There are currently 2 operational space stations in orbit, the International Space Station and the Tiangong Space Station. There are also 14 additional planned or proposed new space stations on the horizon.
What is the catalyst for this big boom? They are two primary reasons, the first is the United States' priority to develop a strong commercial LEO economy. The other reason is that ISS is scheduled for retirement in 2030.
NASA's plan is to replace ISS by purchasing space and services on commercial space stations. As a consequence, NASA has been working with businesses to stimulate the development of these commercial space stations. There are currently 4 commercial space stations being developed under contract with NASA.
Furthermore, the impending retirement of ISS has prompted Russia to develop their own space station to satisfy their needs post ISS.
Another contributor to the growth in space stations are new programs focused on lunar exploration such as NASA's Artemis. The Artemis program includes the establishment of a space station orbiting the moon.
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