The crew undocked from the orbiting outpost at 5:20 p.m. ET Wednesday — about a month earlier than planned —and are scheduled to splash down on Earth early Thursday.

With its departure ahead of Crew-12's arrival, Crew-11 leaves behind a skeleton crew of three aboard the ISS, including Kud-Sverchov and fellow cosmonaut Sergei Mikaev as well as NASA astronaut Chris Williams. Crew-12 is currently scheduled to launch no earlier than Feb. 15.

The International Space Station has gone from seven crew members down to a "skeleton crew" of three due to a recent medical evacuation.

Four astronauts returned to Earth early Thursday morning after leaving the International Space Station a month early because of a medical issue.

After more than five months in space, four astronauts on a mission known as Crew-11 are about to cut their mission short and return to Earth.

All four Crew 11 fliers looked healthy and in good spirits on a space-to-ground television broadcast of the change of command ceremony with no indication of which astronaut may have experienced the undisclosed medical issue that triggered Crew 11's early departure.

In a new study, terrestrial bacteria-infecting viruses were still able to infect their E. coli hosts in near-weightless "microgravity" conditions aboard the International Space Station, but the dynamics of virus-bacteria interactions differed from those observed on Earth.