NASA research demonstrates how satellite 'light pollution' disrupts space telescopes

WASHINGTON, Dec 3 The rapid rise in satellites orbiting close to Earth has boosted global telecommunications, offering broadband to remote regions. However, this expansion has led to a significant increase in artificial light in space, threatening observations made by orbiting telescopes.

A new study led by NASA analyzed four space observatoriestwo currently operational and two in developmentand found that a substantial portion of their images over the next decade could be affected by light from satellites sharing low-Earth orbit. Researchers estimate that roughly 40% of images from NASAs Hubble Space Telescope and up to 96% of those from the SPHEREx observatory may experience interference. Planned observatories like ESAs ARRAKIHS and Chinas Xuntian telescope could face similar contamination for nearly all of their observations. Hubbles narrower field of view reduces its exposure.

Orbiting telescopes play a crucial role in exploring the universe, capturing data across the electromagnetic spectrum without the distortion caused by Earths atmosphere. This allows them to produce detailed images of distant galaxies and exoplanets.

Previously, light pollution mainly came from cities and vehicles, but the surge in telecommunications satellites is increasingly affecting astronomical observations worldwide, said NASA Ames astronomer Alejandro Borlaff, lead author of the study published in Nature. Satellites crossing a telescopes view leave bright trails that can erase the faint signals from distant cosmic objects. Space telescopes were once considered largely immune to human-made light pollution, but that is changing.

The number of satellites in low-Earth orbit has jumped from around 2,000 in 2019 to approximately 15,000 today. Industry projections suggest that over 560,000 satellites could occupy these orbits within the next decade. Borlaff noted, In the last four years, more satellites have been launched to low-Earth orbit than in the previous seventy years of spaceflight combined.

The team modeled satellite constellations, including SpaceX Starlink, Chinas Guowang, and Amazons plans, taking into account each telescopes altitude, trajectory, and field of view. Using these simulations, they calculated how often satellites would cross a telescopes line of sight and the brightness of each event.

Satellites affect observations in multiple ways. They reflect sunlight, moonlight, and light from Earth, emit infrared radiation from their components, and reflect radio frequencies from their antennas. These combined sources of light create streaks that can contaminate astronomical images.

One potential solution is to place satellites in lower orbits than the telescopes. Observatories positioned further from Earth, such as NASAs James Webb Space Telescope, ESAs Euclid, and NASAs planned Nancy Grace Roman Space Telescope, are largely protected from this type of interference due to their distant orbits. However, these telescopes operate for specific missions and cover only a small portion of total astronomical observation time.

Author: Zoe Harrison