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  2. Lunar theory - Wikipedia

    en.wikipedia.org/wiki/Lunar_theory

    After showing solar attractions LQ on the Moon and SQ on the Earth, on the same scale, Newton then makes a vector decomposition of LQ into components LM and MQ. Then he identifies the perturbing acceleration on the Moon as the difference of this from SQ. SQ and MQ are parallel to each other, so SQ can be directly subtracted from MQ, leaving MS.

  3. 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 ...

  4. Trans-lunar injection - Wikipedia

    en.wikipedia.org/wiki/Trans-lunar_injection

    As the spacecraft begins coasting on the lunar transfer arc, its trajectory approximates an elliptical orbit about the Earth with an apogee near to the radius of the Moon's orbit. The TLI burn is sized and timed to precisely target the Moon as it revolves around the Earth. The burn is timed so that the spacecraft nears apogee as the Moon ...

  5. Spacecraft flight dynamics - Wikipedia

    en.wikipedia.org/wiki/Spacecraft_flight_dynamics

    A space vehicle's flight is determined by application of Newton's second law of motion: =, where F is the vector sum of all forces exerted on the vehicle, m is its current mass, and a is the acceleration vector, the instantaneous rate of change of velocity (v), which in turn is the instantaneous rate of change of displacement.

  6. Escape velocity - Wikipedia

    en.wikipedia.org/wiki/Escape_velocity

    Escape speed at a distance d from the center of a spherically symmetric primary body (such as a star or a planet) with mass M is given by the formula [2] [3] = = where: G is the universal gravitational constant (G ≈ 6.67 × 10 −11 m 3 ⋅kg −1 ⋅s −2 ‍ [4])

  7. Orbital state vectors - Wikipedia

    en.wikipedia.org/wiki/Orbital_state_vectors

    Orbital position vector, orbital velocity vector, other orbital elements. In astrodynamics and celestial dynamics, the orbital state vectors (sometimes state vectors) of an orbit are Cartesian vectors of position and velocity that together with their time () uniquely determine the trajectory of the orbiting body in space.

  8. Apollo Lunar Module - Wikipedia

    en.wikipedia.org/wiki/Apollo_Lunar_Module

    Descent stage may have hit the Moon, ascent stage in heliocentric orbit. Snoopy is the only flown LM ascent stage known to have survived intact (possibly asteroid 2018 AV2 [52]). LM-5 Eagle: Apollo 11: July 16, 1969 Descent stage on lunar surface in Sea of Tranquility, ascent stage left in lunar orbit (could be still orbiting the moon [53]) LM ...

  9. Gravity turn - Wikipedia

    en.wikipedia.org/wiki/Gravity_turn

    The term gravity turn can also refer to the use of a planet's gravity to change a spacecraft's direction in situations other than entering or leaving the orbit. [3] When used in this context, it is similar to a gravitational slingshot ; the difference is that a gravitational slingshot often increases or decreases spacecraft velocity and changes ...