How do Starlink and OneWeb satellite swarms affect astronomical observation in Chile?  |  Digital support The boreal fox

The project of an astronomer from the University of Atacama aims to discover how these mini-satellites make it difficult to study the universe through telescopes located in this region of the world.

You’ve probably seen trains of glowing objects in the night sky. Today we know that these are satellites, because a few years ago the media reported that different projects were trying to light up remote sectors with the Internet, through a satellite connection, some of these initiatives are become better known, such as Starlink, Amazon and OneWeb, among others, and to achieve their objective they must have global coverage, which implies having thousands of satellites in orbit around the planet.

About this phenomenon, the prestigious journal Nature recently published a report entitled: “Unsustainable”: how satellite swarms pose a growing threat to astronomy. SpaceX and other companies are still struggling to make their satellites darker in the night sky; which cited research referring to “a preliminary survey of 50 OneWeb satellites in 2021 found that nearly half of them (low-orbiting satellites) were slightly brighter than the ‘safe’ limit specified by astronomers”, says Jeremy Tregloan-Reed, an astronomer at the University of Atacama in Copiapó, Chile”.

The astronomer explains that the mega-constellations of Low Earth Orbit (LEO) satellites are designed to provide high-speed, low-latency internet access to people in remote areas where, due to their high cost, the installation of cables is prohibited. broadband fiber. Being in low orbit, they can provide faster Internet than previous satellite Internet services, but due to their low orbits, thousands or even tens of thousands of satellites (instead of 10 or 100) are required to provide a maximum coverage on the Earth’s surface, which is why we call them mega-constellations. Therefore, by the end of the decade, there will be potentially 100,000 satellites in LEO, all visible to the naked eye.

Indeed, Dr. Tregloan-Reed, currently directs one of the two Fondecyt projects carried out by researchers from the Institute of Astronomy and Planetary Sciences (INCT) of the UDA, and this one seeks to answer to the questions: What will be the impact of the LEOsat mega constellations in professional observatories in Chile? In this context, the objectives of the project have been developed around the recommendations of the AAS/NSF SATCON 1 and IAU/UNOOSA Dark & ​​Quiet skies reports, to produce relevant results and tools oriented to the processing of astronomical data that allow the mitigation of the impact of mega-constellations of communication satellites in low orbit”.

Regarding the work cited in the journal Nature, the UDA researcher commented that it refers to “a small subset of my Fondecyt project; that of making ground-based optical observations of megaconstellations’ satellites (e.g., Starlink, Oneweb, Amazon, and others) to create models based on reflective luminosity data from them for a range of distances, angles phase reflectors and orientations of the satellites. With the data collected, we hope to begin to understand the impact of mega-constellations on astronomical observatories here in Chile and the quality of the night sky.”

The research takes 2021 data from OneWeb satellites with ESO’s Danish 1.54m Telescope in La Silla, Chile – one of the places that enjoys the darkest nights on Earth. In this regard, Dr Tregloan-Reed commented that “preliminary results indicate that just over half of the OneWeb satellites are in the safe zone (weaker than magnitude 7.9 for an orbital height of 1,200 km), while just under half are too bright, making it impossible to remove them from images obtained with the latest sensitive camera detectors, such as those installed on the new Charles Simonyi Telescope at the Vera Observatory. C. Rubin in Chile.

Some studies have been done in this regard using the information available at the time. In any case, the most affected instruments/telescopes are those with long exposure that use ultra wide field cameras.

“Currently, the most affected telescope in Chile is the new Charles Simonyi Telescope at the Vera C. Rubin Observatory. Based on a study of the first generation of Starlink satellites, it has been predicted that at least 30% of all images obtained at astronomical twilight (first and last hour and a half of each night) would have at least some footage of the satellite.However, with newer Starlink satellites, which use some type of reflective glare reduction design ( i.e. visors or obscuring material), the brightness of satellite trails will be reduced, making it easier to remove them in image processing, although this will require the observatory to devote time, resources and staff to develop the hardware/software to achieve this,” acknowledges the astronomer who was a NASA Postdoctoral Program (NPP) Fellow at the Ames Center in California, USA.

Jeremy Tregloan-Reed argued that: “The exact financial cost – of the adjustments needed to correct the records captured by the observatories – is not known at this time, because many of the new mega-constellations, which have the approval from the Federal Communications Commission (USA) or the International Telecommunication Union, have not yet been published My Fondecyt project is to obtain data from these new satellites (as they are launched) to help researchers to determine the true impact on the quality of our dark skies, and the future financial cost,” said the doctor of astrophysics from Keele University in Britain.

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