Late word has it the launch of Orbital’s Cygnus resupply spacecraft is being delayed due to the cooling problem in the ISS.
Orbital was to launch Cygnus on Tuesday (17-Dec) now are looking at launching no earlier than Thursday (19-Dec) to give ISS experts more time to look at the the problem flow-control valve in the ISS cooling system. Currently engineers are trying to stabilize the cooling loop using another valve to help regulate temperatures in a steady fashion. To that end the engineers are operating a Radiator Return Valve, putting it in various position and checking the results. This is a perfectly reasonable approach and although the precision of control would suffer, it could work just fine in a pinch; in the meantime cooling is provided by Cooling Loop B.
The “second-valve” approach would probably not be something they would want to count on in the long run so repairs are still being evaluated and space suits are being checked for leaks in case the crew are needed to conduct a spacewalk to replace the faulty pump module.
The possibility of the Cygnus launch being delayed until after the first of the year is not at all out of the question.