Largest Ground-Based Optical Telescopes
The Extremely Large Telescope (ELT) under construction by the European Southern Observatory in Chile will have a 39-meter primary mirror, making it the world's biggest optical telescope when operational. Construction began in 2017, with first light expected in the coming years. The ELT will be located at Cerro Armazones in the Atacama Desert and aims to revolutionize exoplanet research and cosmology.
The Giant Magellan Telescope (GMT) at Las Campanas Observatory in Chile features seven 8.4-meter mirrors forming a 24.5-meter equivalent aperture, making it one of the world's biggest eyes for ground-based astronomy. Construction is underway with first light targeted for the late 2020s. The GMT consortium includes institutions from the United States, South Korea, and Australia.
Key Technical Specifications
Mirror Size and Light Gathering
Larger mirrors collect more light, allowing telescopes to see fainter and more distant objects. The ELT's 39-meter mirror will gather roughly 100 million times more light than the human eye, enabling direct imaging of exoplanets and early galaxies.
Adaptive Optics Systems
Both the ELT and GMT use advanced adaptive optics to correct atmospheric distortion in real time, delivering sharper images than the Hubble Space Telescope from the ground. These systems use deformable mirrors controlled by thousands of actuators.
World's Biggest Eyes in Space
The James Webb Space Telescope (JWST), launched in December 2021, has a 6.5-meter gold-coated beryllium mirror, making it the world's biggest space-based optical and infrared observatory to date. JWST orbits the Sun at the second Lagrange point (L2) and has delivered unprecedented images of early galaxies, exoplanet atmospheres, and stellar nurseries since becoming operational in mid-2022.
NASA, ESA, and the Canadian Space Agency operate JWST, with Northrop Grumman as the primary contractor. The telescope's sunshield, the size of a tennis court, protects its instruments from heat, enabling infrared sensitivity that reveals objects too faint or distant for previous telescopes.
Upcoming Space Observatories
Nancy Grace Roman Space Telescope
NASA's Roman Space Telescope, scheduled for launch in the mid-2020s, will carry a 2.4-meter mirror and a wide-field instrument capable of surveying large swaths of the sky, complementing JWST's deep but narrow view.
European Space Agency Missions
ESA's Ariel mission, planned for launch in 2029, will study the atmospheres of hundreds of exoplanets, furthering the search for habitable worlds by analyzing light filtered through their atmospheres.
Companies and Funding Behind the World's Biggest Eyes
Major funding for the ELT comes from the European Southern Observatory's member states and Brazil, with total costs exceeding 1.5 billion euros. Private companies including SpaceX and Blue Origin provide launch services for satellite-based observatories and components, while defense and aerospace firms supply precision optics and sensors.
SpaceX has launched multiple NASA and commercial satellites with large optical and radar imaging systems, including Earth observation satellites for companies like Maxar Technologies. The SEC filings and public contracts show growing demand for space-based imaging, with the global satellite imagery market projected to expand significantly through the decade.