John Spencer Biography and Timeline

Io Volcanic Plume

Spencer leads Hubble observations of an enormous volcanic plume rising hundreds of kilometres above Jupiter's moon Io.

Tvashtar Eruption Imaging

New Horizons records a giant plume from Io's Tvashtar volcano and traces its changing structure.

Role range: 1957-

Io Plume Observations

New Horizons observes giant volcanic plumes and changing surface features on Io.

Role range: 1957-

New Horizons

New Horizons detects Pluto's large moon Charon from deep space as the spacecraft continues its approach to the Pluto system.

New Horizons

New Horizons images Pluto's small moon Hydra during its long-range approach, extending spacecraft observations of the satellite system.

Pluto Moons

New Horizons photographs Kerberos and Styx for the first time, bringing all five known Pluto moons into spacecraft view.

Charon

New Horizons images show Charon as a geologically varied world with enormous canyons and contrasting terrains.

Pluto

New Horizons images show nitrogen-rich ices flowing across Pluto in glacier-like patterns, evidence of recent geologic activity.

Pluto Moons

New Horizons observations reveal that Pluto's small moons are irregular bodies with unexpectedly complex rotational behaviour.

Pluto Moons

New Horizons detects Pluto's moon Nix during approach, adding another small satellite to its own imaging record.

Arrokoth Double-Lobed Shape

New Horizons images show that Arrokoth consists of two joined lobes, revealing an unusual contact-binary structure.