Rising concerns for radio and space astronomy: Q&A with Harvey Liszt

The Scientific Committee On Frequency Allocations For Radio Astronomy And Space Science (IUCAF), formed in 1960, works in the field of spectrum management on behalf of the passive radio sciences, such as radio astronomy, remote sensing, space research, and meteorological remote sensing. The IUCAF brief is to study and coordinate the requirements for radio frequency allocations established by the afore-mentioned sciences and to make these requirements known to the national and international bodies responsible for frequency allocations.

IUCAF aims to ensure that disruptive emissions by other radio services do not interfere with the above sciences. IUCAF is particularly concerned about radio transmissions from aircraft, space vehicles, and land-based telecom services.

IUCAF has official standing as a nonvoting organization at the International Telecommunication Union (ITU), located in Geneva, Switzerland; it is a sector member of ITU-R.

Having been formed by two ISC members, the International Astronomical Union (IAU) and the International Union of Radio Science (URSI) together with the Committee on Space Research (COSPAR), IUCAF recently celebrated its 60^th anniversary.

We talked to the Committee’s Chair, Harvey Liszt, on IUCAF’s accomplishments, goals and future concerns for the radio sciences.

How does IUCAF operate?

Most of what IUCAF does, as an ITU-R sector member, is speak from the floor of ITU-R when matters of spectrum regulation are debated.

IUCAF’s main focus is radio astronomy but it also has a space science segment. However, space scientists have dedicated space agencies that represent them at the ITU-R, whereas radio astronomy until recently largely only had IUCAF.

IUCAF is also an observer in other international organizations, such as the Space Frequency Coordination Group (SFCG) that is organized by operators in the Earth Exploration Satellite Service at ITU-R, for satellite earth-sensing.

IUCAF basically acts as a high-level umbrella organization that allows radio astronomy to express itself in international fora.

How did you get involved with IUCAF?

In ordinary life I’m a somewhat elderly astronomer — I focus on radio astronomy, and I still publish and do research. I’m employed at the National Radio Astronomy Observatory in Charlottesville, Virginia. Almost 20 years ago, we expanded our engagement with spectrum management and created a position that formalized things that the observatory had long been doing more informally.

The amount of activity in spectrum management was starting to ramp up. I got involved because I had been heavily invested with a decade-long legal case regarding the Green Bank Telescope, in which I was the technical adviser to our lawyer.

A lot has changed in spectrum management since I began – things that happened once a decade are now regular occurrences.

What are some of IUCAF’s key accomplishments?

I think the real material accomplishments of IUCAF recently have been several international agreements that removed interference from various segments of the radio spectrum. For example, there was one agreement signed with Russia’s Global Navigation Satellite System (GLONASS), it was very important as it eventually stopped GLONASS from interfering with a very important radio astronomy band.

IUCAF is also about to sign another agreement with ESA regarding the operation of the 94 GHz EarthCARE cloud profiling radar (CPR). Under this agreement, the radar will not transmit over radio astronomy sites. If it did, radio astronomy receivers and radars could potentially point at each other, and the orbiting radars are powerful enough to instantly burn up the radio astronomy receivers.

In the past we’ve also created protected frequency bands dedicated to science that were initially used in radio astronomy, but are now also used in remote sensing to take global warming and climate change measurements. That includes measurements of soil moisture, ocean salinity and wind speeds.

What are some of IUCAF’S priorities in the coming years?

There’s a lot happening in the commercial use radio spectrums, as the result of maturing technology and the availability of vast amounts of money pouring into radio communications. For example, the US just auctioned the use of 300 Megahertz, at 3.6 Gigahertz. That’s basically 10% of the spectrum, and the auction took in $81 billion.

The systems that are now coming online in radio communications are far more sophisticated, use much more frequency and bandwidth, and consume more spectrum. This is confronting radio astronomy because this technology heavily populates the radio spectrum.

One example of this new technology is 5G. It uses frequencies all over the radio spectrum for all kinds of purposes, and requires high levels of connectivity and broadband with fast speeds.

Another rising issue that concerns radio astronomy is the commercialization of earth-mapping Synthetic Aperture Radars (SARs) that will now go from a handful to a couple of hundred.

It would be very rare for these radars and radio telescopes to point at each other, but if they did the consequences for radio astronomy would be so disastrous that we need to take precautions. This is why we have agreements for the use of some of these radars to make sure they don’t eliminate radio telescopes if they were to point at each other.

When it comes to 5G communications, in the stratosphere or in space, you have to look past the 5G to see the stars and the Universe, so interference from those is much harder to avoid. Radio quiet zones can be utilized so that these things don’t interfere with telescopes from the ground. But 5G now foresees operations on stratosphere platforms that are at 20 kilometres and from satellites.

For example, new mega-constellations from SpaceX and OneWeb are being launched to do broadband wireless communications at radio frequencies. But it turned out that some of these satellites were extremely bright and all of a sudden they were coursing through the heavens and destroying astronomical photography. Because of this, the optical astronomers – for the first time – had to engage with the same satellite constellation problems that the radio astronomers have been dealing with. In regards to this, the designers of the constellations hadn’t given any thought to protecting astronomical work.

Therefore, IUCAF is now helping optical astronomers who are dealing with bright satellite solar reflections, similar to how we’ve been helping radio astronomers for a long time.

You’ve mentioned a lot of activities going on in space. Are there any possible solutions that are being discussed?

On the ground, we’ve created radio quiet zones. The first one of these, the National Radio Quiet Zone in the US, which is around the Green Bank Observatory, was created in 1957. It was formed along with the observatory itself.

Currently, there are no protections from satellite broadcasts in radio quiet zones. The next big initiative for radio astronomy is to achieve international recognition of radio quiet zones to protect the operations that exist within them.

In space, there are coordination agreements with radars and with satellites, but they’re somewhat less general. They only concern limited parts of the spectrum. When creating a radio quiet zone on the ground, you can try to coordinate all of the terrestrial interference at all frequencies, but in space, unlike on the ground, we deal with each particular instance of frequency interruption as it arises and use the currently limited protections that we have.

How does IUCAF work to bring about change?

At ITU-R we participate at all levels below the very highest to influence the content. Since IUCAF has participated for so long, I think there’s a great deal of respect for it, and so our opinions are taken very seriously.

Outside of ITU-R we are attempting to get additional protections implemented through the UN Office of Outer Space Affairs (UNOOSA) Subcommittee on the Peaceful Uses of Outer Space (COPUOS).

We are also influencing change through workshops, and the latest one was held last October. In it IUCAF participated with large groups of astronomers. The workshop was on ‘Dark and Quiet Skies’ — where we considered all the pressures that are being put on optical and radio astronomy. With that, we came up with a set of recommendations that were condensed into inputs for COPUOS, who are set to meet in April to look at broadening the limited protections for astronomy.

These are the sorts of things that concern radio astronomy right now and these are just a few examples of how IUCAF tackles issues of frequency allocation.

Photo by Kevin Quezada on Unsplash