Tiangong-1 is dead. Long live Tiangong-2.

China’s first space station fell to the Earth on April 2, disintegrating over the Pacific Ocean off the coast of South America. Launched in 2011, contact with the station was lost in March of 2016, leaving the station beholden to the forces of atmospheric drag and gravity, and ultimately to its fiery end. It will be missed.

While China aggressively pursues a manned space outpost, the countries behind the only other space station in orbit are gradually withdrawing their support.

The news isn’t all bad for China’s space program, however. While Tiangong-1’s uncontrolled reentry was unplanned, it outlived its original two-year mission by almost two and half years. The station was designed to be replaced, and its successor, Tiangong-2, is already in orbit, launched in September 2016. That station is meant to be a temporary testbed for refueling procedures and medium-term habitation, in preparation for a permanent space station, which China aims to start constructing in 2019. For a nation which only achieved manned spaceflight in 2003, China’s space program is moving at a rapid pace.

While China aggressively pursues a manned space outpost, the countries behind the only other space station in orbit are gradually withdrawing their support from the existing station. NASA’s 2019 budget proposal removes funding for the International Space Station past 2025, and the European Space Agency has not pledged support for the station beyond that timeframe. The U.S. has floated the idea of privatizing portions of the space station beyond 2024, transitioning its control to “commercial partners,” which NASA would then cooperate with to continue research in low-earth orbit.

Changing attitudes towards space stations reflect geopolitical trends and evolving goals for space exploration. Constructing and inhabiting a space station has long been considered a marker of success for a country’s space program; soon after the race to the moon, the U.S. and U.S.S.R. raced to build space stations, leading to Skylab and the Salyut Program, respectively. For countries with burgeoning space programs like China or India, constructing space stations is a logical goal. On the other hand, countries which have already proven they can sustain a space station have decreasing incentive to continue doing so.

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The International Space Station turns 18 this year, which, along with high costs and a new station on the horizon, has the involved countries asking themselves serious questions about the future of the ISS and their spaceflight programs.

Photo courtesy of NASA

Space stations have a unique scientific role as a place to conduct experiments in microgravity, especially on sensitive organisms like crops and humans. They’re also incredibly expensive to maintain. Supporting human life amid the vacuum of space necessitates recycling systems up the wazoo for water, air, and heat. Resupply missions must bring fuel and supplies at regular intervals if a station has long-term inhabitants. Communicating with a station means expensive equipment and tracking stations around the world. The International Space Station has cost over $160 billion in its 18 years of life and has an annual operating cost of $3-4 billion.

With the ISS old enough to smoke and play the lotto, some believe it’s time to set higher goals for space exploration.  How much higher? 100 million miles or so. Dr. Daniel Barry, a former astronaut whose three Space Shuttle missions included the first docking with the ISS, writes that “it’s time to go to Mars.” He believes that human exploration of the Red Planet is necessary to further the search for extraterrestrial life and insure humanity’s long-term survival. Human researchers are necessary for the “observation and appropriate sampling” of rocks and strata on Mars which could contain traces of life, says Barry, and he regards a colony on Mars as a way to “ensure human immortality.”

Missions to the Moon and Mars would provide a practical outlet for research conducted aboard the ISS.

While immortality is nearly always a hyperbolic claim, the scientific benefits of a Mars colony are plentiful, and U.S. space policy outlined by President Trump emphasizes “ the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations.” Such a program would likely be a replacement for most ISS activities and a fitting fulfillment to the station’s aims. Missions to the Moon and Mars would provide a practical outlet for research conducted aboard the ISS into long-term effects of life in zero-G and efficient ways to support life in an isolated environment. The spirit of international cooperation developed throughout the ISS program would be vital to any large-scale colonization of territory beyond our Blue Marble.

Will space stations truly be abandoned by countries in favor of daring interplanetary expeditions á la Magellan and Cook? Probably not; at least for a few decades. Grand plans for space exploration are fraught with logistical complications and uncertainties. It will be a hard sell to decommission the ISS before the end of its usable life, currently estimated to be around 2028. By that time, newly delineated uses for an ISS-type station might muster support for a replacement, China’s station should be midlife, and new countries may be on the scene. Still, it’s important to have some more imaginative goals for space exploration. It just won’t be much fun if we stay in low-Earth orbit forever.