The study, which looks at a total of 18 representative satellite constellations,
The study showed that large telescopes,such as ESO's VLT and the upcoming ELT, two giant telescopes, will be “moderately affected” by satellites currently under development. The effect is more pronounced with long exposures (about 1000 seconds), and there may be up to 3% of violations at dusk: before dawn and sunset. A shorter exposure will be less affected - less than 0.5% of observations of this type. Observations made at other times during the night will also be less affected, since the satellites will be in the shadow of the Earth and therefore will not be lit and interfere with work. Depending on the situation, impacts can be reduced by modifying the operating schedules of ESO telescopes, although these changes are expensive.
The study also shows that the greatestthe impact may be on wide field surveys, particularly those conducted with large telescopes. For example, 30% to 50% of exposures at the US National Science Foundation's Vera K. Rubin Observatory (not an ESO facility) would be "severely affected," depending on the time of year, time of night, and simplifying study assumptions. Softening techniques that can be applied on ESO telescopes will not work for this observatory, although other strategies are being actively studied.
Further research is needed tofully understand the scientific consequences of this loss of observational data and the complexity of their analysis. Wide-angle telescopes, such as the Rubin Observatory, can quickly scan large areas of the sky, making them critical for detecting short-term phenomena, such as supernovae or potentially dangerous asteroids. Because of their unique ability to generate very large data sets and find observational targets for many other observatories, astronomical communities and funding agencies in Europe and elsewhere have rated wide-angle telescopes as a top priority for future developments in astronomy.
Professional and amateur astronomers also expressedconcern over how satellite constellations may affect pristine night sky views. The study shows that about 1600 satellites from the constellations will be located above the horizon of the observatory at mid-latitudes, most of which will be at a low level of the sky - within 30 degrees from the horizon. Above this — that part of the sky where most astronomical observations take place — there will be about 250 constellation satellites at any given time. While they are all illuminated by the Sun at sunset and sunrise, more and more of them fall into the shadow of the Earth closer to the middle of the night. ESO research suggests brightness for all of these satellites. Based on this assumption, about 100 satellites can be bright enough to be visible to the naked eye at dusk, about 10 of which will be higher than 30 degrees. All these numbers are rapidly falling, as the night is getting dark, and satellites fall into the shadow of the Earth. In general, these new satellite constellations will approximately double the number of satellites visible in the night sky with the naked eye above 30 degrees.
These numbers do not include satellite flights,visible immediately after launch. Although they are impressive and vibrant, they are short-lived and visible only shortly after sunset or before sunrise and at any given time only from a very limited area on Earth.
The ESO study uses simplifications andassumptions for obtaining conservative estimates of effects, which in reality may be less than those calculated in the article. More accurate quantification of actual impacts will require more sophisticated modeling. Although the focus is on ESO telescopes, the results are applicable to similar non-ESO telescopes, which also work in the visible and infrared ranges, with similar instruments and scientific research.
Satellite constellations will also affectradio, millimeter and submillimeter observatories, including the Atacama Large Millimeter / Submillimeter Array (ALMA) and the Atacama Pathfinder Experiment (APEX). This effect will be considered in further studies.
ESO, along with other observatories,The International Astronomical Union (IAU), the American Astronomical Society (AAS), the Royal Astronomical Society of Great Britain (RAS) and other societies are taking steps to raise awareness of this issue in global forums such as the United Nations Peaceful Uses Committee (COPUOS) and the European Committee on Radio Astronomy Frequencies (CRAF). This is done by studying practical solutions with space companies that can protect large investments in advanced ground-based astronomical installations.