Galileo project

On September 21, 2003, Galileo was deliberately plunged into Jupiter’s atmosphere to avoid any risk of contaminating Europa, where a subsurface ocean—one of Galileo’s major discoveries—might support life. The controlled impact ended the mission, preserving scientific integrity.

Beginning in January 2000, the Galileo Millennium Mission commenced—a second extension of Galileo’s operational life. During this time, Galileo performed additional close flybys of Europa and Io, studied Ganymede’s magnetosphere, analyzed Jupiter’s rings, and coordinated observations with the Cassini spacecraft’s Jupiter flyby in December 2000.

By December 14, 1997, Galileo concluded its two‑year primary mission around Jupiter and began the Galileo Europa Mission extension. This phase focused on intensive flybys of Europa and further investigations of Io, Ganymede, and Callisto to deepen understanding of these diverse satellites.

On December 7, 1995, the atmospheric probe entered Jupiter’s atmosphere, transmitting valuable data for about 58 minutes before being destroyed by pressure. The orbiter also officially entered Jupiter orbit around that time, beginning detailed study of the Jovian system.

On July 13, 1995, the Galileo orbiter released its atmospheric entry probe approximately 80 million km from Jupiter. This probe was intended to penetrate and measure the Jovian atmosphere directly, gathering data as it descended under parachute.

In July 1994—notably around July 22—Galileo captured the only direct observations of Comet Shoemaker–Levy 9’s fragments impacting Jupiter’s atmosphere. These stunning images and data provided a rare real-time glimpse into high-energy cosmic collisions.

On August 28, 1993, Galileo flew by asteroid 243 Ida at roughly 2,400 km, leading to the discovery of Dactyl, the first moon of an asteroid ever observed. This remarkable find fundamentally changed our understanding of small body systems in the asteroid belt.

On October 29, 1991, Galileo achieved the historic milestone of becoming the first spacecraft to fly by an asteroid, passing within about 1,600 km of 951 Gaspra. This pioneering encounter provided humanity with its first close-up views of an asteroid’s surface.

On December 8, 1990, Galileo made its first Earth flyby perigee at about 960 km to gain additional speed. This gravitational boost was critical to sending the spacecraft back into orbit around the Sun en route to its eventual destination around Jupiter.

On February 10, 1990, Galileo executed its first gravity‑assist maneuver, flying past Venus at approximately 16,000 km altitude. This slingshot around Venus boosted its trajectory toward Earth and ultimately enabled its journey to Jupiter, compensating for the change from a direct route.

On October 18, 1989, NASA launched the Galileo spacecraft aboard Space Shuttle Atlantis (STS‑34) from Kennedy Space Center, Florida. The orbiter, carrying an atmospheric entry probe, began its long journey to Jupiter using gravity assists due to the cancellation of its initial direct trajectory.

In October 1977, the mission that would become the Galileo Project began formal planning under NASA. Project manager John R. Casani led early development and solicited a more inspirational name. ‘Galileo’—chosen via votes by the team—honored Galileo Galilei’s discovery of Jupiter’s major moons in 1610. This origin of the name reflects both the heritage and scientific aspirations of the mission.