Orbital-1 rolls out to Pad 0A December 17 at the Mid-Atlantic Regional Spaceport. Image source: NASA.
A problem with an ammonia pump valve outside the International Space Station will force NASA to postpone the first official Orbital Sciences cargo delivery from December 19 to at least mid-January.
Three spacewalks are planned for December 21, 23 and 25 to resolve the problem.
NASA managers are postponing the upcoming Orbital Sciences commercial cargo resupply mission to the International Space Station to proceed with a series of spacewalks to replace a faulty pump module on the space station.
NASA Television will air a news briefing at 3 p.m. EST on Wednesday, Dec. 18 to preview the spacewalks.
Orbital Sciences' Cygnus spacecraft, atop its Antares rocket, now will launch no earlier than mid-January. The postponement of the Antares launch will allow ample time for the station crew to focus on repairing a faulty pump module that stopped working properly on Dec. 11.
NASA currently plans for two Expedition 38 astronauts to venture outside the space station Dec. 21, 23 and 25. NASA astronauts Rick Mastracchio and Mike Hopkins will remove a pump module that has a failed valve. They will replace it with an existing spare that is stored on an external stowage platform. The pump is associated with one of the station's two external cooling loops, which circulate ammonia outside the station to keep both internal and external equipment cool. Each of the three spacewalks will begin at 7:10 a.m. and is scheduled to last six and a half hours. NASA TV coverage will begin at 6:15 a.m.
According to an Orbital press release, the earliest launch date for Orbital-1 will now be January 13, 2014.
Postponing Cygnus by a month might also push back the next SpaceX Dragon delivery to the ISS, currently scheduled for the end of February.
It's important to keep in mind that unscheduled repairs like this are part of humanity learning how to maintain a permanent foothold in space. Sometime in the 21st Century, it's likely that human outposts will be deployed beyond Earth orbit. Incidents like this will become a regular part of life for their inhabitants. The ISS is where we learn how to do this.
UPDATE December 19, 2013 — Here's the video of yesterday's NASA media event about the upcoming spacewalks:
Click the arrow to watch the video on YouTube. Video source: NASA.