Any child born on or after November 2, 2000, belongs to a slightly different category of human being than the rest of us old-timers. Prior to that date, humans had managed to escape Earth’s gravity on multiple occasions, but mankind’s space-borne escapes had all been of the temporary sort. On that date, however, the International Space Station’s first long-term crew climbed aboard what would become their home for the ensuing months, and ever since that date humanity has maintained a permanent presence in orbit above our planet.

For the past 18 years, human beings have been more than just an incredibly bright species of ape clinging to our small bit of rock as it circles our ordinary star — we’ve been the physical embodiment of the next evolutionary step. Over the span of nearly two decades, there has been a continuously manned presence in space — a concept that we’ve come to accept as absolutely ordinary, despite that 18-year window coming only at the most recent end of a 300,000 year span in which Homo Sapiens — genetically no different than you and I — have walked this earth.

After three hundred millennia of human beings scrambling to survive on the planet they were born on, we’ve now spent almost two decades as a species that could support life in even the most inhospitable of places, in a realm of existence most of our ancestors failed to even grasp as a physical reality. We’ve become more than the smartest species on our planet… the permanent crew operating aboard the International Space Station makes us something that, to our current knowledge, has never existed before: a species that isn’t entirely co-located on the same bit of celestial rock.

However, the failure of a Russian Soyuz rocket with two crew members on board two weeks ago now places humanity’s short stint in this new genus of our species at risk: the American astronaut and Russian cosmonaut that had to abort their launch were expected to serve aboard the International Space Station for months to come, allowing the current crew a much-needed opportunity to return home. With another launch scheduled for December and an ongoing investigation into what caused that last rocket to fail, there seems a reasonable chance that any subsequent launches may be scrubbed over safety concerns. At that point, NASA and Roscosmos administrators will be left with a question: do you extend the three-person crew living aboard the ISS indefinitely… or do you bring them home and surrender humanity’s status as a space-fairing species?

The International Space Station could theoretically be left uninhabited for some time and still remain functional, but timing may be conspiring against it. Funding for the International Space Station is already expected to dry up by 2021, with NASA enacting a plan soon thereafter to begin de-orbiting the massive platform on a trajectory that would guarantee its destruction without risking any surface impacts. With ties between Russia and the United States once again in jeopardy, accusations of sabotage aboard the space station itself, no existing manned space flight program out of the United States, and a questionable one in Russia… there’s a solid chance that our short streak as space-monkeys may soon be at an end.

At 239 feet long and 356 feet wide, the International Space Station is a habitat unlike any found on earth. Built to support twice the crew that can currently be found on board, the ISS is a marvel of human ingenuity and problem solving. And whether it comes to an end in the next few months or the next few years, it’s never been more apparent that this spectacle of human achievement is operating on borrowed time.

Take an in-depth tour of the technological marvel that is the International Space Station below: