Odissea was the generic name of a series of balloon launch campaigns transporting scientific/technological payloads which were carried out on the Mediterranean basin from Sicily to the southeastern coast of Spain.
The effort involved a three part agreement between Italy, France and Spain. By the Italian side the collaboration consisted in the use of the Trapani-Milo launch base, all the necessary hardware, a ground crew and initial tracking after launching. The French were in charge of the launch operation itself, providing the operational staff, the balloons and helium used. Finally the Spanish side offered trought the INTA (Instituto Nacional de Tecnica Aeroespacial) tracking/telemetry coverage over the Mediterranean sea using two stations, one located in Palma de Mallorca (39º 36'N 2º 41'W) and the other in El Arenosillo (37º 6'N 6º 44'W) near Huelva. INTA also was in charge of the recovery operations once the payloads touched Spanish soil.
The initiative's name is -according to some sources- due to Mr. Armand Soubrier chief of the balloon sector of CNES at the time and was inspired in the infamous epic poem which Homer wrote in the eight century BC probably as a metaphore of the exploratory spirit fueling the balloon effort. This was also evident in the name of several of the missions performed that were named after characters found in Homer's masterpiece: ULYSSES, NAUSICAA, POLIFEMO, CIRCE or TELEMAQUE to name a few. Even the launch vehicle used in Trapani-Milo base to transport and hold the payloads during launches was baptized as "PENELOPE".
The flights were carried out in summer when the winds blow from east over a more or less straight line following the 38º parallel. The major part of the flight was over open sea overflying land just at the end of each mission. The first of such flights was launched from Trapani-Milo in August 6, 1977 traveling in 20 hours to Spain. That maiden flight marked the start for a succesfull cooperative effort between the 3 countries which allowed the realization of more than 40 balloon-borne missions for several laboratories and Universities from Europe and the rest of the world, in a program that spanned through the entire decade of 80's and the first years of the following.
The Odissea agreement ended in 1992 after suffering the retirement of the French part, but the transmediterranean balloon flights were continued by the Agenzia Spaziale Italiana (Italian Space Agency or ASI) and their Spanish colleagues, with the italians taking over the entire management of the balloon operations.
Several flights were performed until July 2002 when was carried out the last mission completing a total of sixty six successful transmediterranean crossings.