The Pioneer 10 is the first man-made object we sent outside our solar system. It holds the most ambitious visual communication project ever conceived by a human mind: a message to extraterrestrial life. The authors are Carl Sagan, Frank Drake and Linda Salzman, who carried out this incredible project just three weeks to go before launch. In this article, I explain the design problems and the decisions made by the authors to solve them.
The hype around Space and Pioneer 10
The subject of colonising space, quite popular today, has an important precedent in the 1970s. Neil Armstrong recently walked on the moon and there is significant progress in the knowledge of space. Science fiction talks about interplanetary missions and there is a lot of attention on space. So much so that during the historic oil crisis, many prefer to think of turning it into a new mine to colonise rather than reducing the human footprint on our planet.
Among the projects dating back to this time, there’s something you may have seen on social media: a concept for a 10,000 people orbital station, conceived by NASA Ames Research Center. The same centre also worked on the design of the Pioneer 10 plaque, the subject of this post.
Pioneer 10 is a space probe launched in 1972. It was the first man-made object to leave our solar system. For this reason, a few weeks before the launch, NASA decides to add on the ship a message addressed to extra-terrestrial life forms. A metal calling card that graphically represents our position in the galaxy and the epoch we sent the message.
Although the chances of this message in a bottle reaching anyone are remote, the plaque is a unique attempt to communicate something to an unknown life form with graphic design. It is interesting to observe how the designers have dealt with its unprecedented design problems.
The design project
NASA decides to put the plaque on the Pioneer 10 only three weeks before the launch. A relatively short time to solve significant design problems and to reach a consensus within the agency.
The authors are NASA astronomers Carl Sagan and Frank Drake, along with Linda Salzman, who created the graphics. Their article “A Message from Earth”, published in Science in 1972, describes decisions that led to the final product.
How to make the sign last in interstellar space?
The first problem to solve is environmental resistance. The Pioneer 10 will travel in a virtually unknown area for a potentially infinite amount of time. For this reason, the group chooses gold-anodised aluminium as the material, calculating plate thickness and weight with interstellar erosion criteria. They also decide to attach the plate in an outer but protected position, with the engraving facing inwards.
Which language to choose?
Much more complex is to make the message understandable by a life form completely alien to ours. To do it, the signs must therefore find a semiotic generality superior to all previous forms of human communication. About it, the authors will write:
We believe that any such message will be constrained, to a greater or lesser degree, by the limitations of human perceptual and logical processes. The message inadvertently contains anthropocentric content. Nevertheless, we feel that an advanced technical civilization would be able to decipher it.
An alien life form capable of deciphering the carvings must first identify the Pioneer in space and then retrieve it. Tasks that limit the public to a civilisation that has the technologies to accomplish them. The designers, therefore, affirm that such a civilisation must necessarily know mathematics and physics: languages chosen to convey the messages.
Graphic composition and contents of the message
The graphics on the plate comprise four groups. The first, at the top left, describes the unit of measurement of the representation. Immediately below is the distance of the sun from the centre of our galaxy. On the right side, the Pioneer, depicted together with two human figures. In the lower part, the position of the Earth in our solar system.
How to describe time and space with the same sign?
The first sign at the top left, like a graphic scale within a design project, communicates the scale representation: the unit of measurement, of both time and space.
It is a schematic drawing of the hyperfine transition by spin inversion of hydrogen, the most abundant element in the universe. Understanding this physical phenomenon observed by humans in the late 19th century and explained by Wolfgang Pauli in 1924 is the key to deciphering the message.
Inside the paper, Sagan’s group describes the reasons a physicist from another civilisation should be able to recognise it easily by translating it into 21 cm and 0.7 nanoseconds.
In the middle of the hyperfine transition symbol, the binary digit 1 indicates the unit. Again, the choice of binary is not arbitrary. If decimal numbering is a human convention, binary numbering is the most elementary and therefore immediately understandable to a hypothetical alien physicist, no matter how many fingers he has.
As a cross-check to the first sign, the researchers at NASA write the height of the woman on the right in binary numbers so that aliens can measure it to scale with the Pioneer representation immediately behind it.
How do represent the Human Race in a symbol?
This second composition, which also shows a man in a gesture of greeting, depicts humans as the sender of the message.
Today, the idea of representing the entire human race in this way would cause designers many problems. In the 70s, part of the US public was upset about the fact they are naked. However, the authors are aware of the problem, so much so that they write:
With a set of human representations to this degree of detail, it was not possible to avoid some racial stereotypes, but we hope that this man and woman will be considered representative of all mankind. A raised outstretched right hand has been indicated as a “universal” symbol of goodwill, in many human writings; we doubt any literal universality but included it for want of a better symbol. It has at least the advantage of displaying an opposable thumb.
How to describe our epoch and position in the Universe with graphic design?
On the left, a radial shape shows the position of the sun within the Milky Way. The elements shown are the centre of the galaxy, marked at the right end of the horizontal line, and the direction and distance of 14 pulsars, represented by as many lines.
The presence of pulsars in the graph has another function: dating the message. At the end of each line, a binary number describes the period of the pulsar, a value that changes over time and would allow a physicist to trace the launch epoch.
The last group at the bottom represents the Milky Way, starting with the Sun and ending with Pluto, then considered the last planet in the solar system. It was impossible to represent the distances between the planets to scale, so the designers wrote them in binary code near the planets. The plate also shows Earth as Pioneer’s origin and illustrates the spacecraft’s trajectory and its orbit around Jupiter.
At the end of the statement, the authors explain they are aware the message can certainly be improved and hope that future spacecraft launched outside the solar system will carry such an enhanced message. In 1977, as the Pioneer missions give way to the Voyager programme, Sagan himself will take charge of a similar project, the Voyager Golden Record.
Sagan, C., Salzman, L. and Drake, F., 1972. A message from Earth. Science, 175(4024), pp.881-884.