What does the ‘scandalous’ message that astronomer Carl Sagan sent to extraterrestrials say

At 8:42 pm on March 2, 1972, the American space agency, NASA, launched the Pioneer 10 unmanned space probe from Cape Canaveral, Florida. Its destination was Jupiter and then the edge of our solar system.

Their mission was to take detailed pictures of the immense planet and its moons and to study the atmosphere, its solar particles and winds, the flow and speed of the plentiful dust particles. But Pioneer 10 had a second mission.

Attached to the antenna supports, protected from erosion by interstellar dust, was a scientific and artistic diagram, the Pioneer Plate.

a simple message
Just three months earlier, in December 1971, American astronomer Carl Sagan had suggested to his colleague Frank Drake that they work together to design a direct and unambiguous interstellar message.

“We thought the most interesting thing for a̳l̳i̳e̳n̳s would be to know what we are like,” Drake, founder of the SETI Institute, which examines signals of e̳x̳t̳r̳a̳t̳e̳r̳r̳e̳s̳t̳r̳i̳a̳l̳ communication in space, tells the BBC.

Photo Caption,In 1980, astronomer Carl Sagan became world famous
“But we thought they would also like to know where the message came from and when it was sent, because it could take millions of years for it to be intercepted.”

The two scientists started from the premise that science and mathematics are universal languages, that is, they can be understood by any intelligent life.

They first set about devising a way to tell the a̳l̳i̳e̳n̳s where the message was coming from, but talking about a “planet Earth” would make no sense to them.

To understand what they did, imagine that you are trying to find someone in the middle of the ocean and, instead of coordinates, you receive information about the location of various lighthouses and their distance from the place where the person you are looking for is.

In the sky, these beacons are pulsars, remnants of a star\’s explosion that spin very quickly and, as a result, emit very evenly spaced pulses.

So, to tell the a̳l̳i̳e̳n̳s where the message had been sent from, the scientists created a map showing the location of 14 pulsars relative to the Sun. This is what you see where number 1 is in this image:

Each of the lines radiating from the center indicates the direction and distance of a pulsar from the Sun. As there are many pulsars in the Universe, the two scientists recorded in binary numbers the frequency of pulses that, being distinct, serve to identify them.

Photo Caption,Sequence of vertical and horizontal dashes that you see next to the lines are binary numbers that indicate the pulse frequencies needed to identify pulsars
That way, the a̳l̳i̳e̳n̳s would know that the message had come from our solar system. But it would be necessary, however, to give more details of our location.

In the lower left part of the diagram, where the number 2 is, we see the Sun again, now accompanied by the planets. From the third planet – ours – an arrow points to the Pioneer probe.

Photo Caption,Our address: Third planet from the inside out in the solar system
Running against time
With that first part of the message created, Sagan and Drake presented their plans to NASA in hopes of getting it on Pioneer 10.

It had been just over two years since Apollo had landed on the Moon, and the space agency wanted an equally ambitious new project. The Pioneer probe would go where no spacecraft had gone before.

Its launch was scheduled for February, and NASA did not immediately approve the plaque\’s inclusion. Racing against time, astronomers finished projecting the message over the next few weeks.

They had found a way to show where the Earth was, but they found it useful to include a way to calculate time and dimensions. They needed to find a universal unity, and the basic chemistry of the Universe gave them the solution.

The drawing above number 4 in the image below shows the hydrogen atom in its two lowest energy states.

When a hydrogen atom changes from one energy state to another, it radiates a radio wave with a certain wavelength and with a certain frequency of oscillation”, explains Drake.

Frequency served as a unit of time, and wavelength as a unit equivalent to 20 cm.

Photo Caption,Astronomers used constant values ​​of the energy change of hydrogen atoms to fix measurements
Notice now that the woman has a line near her head and another one near her feet. The distance between them is her height.

We see that to the left of the number 5 something is written. “It\’s a binary number that indicates that a woman measures 8 of that fixed unit: 8 x 8 inches = 64 inches, which is actually the average height of women on the planet,” says the astronomer.

This information, as well as the other representation of the Pioneer spacecraft on the plate, served to give message recipients an idea of ​​our size.

The next task was to show how we are. It should have been the easy part, but it turned out to be a lot more controversial than they expected.

The person in charge of representing the human form to the inhabitants of outer space was Sagan\’s wife, Liza, a professional artist who had studied at the prestigious School of Fine Arts at the Boston Museum. But by marrying a famous scientist, she found herself with the responsibility of representing all of humanity with just two figures.

