33.

International Space Station, 14 January 2015

If Mission Control wanted to surprise us with an emergency drill, it would choose a moment like this one, so as not to compromise the activities on board. But we don’t have surprise emergency drills on the Space Station, so it’s only a lucky coincidence that the alarm goes off mid-morning, when we’re all engaged in non-critical activities. It could have been different. We might have been scattered throughout the Space Station, a long way from one another, bent over some delicate operation. Or we might have been holding a cold bag full of scientific samples that had to be transferred quickly from Dragon to an on-board freezer – I did that yesterday for several hours. Or we might just have been on T2, harnessed, or in the toilet, having started but not concluded our business … Instead, Terry, Butch and I are all floating between Node 2 and the Lab. Sasha, Anton and Yelena are in the Russian segment.

When the siren goes off, I’m the first to realize that it’s not the overused fire alarm, the one we’ve begun (oh dear!) not to take very seriously, since it has gone off several times, only to prove a false positive on the Russian smoke detectors. No, this time it’s not the same old script. From a distance, I can clearly see that the third light from the left is on on the Caution and Warning panel at the back of the Lab. The much-feared third light from the left. There’s an ammonia leak.

‘Maaaaasks!’ I cry with all my strength, while opening the closest store of oxygen masks. Terry and Butch start doing the same. We move quickly aft, and they stop in the narrow, funnel-shaped tunnel that connects Node 1 to the Russian segment. I go a bit further, as far as I need to see Sasha, Yelena and Anton, and confirm that we’re all on the right side. Terry and Butch proceed to close the rear hatch of Node 1, and then they come further aft and close the next hatch. Now we’re isolated in the Russian segment.

Ammonia is not used for cooling in here, so there’s no danger of it leaking, but we can’t just remove our protection: the air in the Russian segment could have been contaminated before we closed the hatches. Our oxygen masks will only last seven to eight minutes, so our most urgent need is to prepare the respirators, fitting them with ammonia filters. The ones for our Soyuz crew are in the MIM-1 module. I open the bags and take out the pieces, while Terry updates Houston, trying to make himself heard over the radio with the mask on. Butch is still floating at the junction between modules, where he can see both crews at work. We’re about to change our masks when CAPCOM interrupts: ‘Station, this is Houston. False alarm.’ It seems we’ve had our surprise drill after all.

All the hands that were unwrapping, installing, browsing and rummaging through things suddenly stop, suspended in action like the limbs of puppets abandoned by the puppeteer. We hesitate for a moment, each implicitly seeking confirmation from the others that we’ve understood properly before taking off our masks. We’re relieved, of course, but our reaction is measured. After all, none of us has manifested symptoms of poisoning, so we don’t feel that there was any immediate risk, or that we narrowly escaped danger. And in the dash to follow procedures by memory and get into the Russian segment, perhaps none of us stopped to reflect on an unanswerable question: if the other side had really been contaminated with ammonia, would we ever have been able to reopen those hatches?

We’re back in the Lab now, and there’s an unnatural silence: as soon as the alarm went off, the Space Station’s auto-response shut down all the fans. Ground controllers will take care of turning them back on. But also up here we can’t just go back to what we were doing: the meticulous order of the Space Station – disguised by the apparent mess, the spaces overflowing with stuff – has been disrupted. Houston and Moscow want to know exactly which masks were used and therefore will now be at least partially unusable; what other equipment we employed; the status of the valves and hatches. CAPCOM also poses a question I find curious: ‘Did one of you activate the manual alarm?’ No, of course not. The alarm went off automatically, no doubt because of a faulty sensor. It happens. But I’m beginning to feel that things are more complicated than that. Mission Control has lingering questions. It’s the middle of the night in Houston, but I imagine that in the garages of a number of wooden houses in suburbia, a number of specialists are getting into their cars, probably SUVs, to go to work. They’re in no particular hurry – it’s been established that it was a false alarm – but they mustn’t delay, either.

