SPACE EXPLORATION TERMS

ESCAPE VELOCITY: The velocity required to achieve orbit about a planet whereby the centripedal force pushing an object away fro the planet equals the gravitational force pulling an object toward the planet.

GRAVITY ASSIST: Gravity assist, also known as planetary swingby, uses a planet's gravity encountered encountered on a space trajectory to accelerate the payload's velocity toward the ultimate planetary destination. The technique is compared to a game of interplanetary billiards...a spacecraft's path is altered by diving close to the planet so that the planet's gravity can slingshot the spacecraft to a more distant planet.

HOHMANN TRAJECTORY (HOHMANN TRANSFER ORBIT): This is the most energy efficient route between the planets Discovered by a German engineer, Walter Hohmann in 1925, a Hohmann Trajectory launch point is on the launch planet orbit and is directly opposite the destination point on the destination planet orbit.

KEY TECHNICAL VARIABLES FOR THE HUMAN EXPLORATION OF THE PLANETS ARE:
Launch Vehicle Size, in-space assembly or direct to surface, space station...new spaceport...or direct asembly, chemical...electric...nuclear...or unconventional propulsion, aerobraking...or all propulsive vehicles, expendable...or reusable spacecraft, propellant...or tank transfer, open...or closed life support, zero...or artificial gravity transport vehicle, in situ...or Earth-supplied resources

The above summary was from the SPACE NEWS ROUNDUP, JSC, Vol. 29. No.2, 1-12-90, p. 3.

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