Photo Caption, Linda Salzman Sagan took care of the aspect that turned out to be the most troublesome of all
“I wanted each figure to have different racial traits. The woman has very almond-shaped eyes and straight hair. I made the man with curly hair and a flat nose, so they would be multicultural,” she tells the BBC.

And the clothes? “How was I going to wear them? In tribal attire? In haute couture clothes? No, we decided to leave them naked”, says the artist.

\’Hello\’
As news of the plaque spread, questions arose about whether the female figure appears submissive to the male. Why had man been given the honor of greeting the Universe?

Photo Caption, Some were annoyed that the woman seems to have a submissive attitude towards the man, with him looking straight ahead while she does not
“Feminism was just starting to be a topic of conversation, and a lot of women said, \’Well, why aren\’t we saluting the Universe, why don\’t we have our hands up?\’ a̳l̳i̳e̳n̳s would think everyone on Earth walks around with their hands up. We had to take these things into consideration,” says the artist.

The beauty of the diagram design lies in its mathematical and scientific accuracy. But for Linda, this presented a problem: she had to decide how many anatomical details to include.

Although the early 1970s were permeated by the theme of free love, American society was still generally puritanical when it came to drawings of naked women. “Many of the statues I was looking at didn\’t have very specific female genitalia. I didn\’t know what to do,” Linda recalls.

“Carl said, \’Don\’t do anything that could get us into trouble with NASA or give someone an excuse not to put the plaque on the spacecraft.\'” Linda Sagan decided not to draw the female genitalia. But that did not end the controversy.

Photo caption, Scandal broke out despite the fact that the woman went into space without genitals
Charming, fanciful and obscene
The deadline was running out, the take-off date was approaching, and public reaction to the sign was gathering strength, but it was not clear what the Americans thought: would they support it or would there be public protests?

On the one hand, there were articles like the one by the eminent science writer Walter Sullivan, published in the American newspaper The New York Times, with charming descriptions of the Pioneer probe: “It will sail indefinitely through the vast confines of the Milky Way” and the plate.

Like him, some were excited about the idea of establishing communication with e̳x̳t̳r̳a̳t̳e̳r̳r̳e̳s̳t̳r̳i̳a̳l̳s. However, for others, the initiative seemed a bit fanciful.

Photo Caption,Pioneer 10 and Pioneer 11 carried our business cards to any other space navigators that might find them in the distant future
But the most critical were those who saw the nude figures as a form of pornography. “NASA was very concerned that some members of Congress were very conservative and might be offended because taxpayer money was used to send obscenities into space,” Drake says.

“I remember being invited to a national television program in the morning in Canada, and when I finished describing the sign, I looked around and everyone was horrified. I asked and they said, \’We\’re all going to get fired.\’ It\’s the first time a naked human has been shown on Canadian television and it\’s banned!”

Amid the debate, the probe took off from Florida with the sign and began its long journey through space. In December 1973, sooner than expected, it arrived at Jupiter and immediately sent magnificent color photos of the planet\’s surface.

Photo Caption,On December 4, 1973, NASA\’s Pioneer 10 spacecraft sent high-resolution images of Jupiter
Then it continued on its way to outer space. By the summer of 1983, the Pioneer Plate had passed the orbits of Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. On June 13, it reached the edge of our solar system. And completed the crossing.

Pioneer 10 sent its last message on January 22, 2003, and was never heard from again.

Throughout the 1970s, Sagan and Drake created other messages for space. The Pioneer Board had revealed how difficult it was to capture the variety of human life in a diagram. So in 1977 they developed a more complex message called the Voyager Gold Disc.

This one had greetings in 55 languages, 12 minutes of Earth sounds – like human heartbeats and falling rain – music by Brahms and Chuck Berry, and instead of naked humans, NASA accepted the image of a pregnant woman.

Of course, we don\’t know if the Pioneer Board was seen by a̳l̳i̳e̳n̳s. If so, we still haven\’t received a response. But for Frank Drake, the purpose and importance of the original diagram was not lost.

“The Voyager plate and disk will outlast our planet. In 4 billion years, the Sun will grow, become a supergiant, swallow the Earth and destroy everything we know. The plaque will still be there to show that there was a c̳i̳v̳i̳l̳i̳z̳a̳t̳i̳o̳n̳ like ours in the Milky Way.”