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Mars comes closer to Earth more than any other planet save Venus at its nearest—56 million km is the closest distance between Mars and Earth, whereas the closest Venus comes to Earth is 40 million km. Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the Sun and Mars. Extra-close ...
Simply, if Mars is assumed to be a static perfectly spherical body of radius R M, provided that there is only one satellite revolving around Mars in a circular orbit and such gravitation interaction is the only force acting in the system, the equation would be =,
In gravitationally bound systems, the orbital speed of an astronomical body or object (e.g. planet, moon, artificial satellite, spacecraft, or star) is the speed at which it orbits around either the barycenter (the combined center of mass) or, if one body is much more massive than the other bodies of the system combined, its speed relative to the center of mass of the most massive body.
Phobos orbits so fast (with a period of just under one third of a sol) that it rises in the west and sets in the east, and does so twice per sol; Deimos on the other hand rises in the east and sets in the west, but orbits only a few hours slower than a Martian sol, so it spends about two and a half sols above the horizon at a time.
Thus one cannot move from one circular orbit to another with only one brief application of thrust. From a circular orbit, thrust applied in a direction opposite to the satellite's motion changes the orbit to an elliptical one; the satellite will descend and reach the lowest orbital point (the periapse ) at 180 degrees away from the firing point ...
One of the main challenges in interplanetary travel is producing the very large velocity changes necessary to travel from one body to another in the Solar System. Due to the Sun's gravitational pull, a spacecraft moving farther from the Sun will slow down, while a spacecraft moving closer will speed up.
Several factors make placing a spacecraft into an areostationary orbit more difficult than a geostationary orbit. Since the areostationary orbit lies between Mars's two natural satellites, Phobos (semi-major axis: 9,376 km) and Deimos (semi-major axis: 23,463 km), any satellites in the orbit will suffer increased orbital station keeping costs due to unwanted orbital resonance effects.
Unlike Phobos, which orbits so fast that it rises in the west and sets in the east, Deimos rises in the east and sets in the west, slower than Mars's rotation speed. The Sun-synodic orbital period of Deimos of about 30.4 hours exceeds the Martian solar day (" sol ") of about 24.7 hours by such a small amount that 2.48 days (2.41 sols) elapse ...