A planned spacewalk outside the International Space Station on Thursday was canceled late Wednesday due to a “medical concern” with an unidentified crew member, NASA said in a statement.
An update shortly before midnight said the agency was “exploring all options, including the possibility of ending Crew 11’s mission early.”
NASA 
“These are the scenarios that NASA and our partners train for and prepare to execute safely,” the update said. “We will provide further updates over the next 24 hours.”
While NASA did not identify the astronaut in question or explain the medical problem (a common practice due to privacy concerns), the agency said “the subject was the only stable crew member.”
Space station commander Mike Fincke, flight engineer Zena Cardman, Japanese astronaut Kimiya Yui and Russian cosmonaut Oleg Platonov launched aboard a SpaceX Crew Dragon ferry in August. 1.
Heading into the new year, the crew expected to remain in space until their replacements arrived in mid-February. Crew 11 is expected to return to Earth around February 20. That’s still the official plan.
Meanwhile, Cardman, 38, and Fincke, 58, a veteran of nine spacewalks on previous missions, planned to venture outside the station Thursday to finish building a truss needed to expand the solar array and perform other scheduled maintenance.
A second unannounced spacewalk by two astronauts was scheduled for next week.
NASA 
But NASA canceled the first spacewalk early Wednesday, saying “the agency is monitoring a medical issue with a crew member that originated Wednesday afternoon. Due to medical privacy concerns, it is not appropriate for NASA to share further details about the crew.”
“The situation is stable. NASA will share additional details, including a new date for the next spacewalk, at a later date.”
In a brief radio exchange from space to ground after 2:30 pm EST, Yui called mission control in Houston and requested a private medical conference, or PMC.
Mission control responded that a PMC, using a private radio station, would be established momentarily. Yui then asked if a flight surgeon was available and the flight controllers had a live camera view from inside the station.
“Houston, do we still have a camera view on node 2, uh, lab 3?” Yui asked.
“We don’t have an internal camera right now, but we can put in a lab view if you want,” the mission control communicator replied.
“I appreciate that,” Yui replied. Then he asked, “Do you have a crew surgeon? . . . a flight surgeon?”
No additional exchanges were heard. Later Wednesday, the audio stream from NASA’s space station, normally live around the clock on YouTube, went silent without explanation.