These are used to drive back and forth between the telescopes and the hotel. On top of Cerro Tololo are seven domes , each housing a telescope. Also, one of the telescopes is a radio telescope. This means that instead of looking at the visible light coming from objects in space, it looks at radio waves coming from them. Planets, stars, galaxies, and gas clouds all give off radio waves.
Light comes in many varieties.
The four meter telescope is large enough that an astronomer can actually ride in a cage inside the top of the telescope while observing. This cage is called the prime focus cage. It is rare for someone to use the prime focus cage, but some instruments require you to do this. I could never do it. To get into the cage, the telescope is pointed straight up.