The atmospheric pressure on the surface of Mars is about the same as the atmospheric pressure at an altitude of 100,000 feet on Earth. There are two primary types of telescopes. The image orientation makes the refractor telescope good for observing objects on the Earth's surface as well as the night sky. Small refractors can be found at a reasonable price, but large models can get expensive. Your brain may have a hard time accepting a boat floating on a sky of water.
Reflectors are the most economical for a given aperture size.
The inherently better light gathering ability of the reflectors makes them better for observing dim objects like galaxies and nebulas. The magnification power of a telescope is determined by dividing the focal length of the telescope by the focal length of the eyepiece. As a result, the objects will tend to move out of the field of view relatively quickly when high magnifications are used. For a Newtonian reflector telescope, a larger mirror means more light can be collected. We suggest you purchase the largest diameter you can afford.