AGBRESA – terrestrial astronauts’ experiences of training on the centrifuge
The AGBRESA study is the first to explore using the DLR short-arm human centrifuge as a possible mitigation for the negative effects of weightlessness, which are being simulated by bed rest. This involves eight of the 12 terrestrial astronauts – the AGBRESA bedrest study participants – spinning in the centrifuge for 30 minutes every day. To allow them to experience artificial gravity they adopt a specific position – supine with heads pointed inwards – which exposes their feet to two g (twice Earth gravity) and the centre of gravity of their bodies to one g (Earth gravity). This could become a training method for future long-term missions in space. By the end of their 60 days of bed rest, the participants will have spent 1800 minutes on the centrifuge and will have rotated 54,000 times!.##markend##
Below, some of the terrestrial astronauts describe their experiences of the daily training and what makes this ‘sports programme’ so special.
"It feels like standing still"
Participant A – “Initially, I found the training really rather exciting, but now it has become part of the daily routine. The training sessions look a lot more interesting from outside than they actually are,” he says, laughing. “I watched a video of me on the centrifuge. I have to say that it doesn’t feel that fast, and it’s really quite relaxing.” Although it may seem counterintuitive, the starts and the stops are the most action-packed parts of the process; then, he feels the pressure building up in his legs as the centrifuge accelerates, and reducing during the deceleration phase. “I don’t really notice that I’m spinning in a circle if I close my eyes; the movement is barely perceptible, and it feels almost as if I’m standing still. For me, the daily training has become almost like ‘stretching my legs’, a kind of substitute for the walks I have to go without during my 60 days of bed rest.” His entertainment programme – in between the experiments and his communications with the centrifuge team – is listening to music from his playlist, usually R&B: “Rather quiet tracks, no heavy metal."
“A welcome break from everyday routine”
Participant B agrees with participant A that the rides on the centrifuge are a welcome break from the routine of bed rest. “Mostly I listen to Pink Floyd, which seems like an apt choice. Sometimes I’ll play a teach-yourself French course or an audio book, for instance the abridged version of Twenty Thousand Leagues Under the Sea – which also describes a kind of mission. I’ve even wondered whether a centrifuge like this one would be good as an exercise machine at home – although I’d have to build one first, of course.”
The initial centrifuge training, which the participants all completed prior to the study, made him feel like he was being lifted up. That feeling has gone now: “Actually you just lie there. I only really notice that the centrifuge is moving if I turn my head to the side.”
“Making a contribution to the experiment”
Participant K – “I think it’s good to be part of the centrifuge group, because it gives me some time just for myself, and there is no danger that I might fall asleep. I can let my mind wander and enjoy the ride from start to finish. The muscle contractions in the legs mean we can move a little on the centrifuge, so it’s almost like exercising and makes a welcome break from the time spent lying in bed.” He also listens to a lot of music, between the experiments at least. During the training sessions, the participants are regularly asked to solve arithmetic exercises, hold an ultrasound device to their jugular vein or perform other tasks. “It’s really fun if you locate the vein and can contribute to the experiment.”
He usually closes his eyes when the centrifuge starts moving: “I can feel my feet getting heavier, as if I were standing up again. Then I open my eyes and concentrate on the parts of the centrifuge that are rotating. Admittedly, I was very nervous before my first centrifuge training. My blood pressure was very high, and I felt really quite stressed. But those feelings have subsided since; now it’s just like going for a walk.”
The study has gone by very quickly for him so far: “The first few days were really exciting and new, but everything since then has flown by, and now we are already preparing inwardly for the time when we have to get back on our feet.”
"Like on a children’s merry-go-round"
Participant H – “I don’t think the speed on the centrifuge is really noticeable; it’s a bit like being on a children’s merry-go-round at a funfair, but definitely not a rollercoaster. You can feel the force in your calves and feet, a kind of tension that then becomes less with the muscle pump. I can look around and move my arms without becoming dizzy. I didn’t dare to do it in the beginning, but it works very well now. Often, I listen to the latest music from the charts – all kinds of songs – and am pleased when there are experiments scheduled. Some of them are a bit challenging, especially the mathematics exercises that require abstract thinking. But it’s fun all the same. The ultrasound measurements, where you have to get the right angle and find the vein, are also something that I would never do otherwise in my life. I am really proud when I manage it first time, and I feel really honoured to be part of the project.”
"Like an astronaut in a rocket"
At the start of the study, participant M was concerned that he would eventually become bored by his training sessions on the centrifuge. “That has not been the case at all. Quite the contrary; for me, they bring variety and structure to the day’s routines.” His music of choice is Led Zeppelin and by now the centrifuge training sessions have become just like a stroll. “I am excited every time I’m wheeled into the centrifuge room – all the modern technology, the cables and lamps – it seems to me like a rocket, moments before lift-off. Every time, I have to think of the Apollo missions and I feel like an astronaut sitting in the capsule with the crew running through the final preparations just prior to launch." The 30 minutes also fly by for him – and he is proud to be part of the team: “Everyone here is so professional, helpful, pleasant and completely committed to the project. That just makes everything all the more fascinating for me."