Honolulu-SpaceX said it is committed to working with the astronomy community to solve the brightness problem of its Starlink satellite, but some astronomers still worry that the system and other giant constellations will have a harmful effect on their field. One of the 60 satellites last launched by
Starlink on January 6 has an experimental coating designed to reduce its brightness. SpaceX said it will understand the effects of these coatings in the next few weeks and study their impact on the performance of the satellite itself before deciding how to proceed.
“Our level of brightness and visibility surprised us,” SpaceX Vice President of Government Satellite Affairs Patricia Cooper (Patricia Cooper) said in January. A special session on the influence of giant constellations on astronomy during the 235th session of the 8th American Astronomical Society (AAS). SpaceX President Gwynne Shotwell also said last month that SpaceX was surprised by the brightness of the satellite.
Cooper said that gloss is affected by several issues. Starlink satellites initially look bright when they are launched into a lower parking orbit, and the configuration of each satellite’s large solar array when its orbit is elevated will also affect their brightness. Once in the final orbit of 550 kilometers, the brightness of the spacecraft will be reduced to a visual magnitude of about 5, making them visible only to the naked eye in the darker night sky.
He said one challenge is that the unique design of the satellite makes it difficult to determine what caused the spacecraft to reflect so much light. “It turns out that we believe that surfaces that scatter or reflect light are also important contributors,” he said. This led to surface testing of experimental satellites, dubbed “DarkSat” by some to reduce reflectivity.
Although DarkSat is now in orbit, it will take a while to see its effectiveness. University of Michigan astronomer Patrick Seitzer, who is studying the impact of satellite constellations on optical astronomy, told a subsequent press conference that the satellite might not reach its orbit until the end of February. “Then you can start serious measurements,” he said.
Cooper said that SpaceX will quickly reduce the brightness of its satellites, but did not give a specific timetable or status if other experimental satellites are also in progress. At the same time, the company will continue to launch the originally designed Starlink satellite, which is designed to operate for five years. This plan was criticized by some astronomers at the conference.
“We still don’t know whether these mitigation measures are useful and effective,” he said. “We tend to work very fast. We tend to test, learn, and iterate.
SpaceX has been meeting with an AAS committee to discuss the astronomical community’s concerns about Starlink and to study ways to alleviate these concerns. Jeff Hall, director of the Lowell Observatory and chair of the AAS committee, said that this work is included in this time Six conference calls and a face-to-face meeting during the AAS meeting.
“We don’t have to convince SpaceX in any way. They are very responsive and very proactive,” he said. He said these discussions initially focused on SpaceX’s Starlink implementation plan, but recently, as SpaceX prepares to launch its experimental DarkSat, it’s more about “keeping in touch.”
Hall added that it is too early to discuss regulations regarding satellite brightness. “Wild West regulation is necessary, but it will take a long time to implement,” he said, and the problems caused by Starlink and other constellations are a problem that needs to be solved in the near future. Astronomers like
Hall said that, like SpaceX, they were surprised by the brightness of the Starlink satellite. “What amazes everyone in the astronomical community and SpaceX is how bright their satellites are,” said Cezer. “We know these tens of thousands of giant constellations are coming, but based on the size and shape of the objects currently in orbit, I think they could be the eighth or the ninth. We were not expecting the second or third level. Astronomers
and SpaceX stated that they hope to darken the Starlink satellites as a first step, so that they cannot be seen with the naked eye even in the darkest sky. The next step will be to find out what else can be done. The impact on the main observatories, especially the Villa Rubin Observatory (formerly known as the Great Meteorological Telescope) under construction in Chile. Astronomers say wide-angle telescopes are particularly threatened by Starlink and other giant constellation satellites.
Hall said its AAS committee plans to begin discussions with OneWeb later this month, shortly before the company begins full deployment of its constellation.There are currently six OneWeb demonstration satellites in orbit, which are taller than SpaceX. Seitzer said that these satellites are one-eighth magnitude, too dark to be seen with the naked eye, but in some cases professional astronomers are more concerned than Starlink satellites, because at their altitude, they can be visible all night in summer rather than just just the sunset. and sunrise.
SpaceX is trying to deploy up to 1,500 Starlink satellites in 2020 alone, and OneWeb and other constellations are in development, astronomers warn that this is a major problem for them. “The problem of the giant constellations and astronomy is a serious problem,” said Cezer. “We have little time to deal with this problem.”