Sunday, November 22, 2020

A space junk bestiary: yo-yo de-spin weights

Among the oldest pieces of space junk in Earth orbit are de-spin weights from the US series of TIROS weather and TV satellites. I've been noticing them in debris catalogues for years, and decided it was time to find out what they were really all about.  

TIROS 1 was launched in 1960 - just three years after Sputnik 1. The satellite is now 60 years old! TIROS stands for Television Infrared Observation Satellite Program. One aim of the satellite was to see if Earth observation from space would work, and could be used for weather reporting and prediction. The other was to test television broadcast potential - so you can see that it is one of the progenitors of two very significant satellite-based industries today.

The satellite was a cylindrical drum covered in solar panels with short, angled antennas. It returned one of the earliest pictures of Earth from outside.

Image courtesy of NASA

There were 10 satellites in the first TIROS series, after which they continued as TIROS-N in collaboration with the US National Oceanic and Atmospheric Administration (NOAA). Of these 10, five are still in Low Earth Orbit as pieces of space junk.

So what about these de-spin weights?

When rockets are launched, a key consideration is keeping them stabilised so that they don't pitch, roll or yaw, and end up in a crater in the ground instead of in orbit. One way to stabilise them is to spin them perpendicular to their long axis. This method of stabilisation was frequently used for the launch of small, lightweight spacecraft (Cornille 1962:1). The problem with that is when the satellite is released, it has the same spin as the rocket, which is generally too high for it to function. So you have to reduce the spin and reset the satellite. This is what the de-spin weights are for. There might be one or two weights. Two weights are called yo-yo weights, and one is just a yo-weight. 

Fortunately, I did not have to figure this out all by myself, as the Practical Engineer has done a pretty great job of explaining the principles, as you will see in the video.

This is a description of the mechanism from Fedor (1961:1):

The yo-yo de-spin mechanism is essentially two pieces of wire with weights on the ends ...  These wires are symmetrically wrapped around the equator of the satellite and the weights are secured by a release mechanism. At a pre-selected time after satellite spin-up and release from the launching vehicle, the weights are released, thus discarding enough momentum to reduce the spin of the satellite to the desired value.

The weights are not only released, but discarded as mission-related debris. This kind of discard is now discouraged in guidelines for mitigating space debris. 

Something I wonder about is whether the weights still in orbit belong to the TIROS satellites remaining in orbit, or whether they belong to a re-entered TIROS? Did the de-spin weight tend to re-enter with corresponding satellite? Is the orbit an indicator? 

So many questions! Did the USSR use this mechanism for satellite stabilisation? There are certainly no USSR de-spin weights catalogue from this period that I could find.

And what did they look like? Those illustrated in Fedor (1961) look (from the grainy image) to be rectangular, maybe about an inch long. Fedor (1961) also uses a unit of measurement called the slug-ft/2 and I don't even know what it is. OK, I looked it up and this is what it is.

Where else can we find de-spin weights? The Explorer series used them. Here is a marvellous illustration of them working on Explorer 11, launched in 1961 (from Cornille 1962).

This is a de-spin weight from 1962 British satellite Ariel 1. Note that this one doesn't have a rigid cord, but a tightly coiled spring (also from Cornille 1962). The 'stretch' yo-yo design was patented by Cornille and Fedor in 1970. This example has, to my mind, a rather sinister snake-like aura as if it might suddenly spring to life and start seeking you out with its eyeless head and whipping tail.


