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Apogee is the point in an orbit most distant from the Earth, and perigee is the point closest to the Earth.

Kepler's Laws describe how planets orbit the sun: (1) Orbits are elliptical, (2) Planets sweep equal areas in equal times, and (3) Orbital periods squared are proportional to average distance from the sun cubed.

Escape Velocity is the minimum speed an object must travel to break free from a celestial body's gravitational influence without further propulsion, about 11.2 km/s for Earth.

Orbital Inclination is the tilt of an object's orbital plane around a celestial body, measured in degrees from the reference plane (usually the celestial body's equator or the ecliptic).

Delta-v (Δv) is a measure of the amount of 'effort' to change a spacecraft's velocity, often determined by mission requirements and constraints.

Orbital Eccentricity measures the deviation of an orbit from a perfect circle (0 means circular, 1 means parabolic trajectory, and greater than 1 is hyperbolic).

A Sun-synchronous Orbit is a nearly polar orbit where a satellite passes over the same part of the Earth at roughly the same solar time each day, maintaining consistent lighting conditions.

A Hohmann Transfer Orbit is an orbital maneuver that transfers a spacecraft from one circular orbit to another using two engine impulses.

A Retrograde Burn is an engine burn in which a spacecraft fires its engines in the opposite direction of its current orbit to slow down or descend to a lower orbit.

A Geostationary Orbit is an equatorial orbit where a satellite's orbital period matches Earth's rotation period, making the satellite appear stationary relative to the Earth.

A Bi-elliptic transfer involves three engine impulses to transfer a spacecraft to a higher orbit and may be more efficient than a Hohmann Transfer for certain large ratios of orbital radii.

The Tsiolkovsky Rocket Equation, also known as the ideal rocket equation, relates the velocity of a rocket to its mass ratios and the exhaust velocity of its propellant:

A Prograde Burn is an engine burn wherein a spacecraft fires its engines in the direction of its current orbit to speed up or ascend to a higher orbit.

Orbital Period is the time taken for a satellite or celestial body to make one complete orbit around another body.

Station Keeping is a spacecraft control maneuver whereby small thrusts are used periodically to maintain a satellite's assigned orbit within a designated window, counteracting perturbations.

The Oberth Effect describes the increased efficiency of a rocket engine when it is fired at the point in the orbit with the highest velocity (usually the periapsis).

Also known as a slingshot maneuver, Gravity Assist uses the relative movement and gravity of a planet or other celestial body to alter the path and speed of a spacecraft.