Visual Essays

Seeing how planetary exploration rarely graces the pages of Creative Review, it’s easy to picture the expressions worn by an audience comprised mainly of creatives, as I wheeled out the first slide of my talk: ‘A Graphic Designer’s Guide to: The Pioneer 10 Plaque’.

Space is vast, but its huge vacuum is nothing compared to the yawning gulf between the subject and graphic design. As this time there’s no free bar to cushion the blow, I’ll provide some context before the science…

A few summers ago I had the good fortune to represent Airside at ilovedesign.com’s 8×8 London hosted by Imperial College. Sold as a spin on the familiar Pecha Kucha event, ilovedesign asked 8 designers to talk for 8 minutes on a subject that inspired them. Although this sounded easy on paper, the darn time limit made it decidedly less so.

To encourage a fast paced and lively event (making sure navel gazing was kept to a minimum) the terrifying dual action of a bell and an air-horn were employed to keep our presentations in check and under the 8 minute mark.

The night’s setup (sponsored by Quark) was perhaps the slickest I’ve seen for a talk, and like a fine garnish, we were graced by Noisy Decent Graphics author Ben Terret as our MC. Not only did he do a sterling job of keeping us in check, but I’ve been introduced to more graphic design puns than I’ll ever want to hear.

ilovedesign even managed to film each presentation for posterity, which you can see here at ilovedesign.com.

The evening saw presentations from a nicely varied group, with the design heavyweights of John Bateson, Vaughan Oliver, Ian Tait and Richard Hooker sharing the stage with the comparative upstarts of Hellicar & Lewis, HudsonBec and Matt Dent. In retrospect, if this was a designer sandwich, my presentation would have been gherkin surprise.

With an evening on the subject of ‘inspiration’, there’s always a danger of the audience being ‘inspired’ out of their seats and into the free bar, so I risked a curve ball to talk about the design of the Pioneer 10 plaque.

To many, the Pioneer 10 plaque is one of those all too familiar images that few can actually place. I must admit that until a few years ago I too was in this majority: though the image and its purpose were clear, the design itself possessed little meaning to me.

However, the more I read about the plaque and the thinking behind it, I came to appreciate just a what a colossal achievement of information design it is. The design is worthy not just for what it represents, but how it communicates information in a way that is totally unlike any piece of design produced before or since.

The design is unqiue because it attempts to present information concerning humanity’s place in the universe in a way that can be read without any prior semiotic knowledge. Essentially it’s created for an end-user with absolutely no concept of human communication.

Consequently, the resulting design remains familiar, yet totally alien. A grand feat considering it was completed in just two weeks, and by just two people. And as an added bonus, it’s a fantastic example of inspired 70s thinking — and we all know where they got their inspiration from.

The plaque itself is currently 7.6 billion miles away from Earth having done its job of exploring our outer planetary bodies. Realising that this probe would certainly be the first man-made object to leave our Solar System NASA had the foresight to ask two very different men to undertake the challenge to design what would be man’s eternal calling card.

The men who rose to the occasion were then, and now, two giants of astronomy and astrophysics: Carl Sagan and Frank Drake (he of the famous Drake equation).

Together, with the life drawing skills of Carl’s wife, this odd couple of science created a plaque to be carried by the Pioneer 10 probe — a diagram that would become an enduring image of space exploration.

Though the plaque’s design is not totally perfect (a few leaps of faith are needed to decode it) it’s a fascinating exercise to unravel it, if only to see just how Frank and Carl used only maths and physics to communicate our place in the universe.

The plaque’s design is comprised of four parts: a measurement, a map of our galactic neighborhood, a map of our solar system and a representation of the human species.

Restrictions on the space available meant Frank and Carl had to overlay much of the information, and without words, symbols or numbers the diagram’s constituent parts can seem pretty indecipherable, but the key to translating the design lies with the diagrammatic circles in the top left hand of the diagram. This is the plaque’s key.