The Dawn mission to Vesta and Ceres, launched in 2007, used de-spin weights, as the launch rocket's 3rd stage was spin-stabilised. I wanted to know where the weights ended up. Fortunately my friend Ady James knew where to look for them and located this blog post by Dawn Mission Director and Chief Engineer Marc Rayman for me:

After the third stage has finished firing, it remains securely attached to Dawn for another 4 minutes 50 seconds. Although the stage is stabilized by spinning, the spacecraft does not operate that way; yet by this time, they would be spinning together at 46 rpm, too fast for the latter’s control system. Therefore, starting 5 seconds before separation, the third stage activates a surprisingly simple system to slow its rotation rate. Wrapped around the Delta are two cables, each 12.15 meters (39 feet 10 inches) long. At the end of each is a 1.44-kilogram (3-pound-3-ounce) weight made of aluminum and tungsten. When the cables are released, the spin causes them to unwind. As they carry the weights farther and farther out, the spin slows down because of the same principle that makes an ice skater spin faster by pulling her arms in or slower by extending them to her sides. After 4 seconds, when they are fully unwound, the cables unhook from the spacecraft. With their weights still attached, they enter independent orbits around the Sun; perhaps one of them will be studied by a future solar system archeologist.

Well there you go, he was right as that's exactly what I'm doing! This post adds some interesting details. The weight is let go by releasing the cable, so the cable is still attached to it. I wonder if it remains taut after release? The cables are 12 metres, more than the length of two tall women end-to-end. No information about the shape of the weights, but we do have materials - aluminium and tungsten. Why tungsten, a metal in short supply on Earth? There is no need to make these weights durable as their only purpose is to be heavy. Perhaps tungsten adds the required weight for size. How does this alloy react to space weather, plasmas and bombardment? Is it contributing aluminium particles to the space environment? Could they combine with the atomic elements so common in the space environment to form new compounds? Al2O3 (aluminium oxide) or tungsten oxides?

The weights would, one presumes, behave like a meteorite as they are solid. And more like a metal-rich meteorite too. Would they be distinguishable through a telescope or by spectroscopy?

So many questions.

How many of these weights are circulating among all the space junk? Jonathan McDowell's catalogue of space objects has 286 de-spin weights listed. How many of these are still in orbit is something I'll have to leave for a future calculation.

What about the damage a collision with a de-spin weight would cause? These are dense, heavy, solid objects, and I'm going to guess for that reason would be far more destructive than something of a similar size, cross-sectional area or velocity, but made of different materials. It should also be possible to model how an impact crater from collision with one of them might differ from other pieces of space junk. This would help identify liability for the damage, as the launching state is responsible for this under UN treaties.

Comparatively, there are not that many de-spin weights, compared say to rocket bodies, but perhaps the greater damage they can do would merit being selectively targeted for active debris removal. 

As Fedor and Cornille are rapidly becoming my yo-yo gurus, I thought I should learn a little more about them. Sadly Henry Cornille died in 2019 at the age of 80. He went on to work on the Apollo programme. I couldn't find anything about Fedor online so this clearly requires deeper archival research. If you think about it, they are the pioneers of today's space tether technology.

I've got another loose end to tie up here - the relation to the popular children's toy called the yo-yo. I realise I don't know anything about its origins. *goes and looks up* Well, this was an eye-opener, as my assumptions that it was 1960s invention turn out to be extremely wrong! The yo-yo is very ancient technology, originating in China (as indeed does rocket technology). 

This is a fetching red figure vase showing a boy playing with a yo-yo in the 5th century BCE, from the Antikensammlung museum in Berlin.

The yo-yo despin weights are a lovely thread linking physics from the past to the future. I've become quite captivated by them.


Cornille, Henry J.Jnr 1962 A method of accurately reducing the spin rate of a rotating spacecraft. NASA Technical Note D-1420 

Fedor, JV 1961 Theory and design curves for a  yo-yo de-spin mechanism for satellites. NASA Technical Note D-708

Wednesday, July 01, 2020

Ten more ways to get involved in space without leaving Earth

This post follows on from Ten Ways to Get Involved in Space Without Leaving Earth. When I started to put this list together, it turned out there were SO many more things you could do from the safety of terrestrial gravity and atmosphere! Some of these are also very compatible with Covid-19 isolation. So here are the next ten for your delight and edification.

