The message that will be used in Wednesday’s test was designed by a team led by Daniela de Paulis, a media artist and former contemporary dancer who is also a ham radio operator. She is an artist in residence at the SETI Institute and at the Green Bank Observatory, which is home to a giant antenna run by the National Radio Astronomy Observatory, in Green Bank, W.Va. Ms. de Paulis’s work is centered on space, and no one will know what her message says until they decipher it.

If they can.

In 1974, Frank Drake, the father of SETI, designed a message to be beamed into space by the now defunct Arecibo radio antenna. It consisted of 1,679 zeros and ones. When arranged in rows and columns, it formed pictures of a stick man, a DNA helix, numbers and more. None of Dr. Drake’s colleagues at Cornell University, including Carl Sagan, the famed evangelist of extraterrestrial life, could completely decipher it.

Wednesday’s event will start with the ExoMars Trace Gas Orbiter, a robotic explorer operated above Mars by the European Space Agency. The spacecraft will transmit the encoded message at 3 p.m. Eastern time. A quarter of an hour later the signal will arrive at Earth, where three telescopes will be listening for it: the SETI Institute’s Allen Telescope Array in Northern California; the Robert C. Byrd Green Bank Telescope in West Virginia; and the Medicina Radio Astronomical Station near Bologna, Italy.

Teams at each observatory will process the signal and then share it on the experiment’s website. And then all Earthlings can have at it.