Before encoding any information Frank and Carl realised they needed something to give them a measurement from which to calculate time and distance. However this proved to be a bit of a challenge, as they needed to find a universal yardstick that was not only readily observable, but crucially, constant throughout the universe.

Thankfully it happened that hydrogen, the most abundant element in the universe, had a particular property that provided just that. It even had a snappy name: the Hyperfine Transition of Neutral Hydrogen.

A scary title for sure, but the property is quite easy to explain. A single hydrogen atom can sometimes flip-flop between two energy states, and when this change occurs a small amount of energy is released.

This change in energy is what Frank and Carl attempt to represent in the key: each circle representing a different energy state of the same hydrogen atom. The left circle shows the atom with a low energy, and the right shows the same atom with a high energy. The line between the two shows the energy change of this atom is worth noting.

But to understand just how a time and measurement can be calculated from this atomic property, we have to look a little deeper into the science of the hydrogen atom. It may seem exhaustive, but it’s this energy change that is the key to understanding the rest of the plaque.

It’s best to first consider a spinning globe — it sits on an axis, and the globe has a direction of spin. In our globe’s case the direction of the spin and the direction of the axis are intrinsically linked — if the globe were to be flipped upside-down, the direction of the axis would be in the opposite direction meaning the direction of spin would be the opposite too.

The sub-atomic particles that make up a hydrogen atom are no different. Each hydrogen atom’s single proton and electron has an axis direction and most importantly a direction of spin linked to the axis.

The proton and electron usually have their axes aligned and spin in the same direction, giving the hydrogen atom a high energy state.

But in the huge gaseous clouds that pepper the Milky Way, hydrogen atoms can sometimes knock together causing their protons and electrons to suddenly spin out in opposite directions, flipping the direction of their respective axes. With the proton and electron now spinning in different directions with their axes unaligned, the hydrogen atom acquires a lower energy state and its excess energy is released in the form of a photon.

And it’s the photon’s release that Frank and Carl attempted to represent with the above diagram. The lines within each circle are aligned differently to represent the two possible alignments of a hydrogen atom’s proton and electron. The line between the two is marked with binary to indicate that the photon’s energy has a unit.

A photon is an excellent measuring tool since it exists both as a particle and as a wave, and a wave has both a wavelength and a frequency, in other words, a distance and a time. Consequently, the whole of the plaque’s translation hangs on the two measurements derived from a photon’s wavelength (21 cm) and its frequency (1420 MHz).

Now with a unit of measurement, the plaque’s galactic map can decoded showing our location in the Milky Way.

Using our Solar System as a centre point, Frank and Carl drew 14 lines encoded with information to show the 14 strongest pulsars that surround our Sun. An longer and unmarked 15th line was added to show our Solar System’s distance from the Milky Way’s centre.

Like the hydrogen atom’s flip-flopping state, Frank and Carl chose the pulsar above the other galactic landmarks for one crucial reason.

Unlike stars, pulsars posses two unique traits that make them very easy to identify: they spin extremely fast, and instead of emitting light they shoot narrow beams of electromagnetic radiation deep into space. Dense bodies, pulsars have their radiation squeezed by tight magnetic fields, forcing their reach further than most other visible radiation. This makes them very easy to ‘see’.

It’s best to think of pulsars as lighthouses of the night sky. Lighthouses appear to flash, but it’s actually a beam of light moving in a circular motion, and the same thing happens with a pulsar’s spinning beam of radiation.

As a pulsar spins, its beam of radiation hits an observer at regular intervals, giving each pulsar their own unique ‘beat’. Frank and Carl realised that if enough of these ‘beats’ could be identified it would be possible to triangulate the Solar System’s position within the Milky Way.

But a pulsar beat and its relative position to our Solar System and our galaxy is a lot of information to fit into one line, so Frank and Carl decided to use the most universal (and logical) communication tool known to man: binary.

By using seperate marks to represent either a 1 or 0, Frank and Carl were able to encode numerical information in a way that was both efficient and universal.

