Hubble Space Telescope
35 years above the atmosphere
Hubble is a 2.4-metre optical and ultraviolet telescope orbiting roughly 547 km above Earth. It was carried to orbit in 1990 aboard Space Shuttle Discovery, and has been operating — with five crewed servicing missions in between — ever since.
From its perch above the atmosphere, Hubble sees a sky that ground telescopes can't: no twinkling stars, no airglow, no atmospheric absorption swallowing UV light. That clarity is what let it pin down the age of the universe, catch the first whiff of an exoplanet's atmosphere, and stare for ten straight days into a patch of empty sky to find thousands of galaxies nobody knew were there.
Today Hubble works alongside the James Webb Space Telescope, covering the wavelengths Webb can't — UV and visible light — and continuing a 35-year unbroken record of observations.
Mission timeline
- 1990 · Apr 24Launch
Lifted off aboard STS-31, carried to 547 km LEO by Space Shuttle Discovery.
- 1990 · JunSpherical aberration discovered
First images come back blurred — the primary mirror was ground 2.2 µm too flat at the edge.
- 1993 · DecServicing Mission 1 — eyesight restored
STS-61 installs COSTAR and a corrected WFPC2; Hubble's vision is finally what was promised.
- 1995 · DecFirst Hubble Deep Field
Ten days staring at a near-empty patch of sky; reveals thousands of galaxies and reshapes cosmology.
- 1997 · FebServicing Mission 2
STIS and NICMOS replace older instruments — adds spectroscopy and near-infrared.
- 1999 · DecServicing Mission 3A
Replaces all six gyroscopes after multiple failures; emergency mission to keep Hubble alive.
- 2002 · MarServicing Mission 3B
ACS installed — wider field, sharper imaging; powers a decade of iconic deep-sky photographs.
- 2009 · MayServicing Mission 4 — final visit
STS-125 installs WFC3 and COS, repairs ACS and STIS. Last time human hands touch Hubble.
- 2024 · JunReduced-gyro pointing
After further gyro failures, NASA shifts Hubble to single-gyro operation to extend mission life.
- TodayOperating alongside JWST
Hubble's UV and visible coverage complements JWST's infrared — together they observe the same targets in different light.
Active instruments
- Wide Field Camera 3
UV, visible and near-infrared imaging — Hubble's main camera
- Advanced Camera for Surveys
Wide-field deep imaging in visible light
- Cosmic Origins Spectrograph
Ultraviolet spectroscopy — chemistry of the cosmic web
- Space Telescope Imaging Spectrograph
Spectra across UV, visible and near-IR; exoplanet atmospheres
- Fine Guidance Sensors
Precision pointing and astrometry
Headline discoveries
Hubble pinned down the expansion rate of the universe to within a few percent — anchoring its age at roughly 13.8 billion years.
Observations of distant supernovae confirmed that the universe's expansion is accelerating — the discovery of dark energy.
First detection of an exoplanet's atmosphere (HD 209458b, 2001) — opened the field of remote chemistry on alien worlds.
Hubble Space Telescope
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Related videos
Track Hubble in real time
Fly alongside Hubble in NASA's Eyes on the Solar System — a real-time 3D simulation of the telescope circling Earth in low orbit.
Data: NASA/JPL — Eyes on the Solar System
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