You might think of satellites as large, imposing spacecraft that cruise through Earth’s orbit like hulking beasts, but that couldn’t be farther from the truth. Many modern satellites are tiny in size, but they do lots of very important work, and the International Space Station just dropped another one above Australia. Its mission will be to find missing matter.

The mini satellite is called a CubeSat because, well, it’s shaped like a box, and this particular CubeSat is going to peer into the Milky Way and study its halo. What’s a galaxy halo? Well, dear reader, I’m so glad you asked!

You see, when it comes to explaining the universe, astronomers have a pretty big problem on their hands. Based on past research and observations, scientists think they have a pretty good idea of how much of the universe if made up of normal matter (that’s what the Earth, the Moon, and even you yourself are made of), dark matter (nobody really knows what this is), and dark energy (a mysterious force that is making the universe bigger). Unfortunately, there’s not nearly enough normal matter for their calculations to make sense.

Based on all the data that exists today, only about half of the normal matter that should exist has been accounted for, and nobody really knows where the rest of it went. One theory is that it exists in the form of gassy “halos” surrounding established galaxies. NASA’s pint-sized satellite has been tasked with studying these gasses and the shape of their massive cloud around the Milky Way. By knowing its shape, the researchers can estimate its mass and perhaps fill in the holes in their calculations of normal matter in the universe.

The mini satellite only weighs in at about 26 pounds according to NASA, and measures a foot on its longest side. Small satellites like this have made it easier for scientists to conduct research thanks to the ability to send many of them into orbit at a fraction of the cost of a larger piece of hardware. Let’s hope this one finds something cool.