For us, the day will return to normal, with a few adjustments to make up for lost time, as soon as we have completed our thorough post-alarm accounting, sending the serial numbers of used masks and cartridges. We also take a few minutes to discuss everything, as we expect our flight director will want a debriefing. So that we’ll be ready to respond promptly to questions about what happened, we reconstruct the sequence of events together, and the actions we took. We don’t know that it was only a dress rehearsal, until CAPCOM comes on the radio again: ‘Change of plans. Ammonia leak! Execute emergency response! I repeat: ammonia leak! Execute emergency response!’

We look at each other for a split second, somewhat incredulous, and immediately start over again. This time it really seems like a drill. It’s been half an hour since the first alarm. If there were really a leak, wouldn’t we be feeling ill by now? If nothing else, shouldn’t we be able to smell traces of the pungent and unmistakable odour in the air, the one we had to smell in training in order to make sure we’d recognize it? Then again, maybe the leak is in a peripheral module, and turning off the fans has stopped the ammonia making its way to us. In any case, we’re soon sheltered in the Russian segment once more, behind two closed hatches, with only one thing to do: continue to execute the emergency response as we know it. Terry, Anton and I get busy in the MIM-1 above the orange box that contains the equipment. When the respirators are ready, we help each other to put them on, one at a time, following the procedure we repeated so many times: take a deep breath in the oxygen mask; still holding your breath, and with your eyes closed, take off the mask and put on the respirator with the hood; then, using both hands, smooth the hood from your forehead to your neck in order to remove any contaminated air inside before tying the laces around your neck. At this stage you can finally exhale and breathe a few times through the filters, which purifies the air left in the hood if necessary. At last we open our eyes.

When we’ve all changed to the respirators with filters, it’s time to find out if there really is ammonia in the air, at least here in the Russian segment. We have a chip-based measuring system that’s simple and easy to use, but we discover to our dismay that its battery is dead, a point we’ll no doubt discuss at length during our debriefing. For now, we need to get the job done, if not with the electronic gauge, then with the Dräger tubes, which contain a substance that changes colour on contact with ammonia. In extreme cases, the Dräger tubes would tell us that we have to evacuate the Station. Or they might tell us that the ammonia concentration is such that we can filter it through our breathing over a reasonable time, as long as we continue to wear our respirators. There aren’t any other ammonia filters on board. Today the Dräger tubes confirm that we can take off our respirators.

What is going on? Why did Houston tell us it was a false alarm, only to change their minds a few minutes later? It’s obvious that the telemetry received on Earth is ambiguous. Evidently there is no sizable leak, true, but there could be a small, subtle one which is slowly rendering the Space Station inhospitable on the other side of those closed hatches, to the extent that we will be unable to go back. None of us really thinks things will come to that, yet there are lingering doubts all the same, and every now and then one of us casually blurts out something like, ‘So what if we can’t go back in there?’ or a joke, to play it down: ‘Butch, Sasha, Yelena – are you ready to go home early?’ This could be one scenario: confinement in the Russian segment while Houston looks for a way to recover the rest of the Station, and an inevitable reduction in crew to three people. They might let Yelena stay, so that two Russians will remain on board, and ask me to take her place as flight engineer on her Soyuz.

It’s all been a mistake, surely. No one really thinks there’s an ammonia leak, right? It’s only that some rather unusual combination of telemetry data was received, Houston tells us, and as yet, there’s no convincing explanation for it. A low-tier computer broke down just before the alarm went off, a malfunction that probably caused the initial alert. At first it seemed clearly like a false alarm, since there wasn’t any other telemetry to confirm the leak. It seemed as though they simply needed to carefully investigate the chain of events on the ground, and, in the meantime, we could go back to the scientific experiments that had arrived on Dragon. But while we were cleaning up following all the excitement, specialists from Mission Control observed an increase in cabin pressure. Where could it have come from? It was impossible to deny that an ammonia leak could, in fact, be the cause. At that stage they couldn’t exclude it, and as a precaution against this eventuality they had us execute the emergency response. Better to have a day of compulsory vacation – it looks like that’s how things will play out today – than six astronauts dead because Mission Control dismissed contradictory telemetry data.