Binary’s great attribute is its logic. Although it was agreed between the pair that language and number could not be used on the plaque, they hypothesised that if a civilization were to actually find the probe they would have to have possess some knowledge of a system such as binary to get there. It was a leap of faith, but it can be argued that they didn’t have a choice.

Looking at the mark again in binary, it’s possible to decode the line into a series of 0’s and 1’s, which can then be translated into decimal figures.

This number is multiplied by the time provided by the hydrogen measurement to calculate the pulsar’s individual ‘beat’ in seconds.

Again, Frank and Carl had to hold onto the belief that the plaque’s future audience would eventually plug in the right unit to get the pulsar’s beat. It’s another leap of faith, but they argued anyone attempting to decode the plaque would surely aim to use only the information supplied on the plaque, rather than introduce outside thinking that could muddy the results.

By applying the same calculation to all the encoded lines on the diagram it’s now possible to calculate the individual ‘beats’ for all 14 pulsars in our galactic neighbourhood.

However, this information is nothing without decoding the line’s other mark, and thankfully it’s a tad easier than the first process.

Within the pulsar line there is another mark set aside from the binary.

Frank and Carl could see the opportunity to include a crude physical map of the pulsar’s position, so included an isolated mark to show the pulsar’s rough distance from the centre of our Sun.

With these marks highlighted it’s easy to see a rudimentary 2D map of the 14 most identifiable pulsars that surround our Solar System.

It was Frank and Carl’s belief that if enough pulsars from the diagram could be identified, they could be used to triangulate the position of our solar system in the Milky Way — greatly increasing the chance the recipient would find where the probe originated from.

The penultimate part of the plaque is a much more local affair. With the position of the probe’s Solar System calculated, Frank and Carl wanted to wanted to show the planetary make up of our Solar System in greater detail to increase the chance of contact. The inclusion of Saturn’s ring was included to make this task easier.

A closer look at the diagram reveals the planets have been headed in binary. Once decoded the planet’s headers reveal the relative distance of each planet from the sun. The arrow was included at the last minute to give an approximation of the probe’s trajectory. In my opinion this is the Frank and Carl’s only glaring oversight, since an arrow loses its meaning once removed from the context of human understanding.

By decoding the binary headers a set of 10 values are given. Together these can be seen as a series of ratios from which a graphic representation of every planet’s relative distance to the sun. While not the pinnacle of accurately, this result at least gives a clear indication of our solar system’s overall layout. Together with the pulsar map, the representation of our Solar System’s make up would prove extremely useful for pin-pointing the probe’s home planet.

The last part of the plaque’s message is to answer the question of who sent it, and ignoring the possibility that extra-terrestrials will forever consider us nudists, Frank and Carl presented a carefully posed man and a woman against a silhouette of the probe.

The male was drawn not only to show the Earth’s universal greeting of good-will, but to demonstrate the movement of joints and reveal our opposable thumb.

As an aside I should add that the two particular figures where chosen as they were meant to be approximations of the most average human beings in the 1970’s.

I find this particularly worrying, because when I think of an ‘average man’ from the 70s, I think of moobs, a pint of lager and a packet of crisps. Still, first impressions count for a lot.

The only information that needs to be actively decoded on this part of the plaque is a small piece of binary between the woman’s height marks. When converted into decimals and multiplied by 21 cm (derived by the hydrogen measurement) a length of 168 cm is calculated.

This height serves as an excellent reference point for relating the scale of the probe to the average size of the human race.

And that’s it. As you’ve seen through my rather bumpy translation the plaque is by no means perfect, but I still have a lot of respect for it. It’s an incredibly brave piece of information design, and a great historical artifact, perfectly encapsulating the 1970’s fascination with the possibilities of space. As a disclaimer I should add that I’m no scientist, and I’m writing purely to bring attention to the logical leaps and bounds used to design this unique diagram. So if you find any faults with my explanation, do please get in touch and I will do all in my power rectify the error.

If the probe is ever found (and it’s Drake’s cautious estimate to wait 2 million years), the key to the plaque’s success is for other civilisations to be way smarter than a slightly stressed graphic designer.