11. Contemplate the Moon
Could anything be more simple than this? There is even a special night for it! International Observe the Moon Night is on September 26 every year. But you can do this one any time of year, any time of day or night. Just look up. Perhaps there will be a white crescent against a blue sky; perhaps a full disc glowing in the night. Just look, and think or feel whatever you want.

12. Experience weightlessness
Ever wanted to know what it was like to be freefall, without having to pay a cool 65 million dollars to go the International Space Station, or even $5000 to go on the Vomit Comet? Hell, you could even do it without any vomit at all! All you have to do is locate your nearest amusement park and find the drop tower. Dreamworld in Queensland has one that's 119 m tall and gives you 5 seconds of freefall. That may not seem like much reading it on a page, but believe me, you will really feel it! The tallest drop tower is the Lex Luthor Drop of Doom in the Six Flags Magic Mountain park in California (120 m).

13. Visit another world through words.
To be transported to another world, all you need to do is read. There are some wonderful books which make you feel immersed in the environments of another planet. One of my favourites is CS Lewis' Voyage to Venus. Sure, it's based on outdated science (Venus is a warm waterworld in this novel), but it truly makes you feel the sensory experience of skies, waters, plants that are alien and yet speak to some deep human dream.

It would be great to put together an anthology of space environmental writing - passages or short stories which really evoke otherworldly places. Science fiction readers will no doubt have plenty of their own favourite examples, but others might appreciate some pointers. It's not like I need more projects at the moment, but oh this one would be so much fun to do!

14. Watch space films
So much choice here! Settle down with an action adventure, a thriller, a documentary, a romantic comedy. OK, so there don't seem to be many romantic comedies set in space, but did you know, for example, that Notting Hill features scenes on board a space station? And soon, it seems we might have a new one actually filmed in space. NASA has confirmed that it's working with Tom Cruise to make a movie on the International Space Station.

Some of my favourite space films are Christopher Riley's First Orbit, the classic 2001: A Space Odyssey, the space mining drama Moon [NB this link has spoilers], and First Man, which I reviewed here.
Aelita, Queen of Mars (1924)

Then there are the vintage classics, many of which you can watch on YouTube. My picks are Forbidden Planet, Aelita Queen of Mars, Frau im Mond, Cat Women of the Moon, and Plan 9 from Outer Space. Night of the Living Dead, the original zombie apocalypse film, involves both space (the origin of the zombie plague) and contagion, so it's very appropriate isolation viewing. It holds up much better than you might imagine.

It's always good to have a laugh about the cheesy plots and clunky pre-CGI special effects, not to mention the notions of what the future was going to be like; but many of these vintage films are also quite insightful and raise issues which are very relevant to contemporary issues in space travel and ethics.

15. Best of the best of space on You Tube
One of the best things on Space YouTube is actual live astronauts demonstrating how things work in microgravity. US astronaut Don Pettit was fantastic. He made a series of videos demonstrating how to do basic tasks in microgravity, which you can watch here. Chris Hadfield has also made a number of excellent videos - of course, one of his most popular was playing David Bowie's Space Oddity on his guitar, which became an instant cult classic! You could start with these astronauts, but there is a wealth of material on YouTube and NASA's channel to delight in.

16. Social media space
Getting involved in space is as simple as finding some topic, organisation or person you like, and following them on Twitter, Instagram, LinkedIn, Facebook, or whatever platform works for you. As well as getting to know the community, you can talk to people, ask questions, or contribute your own thoughts. I've met many lovely people through these encounters! I'm not going to recommend anything here as there is so much, and you will do better to look for the thing that interests you the most.

Why not start your own social media account, or even blog, devoted to the space things you like best? You don't have to be an expert (although it helps not to spread misinformation - please fact check carefully!). And remember it doesn't have to be about hard core science or engineering: perhaps you like space poetry (I know I do), or vintage space-age teacups (another of my favourites). Sharing things you love with other people who love them too is one of the most enjoyable aspects of social media.

