Cosmic Call was the name of two sets of interstellar radio messages that were sent from RT-70 in Yevpatoria, Ukraine in 1999 (Cosmic Call 1) and 2003 (Cosmic Call 2) to various nearby stars. The messages were designed with noise-resistant format and characters.^[1][2]

The project was funded by Team Encounter,^[3] a Texas-based startup, which went out of business in 2004.^[4]

Both transmissions were at ~150 kW, 5.01 GHz (FSK +/-24 kHz).^[5]

Each Cosmic Call 1 session had the following structure. The Scientific Part (DDM, BM, AM, and ESM) was sent three times (at 100 bit/s),^[6] and the Public Part (PP) was sent once (at 2000 bit/s),^[6] according to the following arrangement:

DDM → BM → AM → ESM → DDM → BM → AM → ESM → DDM → BM → AM → ESM → PP,

where DDM is the Dutil-Dumas Message,^[7][8] created by Canadian scientists Yvan Dutil and Stéphane Dumas, BM is the Braastad Message, AM is the Arecibo Message, and ESM is the Encounter 2001 Staff Message.^[6]

Each Cosmic Call 2 session in 2003 had the following structure:

DDM2 → DDM2 → DDM2 → AM → AM → AM → BIG → BIG → BIG → BM → ESM → PP,

where DDM2 is modernized DDM (aka Interstellar Rosetta Stone, ISR), BIG is Bilingual Image Glossary.^[5] All but the PP were transmitted at 400 bit/s^[5]

The ISR was 263,906 bits; BM, 88,687 bits, AM, 1,679 bits; BIG was 12 binary images 121,301 bits; ESM 24,899 bits. Total = 500,472 bits for 53 minutes. PP was 220 megabytes and sent at a rate of 100,000 bit/s for 11 hours total.^[5]

The DDM incorrectly states the neutron mass as 1.67392... instead of the known value 1.67492... This error was corrected in DDM2.

The messages were sent to the following stars:^[9]

• Arecibo message
• Active SETI
• Communication with extraterrestrial intelligence
• Interstellar messages