I live in Balmain, about two kilometres from the centre of Sydney. I have an optical telescope on the roof, but the lights from the metropolis create a fog that covers the night sky, stealing a large portion of its beauty. I can look at some deeper space objects like globular clusters, binary stars and nebulae, but I’ve found it nearly impossible to catch any faint galaxies.
The lights don’t impact what we’re building in my backyard though. We don’t even need the night sky to look into space: we could do it just as well in bright sunlight. In fact, even the Sun is an object on our target list. What we’re really hoping to catch are the giant clouds of hydrogen gas that are the birthplaces of all stars.
And it’s not just my backyard. We have more than 120 astronomy enthusiasts from Perth to Brisbane participating in the SpaceAusScope project. Since early January, teams have been building telescopes, with the aim of observing data from the Milky Way by the middle of the year. Along the way we want to test the construction manuals, refine the materials list and find the most efficient way to produce them, then publish our results with the data we collect.
We hope that by prototyping the process then open sourcing our learnings, trials and achievements, future telescope builders will find it easy enough to pick up the instructions and have a go themselves. We also want the data we collect to be used for science – a community of DIY versions of The Dish, spread across Australia and contributing to the knowledge banks of astronomical data.
Not much space for a kid from the suburbs
Like most people, I recall only a few things from early childhood. Glimpses and flashes, from a time when adults towered over me in what seemed to be a much simpler world. A world that I questioned, to the dread of my parents, armed with a single word: “Why?”
I should thank my Year 1 teacher, Mrs Hamilton, for cementing an idea in my head. In 1986, the year of Halley’s Comet, we made paper comet kites with colourful cellophane tails and learned about space: its vastness, how the Sun was actually a star and of this interplanetary visitor from afar.
Mrs Hamilton told us how lucky we were: “You’ll get to see it twice – once now, and then once when you’re older than me. I won’t be here anymore, but ou’ll get to see it again.”
I never saw Halley’s Comet that year – like most people, we couldn’t afford a telescope and my parents didn’t know the slightest thing about celestial bodies, let alone their movements and coordinates. But I did fly that kite every chance I could, and I imagined what it would be like to look through a telescope and see the tail of a comet whooshing past Earth.
My curiosity in anything space-related was fed with new and exciting events beyond the edge of our atmosphere. A supernova in 1987, Voyager passing Neptune in 1989, an exoplanet confirmed in 1992, Shoemaker-Levy 9 crashing into Jupiter in 1994, Galileo spacecraft arriving at Jupiter in 1995, Cassini spacecraft leaving Earth in 1997.
But other than the news, there wasn’t much space in Australia for a kid growing up in the outer suburbs.
Space was for the elite. From my perspective, space was open only to those who were special enough to be hand-selected to work where all the geniuses were. There were those who put a human on the Moon – and those who did not.
We want to make space open for everyone
Our backyard telescopes will try to observe the radio signature of sunspots, and even look through the galaxy for the ancient remnants of violent supernova explosions. But we’re mostly hunting for something very particular: 21-centimetre- wavelength radio waves.
Radio telescopes collect photons from astronomical objects, phenomena and events that fall within the radio wavelength portion of the electromagnetic spectrum. These waves are much longer than visible light; its waves measure between 400 and 700 nanometres. (In comparison, a red blood cell is about 8000 nanometres long.) Radio waves can measure anywhere between one centimetre and 100,000 kilometres – about a quarter of the distance from the Earth to the Moon.
All matter in the Universe that isn’t dark matter emits electromagnetic radiation based on its temperature, with higher wavelengths corresponding to higher temperatures. A large portion of electromagnetic radiation can’t penetrate Earth’s atmosphere – with great benefit to all life here. For example, the ozone layer protects the surface from dangerous UV and other high-energy radiation that comes from the Sun. This protective layer has allowed life here the opportunity to flourish and evolve across the ages.
However, this protection also limits our ability to access data about these wavelengths from the ground, so some telescopes need to be built on mountains or even sent into orbit.
