In July 1945, a test conducted in the deserts of New Mexico officially propelled humanity into the nuclear era. Only weeks after the Trinity Test, two atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki.In the following decades, while no other nuclear device was detonated in an act of war, military tests and studies continued.Seventy-five years later, space archaeologists are wondering how to warn humanity of the future that the sites where these experiments were carried out are still dangerous, Alice Gorman, associate professor at Flinders University in Adelaide, Australia, told The Jerusalem Post. “Teenagers nowadays do not understand how to work a dial telephone, a device that was incredibly common only one or two generations ago,” she said. “The type of plutonium used in the Trinity Test, plutonium-239, has a half-life of 24,000 years, meaning that after this time, only half of it will have decayed into a safe, non-radioactive element. How do we communicate to people living then that the site is dangerous?”Gorman said the issue presents two challenging elements: What materials can survive such a long time, and what form of language can be used to deliver the actual message?“As for the first difficulty, we know that stones and pottery last a very long time,” she said. “But the second point raises a big archaeological question related to symbolic communication. If we look at rock art from 20,000 years ago, we can see that there are pictures of animals, but we do not know what those pictures mean. Therefore, it is possible that our current symbols to mark radioactive sites, the yellow [and] black sign, will be interpreted as an invitation to explore the area, rather than to keep away from it.”The issue is especially important for archaeologists of the future because in some cases, while the danger would be very limited or not even relevant on the surface, the nuclear waste and its radiation are deeper in the ground, and conducting a dig would be especially risky. For example, such is the case of Maralinga, a remote area in southern Australia where the UK conducted several nuclear tests. Some nuclear tests were conducted in outer space, and nuclear fuel was employed as propellant for rockets.If the UN Outer Space Treaty of 1967 prohibited nuclear weapons in space, the issue of its weaponization remains very relevant.“Recently, Russia tested an anti-satellite weapon, reawakening the debate,” Gorman told the Post.She began to work in space archaeology following years of work focused on stone-tool analysis and the aboriginal use of bottle glass after European settlement.Space archaeology deals with the same issues of regular archaeology, understanding material culture, human behavior and the interaction with the surrounding environment, Gorman said.“However, we are looking at the post-Second World War period, when the very same rockets that had been developed as missiles started to send spacecraft into orbit,” she said. “We are interested in all of what is on earth, like rocket launch sites or tracking antennas and reception development, as well as town or residential areas where people who worked on these projects live, but also satellites, space junk and all the places on other planets where humans have sent spacecrafts.”“We are asking the same questions other archaeologists are, but we have the limitations that we cannot visit many of the sites in person, and instead, we have to rely on records or images,” she added.Gorman was drawn to space archaeology by the idea of exploring space junk, those many objects that cannot even be seen in the sky circling the Earth. Currently, she is working on the archaeology of the International Space Station. The recent attempt by Israel to land a robotic unit on the moon with the Beresheet mission represents a very interesting development for space archaeologists, Gorman said.“For many decades, the only material cultures present on the moon were the American and the Soviet one,” she said. “As new countries have started to reach the moon, this has changed, bringing more diversity to the field.