Pioneer plaque

Hyperfine transition of neutral hydrogen

At the top left of the plaque is a schematic representation of the hyperfine transition of hydrogen, which is the most abundant element in the universe. The spin-flip transition of a hydrogen atom's electron has a frequency of about 1420.405 MHz, which corresponds to a period of 0.704 ns. Light at this frequency has a vacuum wavelength of 21.106 cm (which is also the distance the light travels in that time period). Below the symbol, the small vertical line—representing the binary digit 1—specifies a unit of length (21 cm) as well as a unit of time (0.7 ns). Both units are used as measurements in the other symbols.[4]

Figures of a man and a woman

On the right side of the plaque, a man and a woman are shown in front of the spacecraft.[5] Between the brackets that indicate the height of the woman, the binary representation of the number 8 can be seen (1000, with a small defect in the first zero). In units of the wavelength of the hyperfine transition of hydrogen this means 8 × 21 cm = 168 cm.

The right hand of the man is raised as a sign of good will. Although this gesture may not be understood, it offers a way to show the opposable thumb and how the limbs can be moved.[6]

Originally Sagan intended the humans to be shown holding hands, but soon realized that an extraterrestrial might perceive them as a single creature rather than two organisms.[6]

The original drawings of the figures were based on drawings by Leonardo da Vinci and Greek sculptures.[6]

The woman's genitals are not depicted in detail; only the Mons pubis is shown. It has been claimed that Sagan, having little time to complete the plaque, suspected that NASA would have rejected a more intricate drawing and therefore made a compromise just to be safe.[7] Carl Sagan said that the decision to not include the vertical line on the woman's genitalia (pudendal cleft) which would be caused by the intersection of the labia majora was due to two reasons. First, Greek sculptures of women do not include that line. Second, Carl Sagan believed that a design with such an explicit depiction of a woman's genitalia would be considered too obscene to be approved by NASA.[8] According to the memoirs of Robert S. Kraemer, however, the original design that was presented to NASA headquarters included a line which indicated the woman's vulva,[9] and this line was erased as a condition for approval of the design by John Naugle, former head of NASA's Office of Space Science and the agency's former chief scientist.[9]

Relative position of the Sun to the center of the Galaxy and 14 pulsars with their periods denoted

The radial pattern on the left of the plaque shows 15 lines emanating from the same origin. Fourteen of the lines have corresponding long binary numbers, which stand for the periods of pulsars, using the hydrogen spin-flip transition frequency as the unit. Since these periods will change over time, the epoch of the launch can be calculated from these values.

The lengths of the lines show the relative distances of the pulsars to the Sun. A tick mark at the end of each line gives the Z coordinate perpendicular to the galactic plane.

If the plaque is found, only some of the pulsars may be visible from the location of its discovery. Showing the location with as many as 14 pulsars provides redundancy so that the location of the origin can be triangulated even if only some of the pulsars are recognized.

The data for one of the pulsars is misleading. When the plaque was designed, the frequency of pulsar "1240" (now known as J1243-6423) was known to only three significant decimal digits: 0.388 second.[1] The map lists the period of this pulsar in binary to much greater precision: 100000110110010110001001111000. Rounding this off at about 10 significant bits (100000110100000000000000000000) would have provided a hint of this uncertainty. This pulsar is represented by the long line pointing down and to the right.

The fifteenth line on the plaque extends to the far right, behind the human figures. This line indicates the Sun's relative distance to the center of the galaxy.

The pulsar map and hydrogen atom diagram are shared in common with the Voyager Golden Record.

The Solar System with the trajectory of the Pioneer spacecraft

At the bottom of the plaque is a schematic diagram of the Solar System. A small picture of the spacecraft is shown, and the trajectory shows its way past Jupiter and out of the Solar System. Both Pioneers 10 and 11 have identical plaques; however, after launch, Pioneer 11 was redirected toward Saturn and from there it exited the Solar System. In this regard the Pioneer 11 plaque is somewhat inaccurate. The Saturn flyby of Pioneer 11 would also greatly influence its future direction and destination as compared to Pioneer 10, but this fact is not depicted in the plaques.

Saturn's rings could give a further hint to identifying the Solar System. Rings around the planets Jupiter, Uranus, and Neptune were unknown when the plaque was designed; however, unlike Saturn, the ring systems on these planets are not so easily visible and apparent as Saturn's. Pluto was considered to be a planet when the plaque was designed; in 2006 the IAU reclassified Pluto as a dwarf planet and then in 2008 as a plutoid. Other large bodies classed as dwarf planets, such as Eris, are not depicted, as they were unknown at the time the plaque was made.

