The Cosmic Slingshot: Gravity Assist Maneuver Quiz

If a ball (spacecraft) bounces off a moving train (planet), it gains speed from the train's motion; if the train provides the "push" to the ball, then the train is the best representation of the moving planet.

If we want to measure the net change in speed from a flyby, we compare the velocity when the craft is entering the planet's "sphere of influence" to when it is exiting; if these distances are considered "infinite" for the math, the velocity is called asymptotic.

If every kilogram of fuel requires more fuel to lift it into orbit, then reducing fuel needs makes the rocket smaller; if the rocket is smaller or the fuel is replaced with tools, the mission becomes more efficient.

If the gravitational force follows the inverse square law (1/r^2), then increasing the distance (r) causes the force to drop rapidly; if the force is weak, then the change in the craft's velocity will be minimal.

If "helio" refers to the Sun and "centric" refers to the center, then the measurement of an object's speed using the Sun as the fixed reference point is heliocentric velocity.

If the probe needs to lose orbital momentum to drop closer to the Sun, and if it passes in front of Venus to transfer energy to the planet, then it is using gravity assists to slow down and adjust its trajectory.

If a flyby requires a specific distance and speed, then navigation must be perfect; if the path is indirect, the trip takes longer; and if the craft gets too close to a planet like Jupiter, it must withstand intense radiation.

If a spacecraft needs to slow down significantly to be captured by Mercury's gravity, and if it uses several flybys of Venus and Mercury to shed speed, then that specific mission was the MESSENGER probe.

If we are analyzing the mathematical laws of motion for satellites and planets, then the branch of science we are discussing is orbital mechanics.

If energy is transferred from the planet to the spacecraft, then according to the law of conservation of energy, the planet must lose that same amount of energy; if the planet loses energy, its orbital speed must decrease.

If a spacecraft passes close to a moving planet, then it enters the planet's gravitational influence; if the spacecraft exits that influence, it "steals" a tiny amount of the planet's orbital energy, resulting in a change in the spacecraft's speed or direction relative to the Sun.

If the gravitational force depends on mass (F = G * M * m / r^2) and the boost depends on the planet's motion, then planet mass, proximity, and orbital speed are the primary variables that dictate the energy transfer.

If the planets were aligned in a specific way, and if Voyager 2 used a gravity assist maneuver at each planet to reach the next, then it could visit Jupiter, Saturn, Uranus, and Neptune without carrying impossible amounts of fuel.

If an orbit or flyby path has a point where the distance between the two bodies is at its minimum, then that specific point is defined in physics as the periapsis.

If a spacecraft is directed to pass "in front" of a planet's orbital path, then the planet's gravity pulls the craft backward relative to its motion around the Sun; if the craft is pulled backward, then it loses speed, which is useful for reaching the inner solar system.

If a spacecraft is traveling faster than the escape velocity of the planet it is passing, then its trajectory will not be a closed loop; if the path is open and curved by gravity, then the geometric shape is a hyperbola.

If gravity is a vector force, then it can pull a craft to speed it up, slow it down, or bend its path; if the planet provides the energy, then the spacecraft requires less chemical propellant to reach its target.

If a spacecraft approaches a planet from "behind" in its orbital path, then the planet's gravity pulls the craft along; if the craft is pulled in the direction of the planet's motion, it gains a portion of the planet's orbital velocity.

If the spacecraft gains momentum during the flyby, then the planet must lose an equal amount of momentum; because the planet's mass is so much larger, its speed change is undetectable, but the spacecraft's gain is significant.

If the encounter is viewed from the planet's frame of reference, and if we ignore atmospheric drag, then the law of conservation of energy dictates the craft exits the planet's "gravity well" at the same speed it entered, though its direction and speed relative to the Sun will have changed.