Ever ridden your bike and waved at
a friend as you zoomed past them?
NASA does it all the time when
spaceships fly by other planets. But
we’re doing it to help our ships gain
speed along the path to their final
destinations.
During a flyby, computers tell the
spacecraft to fly very close to a nearby
planet. It gets just close enough to
allow that planet’s “pull” (of gravity)
to “tug” them a bit, providing more
energy to help propel them along their
way, kind of like using a slingshot.
The added tug means less fuel is
needed, and that means less weight,
which saves us money.
One of the most famous NASA
flybys was performed by the Galileo
spacecraft, which was on its way to
Jupiter in 1989. In order to build up
enough speed to ensure it would arrive
at the right time and place, Galileo
flew around Venus once and then
twice around Earth, gaining enough
speed and energy to help slingshot it
all the way to Jupiter. The trip took
over six years to complete!
