Between 1993 and 2009, Hubble was serviced for repairs and upgrades 5 times

Hubble overcame early optical failure and became a critical scientific instrument

The flaw in Hubble's mirror was smaller than the width of a human hair, but fixing it required a space mission as complex as a Hollywood rescue story—with astronauts installing corrective optics like contact lenses for a giant eye in the sky.

Watch a firsthand account of Hubble's first service mission to repair its faulty mirror

Hubble senior project scientist David Leckrone recalls initial public ridicule over the microscopic manufacturing error that put NASA's reputation at stake. In this behind-the-scenes interview, he breaks down the innovative fix deployed by space shuttle astronauts during Hubble's first servicing mission.

Atmospheric drag is causing the Hubble Space Telescope to drift toward Earth slowly

Without interventions to boost the observatory to a higher orbit, Hubble is expected to fall to Earth's surface in the mid-2030s. In the meantime, the telescope is expected to continue to be productive by shifting its mode of operation to rely on a single gyroscope, down from three.

The Challenger disaster delayed the launch of the Hubble Space Telescope

The 1986 explosion of the space shuttle shortly after liftoff killed seven crew members and grounded NASA's space fleet. Scientists used the downtime to refine ground control software and upgrade telescope instrument sensitivity, but maintaining the telescope's clean room storage cost NASA approximately $6M per month.

View galleries of images taken by the Hubble Space Telescope

With more than 1.7 million observations made since 1990, the Hubble Space Telescope has captured images of space missions, planets, stellar nurseries, interstellar comets, star clusters, galaxies, and more. This search tool allows users to sort and filter across these celestial objects to explore over 35 years of Hubble's astrophotography.

Hubble's average used power is less than half the power generated by its solar arrays

The space telescope's components use about 2,100 watts, or about as much power as five refrigerators. When exposed to sunlight, the solar arrays can generate over 5,200 watts for the observatory, which was engineered by a team that included Judith Love Cohen, mother of actor Jack Black.

The twenty-year effort to design the Webb's optics

Since its located 1 million miles from Earth, the Webb space observatory has to be able to repair itself—no Space Shuttles can be dispatched with astronaut engineers to repair it. That's why over two decades teams reiterated, cross-checked, and hyper-optimized the Webb's observing surface. Their efforts produced the world's largest space-based optical surface that is peering billions of years back in time. Learn the wild engineering of the telescope here.

Take a 360-degree tour of Discovery with Kathryn Sullivan and Charles Bolden, who flew together on the space shuttle during its deployment of the Hubble Space Telescope. (VR device-compatible)

An imperfection 1/50th the width of a human hair blurred Hubble's initial images

Not all parts of the space telescope's primary mirror focused incoming light to the same location, an effect known as spherical aberration. Because Hubble was designed to reside in low Earth orbit and be serviced by astronauts, service missions were deployed in the years after its launch to conduct repairs.

The Hubble Space Telescope made discoveries within our solar system and across the universe

The observatory helped confirm the presence of water on Jupiter's moon Europa, and uncovered seasonal variations on planets like Uranus. It also observed exoplanets and gravitational lensing, proved the existence of supermassive black holes at the centers of galaxies, and detected the accelerated expansion of the universe.

Fly through the deepest image of space ever taken by the Hubble Space Telescope

Taken over 11 days between 2003 and 2004, when the space telescope was aimed at a seemingly empty patch of the sky, the Hubble Ultra-Deep Field revealed about 10,000 sources of light, most of which are entire galaxies. This visualization expands the 2D image into a 3D view spanning 12 billion years.

Space telescope development was driven by a desire to bypass Earth's atmosphere

The most important figure in the effort to create what would become the Hubble Space Telescope was Lyman Spitzer, who first proposed a telescope in orbit in 1946. The nearly 50-year endeavor led to space-based observatories, which are not limited by Earth's atmosphere absorbing or distorting most wavelengths of light.

Intended to last four years, the Voyager spacecraft have lasted nearly five decades

Launched in 1977, the Voyager probes still send data from billions of miles away, guided by engineers who’ve turned down promotions to stay with the mission. The team continues to support the probes as they move 37,000 mph through space.

View a timeline of NASA's Space Shuttle program, which saw five reusable orbiters take a total of 355 astronauts across a combined distance of almost six trips to the sun.

Over a decade before the launch of the Hubble Space Telescope, Nancy Roman oversaw the Orbiting Solar Observatory program, which launched eight spinning spacecraft into low Earth orbit to study the sun.

The Hubble Space Telescope uses curved mirrors to collect and focus light

Classified as a Cassegrain reflector, the observatory bounces incoming visible light and some infrared and ultraviolet light off a primary mirror with a diameter of 2.4 meters. The reflected light is directed to a secondary mirror, which reflects it through a tiny hole in the primary mirror and onto detectors.

The most common spacewalk spacesuits are over four decades old

NASA's Extravehicular Mobility Unit has been in use since the 1980s, with 11 units of the model in existence and four in active use on the ISS at any given time. It consists of 11 layers, a primary life support system (which resembles a backpack), a drinking bag, and more.

Play an interactive game to explore and learn about Hubble images

Aboard the fictional USS Hubble, users can choose their own adventure to investigate the solar system, our galaxy, and the universe beyond. Each option directs users to a real image accompanied by relevant information and additional media elements, such as a time-lapse of the moon Phobos orbiting Mars.

