Space telescopes allow us to peer into the farthest reaches of our universe and observe everything from distant galaxies to recently discovered exoplanets. But launching these high-tech marvels into space is no easy feat – the larger the telescope, the more challenges are involved getting them into orbit.
In this guide to the 10 largest telescopes in space, we‘ll explore what makes each instrument unique, the key discoveries they‘ve enabled, and the cutting-edge technology allowing them to detect wavelengths we can‘t see with the naked eye. Read on for an awe-inspiring tour of these essential tools expanding our understanding of the cosmos.
Why Size Matters for Space Telescopes
The sheer size of space telescopes is crucial for collecting enough light to observe faint, distant cosmic objects. Larger primary mirrors mean the telescope can gather more light, allowing it to detect galaxies farther than ever before. Massive instruments with wide spans are also less affected by disturbances that could impact image quality.
Once in the frictionless environment of space, it‘s possible to launch truly enormous telescopes on stable orbits. Without atmospheric interference, Hubble and other space telescopes achieve optical precision vastly superior to Earth-based instruments. The tradeoff is the immense cost and complexity of not only building these high-precision optics, but actually getting them into orbit.
Overcoming the Challenges of Space Telescopes
To work in space, telescopes and sensors need to withstand dramatic temperature changes, high radiation, zero gravity conditions and the forceful vibrations of launch. Each component must be engineered and tested for the rigors of spaceflight before integrating into the full observatory.
Once in orbit, advanced control moment gyroscopes finely point the telescopes with extreme precision. Onboard batteries and solar panels generate steady power even in the dark reaches of space. Data is transmitted through high gain antennas often located on articulated arms to stay locked onto Earth. Teams of experts work continuously to maintain telescope operations for years far beyond their planned lifetimes.
Let‘s explore some record-breaking space telescopes that represent decades of innovation in overcoming the ultimate challenges of observing the cosmos.
10. Planck – Mapping the Oldest Light
Size: 14 feet wide
Weight: 452 kg
Wavelengths: Microwave/Radio
Discoveries: Detailed all-sky map of the early universe
As the 10th largest telescope in orbit, Planck had a bold mission – to study light from the very dawn of creation. After its 2009 launch, this European Space Agency observatory traveled to the L2 Lagrange point a million miles from Earth. Free of hindrances, it could focus completely on detecting the faint cosmic microwave background (CMB) leftover from the Big Bang 13.8 billion years ago.
Planck’s super-sensitive instruments mapped tiny variations in this extremely old light. By revealing fluctuations in density and temperature in the early universe, Planck enabled precise calculations of its age, content, and evolution. It peered back in time to just 380,000 years after the Big Bang, providing unprecedented clues to how the first stars and galaxies were born.
9. CoRoT – Pioneering Exoplanet Discovery
Size: 7 x 13 feet
Weight: 626 kg
Wavelengths: Visible & Infrared
Discoveries: First exoplanet sized like Earth; over 30 exoplanets discovered
The CoRoT Space Telescope demonstrates enormous discoveries are possible even with smaller space telescopes. Launched by the French Space Agency CNES in 2006, its 0.27-meter aperture main mirror was relatively modest. But its highly sensitive camera and optical system specialized in photometry – continually measuring star brightness over time.
So CoRoT was perfectly positioned in 2008 to witness an enticing dip in a star’s light curve. Further analysis confirmed the telescope had found COROT-7b, the first exoplanet comparable in size to Earth orbiting another star. This intriguing rocky world sparked hopes we may eventually find life-friendly planets across the galaxy.
Over its 8 year lifetime, CoRoT went on to discover over 30 exoplanets before being retired in 2014. Its pioneering methods blazed a trail for today‘s advanced exoplanet hunters like Kepler, TESS and the James Webb Space Telescope.
8. Herschel – Revealing the Infrared Cosmos
Size: 13 x 25 feet
Weight: 694 kg
Wavelengths: Infrared & Submillimeter
Discoveries: Water plumes on Enceladus; rings around asteroid Chariklo
The European Space Agency’s Herschel space observatory brought unseen infrared wavelengths into clear view starting in 2009. With its 3-foot wide mirror, Herschel could finally discern extremely cool, dusty regions like star-forming clouds and nebulae. Its two onboard cameras captured wavelengths far beyond what Hubble can see – from 55 to 620 micrometers.
Peering through obscuring dust, Herschel observed stars in earliest stages of formation for the first time. It conclusively found water vapor gushing from Saturn’s icy moon Enceladus by identifying its chemical signature. Most unexpectedly, the telescope revealed two subtle rings surrounding the minor planet Chariklo – the smallest object known to have rings.
Herschel transformed our understanding of star and galaxy creation through detailed infrared imaging of hidden stellar nurseries. When its supply of coolant ran out in 2013, the pioneering infrared telescope was retired after exceeding expectations.
