00:00Usually, when we look at photos of astronauts in space, we can see that they are somehow attached to their spacecraft.
00:08But there was a brave astronaut who took a big step into the unknown, without any security cable to connect him to his shuttle.
00:16This brave man was called Bruce McCandless, and he made this feat in 1984.
00:22How did he come back, you ask?
00:25He made this turn of force using a back-to-nasal reactor, a NASA manual maneuvering unit.
00:32He first performed test maneuvers in the Challenger suit.
00:37It was only after making sure that everything was working well that McCandless decided to take off and go for a walk a hundred meters from the shuttle.
00:47Some sad statistics.
00:49Of the 430 people who made the jump into space, 18 unfortunately lost their lives, which gives us a mortality rate of just over 4%.
01:00Given these figures, we can say that space shuttles are very unsafe means of transport, it's obvious.
01:06But let's clarify things a bit.
01:08If we calculate these figures better, we can get a lower percentage.
01:12How?
01:13Well, 4% is a bit misleading, because with this calculation, we take into account all space flights.
01:20However, some people have made several flights, which reduces the probability.
01:25With more than 600 seats occupied during 113 flights, the real mortality rate of missions is actually closer to 2%.
01:34Now let's test your general knowledge, shall we?
01:38What was the first living being sent into space?
01:41Did you answer a monkey?
01:43You're wrong.
01:44For those who answered a dog, sorry, that's not correct either.
01:48On July 9, 1946, drosophiles were the first living beings to go into space during a suborbital flight aboard a V2 rocket.
01:58On February 20, 1947, these little animals came back safe and sound from their journey, thus opening the way for human exploration of space.
02:08Before sending mammals on missions, like the Rhesus Albert II monkey in 1959, or the famous space dogs,
02:16scientists spent a lot of time studying fruit flies to see how they reacted to radiation and travel conditions.
02:24Researchers had started using drosophiles for their experiments as early as the 1910s.
02:30Do you know why?
02:31Because humans share a large number of genes with these little animals.
02:36Imagine that you were listening to scary music as you dived into the darkness and there was no one to help you.
02:44Now imagine how much the astronauts who heard this disturbing music in their spacecraft could have been upset.
02:52A few months before landing on the moon, the astronauts of the Apollo 10 mission were in orbit around our satellite,
03:00testing their equipment when they heard strange noises.
03:04Eugene Cernan, jokingly, noticed that these noises were sinister and that they sounded like strange music.
03:11At that moment, the astronauts had no contact with the control center.
03:16They were near the hidden side of the moon.
03:18These noises sounded like the soundtrack of a science fiction movie.
03:23But NASA decided not to pay much attention to it, wanting to protect the astronauts' mental health.
03:28Despite years of speculation,
03:32theories ranging from radio interference to the activity of charged particles,
03:36the source of the noises remains unknown.
03:38Cernan noticed later that no one on board had taken these noises seriously and that they had not reported them after the mission.
03:48There is a good chance that we have already received messages from new friends from other galaxies,
03:53but that we have not managed to understand them.
03:56In August 1997, astronomers using the Big Ear radio telescope from the University of Ohio
04:03captured a strange radio signal from the Sagittarius constellation, which lasted 72 seconds.
04:12This signal was at a frequency of 1420 MHz,
04:16which is significant because it corresponds to the natural emissions of hydrogen.
04:21This frequency had been reported by scientists nearly 20 years earlier
04:25as a probable choice for extraterrestrial civilizations that would try to contact us.
04:30They called it the WOW signal.
04:34After one of the astronomers was thus exclaimed in writing on his report.
04:39We have never heard this signal again,
04:41and no one has been able to explain its origin in a satisfactory way.
04:48After spending about a month in space,
04:51astronauts begin to lose a lot of skin under their feet,
04:54especially the calluses they have accumulated over time.
04:58An astronaut even called the mission control center a little panicked
05:03when he noticed that a piece of his heel was literally coming off.
05:07But no worries.
05:09As the old calluses disappear,
05:12new ones appear quite quickly on the top of the feet.
05:15This allows astronauts to hang on to the supports,
05:18a bit like space trapeze artists.
05:23Seeing blood in these urines is scary.
05:25In weightlessness, the blood does not go down to the bottom of the body in the same way as on Earth.
05:30This can lead to a little scary situations in spaceships.
05:36Natural impulses are universal,
05:39wherever we are.
05:41There are two main reasons
05:43why astronauts cannot use traditional toilets in space.
05:48First of all, water is an extremely precious resource on board a space vehicle.
05:53Secondly, there is no gravitational flow of water in space.
05:58Drinking water on board a space station is contained in pockets,
06:02and we deflate differently than on Earth.
06:04In weightlessness, a special device,
06:07with suction cups and disposable bags,
06:09is used to collect waste.
06:11The storage is evacuated every ten days.
06:14In addition, spaceships are equipped with complex systems
06:17designed to recycle and filter liquid waste,
06:19and convert it into usable water,
06:21for the daily needs of astronauts.
06:27As if all this was not enough,
06:29spending a long period floating in space poses another problem.
06:34The body can lose its tight belts,
06:36these little cushions that are found between the joints of the hip.
06:40If this does not pose immediate problems in an environment without gravity,
06:44returning to Earth can turn the simple fact of sitting,
06:48whether on a chair or on toilets,
06:50into a real torture.
06:55The fluid movements that contribute to blood problems do not stop there.
06:59They can also wreak havoc in the sinuses of astronauts,
07:03creating a constant feeling of congestion.
07:05It is as if we were permanently living in a suffocating room,
07:09without being able to relax.
07:10Thus, there are many challenges to face during a long-term space trip,
07:15an experience as difficult as exciting.
07:19Another challenge that astronauts are faced with
07:22is loss of vision,
07:24also known as ocular syndrome,
07:26which seems quite scientific.
07:29Although the exact cause remains a bit mysterious,
07:32it is thought that the additional pressure exerted on the brain
07:35can damage the retina and optic nerve.
07:38And here is a funny fact.
07:40This disease affects all humans.
07:42In addition, you might think that closing your eyes in space
07:45is equivalent to diving into the dark,
07:48but it is not the case.
07:49Because of the high levels of radiation,
07:52astronauts still see bright light
07:54crossing certain parts of their orbits.
07:57It is a rather strange phenomenon that affects those who live,
08:01even with their eyes closed.
08:04Let's move on to higher speed
08:06and talk about bone health in space.
08:08It turns out that weightlessness can really wreak havoc
08:11on the skeleton of astronauts.
08:13They can lose up to 2% of their bone mass every month,
08:17which is quite incredible.
08:19But the good news?
08:20Researchers have developed new exercises
08:23that help them fight bone mass loss.
08:26Thus, even if space travel is not without problems,
08:31scientists are working hard
08:33to keep our astronauts in good shape
08:36while they explore the universe.
08:39Terminal collapse is an interesting theory
08:42about how the universe could end.
08:44It is actually the opposite of the Big Bang.
08:47Imagine that the universe extends for centuries and centuries,
08:51then it slows down and begins to collapse on itself,
08:55perhaps even forming a huge black hole.
08:58Scientists study this issue
09:01by looking at the density of the universe.
09:03If it is too dense,
09:04such a collapse could actually occur.
09:07At first, we thought that gravity would eventually take over
09:11and stop the expansion due to the Big Bang.
09:14But then we discovered this mysterious thing
09:17called black energy,
09:19which actually accelerates this expansion.
09:22Thus, it seems that the terminal collapse is unlikely.
09:26At present, all data indicate that black energy is there to stay,
09:30and that the universe will therefore continue to extend indefinitely.
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