Visible light makes it through to the surface – that’s the range of frequencies we can see. Infrared light also makes it through – it’s how we feel the heat from the Sun, which drives the mechanisms that warm our atmosphere. And some UV light comes through, which is what gives us sunburn. Lastly, radio waves make it to the surface (some microwaves do as well).
Our DIY telescopes focus on that 21cm wavelength, generated in space by a peculiar process that occurs on the subatomic scale, from the most abundant element in the Universe.
Hydrogen makes up most of what’s around us: oceans, the human body, stars and gas. It exists in large quantities across the Universe, forming part of the interstellar medium and giant reserves, some hundreds of light-years long, with the mass of tens of thousands of suns.
At a subatomic scale, hydrogen is fairly simple. It features a central nucleus made from a proton, which carries a positive charge, and an orbiting electron, which carries a negative charge. (There are isotopes of hydrogen that also feature neutrons in the nucleus.)
Both the proton and the electron have a spin axis. Imagine a pole running through both particles with an imaginary north and south. Normally, the proton’s axis points upwards (so its north is going up) and the electron’s axis is pointing down (its north points downwards). This is when the hydrogen atom is in its most relaxed state (known as F = 0).
Sometimes, though, through collisions with other particles, the electron gains a little bit of energy that spins its axis to be facing the same direction as the proton (both particles have north pointing upwards).
The hydrogen atom is now in an excited state (known as F = 1).
After remaining in this excited state for about 10 million years, the electron spontaneously spins back to its relaxed state, and when it does this it releases the amount of energy it originally absorbed as a single photon. This photon, with a wavelength of 21cm (its frequency is 1.420 GHz), is now unbound to travel across the Universe.
A single photon is a very small package of energy, and given it takes 10 million years to release, we’d expect this to be a rare observance. However, there is so much neutral hydrogen in those galactic reserves and clouds that this cycle occurs in volumes large enough for strong detection at all times.
But why are we interested in neutral hydrogen?
As we point telescopes to the sky, we are often looking at different regions of the Milky Way. Most of the material that makes up our galaxy resides in the galactic plane – the disc-like structure that we see edge on. Our Solar System exists in one of the Milky Way’s spiral arms, about two-thirds of the way out from the galactic centre. So when we look into the centre, we are looking at one arm of the galaxy wrapping around in front of us and – in the opposite direction – one wrapping around behind us.
In both directions, we should be able to see 1.420 GHz, but neutral hydrogen gas is star-making material, and from what we know about our galaxy there is a higher concentration of older stars closer to the centre that have been born from this hydrogen gas, consuming a lot of it in the process. So when you look away from the centre, there is more hydrogen left – and we see these regions associated with a high proportion of star birth.
We can also look across the galaxy (side view), which also is looking into the disc – but across the spiral arm structures of the Milky Way.
We can also do something interesting with this view. The Solar System is moving with respect to the Milky Way, and the galaxy itself is rotating, which means that some parts of the spiral arms will be moving towards us, while others are moving away. We can measure this movement as a small shift away from the central 1.420 GHz line in our data (known as Doppler Shift) by observing the central peak of our plots slightly before or slightly after the normal 1.420 GHz line. This shows that the region we are measuring is moving towards or away from us, and we can use this shift to calculate the maximum velocity of this movement.
Lastly, if we look above and below the galactic disc, we should see a reduction in the 1.420 GHz signal, which tells us that the Milky Way is in fact a disc galaxy, as opposed to an elliptical or irregular- shaped galaxy. Our telescopes will be pointing into open space and they’ll pick up the wavelength, but it won’t peak as high as when we are looking within the Milky Way disc.
It’s great to be part of something bigger
The SpaceAusScope project started as a joke with my friend Eric late last November. We were setting up the optical telescope and laughing about building an observatory on my rooftop.
As we trawled through a couple of web pages set up by other amateurs with the same idea, we realised that the joke might be possible. Week 1, we’d do the research. Week 2, we’d buy the materials. Week 3, we’d commence our building, and so on. We realised that while there were instructions available on how to build the telescope and mount, there wasn’t a single source that covered the process end-to-end, so we decided to document our project.