7. Kepler – Revelation of Thousands of Exoplanets
Size: 15 x 9 feet
Weight: 1,052 kg
Wavelengths: Visible & Ultraviolet
Discoveries: 2,600+ confirmed exoplanets; identification of super-Earth Kepler-452b
Humanity’s awareness permanently shifted after NASA’s exoplanet hunter Kepler lifted off in 2009. Fixated on a small patch representing just 1/400th of sky near the constellation Cygnus, Kepler continuously monitored stars for minuscule dips signaling possible planets crossing in front.
With a 1.4-meter mirror and extreme visible light sensitivity, Kepler confirmed over 2,600 planets outside our solar system – more than all discoveries in history combined before its launch. By revealing the vast population and diversity of exoplanets, Kepler forever changed our notion that planets must resemble Earth to be habitable.
Among its illustrious catalog is Kepler-452b, larger and older than Earth with a 365 day orbit around a Sun-like star. Our first near twin in the habitable zone, tantalizing Kepler-452b hints that rocky worlds suitable for life may be common after all.
After 9 prolific years of literally revolutionizing exoplanetary science, Kepler was retired when it finally exhausted its fuel supply in 2018. But astronomers continue poring over almost a decade of Kepler’s precious readings, with further discoveries assured for years ahead.
6. Neil Gehrels Swift Observatory – Catching Cosmic Fireworks
Size: 18 x 18 feet
Weight: 1,858 kg
Wavelengths: Gamma-ray, X-Ray, UV, Optical
Discoveries: Rapid observation of gamma-ray bursts; black hole formation theories
Swift has its sights set on the biggest and brightest explosions in the cosmos. Originally called Swift Gamma-Ray Burst Explorer, this multipurpose NASA observatory catches rapidly fading gamma-ray bursts with great speed and sensitivity. It can swiftly pivot its mirrors to bring the burst location into view of its onboard telescopes and spectrometers.
Within seconds, Swift is obtaining X-ray, ultraviolet and optical data to monitor an explosion as it unfolds. Catching immediate afterglow of these highest-energy events provides clues to deaths of massive stars and formation of black holes. In one case, Swift observed the longest recorded duration of gamma-ray burst afterglow – an astonishing 125 days.
Nearly 20 years since its 2004 launch, NASA’s Neil Gehrels Swift Observatory remains a dynamic sentry constantly seeking out shockingly brilliant eruptions happening randomly in distant galaxies.
5. Spitzer Space Telescope – New Understanding with Infrared
Size: 3 foot wide primary mirror
Weight: 977 kg
Wavelengths: Infrared
Discoveries: First exoplanet atmosphere; composition analysis of distant planets & rings
Though smaller than other Great Observatories, Spitzer plays an outsized role in revealing hidden aspects of cosmic objects through penetrating infrared light. Initially chilled to just 10 degrees above absolute zero, Spitzer’s receivers could isolate faint heat radiation from extremely distant features. This ability unveils stars swaddled in dust that visible light can’t penetrate.
By measuring infrared variations as a planet passed behind its star, Spitzer marked an astronomical first in 2005 – directly identifying composition of an exoplanet atmosphere over 50 light-years away. It performed similar miracles to study atmospheres and surface characteristics of Mercury, Saturn’s moon Titan and the comet Tempel 1.
Spitzer brought an infrared eye to complement Hubble with spectacular color panoramas of nebulae, views into galaxy clusters, and survey maps showing distribution of stars and dust. Retired in 2020 after exceeding all expectations, this infrared pioneer compiled over 10,000 scientific papers transforming our view of the cosmos.
4. Fermi Gamma-ray Space Telescope – Illuminating Secret Cosmic Drivers
Size: 9 x 8 feet
Weight: 4,303 kg
Wavelengths: Gamma-ray
Discoveries: Resolve countless gamma-ray sources; Growing giant radio lobes associated with quasars
Swooping just 350 miles overhead, NASA’s Fermi Gamma-ray Space Telescope continuously scans the entire sky every three hours seeking extreme bursts of photon energy. By timing and charting these bright gamma-flashes, Fermi sheds light on underlying cosmic engines like supermassive black holes.
One stunning breakthrough arrived in 2010 when Fermi connected a galaxy’s core to its sprawling two-million light-year wide lobes of plasma spotted in radio surveys. Fermi confirmed these giant structures shine brightly with gamma-rays when viewed up close – directly linking them to quasars and their intense energy releases traveling at near-light speed.
Now over 14 years into its mission, Fermi’s all-sky gamma vision makes it an invaluable tool for monitoring high-energy changes in pulsars, probing gravity waves, and even searching for dark matter signatures.
