This is a walk of a different kind and a historic one at that. These images show the first privately funded spacewalk more than 700 kilometers above Earth. Jared Isaacman, the mission commander, is the first private astronaut in space. He and Sarah Jones, a SpaceX engineer, climb out of the spacecraft for about 15 minutes each. The four-person crew was launched into space on Tuesday from the Cape Canaveral spaceport in Florida. During the mission, the astronauts will find out what effects space travel and space radiation have on human health. I am now joined by astronaut and space expert Professor Ulrich Walter. I greet you very warmly. I greet you! So, this spacewalk was a success. How relieved are you? Oh yeah, well it wasn't as dangerous as you might think, but it was n't without danger either. I'm relieved that everything went well. But you have to know that Elon Musk attaches great importance to security. That's why I didn't doubt that it would work. In addition, the people did not leave the spaceship, but instead held on to a ladder. They could then look out and see the earth. The bad luck, however, was that it was night. So, they had to look into the night and therefore couldn't really see much of the Earth. It's pretty stupid to take such a long journey. But let's talk about why this time was chosen. It was postponed several times and we thought it would take place later. Why? SpaceX hasn't commented on this, but I suspect it was because of the spacesuits. The spacesuit must be set to a third of normal pressure, otherwise it will inflate like a Michelin Man. You can then no longer move. At a third of the pressure, the suit must be filled with pure oxygen, and to do this the nitrogen must be removed from the body. This takes more than a day so that you don't get so-called decompression sickness. The pre-breathing probably took longer than expected and that's why the spacewalk was postponed. SpaceX has not officially said anything about this. These are amateurs taking part in this private space mission. What training is necessary for this? The training is conducted by SpaceX together with NASA. It takes about half a year. For the spacewalk, training takes place underwater, in a special NASA swimming pool. These four astronauts also trained there to be able to handle the spacesuits in weightlessness. I trained for my mission for five years . Professional astronauts know better what to do in serious situations. What could go wrong on a walk like this if you're not a professional astronaut? Nowadays, operating a capsule has become easier, so that even rookies, i.e. people without professional astronaut training, can do it. This is progress in space travel. You used to need a chauffeur to drive a car, but today anyone can get a driver's license. It's the same in space travel. After six months of training, practically anyone can operate a capsule. This is great and an advance that will make space tourism possible. Would you get into a SpaceX capsule and fly into space yourself? Yes, immediately. Elon Musk builds excellent rockets, and the capsule is extremely safe. There were over 280 flights and nothing happened. This is much better than the shuttle back then. After 130 shuttle flights, there were two fatal missions. Elon Musk places extreme importance on security, so I would jump in straight away. I wouldn't do that with other providers like Richard Branson . I would be careful, but anyone can get into the SpaceX capsule. However, there will always be risks in the future, because space travel is and remains an adventure. But the risk has become very small. Thank you, Professor Walter.