There are now 40 nations in the United States' moon-exploration coalition.
Lithuania joined the club on Wednesday (May 15), signing NASA's Artemis Accords during a ceremony in Vilnius.
"Welcome to the Artemis Accords family, Lithuania," NASA Administrator Bill Nelson said in a statement.
"Our nations are strong partners — and now we expand this partnership to the cosmos," Nelson added. "In just four years, a remarkable 40 countries have signed the Artemis Accords. Together, as a global coalition, we will explore the stars openly, responsibly and in peace."
Related: Cooperation on the moon: Are the Artemis Accords enough?
As Nelson noted, the Artemis Accords lay out a framework for sustainable and responsible exploration of space destinations like the the moon.
NASA is eyeing Earth's nearest neighbor intently. The agency plans to establish a permanent human presence on and around the moon by the end of the decade via its Artemis program, which has launched one mission to date — Artemis 1, which sent an uncrewed Orion capsule to lunar orbit and back in late 2022.
Sustained crewed exploration will be a difficult and expensive undertaking, one that requires cooperation with industry, academia and international governments, NASA officials have stressed. And the agency is lining up many such partners, as the ever-growing tally of Artemis Accord signatories shows.
Those signatories include some major players in space exploration, such as France, Germany, India, Israel, Japan, South Korea, the United Kingdom and (of course) the United States.
China has serious moon ambitions as well; it plans to set up a crewed outpost called the International Lunar Research Station in the 2030s.
Like the U.S., China is enlisting international partners to aid in this effort. Russia is the chief partner; others include Azerbaijan, Belarus, Ethiopia, Kenya and Serbia.
