Right now, there are over 12,000 active satellites orbiting Earth. This number has nearly doubled in just a few years. This explosion in satellite launches is causing problems for astronomers. Bright satellites create streaks in telescope images, ruining beautiful views of the night sky.
A recent study reveals that most satellite constellations are brighter than what astronomers recommend. Only one company is following the guidelines. The study, available on the preprint server arXiv, compares the brightness of these satellites to the limits set by the International Astronomical Union (IAU). Nearly all satellites exceed the +7 brightness magnitude limit, which interferes with celestial observations. Texas’s AST SpaceMobile leads with its BlueWalker constellation, shining at a brightness of +2.
Affordable access to space has made launching satellites cheaper than ever. In response to the growing number, the IAU created a center in 2022 to ensure that satellite constellations don’t disrupt our view of the cosmos. They have established recommendations for maximum brightness for satellites below 341 miles (550 kilometers). Their target is a maximum of +7 for professional astronomy and below +6 for casual stargazers.
SpaceX’s Starlink constellation, with over 8,000 satellites, is a significant concern for astronomers due to its brightness. The company is collaborating with the IAU to minimize its satellites’ impact on observations. Initial Starlink satellites were around +3 in brightness, but modifications have since reduced that to +5 or +6. However, the latest Starlink Mini satellites are larger and orbit lower, making them brighter, despite SpaceX’s attempts to cut down on reflections.
AST SpaceMobile has emerged as the biggest violator. Its BlueWalker satellites shine at an average magnitude of +3.3, often eclipsing most night sky objects. With an impressive array spanning 693 square feet, these satellites hold the record for the largest communications setup in low Earth orbit and are part of a plan for a constellation of 100 satellites.
Among the players, one stands out for meeting the guidelines: London-based OneWeb. With 652 satellites at an average brightness of +7.85, they comply with the adjusted limits given their altitude of 745 miles (1,200 kilometers).
While the IAU’s guidelines are not yet mandatory, they aim to push for government regulations to manage this fast-growing industry. As interest in space expands, so does the need for effective oversight. The balance between innovation and preserving our night sky is becoming crucial.
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AST SpaceMobile,Low Earth orbit,oneweb,satellites,SPACEX
