation satellites was launched in August.

Early observations of the deployed satellites indicate that their luminosity far exceeds the guidelines established by astronomical authorities.

China’s planned Qianfan network is designed to rival SpaceX’s Starlink in providing high-speed internet service.

According to Reuters , this constellation includes 15,000 satellites, which will be deployed into orbit by 2030.

The problem is that these satellites are so bright, they can interfere with astronomical observations, particularly those of faint celestial objects. The light from these satellites can completely overwhelm the scientific data and imagery.

High brightness of 18 satellites

Qianfan means Thousand Sails, which will form a massive network of communication satellites once complete. The satellites are being developed by the state-owned Shanghai Spacecom Satellite Technology (SSST). China has remained secretive about its design and deployment plans.

This August, the first batch of 18 satellites were deployed into a low-Earth orbit (LEO). Despite this small number, the satellites have already started to threaten astronomy.

The study — posted on the preprint server arXiv — performed the first ground-based observations of the 18 satellites.

The study measured the satellites’ brightness variation from magnitude 8 to 4 — with the highest brightness occurring at near-overhead positions.

This may even make the satellites visible to the naked eye. Moreover, the satellites far exceed the recommended brightness limit of magnitude 7 for ground-based astronomical observations.

“Observed magnitudes of Qianfan spacecraft range from 4 when they are near zenith to 8 when low in the sky. These satellites will impact astronomical research unless their brightness is reduced,” noted the study paper led by Anthony Mallama, who has also researched on brightness of Starlink satellites.

It can be compared to trying to observe a firefly in a city full of skyscrapers. The light pollution from the satellites is making it increasingly difficult to see distant stars.  The large number of satellites can reflect sunlight, making them appear bright.

Proper solutions required for future satellites

The study examined how the brightness of the satellites changed as they moved higher in the sky. They discovered that the brightness changes matched a model of a satellite with a large flat panel facing Earth and a solar panel facing away from Earth.

“Nearly all of the observations can be modeled with a nadir-facing flat antenna panel and the underside of a zenith-facing solar array, both with Lambertian reflectance properties,” the study noted.

Unlike Starlink , the Qianfan satellites do not appear to have mirrors that reflect sunlight away from Earth. SpaceX uses this measure to mitigate the brightness of its satellites.

SpaceNews reported that the study seeks to raise awareness and prompt modifications to the design of subsequent Qianfan satellites.

Starlink and Qianfan are not the only culprits; the problem of brightness from commercial space launches is growing at an alarming rate.

In October, AST SpaceMobile deployed a large phased array antenna on one of its BlueBird satellites, which are designed to provide direct-to-device services. This antenna is among the largest commercial antennas in low Earth orbit and has raised concerns about its brightness due to its size.

While satellites have enhanced communication and observation capabilities, the increasing number of launches in low-Earth orbit will continue to pose a significant threat to the view of the cosmos unless proper measures are taken.