Radio telescope faces ‘extremely worrying’ threat from satellite constellations – .

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Radio telescope faces ‘extremely worrying’ threat from satellite constellations – .


WASHINGTON – A multibillion-dollar radio telescope enters its construction phase as it continues to raise funds and deal with satellite mega-stellations whose interference “is a game-changer” to their plans.

Speaking at the annual meeting of the European Astronomical Society on June 29, Philip Diamond, CEO of Square Kilometer Array (SKA), announced that the observatory board has officially approved plans to move on to the construction phase of the radio telescope.

SKA are two separate facilities. SKA-Low in Western Australia will eventually be a network of more than 130,000 antennas performing low frequency observations. SKA-Mid will feature 197 dishes in South Africa for mid-range radio frequencies, including 64 dishes from the existing MeerKAT network there.

The council’s decision allowed the SKA to enter its construction phase on July 1. “We won’t see any excavators on tour on July 1,” he said, but rather requests for proposals to build various aspects of the two facilities. The observatory expects construction to be completed by 2029.

The SKA is designed to support a wide range of astronomical research, from dark energy and pulsar studies to astrobiology. The concept of the SKA dates back three decades, when astronomers first envisioned concepts for a radio telescope that, as the name suggests, would span a square kilometer. These concepts then evolved into the current design with facilities on two continents.

A technological challenge that has also evolved during this period is that of radio interference. “We radio astronomers have been used to dealing with interference from satellites and aircraft systems,” Diamond said at a press briefing on June 29. “What the mega-stellations do is they are a game-changer for us. “

The difference is the large number of satellites, with proposals for potentially tens of thousands of satellites. Many will operate on frequencies that SKA-Mid, which operates between 350 megahertz and 15.3 gigahertz, is tuned to observe. While radio astronomy is a priority for a few bands in this range, satellites will broadcast – legally, he acknowledged – on many others.

Diamond said the SKA was in technical discussions with satellite operators over mitigation measures “that would significantly limit the impact on SKA telescopes.” He did not specify the specific measures.

Speaking at the July 2 conference, Federico Di Vruno, spectrum manager at SKA Observatory, said the observatory has developed “signaling and excision” technologies to identify radio interference from satellites and delete them from the data. “This is a waste of observation time,” he said, but such constellation interference by OneWeb and SpaceX would represent less than four percent of observations.

However, he warned that while the problem is manageable with these constellations, future systems would only make the problem worse. This includes SpaceX’s OneWeb and Starlink expansions, as well as the proposed Chinese constellation of Guowang which could eventually have 13,000 satellites.

“The prospect of constellations of tens of thousands of satellites is extremely worrying for radio astronomy,” he said. Operators, he suggested, could help by agreeing not to broadcast when their satellites pass over “radio silence zones” surrounding the antennas.

SKA faces a separate challenge: raising the funds to build the two facilities. The observatory estimates spending 2 billion euros ($ 2.4 billion) to build and operate the SKA over the next decade. Diamond said the SKA Observatory, a multinational organization, is still working to raise funds in more than a dozen countries.

“We have raised the vast majority of the required funding,” Diamond said, but declined to give a specific number. “Members would not have been willing to move forward with the decision to proceed with the construction if they did not feel comfortable with the necessary funds being provided. “

“We have a few years ahead of us to raise the additional funds we need, which is a very small minority,” he said.

The United States are notably absent from the SKA Observatory. Diamond said American astronomers were involved in the initial planning for the radio telescope and at some point the United States was to provide a third of the funding. However, the SKA did not appear as a priority in the 2010 Decadal Astrophysics Survey, where US astronomers instead selected other ground-based telescopes as more worthy of funding.

“The ten-year survey schedule did not match the SKA schedule,” he said. “The activities of the US SKA were not given a high enough priority, so US funds were – unfortunately, from our point of view – directed to other very deserving projects. “

American astronomers, he added, remain involved in SKA activities, including reviews. “It’s definitely not a divorce,” he said. “This is only a reality of the 2010 ten-year survey.

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