The European Space Agency, or ESA, was a multi-national Human space exploration organization founded in the late 20th century Europe. This agency would apply the lessons and knowledge learned in the Apollo program to their own endeavours. (Star Trek: Insurrection)
In 2143, the Ariane 1 assignment patch, which was on display in the 602 Club, bore the flags of ESA members: Sweden, Switzerland, Germany, Denmark, Italy, United Kingdom, Belgium, Netherlands, Spain, France, and Ireland. (ENT: "First Flight")
Many of these nations were members of the International Space Agency in the 21st century, according to the Star Trek Fact Files.