Compulsory vacation, yes, but it’s not really calm. It’s the third time the fire alarm has gone off, and now the Caution and Warning panel on the Service Module is lit up like a Christmas tree. We diligently execute the procedure again, and this time, too, we conclude that there’s no fire anywhere. The smoke detectors on the Russian segment, themselves prone to false alarms, appear to be in crisis due to the uncommon crush of humanity. On the other hand, Moscow is doing all it can to make our forced stay as pleasant as possible. In addition to a few obvious, but nonetheless important things, like having enough air to breathe, something ensured by the prompt reactivation of the Russian carbon-dioxide removal system and the equipment generating oxygen by water electrolysis, TsUP extends its hospitality to Terry, Butch and me by giving us permission to open up some food containers early. We are castaways on our own spaceship.

There’s little we can do on board, but things must be frenetic in Houston. External cooling loop B has been isolated as a precaution, and the pump has been turned off. Luckily they haven’t considered it necessary to vent the ammonia, something that would have compromised the Space Station for a long time, but they nevertheless had to turn off a lot of equipment that was in danger of overheating. The specialists are now reconfiguring the systems one by one to restore critical functions, and we’re trying to use the radio as little as possible so they can work in peace and quiet. We know they’ll update us as soon as they can.

Around the middle of the afternoon, Ku-band is restored, and we have the luxury of our phone and our painfully slow internet connection. I ask Yelena if I can borrow her computer to make a quick call to my family and tweet. My close family were in contact with ESA straightaway, and they’ve had reassuring news, but I don’t know what the rest of the world has heard from the media, and I fear my friends and contacts may be worried. ‘We’re all safe and doing well in the Russian segment,’ I write. Hmm. Tweeting in the middle of an emergency means I won’t be able to construct a thrilling story of danger and heroic drama about it one day. How short-sighted of me … We’re still together in the Service Module when it’s time for the evening DPC. It’ll be another few hours, CAPCOM tells us, because Mission Control is waiting to recover a final batch of telemetry data before they’ll allow us to return to the potentially contaminated modules. They assure us, however, that we’ll be reunited with our toothbrushes before we go to bed. Houston asks Butch to designate two people to leave the Russian segment and measure the concentration of ammonia in the Lab, while the others wait in their respective Soyuzes, ready to evacuate if necessary. The possibility that we might have to evacuate the Space Station today is remote, we all know that, but given that we’re considering this highly unlikely possibility, Butch decides that he and Terry will be the ones to venture forward. That way, each Soyuz will be sure to have an unaffected flight engineer and commander on board. About an hour later, with Houston’s authorization, we all put on our respirators and split up. Some of us go up, some down, and some forward. A short time later we finally have the definitive confirmation: there hasn’t been an ammonia leak.

When I emerge from the tunnel and leave the Russian segment behind, I have a sudden feeling that something is wrong. Node 1 doesn’t smell right; or rather, Node 1 has an odour, and it hasn’t had one before. After a few minutes of concerted sniffing I realize what’s wrong. What a dunce, I tell myself. Really! The air in here has stood still all day long, and the fan has only recently been restored. What I’m smelling is the clammy odour of stale air: the Space Station smells like an old cellar.

By this time it’s late evening, but after a day of waiting and forced inactivity, Terry, Butch and I are ready for action. We collect all the used emergency equipment and put back whatever can be reused; the rest we put in the bin. We spend a long time consulting with Houston about the oxygen masks: how many are left and the best way to redistribute them throughout the Station. We reconfigure some of the power cables so the controllers can restart some of the critical machines. We reboot the odd computer that hasn’t coped well with the upsets of the day. At last we find a place to camp for the night. We can’t sleep in our crew quarters tonight because Node 2 isn’t yet ready to welcome us back: most of the lights and electric plugs aren’t working, there’s no cooling, and the fans are turned off. The same goes for JEM and Columbus. Butch has put his sleeping bag in Node 3 so he won’t disturb anyone tomorrow morning when he gets up early, as usual, to work out. I make myself comfortable in a corner of the Lab. The campsite up here is quickly organized. All we have to do is attach our sleeping bags somewhere, using a simple hook, and the deed is done.

It’ll take days to get everything back to normal on the Space Station. Cooling loop B will have to be progressively reinstated with great caution, so as not to risk freezing the water in the heat exchangers, which would cause them to rupture. Then we really would have an ammonia leak!