Hello everybody,

There are certain experiences you can expect to encounter in space, and yet, no matter how much you may train for them and undergo countless simulations, you’ll never achieve the actual experience. One of these is this weightlessness thing. The instant I stepped out of Dragon, I could feel the difference. Body fluids rise upwards and the feeling is as if your head’s filling up. This is also the reason I sleep upside down – with my head downwards. In my opinion, in this position the body fluids are better balanced.

Of course every single item has to be tethered or connected to something, otherwise it’ll simply drift endlessly all over the place.

Although you have actually seen me standing “normally”, this was thanks to a strap that’s holding my feet in place. When my foot wiggles free of the strap, I immediately turn upside down, and this isn’t because I’ve become an acrobat, this is what weightlessness does to any object, including the human body.

To understand weightlessness, we have to start with Newton and his law of universal gravitation: “any particle of matter in the universe attracts any other particle with a force directly proportional to the product of the masses and inversely proportional to the square of the distance between them. This is the universal gravitational force”.

Too complicated? So here’s a slightly simplified version: we’re not really floating. The truth is we’re falling. Yes. The astronauts, everything inside the International Space Station, and also the International Space Station itself - is all falling, the Earth’s gravitational acceleration is working on all of this, regardless of the mass of the falling body itself. We aren’t floating. We’re falling. This state is called “microgravity”. It means that gravity does still exist, but in space it affects objects differently than it does on Earth.

To be more precise with the terminology, we can say that what is defined as “micro” in the term microgravity, actually means tiny. Miniscule. Microscopic. As opposed to the scientific quantitative term, which is “a millionth”. Even the term, “microgravity”, can be misleading. Gravitation along the orbit of space shuttles and space stations, is really quite strong. So the term “microgravity” actually describes a situation in which weight is minuscule, but gravity can still be perceived.

The secret that prevents all of us from being powerfully attracted toward the Earth, is the secret of flight. The elliptical motion at a very high speed. For example - that of the International Space Station, which is orbiting Earth in an orbital course at an altitude of between 278 km and 460 km, is traveling at an average speed of 27,743.8 km/! It completes 15.7 orbits around Earth every single day. This is why every day we see 16 sunrises and 16 sunsets.

Life in conditions of microgravity has considerable effects on the body. Among other things it causes loss of muscle and bone mass. This is why it is important to maintain a high-calcium, high-protein diet to help compensate for that. This is also the reason why the nutrition for space flights is carefully planned a long time in advance and involves dieticians and physicians that supervise the composition of the food to ensure it contains all the important nutritional values.

And speaking of food, the thing that’s really missing up here is fresh fruit and vegetables. But I am well aware that whatever I, and all other astronauts, eat nowadays in space, is way better quality and tastier than what astronauts were served just a few years ago.

The world is making progress in its space research, and what the Rakia Mission is doing here, is making a significant contribution toward progress in technology, science and medicine. Take two of our experiments as an example:the effect of microgravity on aging, on the immune system and on Alzheimer’s Disease, or CRISPR-based genetic diagnosis under weightlessness.

As we have been informed that our return to Earth is to be delayed by a day, I’m hoping to test everything I brought along. Hopefully, we can return with some interesting answers and provide some sense of certainty for all the scientific questions posed to us up here.

So that’s it for today. Stay tuned. It’s going to be interesting.

Yours, Eytan

The International Space Station