Washington – Astronomers who were concerned about the impact of SpaceX’s Starlink satellites in their observations last year said they are increasingly concerned about the impact of other proposed giant constellations. 4,444 astronomers were surprised by the impact the Starlink satellite will have after the launch of the first 60 spacecraft in May 2019. Since then, the American Astronomical Society (AAS) committee has been working with the company to discuss ways to mitigate the impact of satellites to be used in astronomy.
SpaceX first responded to these concerns with the experimental “DarkSat” launched in January, which darkened its surface to reduce the amount of sunlight it reflects. SpaceX closely followed the launch of the “VisorSat” at the recent launch of Starlink on June 3, a satellite with a sun visor designed to prevent sunlight from reaching the satellite’s reflective surface.
Although VisorSat’s effectiveness should be measured within a few weeks after the spacecraft reaches its final orbit, the astronomers said they are happy that SpaceX is willing to work with them to solve this problem. “Most importantly, a lot of SpaceX’s resources are dedicated to these technical solutions,” Smith College’s James Lowenthal said in a press conference at the 236th AAS meeting on June 3. However,
SpaceX isn’t the only company with a giant satellite constellation plan. Lowenthal said astronomers have far fewer discussions with other satellite operators. “We had a phone call with OneWeb, but then they went bankrupt,” he said in a speech at a conference on June 2. “We haven’t had important conversations with other operators.”
New proposals to expand their constellation by companies including OneWeb have exacerbated this lack of discussion. Although it filed for Chapter 11 bankruptcy protection in March, OneWeb submitted a plan to the Federal Communications Commission on May 27 to increase the number of its constellation by 48,000 satellites so that it “has greater flexibility to meet the growing Demand for global connectivity”, according to a statement from the company. proposal.
“The situation has gotten worse,” Pat Seitzer of the University of Michigan said at an AAS press conference. He has been studying the impact of Starlink and other satellite constellations on astronomy. In addition to proposing system plans for up to 60,000 satellites, proposals submitted by OneWeb and other companies will add up to 50,000 satellites. “This is a very serious problem.”
OneWeb’s proposal puts its satellites in an orbit of about 1,200 kilometers, much higher than the 550 kilometers of Starlink satellites. He said that at that higher altitude, the satellite will be visible longer after sunset and before sunrise. In a scene from the inspection conditions of the Villa Rubin Observatory under construction in Chile, at least 500 satellites can be seen at any one time during the summer night.
At higher altitudes, the satellites will be too dark to be seen with the naked eye, assuming the new constellation uses a similar design to existing OneWeb satellites. However, Sezer said they are still bright enough to saturate the observatory’s sensitive instruments and interfere with observations.
Other observatories are also concerned about the new constellations. Lowenthal said at the briefing that AAS surveyed 23 observatories around the world to understand the impact of mega-satellite constellations, starting with the impact of the original 1,584 Starlink satellites.
“Most of the responding observatories expressed serious concerns, serious challenges to science, and predicted huge financial costs,” he said. He said the affected research includes wide-field studies where satellites cannot avoid crossing the field of view and time-sensitive observations of transient phenomena.
When asked to assess whether there are 20,000 satellites of different giant constellations in orbit, he said that most people said that almost all observations would be affected. “About half of the people said the facility will have a serious breakdown.”
AAS will hold a webinar in late June to discuss this topic with astronomers and satellite companies. In addition to SpaceX, Lowenthal said that Amazon, which is developing a satellite system called Project Kuiper, also plans to participate.
“Will all these companies become good citizens? We don’t know,” he said of the supporters of the giant constellation, warning that such a system might “close” the blinds in the night sky. “Astronomers are working with SpaceX and other satellite operators we hope to understand and reduce the impact on astronomy and the night sky.”