The Hubble Space Telescope is named after astronomer Edwin Powell Hubble

Using the Hooker Telescope at the Mount Wilson Observatory in California in the 1920s, Hubble identified Cepheid variable stars in what was believed to be the Andromeda nebula. These stars can be used to determine distance in space, allowing Hubble to realize that Andromeda was a galaxy of its own.

Designs for the Hubble Space Telescope were based on Cold War spy satellites

By incorporating elements of the KH-11 KENNEN reconnaissance satellites, NASA could incorporate existing classified manufacturing expertise and infrastructure from the intelligence community to expedite the research project.

The next generation of space-based observatories

How exactly does a space telescope come to be funded by NASA? NASA's most famous telescopes, like Hubble and James Webb, were once featured in the decadal survey–a once per decade survey run by the National Academy of Science that recommends which projects to support. This article and podcast covers which telescope designs are in contention to be part of NASA's next generation of space-based observatories.

Voyager spacecraft defied expectations and only powered down after 47 years in space

Originally built for a four-year mission, Voyagers 1 and 2 used a rare planetary alignment and gravity assists to reach interstellar space. With limited power and aging systems, they will continue to send data until the mid-2030s. (Some readers may experience a paywall.)

Between 2002 and 2025, upgrades have increased LIGO's detection range tenfold

After the construction of Initial LIGO was completed in 1999, no gravitational waves were detected during operations between 2002 and 2010. Instrument redesigns and significant technological improvements brought about Advanced LIGO, which began observations in 2015. Continued upgrades between continuous laser runs have improved detection sensitivity and stability.

Most elements of the International Space Station were installed over two decades

Space shuttles delivered storage carriers, docking compartments, airlocks, solar arrays, and labs, which were assembled in low Earth orbit. The station’s Canadarm2 robotic arm, alongside maneuvering spacewalkers, has assisted with this assembly since its installation in 2001.

See where the James Webb Space Telescope is in space right now

Webb travels through space in a stable orbit, but unlike the Hubble, it doesn't orbit around Earth. The Webb orbits around the sun in a way that allows it to always be in line with the Earth, as you can see in this visualization of the telescope's real-time position.

Major milestones of the Space Shuttle program's 135 missions included the launches of the Hubble Space Telescope and the Chandra X-ray Observatory, and the first American woman and African-American astronauts in space.

Voyager science teams still collect valuable space data using four active tools

These instruments track magnetic fields, solar wind particles, radio emissions from the heliopause, and hydrogen levels in the outer heliosphere. Even though each Voyager sends data at just 160 bits per second, NASA receives 6–8 hours of tracking data daily.

The breakthrough that changed our perception of the universe

In the 1920s, the Hooker Telescope helped Edwin Hubble make a discovery that forever changed how we see the universe. Building on the work of astronomers like Henrietta Leavitt and Harlow Shapley, Hubble used the telescope to prove that galaxies exist beyond the Milky Way—revealing a vast and expanding universe.

Hubble's first light test produced an underwhelming photograph

This test represents the first time light travels entirely through an observatory's optical system and reaches its detectors, producing an image. Although the telescope's warped mirror was not discovered and announced until a month after first light, the issue was not responsible for the simplicity of the first light image.

View a simulated demonstration of how the Nancy Grace Roman Space Telescope will survey large portions of the sky to capture in 90 minutes what took three years for the Hubble Space Telescope.

The James Webb Space Telescope is rewriting what we know about the early universe

Thanks to its advanced infrared sensors and massive mirror, the James Webb Space Telescope can see farther back in cosmic history than Hubble, revealing galaxies formed just 500 million years after the Big Bang.

Explore the interior and exterior of the Atlantis and Endeavour space shuttles, including their flight decks, cargo bays, and other compartments.

The International Space Station is powered entirely by large solar arrays

Launched in 1998, its original solar panels were designed to withstand no more than 20 years of wear from temperature swings and micrometeoroid impacts in space. Replacement panels that roll out like carpets have since been installed.

See a timeline of James Webb Space Telescope discoveries

Since its launch on Christmas Day 2021, NASA's $10B James Webb Space Telescope has captivated the world with its rapid revelations of ancient galaxies, star-formation hotbeds, and more. This regularly updated timeline of Webb's discoveries keeps you up to date with the latest developments.

During Nancy Roman's tenure as the agency's chief of astronomy, NASA launched Stargazer—the first successful space telescope—as part of the Orbiting Astronomical Observatory program.

Throughout its 10-year mission to create a time-lapse of the universe, the Vera C. Rubin Observatory will generate 500 petabytes of data by taking an ultrawide, ultra-high definition image every 34 seconds.

NASA fixed Voyager 1’s glitchy memory from 24 billion kilometers away

In November 2023, Voyager 1 began sending unusable data due to a stuck bit in a decades-old memory chip. After months of investigation, engineers managed to reroute the faulty code to a new memory location, restoring functionality in April 2024.

Colorizers convert Hubble's gray scale images into color composites of different wavelengths

The near-infrared and ultraviolet light captured by the space telescope is not visible to human eyes, but observational data of these types of light can be filtered and modified into visible colors. Many detailed images of astronomical objects are the result of combining these artificially colored images into layers.

Nancy Roman, NASA's first chief of astronomy and the architect of the Hubble Space Telescope, was discouraged from pursuing science throughout her academic career.