17. Support a crowd-funded project
Amateurs have been the mainstay of space since the rocket societies of the 1930s, and have been launching and tracking their own satellites since the 1960s. I'm a huge fan of citizen or community science. We don't have to leave space to the big boys (I say that deliberately). You might not have space or rocket expertise yourself, but you can support those who do and feel part of a project. Of course, it's best to be prepared for disappointment - your chosen project may not make it into space or even get off the ground. For me, it's the participation that is the important thing.

Here's a lists of space projects currently listed on Kickstarter:

Perhaps you have a space project that you would like to resource using crowd-funding! This might be a good place to start:

18. Invite someone to give a talk to your group
In the Covid-19 era, in-person talks have been replaced by Zoom events. These are great as they allow for remote participation, even people from other countries! They reduce costs and allow people who are not able to easily move about or leave the house the opportunity to participate.

Be conscious that people are often asked to give enormous amounts of their time for free, so it's best to have a budget for a speaker - even if the talk is online. Academics and space professionals are often expected to do some public outreach as part of their job, so this is far more critical for freelancers, those without a full-time job, or those for whom public outreach is not part of their job. I'm not saying don't ask if you don't have a budget, just be aware.

19. Attend a conference
Although conferences are usually academic or industry events, if you are able to pay the registration fee there is no reason you can't attend a space conference. You can hear all the talks, meet the people, and feel part of a community. In Australia, the annual space conference is the Australian Space Research Conference, usually held in September-October.

SpaceUps are wonderful 'unconferences' which you can find all over the world. The unconference format is driven by the participants: when you arrive there is usually a big board or wall where people offer talks or workshops, or ask for talks or workshops they would like. It all happens organically on the day. Usually there will be a couple of invited speakers as well.

Of course, the Covid-19 world has meant that many conferences are being run entirely online. This radically reduces the cost of travel and accommodation and all those other incidentals you incur if a conference is not in your home town. Participation has never been easier! The down side is that you don't get to meet and know people in the same way and you need a good internet connection which not everyone has.

20. Download a space app
Space is only as far away as your smartphone or device! There are so many good things out there. Here are a few that I fancy.
What you see with Stellarium

Stellarium: point your phone at the sky, and this app will tell you all the constellations, stars, planets and space stations that are in the sky above you!

Fireballs in the Sky: this is a community science that allows you to contribute your sightings of meteors, fireballs and space junk to a scientific project.

Deluxe Moon: all things Moon including gardening advice. It's got astrology information too, if that is your bag.

Want to photograph the Moon or other night sky features? These apps will help!

So there you have it. No excuses to languish on Earth when there are so many ways to leave the planet without a rocket!

Saturday, April 25, 2020

Dr Space Junk's Pan-Galactic Birthday Party

This is an exercise I created to allow my friends to join me online (through Twitter) to celebrate my recent birthday, as the Covid-19 virus has stopped all physical parties across the world. It was such fun I thought it was worth preserving!  Here it is in nine tweets.

You might need a pen and paper for this. We are going to create a pan-galactic party. I'm going to stay here on Earth for the moment, but you, my Twitter friends, are going to join me from elsewhere in the cosmos. 
And where might this elsewhere be? I will show you how to find out. Please take a moment to get a beverage of your choice (I'm going for some more sparkles) and instructions will follow. 
Step 1. Using this random planet generator, find out which planet you are currently tweeting from. It might not be your home planet, just where you are right now. Save it or write it down! 
Does everyone have their planet now? Step 2. Because you are a super-galactic traveller, you also need your own starship. It will have a witty and satirical name. Of course, it's a Culture ship! Here's how to find your starship's name.  
Step 3. An intrepid astronaut like you doesn't have a regular name, you have a special name befitting your status. This is how you get your astronaut name. Choose from the list
Step 4. Everywhere you travel in this crazy cosmos of ours, you are accompanied by your favourite pet. What species? You decide! But choose it's name from here.  
OK so now you have a planet, a ship, a special astronaut name, and your faithful pet. Step 5. Go to the kitchen and pick a random object. Just whatever speaks to you.  
Step 6. Pretend your random kitchen object is something from your ship, or the planet, or from your last stop. Describe what it does and what it's for. It could be anything. 
Final step! Take a picture of your space (kitchen) object. Tell me your planet, ship, astronaut and pet names, and what your object is for. I can't wait to hear the results!
To give you an idea of how it works, here is one I made earlier. I'm at the planet Rada (see below), not a very hospitable place, so probably I am just orbiting it. My ship is the Rapid Offensive Unit (ROU) Trade Surplus, and I am Commander Jaylen Elmes. I travel the galaxies with my faithful pet Pipsy, a snorgle from the planet Bepo. (I looked up the Random Planet Generator again to find this planet).