In our excitement, I posted our plans on Twitter and asked if anyone across Australia wanted to join in. A few individuals put their hands up, then a few more. By the end of the first week of December we had 11 teams, and this number grew steadily. By the end of the year we had 35, put together by families, friends, schools, and volunteer groups.
And such was their enthusiasm and excitement, we decided the project was no longer just about building a DIY telescope; it was equally about fostering an amateur radio astronomy community.
Each team has had a different experience, depending on what telescope they’re building and how they operate. Our mob – Team Orion – decided we’d build four different telescopes to test different ideas and objectives. It’s easy to head to the local Bunnings and pick up materials, but not everyone has one in their town. We wanted to ensure that a telescope could be built anywhere.
For the first Team Orion telescope, we wanted to test how much signal a smaller feed horn would receive, so we made it from cardboard trapezium- pieces cut using a 30cm ruler, covered in aluminium foil. That short-gain prototype proved useful for our next effort, where we went bigger, using thicker cardboard and more aluminium foil for an feed horn 102cm high. Suddenly we met complexities such as how to mount it, how to shield it from the EM signal generated by our laptops, and how to dampen vibrations across the larger surface area introduced by even the slightest breeze.
Our third feed horn – made of plywood and covered in the aluminium insulation (called sarking) commonly used inside roofs – is bigger (122cm), bulkier and more expensive. For our wave guide, we used an empty 3l olive oil can, which turns out to have the perfect dimensions to collect the 21cm radio wave from space.
Our final feed horn, custom-designed from sheetmetal, will be the Rolls Royce of backyard radio telescopes. The third telescope taught us another thing to think about: doors. Building to any size was possible, but we ran into trouble moving it outside – and so our metal feed horn will be the same size as version three.
Peter Frankland is a one-person team in Queensland. He works at the Sir Thomas Brisbane Planetarium and has been fascinated by space his entire life; his grandmother reckons his first word was “moon”.
Peter’s scope is also a horn antenna, using a repurposed tin can for the wave guide. Building the horn and wave guide were fairly straightforward, but as for many of us in this project, the complexities began to rise with the introduction of the electronic components.
“I’m now a bit stuck with the copper antenna,” says Frankland. “The scientist in me wants to make sure that I get it right.”
Other teams have overcome these frustrations and are already listening to space. The Space GW Worm team – a family of four adults and three kids based in Glen Waverley, Victoria – contributed to the build that has utilised lightweight corflute sheeting from the garage and an abundance of aluminium foil.
The Worms include Sam and Josephine, aged 8 and 10. “Building the horn antenna was lots of fun, especially when we first saw the signal coming through,” says Sam. “It was really cool that we could learn about space using radio wave signals.” Personally, I hope he and Josephine grow up to become radio astronomers working on projects like the Square Kilometre Array.
Much to her surprise (and indeed ours), their teammate Elina adds that getting into a community science project is rather easy. “It’s not that hard to be an amateur space enthusiast,” she says. “The parts are easily available and there are lots of people willing to help, guide and pitch in.”
At the John Therry Catholic College in Wollongong, NSW, the project took on an extra organisational dimension. Year 11 students, supervised by their teacher Aidan Johnson, were split into two teams and assigned specific roles, such as software managers, hardware assembly officers and data managers. And they worked furiously until COVID-19 interrupted schools nationwide. “We are still in the early stages,” Johnson tells me, “but it is great to be part of something bigger. The students love that this is not just a school project, and they want to show that they can contribute to real science.”
The teams have been reading up on radio waves to work out the best horn antenna dimensions, he says, and are “continuing to develop their design and start on the software side of things until the isolation is over”.
Not all teams are building horn-antenna style telescopes. The Space Cadets – a loose-knit group of amateur radio operators that form the Manly Warringah Radio Society – have repurposed an old satellite dish for the antenna of one telescope, while another is taking on a more helical antenna design, created using a PVC pipe.
