Tag: emergency

Practicing emergencies is necessary so I accept that the volunteer fire department near our home at Hochstadt runs their siren in the evening, even though it excites our 3-year-old daughter just before bedtime. We also need to practice emergencies on the International Space Station in space you cannot phone highly-trained rescue workers to come to the rescue. Astronauts must be able to fend for themselves, extinguish a fire and protect themselves from any fumes. Even radio contact with experts in control centers cannot be assumed to work in a worst-case scenario.

In today’s emergency exercise the control centres and astronauts worked together on a so-called On-Board Training or simply OBT. We had “stage directions” that defined for example that a leak would appear in the Japanese Kibo module through which air would escape.

The alarm sounded on the Space Station with its penetrating noise and the computer screens of our Flight Controller filled up with numerous error messages, proving that the International Space Station had configured itself in emergency mode. The astronauts onboard reported shortly afterwards to Mission Control Houston with the news that they had a pressure drop on the Space Station to contend with. All radio communication between crew and flight controllers began with the words “For the workout exercise:” to ensure that everybody knew it was not a real emergency, but an exercise.

The flight director in Houston declared a “Space Craft Emergency” – of preceded by “for the training exercise”. Sinje Steffen of the STRATOS team at the Columbus Control Centre checked whether Columbus was automatically reconfigured for this Rapid Depress scenario.

The astronauts convened in the meantime 350 km above close to their Soyuz spacecraft. Since the Russian capsules are the Station’s lifeboats, each astronaut has a well-defined place there. They are usually the first assembly point of crew in an emergency. Once there, they decide together on how to proceed based on the scheme “Warning – Gather – Fight”. In our emergency script scenario, the astronauts had about five hours until critical low pressure (designated as T.Res) would be reached – time enough to try to find the leaking module and possibly stop the International Space Station from ‘bleeding out’.

The astronauts followed the well-defined sequence to close various hatches to measure on which side the pressure dropped further. Slowly they were able to find their way closer and closer to the actual leak.

Columbus Flight Director Katja Leuoth and her team was busy keeping up with the falling pressure values: a long list of minimum air pressure certification values exist for all Columbus components – each of these elements had to be switched off before their critical pressure was reached. Today’s commands were “for the training exercise”, so actual commands were not issued and power was not actually switched-off…

The rapid pressure-drop (rapid depress) is one of three major emergency scenarios that are defined for the International Space Station.

Depending on the size of the leak, there are various ways to “clog the hole”: from an oversized bicycle-patch to a plasticine-like material. All sealing is done of course from inside the space station – and is easy: Compared to the vacuum of space the pressure inside the ISS is considerable higher and pushes any seal onto the leak – a clear advantage compared to repairing a bicycle inner tube…

Thomas Uhlig, Columbus Control Centre

In the photo: astronaut Samantha Cristoforetti during an emergency simulation.

---

Don’t panic is written in large letters across the Hitchiker’s guide to the galaxy in Douglas Adam’s novel of the same name. Don’t panic was also our motto yesterday in the Columbus Control Centre in Oberpfaffenhofen, Germany as well as in the International Space Station control centres in Houston, Moscow and Tsukuba, Japan.

At 9:44 CET an emergency alarm was triggered on the International Space Station that implied ammonia from the external cooling circuit could have leaked into its interior. Following emergency protocol the astronauts quickly went to the Russian part of the Station as no ammonia is used for the cooling circuits in those modules. The astronauts could see from air measurements that they were perfectly safe in the Russian segment.

From the start there was some doubt as to whether ammonia really was leaked but for safety the crew was told to stay in the Russian segment while the situation was analyzed in detail. The astronauts were fast to inform us that they were fine: Samantha tweeted to the world: “Thanks for your concern, we are all doing well!” In this type of emergency the external ammonia cooling circuit is quickly shut down and working pressure is reduced to prevent further inflow of toxic gas to the modules. Yesterday the ammonia loop B was shut down meaning half the cooling performance of the Space Station was no longer available. The Columbus Control Centre had to partially shut down the Columbus space laboratory to reduce heat production. While the astronauts waited for the call to reopen the hatch, the control centers were busy trying to get a first idea of what was happening and adapt the Station’s configuration to the new situation. While we were doing this experts were called in to find out why the emergency alarm sounded. In the afternoon we came to the conclusion that the reported measurements that triggered the alarm could not be trusted. Detailed analysis based on other measurements indicated a computer problem and not a real emergency scenario. In the evening the crew was given a “Go” to enter the American part of the Space Station wearing gas masks and take measurements – no ammonia was detected. At around 21:00 CET the astronauts opened the hatch and could sleep in the American part of the station. Although the danger was a false alarm the B Loop is still shut down – we do not want to rush things but bring the Station slowly back to full operations from its present configuration. The emergency has evolved into a scheduling problem for us as we try to readjust the schedule to make up for the lost time.

In a way the situation happened at the best possible time. The astronauts were just about to set up experiments with living fruit flies and other biological experiments. These experiments would have failed if they had left them alone during their time in the Russian segment. ‘Luckily’ the alarm was triggered just before they started so the experiments will be able to run safely in the near future.

The experiments and hardware in the Columbus laboratory seems to have survived the emergency power down as well. Tomorrow we think Samantha and Terry will be able to conduct the first session of the Airway Monitoring experiment as planned despite yesterday’s problems.

In conclusion: if there really had been an ammonia leak, the astronauts and control centres had the situation fully under control. But this is a reminder to us all of the importance of training for emergencies over and over again and to play them out in our minds, so when they happen we don’t panic…

Thomas Uhlig, Columbus Flight Director

Original blog post (in German): https://www.dlr.de/blogs/de/desktopdefault.aspx/tabid-9260/15960_read-791/