Planet Rada. Perhaps I'll go home now.

I always take one of these when I travel. It's a matter re-organiser. You can choose from four different fields, which will recreate the material you feed into it as crystal, antimatter, dark matter or cheese.  

Matter re-organiser, a very handy machine.
So there you have it, a way to create your own galactic adventure. If you were sufficiently energetic you could write a story to go with it. I just sat back and enjoyed what my friends came up with. Many added their own witty touches to the basic structure, and I was vastly entertained! I might have been in isolation, but it was one of the best birthdays!

Monday, April 13, 2020

Is Earth's core a global commons and what does this mean for outer space?

On April 6, 2020, US President Trump issued an Executive Order rejecting the 1979 Moon Agreement and the idea that outer space is a global commons. 

What is space if it is not a global commons? Other such commons include Antarctica, the deep sea, the atmosphere, and cyberspace. We plebs cannot be denied use and access to these places - no-one is going to be selling us oxygen to breathe, on Earth at least, and for the foreseeable future. But as the amount of carbon dioxide in the atmosphere increases, I don't think anything can be ruled out. (Note that the atmosphere on Mars might also be a global commons, but as it's not suited to human use, manufactured breathable air may be a commodity there). 

I think Trump's rejection of space as a global commons is really insidious, and the precursor to carving up space between commercial interests. It got me to thinking about a place that mirrors outer space, only you couldn't get any more inner, or deeper into the gravity well. I'm talking about Earth's core.

Journey to the Centre of the Earth

Image by Roen Kelly

The core has two layers. The outer core is a fluid iron-nickel layer about 2400 km thick wrapped around the inner core, a solid iron-nickel sphere, about 1220 km in diameter.  They're both rotating, but in different directions. The temperature of the outer core ranges from 4000 to 6000 degrees celsius. One of the key effects of the core is to generate Earth's magnetic field, which protects us from the solar wind. Without it life on Earth would be very different.

Sure, it's a big ball of molten metal that we can't get to, but I don't see why this prevents us from thinking about it's status. Space was once inaccessible too, and Jules Verne imagined journeys to both. In 1864, he published Journey to the Centre of the Earth, where his heroes attempt to descend to the core through lava tubes. They don't achieve their goal and there is, sadly, no hidden path straight to the centre. At this stage the nature of the core was unknown but one theory was that it was molten. It was also thought that there were large cavities inside Earth which might sustain ecosystems of different kinds (some containing prehistoric fauna). About 200 km down, Verne's intrepid explorers find a vast underground lake and caverns with their own weather systems.

Source: Wikimedia
The existence of the core was proven by Richard Oldham in 1906, and by the early 1930s, the analysis of seismic waves passing through Earth showed that it was indeed liquid. The solid inner core was discovered by Danish seismologist Inge Lehmann in 1936 from analysis of a New Zealand earthquake. 

These days we think of Earth as solid, like a boring Easter egg. There are some very deep caves both on land and under the sea, but they're only about 2 km. 

