Tekni (ph) from Beeton, Ontario asks: 
Is it challenging to brush your teeth in space without getting toothpaste up your nose from weightlessness? 
Well, let's talk about how to brush your teeth in space. 
Standard toothbrush, nothing magical there. But we've got a few different things. 
We don't have running water. You can't have a tap, you can't have a sink because water would flow everywhere. 
And so what do you do to wet your toothbrush, and where do you spit afterwards? 
Those are the big questions. 
So first, we just fill up a water bag with water. 
And this is where we're going to put on our toothpaste. So let me get a ball of water here. 
There's a nice ball of water floating in the ends. 
Shut off the straw - very carefully. OK, and get my toothbrush wet. 
Toothbrushes soak up water nicely. 
So now I have a nice, wet toothbrush. 
Good. So I'm partway there. Got my toothbrush wet, now I just need to put some toothpaste on it and get cleaning my teeth. 
So I'm going to suck the water off it, because where else would it go? 
Nice, wet toothbrush. Grab some toothpaste. 
We just use standard toothpaste in space. 
Squeeze a little on, not too much because you're going to have to clean it up later. 
OK, so there's my toothpaste on my toothbrush. It's wet, it's ready to go, it's loaded. 
Brush my teeth, just like normal. 
Get 'em all, especially the ones in the back. 
You should brush your teeth for about as long as you can sing Happy Birthday. That should be long enough. 
OK, so now what am I going to do? I've got a mouth full of toothpaste stuff, I've got a dirty toothbrush. 
So what I do is I just swallow the toothpaste. 
It's edible, won't kill you. And what else am I going to do - put it in a rag and have a dirty rag? 
Doesn't make any sense. So in space, you just swallow your toothpaste. 
It leaves my toothbrush just a little bit dirty, so I need to find where my water went and rinse it out. 
Fortunately, things are weightless, so things don't go too far. 
So here's my water again, so now I'll get a little water in my mouth, rinse out my toothbrush. 
So I have a relatively clean, slightly damp toothbrush to put back in my toothbrush case. 
The toothpaste is hung back on the wall. We communally share one toothpaste tube, just like living in a dormitory. 
And I still have good water to drink. 
And it doesn't go up your nose. 
There's nothing to push it up your nose. It just floats. 
So it works fine. That's how you brush your teeth in space. 
