Washington A multi-billion dollar radio telescope is entering the construction phase, as it continues to work to raise funds and deal with the “groundbreaking” plan for interference from the giant satellite constellation.
In a speech at the annual meeting of the European Astronomical Society on June 29, Philip Diamond, Director General of the Square Kilometer Array Observatory (SKA), announced that the Observatory Council formally approved the plan to enter the construction phase. Radio telescope.

SKA are two independent facilities. SKAlow in Western Australia will eventually become an array of more than 130,000 antennas for low-frequency observation. SKAMid will provide 197 MF radio antennas in South Africa, including 64 antennas from the existing MeerKAT array there.
The decision of the council allowed SKA to enter the construction phase on July 1. “We won’t see shovels on July 1,” he said, but instead asked for suggestions for all aspects of the construction of these two facilities. The observatory is expected to be completed in 2029. The
SKA is designed to support a wide range of astronomical research, from dark energy and pulsar research to astrobiology. The SKA concept can be traced back to three decades ago, when astronomers first considered the concept of a radio telescope. As the name suggests, it would span one square kilometer. These concepts then evolved into the current design with facilities on two continents.

A technical challenge that also emerged during this period was radio frequency interference. “Radio astronomers are used to dealing with interference from satellites and aircraft systems,” Diamond said at a press conference on June 29. “What the giant constellation does is to change our game rules.” The difference of
is that there are many satellites. It is suggested that there may be tens of thousands of satellites. Many will run on the frequency at which SKAMid runs, which runs between 350 MHz and 15.3 GHz and can be adjusted for viewing. Although radio astronomy has priority in certain frequency bands within this range, he acknowledged that satellites will legally transmit in many other frequency bands.
Diamond stated that SKA is in technical discussions with satellite operators on mitigation measures, “this will significantly limit the impact on SKA telescopes.” He did not elaborate on specific measures.
At the July 2nd meeting, Federico Di Vruno, the spectrum manager of the SKA Observatory, said that the observatory has developed a “mark and separate” technology to identify radio frequency interference from satellites and remove it from the data. “This represents a waste of observation time,” he said, but this interference from the OneWeb and SpaceX constellations accounts for less than 4% of observations.

However, he cautioned that even if these problems can be solved by these constellations, future systems will only exacerbate the problems. This includes SpaceX’s OneWeb and Starlink expansion, as well as the proposed China State Grid constellation, which may eventually have 13,000 satellites.
“For radio astronomy, the prospects for tens of thousands of satellite constellations are very worrying,” he said. He suggested that operators can help by agreeing not to transmit when their satellites pass the “radio quiet zone” around the antenna.
SKA faced a different challenge: raising the funds necessary to build these two facilities. The observatory estimates that it will spend 2 billion euros (2.4 billion dollars) over the next ten years to build and operate the SKA. Diamond said that the multinational organization SKA Observatory is still trying to raise funds in more than a dozen countries.
“We have raised the vast majority of the funds needed,” Diamond said, but declined to give specific numbers. “If members are not satisfied with the required flow of funds, they will not be willing to proceed with the construction decision.”

“We still have a few years to raise the additional funds we need. This is a minority,” he said.
It is worth noting that the SKA Observatory is absent from the United States. Diamond said that American astronomers participated in the preliminary planning of the radio telescope, and it was once expected that the United States would provide one-third of the funding. However, in the 10-year astrophysics research in 2010, SKA did not become a priority. American astronomers chose other ground-based telescopes that are more worthy of funding.
“The ten-year survey time is not consistent with the SKA time,” he said. “SKA America’s activities are not given high enough priority, so unfortunately, from our point of view, American funds are used for other very worthwhile projects.” He added that 4,444 American astronomers are still involved in SKA Activities, including reviews. “This is definitely not a divorce,” he said. “This is just a fact from the 2010 10-year survey.

By Peter

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