Technology may help where we can't find natural routes to the underworld. The problem is the increasing temperature and pressure as you go down through the mantle, which crushes and melts the equipment. The deepest humans have ever drilled is 12 km. That's just 0.4% of the 2900 km you'd need to go to get to the core.

All the same, the mysteries of the interior of Earth continue to influence our desires and imagination. Only in recent years have scientists started to explore the dark biosphere, microbial and wormy life which thrives in the dark fissures and seams of the deep rock. Perhaps there aren't plesiosaurs in subterranean lakes, but it seems the deep Earth is not sterile, either. And perhaps we need Planetary Protection policies for the deep layers of this, and other planets.

A global uncommons?

The next question is whether there are any resources in Earth's core that could be used by humans.  We may run out of easily accessible iron ore near the surface, for example. This is one of the reasons asteroid mining is being pursued. We might not quite be equipped to deal with extracting it in liquid form, though. 

Heat from the core is already used in geothermal energy, but the extraction happens close to the surface. Geothermal energy is a renewable energy source, and is regulated at a national level. 

How much can be owned below the surface of Earth is also a matter for national regulation. In Australia before 1891, land titles extended to the core in the common law principle of usque adcoelom et usque ad inferos.  The complete sentence is 'whoever's is the soil, it is theirs all the way to Heaven and all the way to Hell'. After 1891, states placed limits on the depths below the surface. In Victoria, for example, the Crown owns the land below 15 m to the centre of Earth. 

And what about treaties or conventions setting out the ground rules for interacting with the core, like there are for outer space? If they exist, I couldn't find them. There seems to be nothing to prevent me claiming ownership of the core, apart from the tiny annoyances of being unable to access it or enforce my ownership. (In 2010, a woman claimed legal ownership of the Sun).

Perhaps we could call Earth's core - and by analogy all planetary cores, and unbreathable atmospheres, a global uncommons or perhaps even dyscommons. Everyone has rights to them and the benefits that derive from them (for example, the protection of magnetic fields), but they have limited or zero commercial use for the people who think of Earth in that way (which I'd prefer not to). The uncommons may underlie the commons that are the subject of competing claims and conflicts.  The commons then only comes into being when it has something of value to offer. For example, geostationary orbit is very valuable real estate, but only became so when it was possible to elevate satellites to this region. We may see something similar with cislunar space in the future.

But uncommons don't have to be metrically defined regions of Earth or space at all. As Judith Farquhar, Lili Lai and Marshall Kramer say,
The uncommons is not, in other words, an exterior to the one-world world; rather, it is a possible world that can make itself partly known in a mottled and ever-changing light and shade. (2017)

The one-world world (Law 2011, 2015) is a single vision of what Earth or the cosmos is. Pretty much all of our legal and scientific approaches to space are based on a one-world world. Law argues that the dominance of this one-world world by northern hemisphere thinking (ie industrial capitalist nations) makes the raising of multiple, but simultaneous, ways of experiencing the world seem eccentric and self-indulgent. Think about this and tell me it has not sometimes been your reaction when hearing about, for example, Indigenous worldviews about space. It's not easy to train yourself out of this, to see a fractiverse, as Law puts it, rather than a universe. For me, at least, it's an ongoing project.

My final question is both about how this furthers our thinking about outer space as a global commons, and what this means for defining commons or uncommons on regions of other planets. I don't have any answers just now but I feel I'm on a path of thought that might be productive.


Farquhar, Judith, Lili Lai and Marshall Kramer 2017 A Place at the End of a Road: A Yin-Yang Geography. Anthropologica 59(2): 216-227

Law, John 2011 What’s Wrong with a One-World World? Paper presented to the Center for the Humanities, Wesleyan University, Middletown, Connecticut on 19th September, 2011 d.pdf

Law, John 2015 What's Wrong with a One-World World? Distinktion: Scandinavian Journal of Social Theory 16(1): 126–139

Friday, January 31, 2020

Australian space icon: Mr Squiggle, the Man from the Moon

The impact of the Space Age was not just in science and technology - it was also in popular and everyday culture. If you were a kid growing up in Australia from the 1960s until the the 1990s, you would have been familiar with a children's television icon: Mr Squiggle, the Man from the Moon. Mr Squiggle is a huge part of Australian television history, but I'm more interested in what the programme says about how space travel was perceived in the 1960s and after.

