posted 01-14-2015 06:46 AM               

The Expedition 42 crew members are safe inside the Russian segment of the ISS following an alarm in the U.S. segment at about 4 a.m.

No ammonia leak confirmed. Crew responded to coolant loop pressure increases. Crew is following safety procedures while assessments continue.

ISS flight controllers are not sure if the alarm was triggered by a pressure spike, a faulty sensor, or a problem in a computer relay box.

Following safety procedures, the ISS crew was directed to isolate themselves in the Russian segment while the teams evaluate the situation.

posted 01-14-2015 07:04 AM               

Crew safe after alarm on station

The Expedition 42 crew members are safe and in good shape inside the Russian segment of the International Space Station following an alarm in the U.S. segment at about 4 a.m. EST [0900 GMT].

Flight controllers in Mission Control at NASA's Johnson Space Center in Houston saw an increase in pressure in the station's water loop for thermal control system B then later saw a cabin pressure increase that could be indicative of an ammonia leak in the worst case scenario.

Acting conservatively to protect for the worst case scenario, the crew was directed to isolate themselves in the Russian segment while the teams are evaluating the situation. Non-essential equipment in the U.S. segment of the station was also powered down per the procedures.

In an exchange at 7:02 a.m. with Expedition 42 Commander Barry Wilmore of NASA, spacecraft communicator James Kelly said flight controllers were analyzing their data but said it is not yet known if the alarm was actually triggered by a leak or whether the situation was caused by a faulty sensor or by a problem in a computer relay box that sends data and commands to various systems on the station.

posted 01-14-2015 07:53 AM               

Good news for you guys. We started back up the Node 2 LTL [Low Temperature Loop] and right now everything is looking normal. We've got almost complete insight back and so everything is looking pretty normal right now, so it is becoming a stronger case this is a false indication, which is great news. We're going to keep continuing down this path, just wanted to pass on to you that it is a little more positive than we thought before.

So we're working towards making sure this is a false indication and getting you back in the other [USOS] side. No idea when that would happen. I would still lean towards the fact you guys won't re-ingress tonight but we're heading down this path and we'll keep you guys updated.

There's a possibility that this is a combination of sensor problems, MDM [Multiplexer-Demultiplexer] partial failures and thermal effects all thrown together in the exact wrong way to make this thing look like it was your classic ammonia leak.

Bottom line is we've got all the experts here coming in now and pouring over the data. We've got all the smart folks looking at it and we're trying to figure out exactly what is going on.

...we wish we had more for you guys to do at this point. We don't. Enjoy your impromptu day off and we'll keep you informed on what is going on.

posted 01-14-2015 11:29 AM               

Ammonia leak alarm on space station has crew evacuate to Russian segment

A possible toxic ammonia leak inside the International Space Station on Wednesday morning (Jan. 14) caused the crew to evacuate to the Russian segment of the orbiting outpost, but further analysis by NASA flight controllers suggest it was likely a false alarm.

At around 3 a.m. CST (0900 GMT) on Wednesday, flight controllers in Mission Control at NASA's Johnson Space Center in Houston saw an increase in pressure in a water loop for the space station's thermal control system B, one of two redundant coolant loops that regulate temperatures aboard the orbital laboratory. They then saw an increase in cabin pressure that could have indicated an ammonia leak inside the station...

posted 01-14-2015 02:55 PM               

Astronauts re-enter U.S. side of station

The crew onboard the International Space Station has re-entered the U.S. side of the orbiting laboratory, 11 hours after evacuating into the Russian segment due to a possible toxic ammonia leak.

Expedition 42 flight engineers Terry Virts and Samantha Cristoforetti, both wearing protective face masks, were the first to re-enter the U.S. segment at 2:05 p.m. CST (2005 GMT). The two astronauts sampled the atmosphere in the modules and reported finding no indications of ammonia.

Above: Astronauts Butch WiImore (front) and Terry Virts entered the U.S. segment wearing protective masks.

Shortly thereafter, the hatch separating the U.S. and Russian sides of the complex was opened and the rest of the crew, including NASA astronaut and Expedition 42 commander Barry "Butch" Wilmore," was allowed to doff their masks and enter the U.S. segment to resume normal operations.

Prior to Virts and Cristoforetti taking air samples, flight controllers in Mission Control at NASA's Johnson Space Center in Houston studied data received from a variety of the space station's onboard systems, which also indicated no leakage of ammonia. The alarms that initiated the movement of the crew out of the U.S. segment early Wednesday morning (Jan. 14) are suspected to have been caused by a transient error message in one of the station's computer relay systems, called a multiplexer-demultiplexer (MDM).

Commands were sent from the ground to turn that relay box off and then back on again, which cleared the error message. The relay box is now reported to be in good operating condition.

Flight controllers are continuing to analyze data in an effort to learn what set today's actions in motion. Work to reactivate the station's cooling loop B will continue throughout the night and into the day on Thursday. The crew is expected to resume their normal schedule of research activities on Thursday as well.