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  2. Orbit of Mars - Wikipedia

    en.wikipedia.org/wiki/Orbit_of_Mars

    Extra-close oppositions of Mars happen every 15 to 17 years, when we pass between Mars and the Sun around the time of its perihelion (closest point to the Sun in orbit). The minimum distance between Earth and Mars has been declining over the years, and in 2003 the minimum distance was 55.76 million km, nearer than any such encounter in almost ...

  3. Tidal acceleration - Wikipedia

    en.wikipedia.org/wiki/Tidal_acceleration

    By twice integrating over the time, the corresponding cumulative value is a parabola having a coefficient of T 2 (time in centuries squared) of (1 / 2) 63 s/cy 2 : ΔT = (1 / 2) 63 s/cy 2 T 2 = +31 s/cy 2 T 2. Opposing the tidal deceleration of Earth is a mechanism that is in fact accelerating the rotation.

  4. Orbital speed - Wikipedia

    en.wikipedia.org/wiki/Orbital_speed

    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.

  5. Mars atmospheric entry - Wikipedia

    en.wikipedia.org/wiki/Mars_atmospheric_entry

    Mars atmospheric entry is the entry into the atmosphere of Mars. High velocity entry into Martian air creates a CO 2 -N 2 plasma, as opposed to O 2 -N 2 for Earth air. [ 1 ] Mars entry is affected by the radiative effects of hot CO 2 gas and Martian dust suspended in the air. [ 2 ]

  6. Free-return trajectory - Wikipedia

    en.wikipedia.org/wiki/Free-return_trajectory

    Sketch of a circumlunar free return trajectory (not to scale), plotted on the rotating reference frame rotating with the moon. (Moon's motion only shown for clarity) In orbital mechanics, a free-return trajectory is a trajectory of a spacecraft traveling away from a primary body (for example, the Earth) where gravity due to a secondary body (for example, the Moon) causes the spacecraft to ...

  7. Mars - Wikipedia

    en.wikipedia.org/wiki/Mars

    Mars is the fourth planet from the Sun.The surface of Mars is orange-red because it is covered in iron(III) oxide dust, giving it the nickname "the Red Planet". [22] [23] Mars is among the brightest objects in Earth's sky, and its high-contrast albedo features have made it a common subject for telescope viewing.

  8. Sky crane (landing system) - Wikipedia

    en.wikipedia.org/wiki/Sky_crane_(landing_system)

    This system is also much more precise: while the Mars Exploration Rovers could have landed anywhere within their respective 93-mile by 12-mile (150 by 20 kilometer) landing ellipses, Mars Science Laboratory landed within a 12-mile (20-kilometer) ellipse. [7] Mars 2020 has even more precise system, and landing ellipse of 7.7 by 6.6 km. [8]

  9. Newton's theorem of revolving orbits - Wikipedia

    en.wikipedia.org/wiki/Newton's_theorem_of...

    All three planets (red, blue and green) are at the same distance r from the center of force C. It is required to make a body move in a curve that revolves about the center of force in the same manner as another body in the same curve at rest. [42] Newton's derivation of Proposition 43 depends on his Proposition 2, derived earlier in the ...