Geoff – one of those building the helical antenna – is certain about what he wants: “Confirmation of extra-terrestrial intelligence,” he jokes, “or at least the knowledge that free hydrogen in the Milky Way isn’t going to annihilate us any time soon.”
“I’d never considered being able to pick up radio waves from the Milky Way,” he adds; this project has allowed him to understand how radio telescopes work and what sort of information astronomers look for.
Much to her surprise, Elina has discovered “it’s not that hard to be an amateur space enthusiast”.
The scope using an up-cycled 1.5-metre satellite dish is decidedly more high-tech, with Space Cadet Clifford custom designing the wave guide and choke. Most of the horn antennas are going to face directly up and allow the rotation of the Earth to sweep the beam across the Milky Way; Clifford, however, w be able to point the team’s dish at different parts of the sky to determine what different locations reveal about the hydrogen gas in that region.
We built a community
What started as a fun, backyard DIY idea has bloomed into a real space community, where problems and ideas are shared in the hope of learning more and becoming part of a bigger picture of the Australian space story. None of us has all the answers, but all of us are willing to learn and add value along the way.
Australia has a rich history in radio astronomy. Some of the world’s first radio astronomers were Australian, the result of the boom in radar technology following World War II.
Legends such as Ruby Payne-Scott, widely regarded as the world’s first female radio astronomer, advanced the field by working on projects such as mapping radio bursts from the Sun’s surface, using an interferometer that sat on the coastal cliffs in Sydney’s east.
Australia has world-class radio astronomy institutions such as CSIRO, which manages some of the best (and most iconic) telescopes in the world, including the Parkes Radio Telescope and the Australian Square Kilometre Array Pathfinder. We’re even soaring ahead with construction of the world’s biggest science instrument – the Square Kilometre Array, which when completed will stretch across two continents.
Now we’re building a grassroots base to filter into that community.
When we started this project, we didn’t realise we would tap into something bigger than just our own nerdy desire. Personally, one of the greatest experiences in running this project has been seeing people from across the country become inspired to learn about radio astronomy and science.
In the early 1990s, using engineering instrumentation, CSIRO radio astronomers were looking for the tell-tale signatures of tiny black holes when they stumbled across the ability to transmit signals between devices. Today, we call this technology Wi-Fi. It’s a beautiful example of a niche project yielding outcomes that provide benefits to a far larger audience – benefits that are unknown until we start exploring.
While radio astronomy is the scientific goal of SpaceAusScope, we don’t expect it to be the end goal for all DIY telescope builders. It’s a space-based project that allows participants to build, solve problems and then collect and use real scientific data, which hopefully opens up a future in any field they choose to enter. But we also want to inspire young people to continue to follow education and career paths into radio astronomy, seeding future generations of the field here and in the global community.
Geoff is certain about what he wants his telescope to do: “Confirmation of extra-terrestrial intelligence”.
It took almost 30 years for me to return to my childhood passion of studying and working in astronomy. These days, Australia has a rapidly growing space industry – including our own space agency. Across the country we’re building rockets and launch facilities, as well as CubeSats to help us better manage natural disasters through Earth observation, while integrating space technology in nearly everything we do, from agriculture to banking.
Amateur astrophotographers, backyard astronomers and space-artists are all helping to expand data sets across our vast continent, supporting research facilities in tracking space objects and events.
It’s my hope that the SpaceAusScope project gets young people building their own telescopes for years to come. I hope that when young children tell their parents they want to be an astronaut that there’s an accessible career pathway in front of them. I hope that the space community in Australia continues to grow.
I also hope my Year 1 teacher, Mrs Hamilton, was right. In 2061, Halley’s Comet will return. I’ll be 81 then, having spent half of my life doing exactly what I wanted to do – being a part of the space community. I look forward to gazing into the night sky, this time with the knowledge and experience to address that question I asked when I was six years old: “Why?”
But this time I hope we’re all amongst the stars..
Rami Mandow is completing his Masters of Astronomy with Swinburne University and is the Founding Director of SpaceAustralia.com
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