Okay kiddo, imagine you are trying to find something really tiny, like a grain of sand, in a big pile of other things. It would be really hard to see, right? Well, scientists have the same problem when they're trying to study things in space, especially things that give off X-rays.
X-rays are a special kind of light that can go through things that normal light can't. But things on Earth, like buildings and clouds, can block X-rays from space. So scientists need to find a way to get above all the things that block X-rays.
That's where balloons come in! Scientists can send special balloons high up in the sky where there is less stuff to block the X-rays. These balloons have special X-ray detectors on them that can "see" the X-rays from space.
But there's a problem. Balloons can only stay up in the air for a little while before they come back down to Earth. Scientists need to figure out a way to make the balloons stay up much longer, so they can keep studying the X-rays from space.
So, they use big helium balloons. Helium is a special gas that makes things float. We use it to make party balloons float, too! These big helium balloons can lift up heavy X-ray detectors and other equipment up high above the Earth.
These balloons can stay up in the air for many hours, even days or weeks! Scientists can control where the balloon goes by changing the amount of helium in the balloon. They can also bring the balloon back down to Earth safely when they're done studying the X-rays.
So, that's why scientists use balloons for X-ray astronomy. They help scientists see things in space that they can't see from the ground, and they can stay up in the air for a long time so scientists can study the X-rays more closely.