Hubble Space Telescope
The Hubble Space Telescope is a NASA/ESA observatory launched on 24 April 1990 aboard the space shuttle Discovery. Orbiting about 483 km above Earth, its 2.4-meter mirror has made more than 1.7 million observations, from the deep fields that revealed thousands of galaxies to measurements that fixed the universe's expansion rate at near one percent precision. Astronauts serviced the telescope five times between 1993 and 2009 — the first mission correcting the spherical aberration that blurred its early images — and since June 2024 Hubble has operated in one-gyro mode, continuing its work alongside the James Webb Space Telescope.