Thomas Pesquet becomes this Thursday the Frenchman having spent the most time in space, surpassing the record of 209 days held by Jean-Pierre Haigneré.
The opportunity to take stock of the effects of an extended stay in space with Adrianos Golemis.
Flight doctor at the European Space Agency (ESA) since January 2018, he deals in particular with the health of European astronauts during preparation, during the mission and after landing.
He is currently assigned to the Alpha mission of Thomas Pesquet, who left for the International Space Station (ISS) on April 23.
Thomas Pesquet is due to spend six months in space.
What are the effects of weightlessness on the human body over time?
After the launch, usually there are some changes in the blood flow. Humans evolved on Earth to have a good distribution of blood in the body. In space, there is a large volume of blood that rises to the head, due to the absence of gravity. You can have a headache. The face may be a little swollen at first. A few days later, most astronauts adjust very well, so these effects stop. There are also problems at the vestibular level, with balance. We think we fall because there is no gravity. But on the other hand, we don't see any change for the eyes, whereas normally, when we fall, it changes the vision too! As for the orientation, it is not easy, you may want to vomit. Once we are in spacemuscle mass is also lost and there is a decrease in bone density. These two effects are reversible: once you come back to Earth, you get everything back. If someone is selected as an astronaut, it is because they have the capacity to return to normal level.
This is not the case for radiation, these high-energy particles that travel in space and whose Earth's atmosphere protects us ... Is there a cumulative effect from one mission to another?
Yes, the effects of the Proxima mission are still there.
If you go into space for a year, you receive twice as much radiation as in six months.
Radiation adds a health risk.
But there are limits that are set, models developed in particular by NASA.
The risk for an astronaut of developing cancer upon leaving for space should not be 1% to 3% greater than the risk he has while remaining on Earth.
During the mission, we monitor radiation levels every day to anticipate exceptional events [like solar storms, Editor's note].
Astronauts have a sensor that allows them to be protected if necessary.
Regarding the Moon or Mars, destinations that make Thomas Pesquet dream, it will be more complicated not to exceed the thresholds, right?
As long as the astronauts don't get too far from Earth, they can do multiple missions.
This is Thomas Pesquet's second mission, we can hope that there will be a third.
When an astronaut leaves for Mars, it may be his only mission if the cumulative radiation is seen to exceed certain limits.
For now, the next step is the Moon.
This will give us ideas on radiation protection.
For Mars, we are talking about stays of three years and one approach envisaged is to use water, which is an effective screen.
In the spacecraft that will leave for this destination, it will be necessary to have a sufficient quantity of drinking water, which will of course be recycled and which will allow the astronauts to be enveloped.
Adrianos Golemis, Kazakhstan.
As an ISS flight medic, how do you intervene?
For us, the most important thing is preparation and prevention. It all started a year before the flight. We are there to follow the astronaut and assess the results of tests repeated several times. It's a lot of fitness, medical exams, neurological tests… There are also psychologists. The goal is to make sure the astronaut is 100% ready to go. Of course, we are also preparing for nominal off scenarios. We prepare some medicine that the astronaut may need. There are some that are always available in the ISS for the whole team, but there are also personalized medications. For us doctors, launching and landing are very important phases, because someone can be injured. During the flight, once a week, more often if necessary,we have a teleconference with the astronaut set up in a confidential, protected, encrypted manner, which allows us to talk to him and see if there are any problems. This follow-up is very important to us. It gives us the opportunity to react and give advice. If there is a big problem, we can always evacuate the station, but that has never happened yet.
Astronauts can also do their own blood tests.
There are some blood tests that are done for scientific purposes.
The samples are put in the fridge and are analyzed once the team has landed.
In the station, we can see the hematocrit at the level of the blood test.
But all the time, we don't really have a lab to do all the analyzes.
In general, this is not too inconvenient, because we make sure that the astronaut is 100% ready before leaving.
We also have ultrasound which also helps us make diagnoses.
Is mental health also monitored?
Two psychologists work at ESA to follow Thomas and the other astronauts of the European agency during their missions.
They interact with them via teleconferences every two weeks, or more often, if necessary.
Its very important.
I spent several months at the Concordia base in Antarctica.
We were really isolated.
Under these conditions, the psychology changes but the cognitive performances can also decrease a little.
The astronauts therefore carry out tests, which makes it possible to see if, for example, they need a few more seconds to solve a problem, which is normal because of the confinement.
How do you accompany the astronauts after the missions?
At the physical and psychological level, you have to adapt again to normal life. They are followed for several months to see if they are recovering muscle and bone density. There are exercises to be done, the volume of which gradually increases for a return to normal. Since the immune system is more weakened in space, it is necessary to protect the astronauts against infections for a few days. Then the astronaut can resume a normal social life. But after landing, there is the media, relatives, family. Everyone wants to see the astronaut, it can be a bit stressful. There are three weeks of rehabilitation or reconditioning, as we say in English, during which we support this transition. To resume driving, they must do a neurological test after two weeks,to make sure they don't have a problem with orientation.
I know you are bound by professional secrecy, but can you tell us how Thomas is doing?
He is fine !
We cannot go into details, indeed, but everything is going well!