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Radio astronomers claim negative impact from satellite constellations

Put them on the Moon! Radio astronomers have released a paper claiming that the coming large communication satellite constellations, such as Starlink and OneWeb, will seriously impact observations with the Square Kilometer Array (SKA) of radio telescopes being built in the remote western outback of Australia.

Saturation of the instruments: very strong interfering signals can saturate the receiver systems and thereby drown out all other signals seen by the Band 5b receivers. As a consequence, all data in that frequency band would be lost, rendering these receivers useless for a portion of the time. For the first phase of the constellation deployments (about 6,400 satellites in total), saturation is predicted to occur for a few percent of the time assuming there is no direct illumination of the dishes by the satellites. For significantly larger constellation sizes (up to more than 100,000 satellites), saturation would be essentially continuous without significant mitigation measures implemented by the satellite operators.

Based on this conclusion, the astronomers estimate that for observations in this particular band they will need to look about 70% longer to get the same data, thereby cutting the number of observations by about half.

The astronomers propose this solution:

One of these mitigation techniques is for the satellite transmitters not to point their beams near the SKAO dishes. SKAO would require operators to steer their satellites’ beams away from the telescope site, a measure which would require a simple software modification with no repercussion on the constellation’s deployment, positioning or hardware. While a cost-effective implementation of this solution does depend on the hardware and software deployed on the satellites, operators already use this technique to comply with international regulations when their satellites cross the path between geostationary satellites in higher orbit and their receiving ground stations, for example to avoid affecting telecommunications and TV transmissions.

This mitigation could reduce the impact on the SKA by a factor of 10 over that noted previously and result in a 7% increase of integration time for SKA observations within the satellite transmission range 4. While any loss of sensitivity is regrettable, SKAO recognises the need for compromise between the competing scientific and commercial drivers.

The solution seems reasonable, but in truth it is only a temporary one. The permanent and smart solution for the astronomical community is to move their telescopes, in all wavelengths, off the Earth. For radio astronomy the far side of the Moon would be ideal.

And with SpaceX now developing a reusable big rocket, Starship, to put such payloads in orbit at low cost, the astronomers need to start thinking about taking advantage of this engineering. The situation for ground-based astronomer will only get worse.

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On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.

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  • Tom Billings

    “And with SpaceX now developing a reusable big rocket, Starship, to put such payloads in orbit at low cost, the astronomers need to start thinking about taking advantage of this engineering. ”

    From what I have seen in the comment sections at Space News, and other venues, the astronomer community is balking at this for a simple reason. Most of the money they get from space telescopes is *not* in operating the telescopes, but in designing their purpose to fit the needs of academia’s *present* “lines of research”. The high cost of launch started the cycle of increasing cost, but has not perpetuated it.

    Most of the total lifetime system cost is in conceptualization, design, and engineering, which means most of the jobs that get the attention of politicians is in that phase of lifetime cost. Make launch so cheap that you could launch a space telescope every week, and all that you will do is to destroy the majority of those jobs! Why? Because, if the instrument you are designing can fly on any one of the 50 space telescopes being launched this year, then it is no longer a career breaker to not fly on telescope A, because it can go on A’, or B, or B’, or ……..

    Senator Barbara Mikulski, (D) Maryland, worked for 30 years to build and sustain the primacy of the Space Telescope Science Institute at the JHUH campus in Baltimore, specifically because it would employ and channel all of that highly paid work into the Maryland economy. Neither she, nor her successors, are interested in seeing the few telescopes operated by STSI become a few out of hundreds, operated by everyone down to Science High Schools. If they cannot direct the flow of information, then they soon cannot direct the flow of money, and take credit for that money and the jobs it pays for, with voters.

    At the same time, the politics *inside* academia dependent on that money would fall, and smash the money flows, and careers would be broken in the rubble. When space telescope data becomes so cheap that *anyone* can get tasking on *someone’s* telescope, then`STSI, and its political patrons drop in power.

    So, opposition will continue. Ground-based Astronomy has its own separate funding, and has developed its own encrustation of professional telescope planners and builders. They will *not* go away easily, at least as long as they can point to how much money is spent to build space telescopes, before launch.

  • eddie willers

    As I was composing my thoughts, here’s what I was going to post:

    The permanent and smart solution for the astronomical community is to move their telescopes, in all wavelengths, off the Earth. For radio astronomy the far side of the Moon would be ideal.

    But you beat me to it.

  • Patrick Underwood

    Musk’s evil plan: make ground-based telescopes unusable, then charge astronomers to launch space-based telescopes. For the win!

    And yes I am joking.

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