A crew member aboard the International Space Station has a medical issue that forced postponement of today's two-astronaut spacewalk — and NASA is considering sending the Crew-11 astronauts home earlier than planned, the agency announced.

NASA did not identify the crew member or provide details on the medical concern, citing privacy issues in a brief blog post. The crew member's medical condition arose the afternoon of Wednesday, Jan. 7, and the member is in stable condition.

"Safely conducting our missions is our highest priority, and we are actively evaluating all options, including the possibility of an earlier end to Crew-11’s mission. These are the situations NASA and our partners train for and prepare to execute safely," a NASA statement said.

NASA public affairs personnel did not immediately return messages seeking more information this morning.

NASA astronauts Mike Fincke, the ISS commander, and Zena Cardman, a flight engineer, were scheduled to exit the ISS and perform power upgrade work during a 6½-hour spacewalk, including installing equipment and routing cables for a future solar array.