Shouting at Stars: A History of Interstellar Messages

TL;DR

Humanity has sent aliens plaques, records, radio blasts, and even vaginal contractions — and so far received total silence in return.

Key Points

• 1.Pioneer 10 Plaque (1972): Carl Sagan, Linda Sagan, and Frank Drake had just 3 weeks to design a gold-aluminum plate encoding hydrogen physics, a pulsar map of 14 stars, human silhouettes, and a Solar System diagram to answer "where, when, and who we are."
• 2.Universal unit of measurement: The plaque uses the hyperfine transition of neutral hydrogen (frequency ~1420 MHz, wavelength ~21 cm) as a shared unit of time and length that any advanced civilization would recognize.
• 3.Built-in error: The human figures are ~10 cm too tall relative to the spacecraft outline, likely due to a confusion between the antenna dish's major and minor axes — an oversight blamed on the extreme 3-week deadline.
• 4.Pulsar map problems: The 14 pulsars were chosen as cosmic GPS, but pulsars experience unpredictable glitches, can only be seen from specific angles, and aren't as stable as assumed in 1972 — undermining the "cosmic clock" concept.
• 5.Arecibo Message (1974): Frank Drake transmitted a 1,679-bit binary image (23×73 grid) toward globular cluster M13, 24,000 light-years away — earliest possible reply date is the year 50,370.
• 6.Arecibo was mostly a publicity stunt: Message length was capped at ~3 minutes to avoid boring ceremony attendees; M13 was chosen simply because it was visible that day; Sagan claimed a 50% chance M13 hosted alien life — later found to be extremely unlikely due to low heavy elements and unstable orbits.
• 7.Voyager Golden Records (1977): Two gold-plated copper phonograph records included 116 images, greetings in 58 languages, Earth sounds, and ~90 minutes of music — encoded using analog frequency mapping where shades of gray correspond to audio frequencies.
• 8.Record cover instructions: The aluminum sleeve encodes playback speed (~1 rotation per 3.6 seconds), image decoding method (512 slices, 4:3 ratio, ~8ms per slice), pulsar map, hydrogen diagram, and a diamond-tipped needle was physically included for playback.
• 9.Golden Record controversy: NASA rejected a nude photo of a pregnant woman; the Pioneer Plaque's female figure had no visible genitalia despite the male figure being anatomically detailed — authorship of that decision remains disputed.
• 10.Message to Altair (1983): Japanese manga magazine Weekly Shōnen Jump ran a children's competition (50,000 entries); astronomers Morimoto and Hirabayashi designed 13 bitmap images (71×71 pixels) and transmitted them toward Altair (~17 light-years) — a round-trip was theoretically possible by 2017, but no reply was detected.
• 11.Altair Message fun fact: The final bitmap included the word "TOAST" equated to the chemical formula for ethanol (C₂H₅OH) — Hirabayashi later admitted the two astronomers weren't entirely sober during the 3-day design session.
• 12.Poetica Vaginal (1986): Artist Joe Davis recorded muscular contractions from inside the female reproductive system, transmitted them toward Epsilon Eridani and Tau Ceti — the broadcast was shut down after 15–20 minutes by an Air Force Colonel overseeing the MIT facility.
• 13.NASDA Cosmic College (1995–1998): Japanese children's space camp transmitted simple 11×11 pixel bitmap images annually from Usuda Deep Space Center to various targets including Spica and unknown Libra-region stars — these transmissions received virtually no public attention and remain largely undocumented.
• 14.Encounter 2001 / Cosmic Calls (1998): Entrepreneur Charles Chafer charged $50 per person for a crowdfunded DNA-carrying light-sail spacecraft; 43,000 people signed up including Arthur C. Clarke, who submitted "Fare well, my clone!" — the project also commissioned Canadian astrophysicists Dutil and Dumas to design a step-by-step alien "primer."
• 15.Core paradox of all messages: Every interstellar message relies on assumptions about alien perception (binary, 2D images, arrows, pictograms) that could be completely wrong — yet the counterargument is that a civilization advanced enough to retrieve a spacecraft probably won't be stumped by an "interstellar cave painting."