WASHINGTON — NASA postponed a spacewalk outside the International Space Station by two astronauts just hours before it was scheduled to start after getting a warning that debris would pass close to the station.

In a brief statement issued early Nov. 30, NASA said a “debris notification” it received on the evening of Nov. 29 led the agency to postpone the spacewalk by astronauts Tom Marshburn and Kayla Barron, which had been scheduled to start at about 7:10 a.m. Eastern. The two had planned to replace an S-band antenna on the station’s truss that recently lost the ability to transmit data.

“Due to the lack of opportunity to properly assess the risk it could pose to the astronauts, teams have decided to delay the spacewalk until more information is available,” NASA said in the statement. The agency did not identify the debris in question or the times and distances of closest approach to the station.