Space exploration is a thing in Earth, as in traveling in a direction perpendicular to the ground and beyond the constellations? That is not possible in Equestria, at least not in a Euclidean sense. What we can do is move orthogonal to the Equestrian _universe_ and cross over into a parallel universe. That's what the Breezies do, by way of tunneling through the fabric of our perceived reality. But just flying straight up here does not get you out of Equestria. Should you try to fly much higher than the constellations, you will find the edge of Equestria rushing up to meet you. As such, to step down to the ground, the constellations need just step up.