Torrence Johnson Biography and Timeline

Galileo Arrives at Kennedy Space Center

The Galileo spacecraft arrives at Kennedy Space Center for final testing, mating with its probe and launch preparations.

Galileo Probe Integration

Engineers integrate the atmospheric probe with the Galileo orbiter before launch preparations are completed at Kennedy Space Center.

Galileo Venus Flyby

Galileo flies past Venus for a gravity assist on its journey to Jupiter and obtains additional planetary observations.

Venus Cloud Observations

Galileo instruments observe Venus's clouds and atmospheric properties during the spacecraft's gravity-assist encounter.

Earth-Moon Imaging by Galileo

During the first Earth flyby, Galileo obtains images of Earth and the Moon for calibration and planetary studies.

First Galileo Earth Flyby

Galileo flies past Earth for a gravity assist that increases its heliocentric speed on the journey to Jupiter.

Galileo Gaspra Flyby

Galileo becomes the first spacecraft to make a close encounter with an asteroid when it passes Gaspra.

Gaspra Surface Imaging

Galileo images Gaspra as an irregular, heavily cratered asteroid with a surface layer of loose material.

Gaspra Shape Measurement

Galileo observations establish Gaspra's strongly irregular shape and provide the first close spacecraft measurements of an asteroid.

Galileo High-Gain Antenna Failure

Galileo's high-gain antenna fails to deploy fully, forcing the mission to rely on its lower-bandwidth low-gain antenna.

Second Galileo Earth Flyby

Galileo makes a second Earth gravity assist, completing the planetary slingshot sequence that sends it toward Jupiter.

Galileo Lunar North Polar Imaging

During its second Earth encounter, Galileo obtains views of the Moon useful for studies of lunar surface composition.

Galileo Ida Flyby

Galileo flies past asteroid Ida, becoming the second spacecraft encounter with an asteroid.

Ida Surface Imaging

Galileo images Ida's heavily cratered surface and extensive regolith during the close asteroid encounter.

Galileo Views Shoemaker-Levy 9 Impact

Galileo observes Shoemaker-Levy 9 impacts on Jupiter's far side from a unique spacecraft viewpoint.

Role range: 1948-

Dactyl Discovery

Scientists examining Galileo images discover Dactyl orbiting Ida, the first moon ever found around an asteroid.

First Asteroid Moon

Galileo observations establish that asteroid Ida possesses a natural satellite, showing that asteroid moons can exist.

Galileo Jupiter Arrival

Galileo becomes the first spacecraft to enter orbit around Jupiter.

Role range: 1948-

First Galileo Ganymede Flyby

Galileo makes the first of its close Ganymede encounters during its Jupiter orbital mission.

Role range: 1948-

Second Galileo Ganymede Flyby

Galileo makes another close Ganymede encounter, passing much nearer the surface than during its first targeted flyby.

First Galileo Callisto Flyby

Galileo makes its first close pass of Callisto, mapping the moon's ancient cratered surface.

Role range: 1948-

First Galileo Europa Flyby

Galileo makes its first targeted close flyby of Europa and images its fractured icy terrain.

Role range: 1948-

Galileo Europa Flyby

Galileo data strengthens evidence for a subsurface ocean at Europa.

Role range: 1995-2003

Europa Close Flyby

Galileo passes within about 586 kilometres of Europa and images additional regions of its fractured icy surface.

Ganymede April Flyby

Galileo conducts another Ganymede encounter, extending surface, plasma and magnetic observations.

Ganymede May Flyby

Galileo returns to Ganymede for another targeted encounter during its primary Jupiter tour.

Europa Layered Interior Evidence

Galileo results indicate Europa has a differentiated interior with a metallic core and rocky mantle.

Role range: 1948-

Callisto June Flyby

Galileo flies close to Callisto, adding detailed imaging and geophysical measurements of the heavily cratered moon.

Callisto September Flyby

Galileo performs another targeted Callisto encounter late in its primary mission.

Europa November Flyby

Galileo returns to Europa for another close encounter near the end of the primary mission.

Galileo Europa Mission Extension

NASA approves an extended Galileo mission emphasizing repeated close encounters with Europa.

Role range: 1948-

Europa Extended-Mission Flyby

Galileo makes a close Europa flyby as the extended Galileo Europa Mission begins.

Europa Ice Raft Terrain

Galileo images reveal disrupted blocks of Europa's icy crust that appear to have rotated and shifted relative to surrounding terrain.

Europa Young Surface Evidence

The scarcity of large impact craters in Galileo images indicates that Europa's visible surface is geologically young.

Io Volcanic Surface Changes

Galileo imaging documents major surface changes on Io caused by continuing volcanic eruptions.

Galileo Ganymede Flyby

Galileo measures evidence of Ganymede's magnetic field.

Role range: 1995-2003

Europa March Flyby

Galileo makes another targeted pass of Europa during the extended mission.

Europa May Flyby

Galileo conducts a further Europa encounter to examine the icy surface and surrounding environment.

Europa July Flyby

Galileo returns to Europa during a sequence of repeated extended-mission encounters.

Europa September Flyby

Galileo passes Europa again, continuing the extended survey of its geology and space environment.