Have you ever let a helium-filled balloon go outside and watched it float up into the sky? It makes you wonder how far it will go – can balloons go to space?
The other day, one of my kids felt he needed a little more excitement. So, he took a balloon we had in the house, walked outside, and let it go, for no other reason, but to watch it fly.
It happens all of the time. A little kid accidentally (or if it’s my kid – purposefully) lets go of their balloon, people release balloons in honor of somebody, or maybe a balloon just gets loose and flies off.
If it’s filled with helium, it’s swept away by the wind and you never see it again. A balloon will float up and up, but will it get to space?
The answer is no. But, why? The reasons might surprise you.
Why Do Balloons Float?
First, let’s establish why balloons can float to begin with. A balloon does not float when it is filled with air; balloons float when they are filled with a gas less dense than air.
Everything has a weight to it, even gases!
The two lightest gases on Earth are Hydrogen and Helium. Both gases are lighter than air and can be used to make a balloon float.
Hydrogen is lighter than Helium, but Helium is an inert, non-reactive gas, while Hydrogen is not. It has become common practice to fill balloons with Helium, and not Hydrogen, because it is safer.
Learn more about helium balloons here: Are Helium Balloons Dangerous?
So, because helium is less dense than air, and the weight of the balloon enveloping it is light enough, it allows the balloon to float upward.
But, what exactly is density? And what role does it play in the balloon/space conundrum? Let’s look more at density.
All About Density
The Definition of Density
Density is defined as the relationship between the mass and the volume of a substance (d = M/V).
According to the dictionary, mass is defined as “the quantity of matter which a body contains.” And, volume is defined as “the amount of space that a substance or object occupies.”
Therefore, density isn’t simply the weight of something, but how much of something is occupying a certain amount of space. Two different objects can be roughly the same size, but completely different densities.
For example, a balloon filled with air is going to occupy the same amount of space as a similarly sized balloon filled with water. But, the one filled with water will be much denser, because water has more mass.
So, what does this have to do with a balloon going to space? It’s all to do with air density.
If you’re standing on Earth’s surface, you have the full pressure of the atmosphere coming down on you. The higher the altitude, the less pressure there is.
Density and pressure are directly related. If the pressure decreases, so does density.
The higher up in the atmosphere, the less dense the air becomes. This is because the molecules of the air move farther apart with less pressure being exerted on them.
Remember, density is the relationship between the mass and volume of a substance. If the molecules that make up the air move farther apart, they’re occupying more space, thus increasing their volume.
The same amount of mass over an increased volume equals lower density.
Since the air becomes less dense, at some point the balloon will be equal to the air. Helium will always be lighter than air, but we cannot forget that the material of the balloon has weight.
Therefore, the density of the balloon plus the helium inside will be as dense as the air around it.
This leads us to the next part of the puzzle: buoyancy.
All About Buoyancy
The Definition of Buoyancy
Many people might associate the word buoyancy with a boat or object floating in water. But, it applies to air, as well. In fact, the concept of buoyancy plays a big role in questioning whether or not balloons can go to space.
According to the dictionary, buoyancy is defined as “the ability or tendency to float in water or air or some other fluid.”
Furthermore, Archimedes’ Principle states that when an object displaces water or air, it creates a buoyant force, or an upward force, on the object.
So, how does all of this fit together?
Buoyancy, Air, & Balloons
In this case, the balloon filled with helium displaces the air around it. The displaced air creates that upward force, and because the helium balloon is lighter than the air, the balloon rises.
As the buoyant force continues to exert pressure upward, the balloon will rise. But, once the densities are equal, this force will no longer be able to move it upward.
The balloon has to be less dense than the air to rise. And, as long as the balloon enveloping the helium adds weight, it will never get far enough to leave Earth’s atmosphere.
Can Balloons Get to Space?
Density and buoyancy aside, everything on planet Earth is held inside the atmosphere due to gravity. And, according to Britannica, for something to break the pull of gravity, it would have to be moving at “34 times the speed of sound.”
Even if you could create a balloon that added no extra mass to the equation, it is unlikely the material would be strong enough to hold up to escaping gravity’s pull.
Interestingly enough, it is actually possible for Hydrogen and Helium gases to slowly escape the atmosphere. But, this does not mean a helium-filled balloon could.
Therefore, our balloons will remain within the confines of Earth.
Keeping Earth Safe
It may be fun to let a balloon go and watch it wisped away into the seemingly limitless boundaries of the sky above us. But, it is important to know that this is something we should not be doing intentionally.
Balloons are made of latex, which is porous. This means that there are tiny, little holes in the material that allow the gas inside to slowly escape.
And, as we’ve learned, the balloons we let go will not make it to space. Therefore, as the helium escapes, the balloons will eventually float back down to the Earth’s surface.
This also applies to foil balloons. Foil balloons do have a tighter seal, so they will float longer, but the helium will eventually escape and their return to our environment is inevitable.
Balloon materials are not environmentally friendly. They add to the pollution of our land and water and endanger our wildlife.
Foil balloons also pose a danger to the public. If foil balloons come in contact with power lines, it can cause explosions, fires, and power outages.
All in all, balloons are here to stay with us on Earth, so we should use our balloons responsibly to help keep Earth and all its inhabitants safe.
Density, buoyancy, pressure, altitude, gravity. There are so many factors that come into play when we question balloons going to space.
The answer to the question – can balloons go to space – is a bit more complicated than one might imagine at first, as most things are in the vast world of Science.
But, now that we know the answer, we can use our balloons safely and for the fun uses they were intended for.