The binary numbers above and below the planets show the relative distance to the Sun. The unit is 1/10 of Mercury's orbit. Rather than the familiar "1" and "0", "I" and "-" are used.

Silhouette of the Pioneer spacecraft relative to the size of the humans

Behind the figures of the human beings, the silhouette of the Pioneer spacecraft is shown in the same scale so that the size of the human beings can be deduced by measuring the spacecraft.

• In the Star Trek Encyclopedia paperback – International Edition, October 1, 1999, the plaque is shown with Pioneer launching from the second planet rather than the third.
• In the science fiction film Star Trek: The Motion Picture, the plaque's diagram is fleetingly shown during Spock's mindmeld with V'ger, a transformed NASA space probe, Voyager 6. This style of plaque was not used in the two actual NASA probes in the Voyager program.
• In Star Trek: Voyager, the plaque appears on the viewing screen when Rain Robinson sends a signal trying to communicate with Voyager in the season 3 episode "Future's End".
• In the science fiction film Star Trek V: The Final Frontier, the plaque is shown attached to a Pioneer probe floating in space, just before a bored Klingon ship captain, who scoffs "Shooting space garbage is no test of a warrior's mettle", intercepts and destroys it. The plaque is erroneously depicted as facing outwards rather than inwards.
• In the Star Trek novel Federation, a character mentions that humans had shown copies of the plaque to several alien races they encountered, but none had been able to decode it.

• In "The Message," an episode of the science fiction series The Outer Limits, a deaf woman was featured receiving alien signals through her cochlear implant, prompting her to write out Xs, 1s, and 0s on paper. When put together, the Xs depicted the images of the man and woman from the plaque, along with an extraterrestrial humanoid raising a hand in a peaceful gesture.
• On her album United States Live, American performance artist Laurie Anderson contemplates extraterrestrials finding the plaque and asks "do you think that they will think his arm is permanently attached in this position?"
• In the Futurama episode "Godfellas," the robot Bender finds himself doomed to drift through space, during which time he etches a modified version of the Pioneer plaque, with himself towering menacingly over the human figures, so that "When I'm found in a million years, people will know what the score was."
• In Buck Rogers season 1, episode 15 "Ardala Returns," Princess Ardala constructs a fake probe (allegedly launched in 1996) that uses a copy of the plaque to trick Buck into thinking the probe was from his own time period — the distant past. The male and female images are altered and positioned separately on either side from the Pioneer plaques.
• In the L. Ron Hubbard novel Battlefield Earth, the principal alien character mentions that his race's conquest of Earth was made possible by their discovery of a space probe "that gave full directions to the place, had pictures of man on it and everything".
• In "Beware My Cheating Bart" (18th episode of Season 23) of The Simpsons, the plaque was briefly shown at the end of the episode. It was depicted with an extraterrestrial holding the plaque upside down, obviously confused by its strange depictions.
• The plaque is used as the artwork for the album Aufheben by the Brian Jonestown Massacre and for Accept the Signal by Regular Fries.
• In the TV show Eureka, on episode 5 of season 2 (Duck Duck Goose), the plaque is shown as part of the debris that lands on Earth.
• In the TV show The Big Bang Theory, on episode 21 of season 8 (The Communication Deterioration), the characters mention the plaque while discussing ideas about sending a message to alien races in space.
• In the video game by Paradox Development Studio, Stellaris, one of the scientific missions discovers the plaque on an alien world in the distant future.
• The Pioneer plaque appears in the booklet of David Bowie's 2016 album Blackstar, on the page for the song "Girl Loves Me".
• 17776 has Pioneer 10 (named Ten in the story) as a sentient being who is made fun of by Pioneer 9 (Nine) and Jupiter Icy Moons Explorer (JUICE) for being sent into space with a plaque displaying naked humans.
• In the Wii U title Xenoblade Chronicles X by Japanese developer Monolith Soft, the plaque is seen in the opening cut scene, damaged and floating in midspace, before one of the alien ships that later approaches Earth. In this instance, the genitalia and nipples on the male and female depictions respectively are absent, most probably due to Japan's strict censorship of explicit material.
• Edwin Morgan's poem, "Translunar Space March 1972", refers to Pioneer 10, and passes critical commentary on the images on the plaque: "A deodorized American man / with apologetic genitals and no pubic hair / holds up a banana-like right hand"[19]