"Years ago, Fermi famously questioned the existence of intelligent life throughout the universe," says experimental philosopher Jonathon Keats. "Fermi asked, 'Where is everybody?' Maybe the reason we've never encountered aliens is that they never felt invited. From an outsider's perspective, human behavior can appear pretty unfriendly, and that impression has some truth to it."

To counter the hostility of his species, and to communicate hospitality to aliens, Mr. Keats enlisted the most welcoming of human inventions. His cosmic welcome mat, developed in consultation with Flinders space archaeologist Alice Gorman, translates the concept of welcomeness into a visual language that all sentient beings can potentially comprehend.

"In fact, the mat comes in four different versions," says Dr. Gorman. "Since we can't make any assumptions about beings we've never encountered, and certainly can't assume that they're versed in human culture, it's important to present them with different options built on different premises." For instance, one version of the mat expresses welcomeness in terms of geometric fit, while another does so by biological analogy, evoking room for growth.

Dr. Gorman and a team of Flinders students will rigorously monitor use of the intergalactic doormats, employing standard archaeological sampling techniques. The carpeting will be regularly vacuumed for sediment. Comparison of sedimentary deposits can provide important data about how effectively welcomeness has been communicated by each design. These data will inform future iterations of the mat, slated for distribution worldwide, and potential future deployment on the International Space Station.