世界の広い地域に高速インターネットなどのサービスを提供するため、何千もの小型衛星が地球低軌道に投入されています。

READING

Thousands of small satellites are being placed into low Earth orbit to provide services such as high-speed internet to large parts of the world. Because these satellites travel relatively close to Earth, they can appear bright when they reflect sunlight, especially shortly after sunset or before sunrise. As the number of satellites increases, more of them may pass through the field of view of ground-based telescopes. Their movement can leave bright streaks across astronomical images, sometimes covering parts of the sky that scientists are trying to study.

These streaks can interfere with research in several ways. Astronomers often need very sensitive images to detect distant or faint objects, and light from passing satellites can obscure the signals they are trying to measure. The problem can be especially serious when researchers observe brief events that cannot simply be recorded again later. If an image is damaged at the wrong moment, valuable information may be lost permanently. As a result, large satellite constellations could reduce opportunities to discover new objects or study rare changes in the universe, even though the satellites themselves provide useful communications services on Earth.

Satellite operators can try to reduce the problem by making spacecraft surfaces less reflective and sharing detailed orbital information with observatories. Astronomers could then adjust observation schedules or telescope directions to avoid some satellite passes. However, these measures have important limitations. It is difficult to make satellites completely invisible from the ground, and reducing brightness may not work equally well under all viewing conditions. Coordination is also complicated because many private companies and national governments operate satellites. Creating and enforcing common international standards for brightness, data sharing, and orbital practices can therefore be difficult, leaving observatories to manage an increasingly crowded sky with only partial protection.