Telescope

Michelle says: I know the way.
Wanna drive?
Jack extends his hand with the keys.
Sure.
She takes them and the four get in the truck. James joins Michelle in the front while Annie and Jack take the rear seats. A few moments later, Michelle pulls onto the street in front of the bunker.
James asks her: How far is it?
A decent bit. Used to be about an hour on the highway. If it's in even somewhat decent shape, I'd say we're gonna make it there in about that time.
She turns right at an intersection onto the on-ramp, saying:
Gonna find out very soon...

The pavement is cracked and has potholes, and the highway is partially overgrown but, despite this, its condition is somehow good enough. Michelle floors it and the truck rattles and shakes as it accelerates on the uneven asphalt. James hangs on to the handle in the door as the remains of the city outskirts fly by. Michelle notices it:
James, relax, that seat belt is gonna hold you.
How are you not absolutely terrified by the speed you're going?
You get used to it after a while... Also, I know very well what I can or can't do with this car – I used to drive the same model. wording?

Within a few minutes, they make it out of Ivydale, leaving its valley behind. The mountains make way for an area of plains and shallow hills. The large, rusty signs above still indicate the proximity of Sentinel Shores where they haven't faded completely. Following them, Michelle takes an exit onto another highway that takes them north, around the western part of Ivydale's lower side.

After a while, they approach what used to be the outskirts of Sentinel Shores and Michelle takes an exit, getting them onto a rural road. The observatory is located on a hill, now ahead of them – a small group of buildings in the distance. As they get closer, the buildings take distinct shapes. Two of them stand out: The one in the center holds a large geodesic dome and another one off to the side is a smooth round dome with a slot cut out of it for a telescope to peek through. Well, it was smooth at one point – now, it has many holes with a tree growing out of the largest one. The geodesic dome has ivy vines clinging to it but looks otherwise surprisingly intact. The other buildings look like mostly unremarkable ruins in various stages of decay.

Michelle says to James:
I'm sorry but it doesn't look like your idea of using telescope is gonna pan out.
Oh well, still worth checking it out – maybe, there are old photos left behind... Didn't you say you also need the telescope?
We need the radio telescope. That's a very different beast. It's in that ball made of triangles in the middle there.

She drives onto what remains of the large paved space inbetween the buildings and parks the truck next to the entrance to the optical telescope. They get out and look around. Trees and bushes grow all over the place, some even out of the buildings. Dora runs up to a bush and barks at it. A young fox jumps out and runs away.
Dora, c'mere!

What now? They start exploring but where to they begin?