Gravity assist for spacecraft

Gravity assist occurs when a spacecraft enters the orbit of other planets and moons and uses their gravity to propel or kick itself forward.

When NASA was planning the mission to the Moon, they sent rockets to the Moon on free return trajectories, which is a trip that begins at the Earth, orbits around the Moon and comes back to Earth.

Gravity assist features in other missions such the ESA’s Rosetta mission and NASA’s Parker Solar Probe.

Related resources:

• To catch a comet – the Rosetta Mission – article

• How to catch a comet – video

• Mission to touch the Sun – article

Transcript

Demonstrate gravity assist on the gravity well by placing two metal balls on the sheet with a distance between them. Place small magnets under the balls to hold them in place. The balls represent the Earth and the Moon.

Use a marble to represent a rocket.

When given the correct trajectory, the rocket can be sent from the Earth to travel around the Moon and back to the Earth in a classic figure-of-eight shape.