Astronomers worried

Elon Musk’s Starlink plans even brighter satellites

The US aerospace company SpaceX is planning to launch so-called Direct-To-Cell (DTC) satellites into space for its Starlink internet satellite service, which, like the terrestrial mobile phone network, would be directly accessible with a smartphone without an additional antenna. Astronomers around the world are therefore concerned.

SpaceX launched six prototypes of the new satellites into space on January 3 this year. Following successful tests, the company applied to the relevant regulatory authorities in the USA for permission to launch 7,500 DTC satellites, which are to orbit at an altitude of 340 to 345 kilometers. Reason enough for the IAU to take a closer look at the effects of the new satellites.

Up to five times brighter
Anthony Mallama and his colleagues from the "IAU Center for the Protection of Dark Skies from Interference by Satellite Constellations" not only collected reports from observers from all over the world about the six prototypes already orbiting in space. They also carried out precise measurements with the MMT9 robotic telescope at the Russian Selentschuk Observatory in the Caucasus. Overall, it was found that the new satellites shine up to 4.9 times brighter than the previous Starlink satellites.

However, the scientists emphasize that the measurements can only provide an initial impression. It is still unclear, for example, how much the satellites' antenna contributes to their brightness. In the past, SpaceX has been very cooperative with astronomers: With the help of a whole series of measures - such as less reflective exterior coatings - the brightness of the satellites could be reduced.

"If such measures are similarly successful with the DTC satellites, the increase in brightness could be reduced by around half to 2.6 times in the best-case scenario," write Mallama and his colleagues.

Observations made more difficult
SpaceX currently operates over 6,000 Starlink satellites in low Earth orbits - this figure is set to rise to over 34,000. And the more there are, the more difficult it will be for sky researchers to observe undisturbed. For two years now, the IAU has therefore been operating its own satellite monitoring system, which astronomers can use to plan their observations.