Squiggle basics

This is Mr Squiggle's theme tune:
Here's Mr Squiggle
With lots of fun for everyone
Here's Mr Squiggle, sing a happy tune
You can see we're as happy as can be
Mr Squiggle, the man from the Moon.

Mr Squiggle was the brainchild of political cartoonist and puppeteer Norman Hetherington. The pencil-nosed puppet's television debut was in 1959. At first Mr Squiggle was part of a six week stint on the Children's TV Club on the ABC, but soon gained his own stand-alone programme. Margaret, who married Norman in 1958, wrote the scripts for the show while Norman performed all the character voices. (Note that while Norman has his own Wikipedia page, Margaret doesn't).

Children would send in their 'squiggles', and Mr Squiggle used his pencil nose to make them into pictures, accompanied by a female sidekick. Other characters included Bill Steamshovel, Gus the snail, Merv Wallop and his nephew Wayne, Reg Linchpin, Doormat, the grumpy Rocket and a talking Blackboard.

Mr Squiggle lived at 93 Crater Crescent on the Moon and travelled to Earth every week in his rocket or by going for a 'space-walk'. He could also break out into gravity-defying 'space-walks' spontaneously in the middle of shows. Sometimes, if Rocket was very grumpy, Mr Squiggle would use an umbrella for the descent. 

The action takes place in a very ordinary, regular backyard, with gum trees, in the fictional location of Bandywallop. (The Collins dictionary defines Bandywallop as 'Australian informal: noun. An imaginary town, far from civilization'). There's a rainwater tank where Bill Steamshovel hangs out, and old, weathered yards surrounded by bush. I guess part of the appeal of Mr Squiggle, as we got so much US and UK children's television, was that it was set in Australia with Australian accents and culture. 

Mr Squiggle's female sidekicks were:
The science fiction writer Terry Dowling was a resident guest on Mr Squiggle, from 1979 to 1982. He wrote songs and performed them on the programme with his guitar.  Comedian and radio personality Mikey Robins played Reg Linchpin for a year in 1989-1990. The programme ended in 1999. 

Two books were spin-offs from the series. Margaret Hetherington wrote them, and Norman did the illustrations. They were Mr Squiggle and the Great Moon Robbery (1980) and Mr Squiggle and the Preposterous Purple Crocodile (1992). There was also a colouring book in 1989 - Mr Squiggle and His Rocket Activity Book

Bradshaw, Richard 2010 Eulogy for Norman Hetherington 1921 - 2010. OPEN: Oz Puppetry Email Newsletter Issue 11

Gorman, A.C. 2018 Gravity's playground: dreams of spaceflight and the rocket park in Australian culture. In Darran Jordan and Rocco Bosco, ed. Defining the Fringe of Contemporary Australian Archaeology. Pyramidiots, Paranoia and the Paranormal. Newcastle upon Tyne: Cambridge Scholars Publishing, pp. 92-107.

Gorman, A.C. 2011 The sky is falling: how Skylab became an Australian icon. Journal of Australian Studies 35(4):529-546

Jones, Melissa 1989 Mr Squiggle chalks up 30 years. The Australian Women's Weekly p 65 (reproduced at

Solman, Peter 2010 Norman Hetherington Remembered. A personal recollection by Peter Soloman. OPEN: Oz Puppetry Email Newsletter Issue 11

Wilkins, Richard 2011 Black Ties, Red Carpets, Green Rooms. Chatswood: New Holland

Wilson, Peter J. and Geoffrey Milne 2004 The Space Between: The Art of Puppetry and Visual Theatre in Australia. Sydney: Currency Press