Nokia and NASA’s 4G lunar network will mess up radio astronomy
Network interference
Radio frequency interference (RFI) is the long-term nemesis of radio astronomers. Jodrell Bank – the earliest radio astronomy observatory in the world still in existence – was createdbecause of RFI. Sir Bernard Lovell, one of the pioneers of radio astronomy, found his work at Manchester hampered by RFI from passing trams in the city, and he persuaded the university’s botany department to let him move to their fields in Cheshire for two weeks (he never left).
Since then, radio telescopes have been built more and more remotely in an attempt to avoid RFI, with the upcoming Square Kilometre Array (SKA) telescope being built across remote areas of South Africa and Australia. This helps to cut out many common sources for RFI, including mobile phones andmicrowave ovens. However, ground-based radio telescopes cannot completely avoid space-based sources of RFI such as satellites – or a future lunar telecommunications network.
RFI can be mitigated at the source with appropriate shielding and precision in the emission of signals. Astronomers are constantly developing strategies to cut RFI from their data. But this increasingly relies on the goodwill of private companies to ensure that at least some radio frequencies are protected for astronomy.
A long-term dream of many radio astronomers would be to have a radio telescope on the far side of the Moon. In addition to being shielded from Earth-based signals, it would also be able to observe at the lowest radio frequencies, which on Earth are particularly affected by a part of the atmosphere calledthe ionosphere. Observing at low radio frequencies can help answer fundamental questions about the universe, such as what it was like in the first few moments after the big bang.
The science case has already been recognized with theNetherlands-China Low Frequency Explorer, a telescoperepurposedfrom the Queqiao relay satellite sent to the Moon in the Chang’e 4 mission. Nasa has also funded a project on the feasibility of turning alunar crater into a radio telescopewith a lining of wire mesh.
It’s not just 4G
Despite its interest in these radio projects, Nasa also has its eye for commercial partnerships. Nokia is just one of 14 American companies Nasais working within a new set of partnerships, worth more than US$370m, for the development of itsArtemis program, which aims to return astronauts to the Moon by 2024.
The involvement of private companies in space technology is not new. And therights and wrongshave long been debated. Drawing possibly the most attention has been SpaceX’sStarlink satellites, which caused a stir among astronomers after their first major launch in 2019.
Images quickly began to emerge with trails of Starlink satellites cutting across them –often obscuringor outshining the original astronomical targets.
Astronomers have had to deal with satellites for a long time, but Starlink’s numbers and brightness are unprecedented and their orbits aredifficult to predict. These concerns apply to anyone doing ground-based astronomy, whether they use an optical or a radio telescope.
Arecent analysisof satellite impact on radio astronomy was released by the SKA Organisation, which is developing the next generation of radio telescope technology for the Square Kilometre Array. It calculated that the SKA telescopes would be 70% less sensitive in the radio band that Starlink uses for communications, assuming an eventual number of 6,400 Starlink satellites.
As space becomes more and more commercialized, the sky is filling with an increasing volume of technology. That is why it has never been more important to have regulations protecting astronomy. To help ensure that as we take further steps into space, we’ll still be able to gaze at it from our home on Earth.
This article is republished fromThe ConversationbyEmma Alexander, PhD Candidate in Astrophysics,University of Manchesterunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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