3. Chandra X-ray Observatory – Deciphering the X-ray Cosmos
Size: 45 x 64 feet
Weight: 10,560 kg
Wavelengths: X-rays
Discoveries: Deepest X-ray images ever; first clear evidence for supernova remnants
The Chandra X-ray Observatory explores wild, unpredictable extremes happening billions of light years away across the cosmos. As part of NASA’s Great Observatory series along with Hubble and Spitzer, Chandra focuses on high energy sources prominently emitting blistering X-rays. It captures exotic realms invisible to not only human sight, but all other telescopes – cloud-piercing views of black holes gorging on infalling matter, shockwaves spreading out from exploded stars, and hot gas clouds tracing galaxy cluster growth.
In over two decades of operation, Chandra has imaged typhoon-like swirls surrounding monstrous Sagittarius A*, the supermassive black hole at our galaxy’s center. Its long exposure image of the Chandra Deep Field South pierced through a staggering 7 million light years of space. Piecing together Chandra’s X-ray puzzle continues advancing our comprehension of star life cycles and energetic processes sculpting our universe’s large-scale structure.
2. James Webb Space Telescope – Unprecedented Infrared Vision
Size: 46 x 66 feet
Weight: 6,500 kg
Wavelengths: Infrared
Discoveries: Record galaxy distance of 13.4 billion lightyears; unprecedented visibility through dust to see earliest stages of star formation
The largest space observatory ever constructed, NASA‘s James Webb Space Telescope is just beginning its quest to solve cosmic mysteries in 2022 and 2023. From a gravitationally balanced point a million miles distant, this $10 billion engineering marvel tuned specifically for infrared light aims to find traces of the very first stars and peer into the atmospheres of exoplanets like never before.
With its mirror over 5 times wider and 50 times more sensitive than previous infrared telescopes in space, James Webb can pierce through obstructing dust clouds to reveal youthful stars emerging inside stellar nursery nebulae. Its spectrographic sensors can discern atmospheric gases and signatures of potential life on distant exoplanets. Already Webb is glimpsing the farthest galaxies ever viewed at 13.4 billion lightyears away, when the cosmos was a fraction of its current age.
Much anticipation surrounds James Webb’s first full year of scientific operations in 2024. Its transformational eye into the infrared universe will tell epic tales spanning eons from nascent planets to dying stars to energetic mergers shaping galaxies over time.
1. Hubble Space Telescope – Legacy of Scientific Marvels
Size: 43 x 14 feet
Weight: 11,100 kg
Wavelengths: Ultraviolet to near-Infrared
Discoveries: Farthest known galaxies; accelerating expansion of universe
The reigning champion Hubble Space Telescope has expanded our visible and infrared view dramatically during 32 years in orbit. Though dozens have followed since Hubble’s launch in 1990, it remains the single most scientifically productive instrument ever sent to space. Its precise optics deliver breathtaking visible and ultraviolet views of stars, nebulae and galaxies unprecedented from the ground.
Among Hubble’s profound impacts on astronomy came verification that nearly all major galaxies contain black holes at their centers; stunning glamour shots of planets inside our solar system; and Voyager 2‘s historic flybys of outer planets.
Hubble galaxies verify our universe is not only expanding – but actually accelerating outward. Measurements of supernovae in distant galaxies suggest repulsive dark energy comprises our cosmos, counteracting gravity’s pull. Insights into the hidden underpinnings of our universe’s dynamics may be Hubble’s lasting legacy that guides cosmology for generations.
While its successor Webb offers infrared vision Hubble can’t match, NASA will continue relying on its veteran space telescope into the 2030s for visible and ultraviolet prowess.
After our awe-inspiring tour across giant observatories in space, we better appreciate why orbital telescopes have opened entire new eras in astronomy. Unbound by Earth’s atmosphere, these great observatories gather light beyond human perception to unveil countless wonders. Ultraviolet and infrared views expose phenomena our eyes simply can’t process directly – embryonic stars buried behind dust, fiery matter circling black holes, exoplanets transiting distant suns.
Through coordinated synergy across the electromagnetic spectrum from radio waves to gamma-rays, space telescopes enrich each other’s revelations about cosmic ecosystems. Chandra’s X-ray acuity delivers a wildly different picture than Hubble’s optical clarity. Meanwhile Spitzer and Webb penetrate dusty regions impenetrable to our most privileged view from Hubble. Each astronomical messenger enriches a unified story expanding our appreciation of the universe’s scale, contents and history.
So what’s next for orbital telescope technology? NASA plans to launch two specialized observatories in 2027 – the compact X-ray Imaging and Spectroscopy Mission (XRISM) and the wide-field Nancy Grace Roman Space Telescope tailored for panoramic visible and infrared imaging. Meanwhile the agency is collaborating with the European Space Agency on the 2034 launch of the groundbreaking LUVOIR multiwavelength observatory, which may eventually succeed Hubble after its retirement.
With each barrier-breaking telescope reaching new wavelengths, resolution, and sensitivity, our collective view becomes that much clearer on the rhythms and relative arrangement shaping our marvelously complex cosmos.
