rewrite this title The No-Fly List: 5 Surprising Things Astronauts Can Never Do in Space | Metaverse Planet

I’ve always dreamed of floating 400 kilometers above the Earth. The idea of staring out of the Cupola module, watching continents drift by, feels like the ultimate freedom. But after digging into the operational manuals of the International Space Station (ISS), I realized something important: Space isn’t about freedom; it’s about survival.

From the outside, the ISS looks like an adventure. Inside, however, it is the strictest, most controlled environment humanity has ever built. It has to be. When you are living in a pressurized metal can traveling at 17,500 miles per hour, “small” mistakes don’t exist. Everything is potentially fatal.

While researching astronaut life, I found a list of prohibitions that seem totally normal on Earth but are absolute taboos in orbit. Here is why the rules in space are rewritten by physics, and why breaking them is a recipe for disaster.

1. The Zero-Tolerance Policy on Alcohol (and Smells)

I love a good celebratory toast as much as anyone. You would think that after completing a successful spacewalk or docking a Dragon capsule, the crew deserves a drink. But on the ISS, alcohol is strictly forbidden.

It’s not just about stopping astronauts from getting tipsy (though a drunk person in zero-G is a liability). The real reason is chemistry.

The ISS uses a complex Environmental Control and Life Support System (ECLSS) to recycle water. And when I say water, I mean everything. Urine, sweat, and even the moisture from every breath is captured, filtered, and turned back into drinking water.

Here is the problem: Alcohol is volatile. If it gets into the air or the waste stream, it creates chemical compounds that the recyclers can’t easily filter out. It can ruin the silicone in the water recovery system.

This rule is so strict that it extends to toiletries.

Mouthwash? Alcohol-free only.Perfume/Cologne? Banned.Aftershave? Forget about it.

If it has ethanol, it stays on Earth. The station’s lungs are just too sensitive.

2. You Can’t Just “Pack a Bag” (The Outgassing Nightmare)

I’m the kind of person who packs way too much for a weekend trip. But astronauts? They don’t have that luxury. Every single item—down to a family photo or a pen—must be tested and approved before launch.

It’s not just about weight; it’s about “outgassing.”

On Earth, materials like plastics, glues, and foams release tiny amounts of gas over time. We don’t notice it because we have windows and an entire atmosphere to dilute it. In the sealed loop of the ISS, those gases have nowhere to go. They build up and can become toxic to the crew or corrosive to the electronics.

I also learned that physical debris is a massive concern. A standard pencil might seem harmless, but graphite dust or a broken tip floating into a computer cooling fan could cause a short circuit. That is why everything is scrutinized. If it can flake, break, or smell, it doesn’t fly.

3. Fire Acts Like a Predator

We are used to flames pointing up. That’s convection: hot air rises, cool air sinks.

But in microgravity, hot air doesn’t rise. I watched some NASA experiments on this, and it’s terrifying. Without gravity, a flame becomes a perfect, pulsating blue sphere that clings to whatever is burning. It consumes oxygen more slowly but is incredibly difficult to extinguish because it doesn’t “jump” like earthly fire—it persists.

Because of this, open flames and cigarettes are the ultimate taboo.

The Risk: The ISS is oxygen-rich. A small spark could turn into a catastrophic fireball in seconds.The Smoke: Even if you put it out, the smoke doesn’t settle on the floor. It hangs in the air, clogging the HEPA filters that keep the astronauts alive.

Every fabric, Velcro strip, and piece of clothing on the station is made of fire-resistant materials. They aren’t taking any chances.

4. The “No Intimacy” Rule (Professionalism vs. Physics)

This is the question everyone asks, but NASA rarely talks about it openly. Is sex allowed in space? The short answer is no.

Officially, this is about professionalism. These are small teams living in a the size of a five-bedroom house for months. Sexual relationships can create emotional drama, jealousy, and command structure issues that could compromise a mission worth billions of dollars.

But let’s look at it from a physics perspective (because that’s what I do).

Newton’s Third Law: For every action, there is an equal and opposite reaction. Without gravity to provide traction, physical intimacy becomes a logistical nightmare of bouncing off walls.Fluid Dynamics: In space, sweat and other body fluids don’t drip; they stick to you or float away in globules. From a hygiene and air-filtration standpoint, it’s a biological hazard.

So, while it’s technically possible, the station is designed for science, not romance.

5. Never, Ever Throw Anything

If I’m working at my desk and I need a pen from a colleague, I might toss it over. Harmless, right?

On the ISS, throwing an object is dangerous.

In zero-G, objects don’t arc downward; they travel in a straight line forever until they hit something. A pen thrown too hard doesn’t just fall to the floor; it becomes a projectile. It could hit a critical switch, crack a screen, or lodge itself behind a control panel.

Astronauts are trained to hand things over directly or “float” them very gently. They also use miles of Velcro. If you don’t stick an item down, it wanders off. There are stories of astronauts losing a screwdriver, only to find it three weeks later floating near an air intake vent.

My Final Thoughts

It’s easy to envy the astronauts. The view they have is unmatched. But the more I read about their daily lives, the more I realize that being an astronaut requires a level of self-discipline that most of us can’t comprehend.

They live in a world where physics is constantly trying to kill them, and their only defense is a strict set of rules.

It makes me appreciate gravity a little bit more. I can toss my keys on the table, light a candle, or splash on some cologne without worrying that I’m going to crash the life support system.

What about you? Could you live with these restrictions for 6 months just to see the Earth from above, or is the “no shower, no privacy” life a dealbreaker? Let me know in the comments.

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