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    IntroductionCallisto and Jupiter’s three other largest moons were discovered in 1610 by Italian scientist Galileo Galilei.

    Almost 400 years later , a spacecraft bearing his name—the Galileo orbiter—began the first in depth study of the Jovian system, including Callisto and its sister moons. Galileo orbited Jupiter until the mission ended in 2003.

    Since then, several NASA spacecraft, including Cassini and New Horizons, have studied the moon, taking images of its surface and gathering other data.

    Significant Events

    Notable Explorers

    Missions

    Careers

    10 Careers That Explore Space

    1

    Astronaut

    Astronauts pave the way for human exploration beyond our Earth. They are pilots, scientists, engineers, teachers, and more.

    2

    Project Manager

    Project managers guide missions from concept to completion, working closely with team members to accomplish what they set out to do.  

    3

    Rover Camera Operator

    A camera payload uplink lead writes software commands that tell a rover what pictures to take.

    The first thing that fired my imagination for planetary science was when the NASA Voyager spacecraft discovered active volcanoes on Jupiter's moon Io.

    4

    Artist

    Melding science with design, artists create everything from large-scale installations to the NASA posters hanging in your bedroom. 

    5

    Media Specialist

    Media specialists tells stories across social media and help feature missions and people on TV and in films, books, magazines, and news sites. 

    6

    Writer/Producer

    Writers/producers capture the incredible stories of NASA's missions and people and share them with the world. 

    7

    Administrator/Director

    Administrators and directors work out of NASA headquarters, prioritizing science questions and seeking to expand the frontiers of discovery.

    8

    Educator

    Whether it's introducing kids to space or teaching physics to PhD candidates, educators help share their knowledge with the public.

    9

    Engineer

    Engineers design and build all types of machines, from what a spacecraft looks like to the software that directs where a rover goes each day. 

    10

    Scientist

    From an astrophysicist to a volcanologist, scientists of all types pose questions and help find answers to the mysteries of our universe.

    The important thing about being a scientist or an engineer is learning how to think critically, learning how to be creative, learning problem solving and learning how to learn.

    Explore in 3D

    Eyes on the Solar System Ad

    Explore in 3D—Eyes on the Solar System

    Eyes on the Solar System lets you explore the planets, their moons, asteroids, comets and the spacecraft exploring them from 1950 to 2050. Ride with the Curiosity Rover as it lands on Mars or fly by Pluto with the New Horizons spacecraft all from the comfort of your home computer.

    Eyes on the Solar System ›

    Solar System News