Since its launch from the Kennedy Space Center aboard Space Shuttle Columbia (STS-93) on July 23, 1999, NASA’s Chandra X-ray Observatory has continued to change our view of the Universe—allowing us to see star clusters, black holes, supernovas, and stellar nurseries in exquisite detail. With Chandra, we continue to see what would otherwise be invisible to the human eye, as its delicate sensors scan the cosmos absorbing the X-ray emissions of immensely distant objects and phenomena.

NASA's premier X-ray observatory was named Chandra in honor of the late Indian-American Nobel laureate Subrahmanyan Chandrasekhar. He was known as Chandra—"moon" or "luminous" in Sanskrit—and was one of the foremost astrophysicists of the 20th century. He developed a new understanding of the life-cycle of massive stars, from formation to their endings as neutron stars or black holes. Chandrasekhar spent much of his career at the University of Chicago.

On July 23, 1999 at 12:31 a.m. EDT, under the command of Col. Eileen Collins, Space Shuttle Columbia lifted off Kennedy Space Center’s Launch Pad 39-B at Cape Canaveral, FL. Its mission: to carry NASA's Chandra X-ray Observatory into space. Chandra was the heaviest payload ever carried by the Shuttle and posed challenges and dangers to the astronauts in charge of getting the telescope safely into orbit. STS-93, as the mission is officially known, was the first commanded by a female astronaut.

At 45-feet long—about the size of a school bus—Chandra is the largest satellite the Space Shuttle ever launched. This made the take-off and landing scenarios more complex than usual, particularly as contingencies had to be planned to land with Chandra still on board. Astronauts Eileen Collins, Jeff Ashby, Cady Coleman, Steve Hawley, and Michel Tognini spent 5 days and 1.8 million miles orbiting the Earth to deliver Chandra to space, and safely touched-down late on the night of July 27, 1999.

When Eileen Collins (b.1956) joined the Air Force ROTC, women weren’t allowed to be pilots. That changed in 1976 while Collins was studying math and economics for her undergraduate degree. In 1990 she was selected to the astronaut corps. She trained at the Johnson Space Center in Houston, TX, and became the first woman to command a NASA space shuttle mission in 1999, when STS-93 brought Chandra to orbit.

Air Force Colonel, chemist, and astronaut Cady Coleman (b. 1960) helped deploy the Chandra X-ray Observatory into space in 1999, and then went on to spend over 180 days on the International Space Station in later missions. She is a renowned flautist and played multiple flutes in space. It was during Coleman’s undergraduate years at the Massachusetts Institute of Technology (MIT), when astronaut Sally Ride shook her hand after a lecture, that Cady first envisioned joining NASA’s astronaut corps.

Once deployed, Chandra went to work. Observational tasks are relayed to Chandra daily from the Operations Control Center (OCC) through NASA's Deep Space Network (DSN). After observing, Chandra transmits data on cosmic objects, plus information about the spacecraft, back to the OCC via the DSN about every eight hours. Engineers analyze spacecraft data for information on Chandra’s health, such as temperature and power. The cosmic observations are then transmitted to scientists around the world.

Earth’s atmosphere absorbs X-rays, the specific wavelengths of light that reveal the mysteries Chandra was designed to unlock. So Chandra and its ultra-precise mirrors and detectors–plus the electronics–had to be designed to survive a rocket launch and thrive in the hostile environment of space. NASA's Marshall Space Flight Center in Huntsville, AL tested Chandra’s unusual, sturdy, barrel-shaped mirrors, and continues to manage the successful Chandra program to this day.

Chandra's resolving power is like being able to read a stop sign from twelve miles away. Northrop Grumman was the primary development contractor that assembled and tested the Chandra X-ray Observatory for NASA. Here you can see the immense size of the instrument; a true challenge to pack into and deploy from the Space Shuttle.

To achieve the groundbreaking resolution that allows Chandra to detect black holes billions of light years away, its mirrors had to be cleaned to the equivalent of at most one speck of dust on an area the size of a computer screen before being coated with iridium. Chandra’s mirrors were coated and cleaned by Optical Coating Laboratories, Inc. of California; now Optical Security and Performance, VIAVI Solutions.

Chandra’s mirrors were assembled by ITT Industries (formerly Eastman Kodak Corporation) of Rochester, New York. The alignment of the mirrors from one end of the mirror assembly to the other is accurate to about one-fiftieth the width of a human hair. Without this extreme precision, the telescope would not have been able to focus the incoming X-rays so accurately.

Chandra’s aspect camera, built by Ball Aerospace, gives highly accurate, real-time data for the observatory to determine where in the sky Chandra is pointing. The aspect camera is so accurate that if it was sitting atop the Empire State Building in New York and staring at a car in Los Angeles, it would be able to resolve the car’s right headlight from its left.

Chandra’s gratings allow scientists to study the temperature, ionization, and chemical composition of objects in space like exploded stars, stellar nurseries, and more. The Space Research Institute Netherlands and Max Planck Institute in Germany were responsible for Chandra’s Low Energy Transmission Grating.

Both gratings diffract (or spread out) intercepted X-rays, changing their direction by amounts that depend sensitively on the X-ray energy, like a prism separates light into its component colors. This information can help astronomers, for example, understand the winds blowing around a black hole. The High Energy Transmission Grating was developed and built by the Massachusetts Institute of Technology.

Light from some objects observed by Chandra has traveled ten billion years or more! Chandra’s Advanced CCD Imaging Spectrometer can make images and detect energies of incoming X-rays of things like quasars, galaxies, and objects like the exploded star Cassiopeia A, seen here.

The Smithsonian Astrophysical Observatory (SAO) manages flight operations and science activities from the Operations Control Center and Chandra X-ray Center facilities in MA. SAO also built Chandra’s High Resolution Camera. Since 1999, thousands of scientists from around the globe have explored the X-ray Universe through Chandra’s powerful instruments. Panels of scientists review proposals and the best ideas are picked. SAO is part of the larger Smithsonian Institution, based in Washington, DC.

Selected Mission Findings: An Exoplanet in X-Ray - NASA’s Chandra X-ray Observatory and the European Space Agency’s XMM Newton Observatory observed the dip in X-ray intensity as planet HD 189733b transited (passed between) us and its parent star, giving us X-ray information of its atmosphere. It was the first time astronomers observed the transit of a planet outside the Solar System in X-rays. The Chandra data suggested that planet HD 189733b had a larger atmosphere than previously thought.

Selected Mission Findings: Streams of High-Energy Particles - Chandra revealed that whirling neutron stars only twelve miles in diameter can generate streams of high-energy particles that extend for light years. The finding provides new insight into the nature of some of the densest matter in the Universe.

Selected Mission Findings: The Power of Black Holes - Astronomers used Chandra and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming. Energy from the rotation of the black hole and surrounding gas is converted into powerful jets and winds that can influence the destiny of an entire galaxy.

The National Air & Space Museum (NASM) and the Smithsonian Astrophysical Observatory (SAO) are both units of the Smithsonian Institution, the world’s largest museum, education, and science complex. NASM is one of the most popular museums on the National Mall in Washington, DC, and SAO is headquartered in Cambridge, MA. SAO and NASM are celebrating Chandra’s 25th anniversary of its launch into space throughout 2024. Join us by clicking below.

Chandra is part of NASA's fleet of "Great Observatories" along with other major facilities like the Hubble Space Telescope and the James Webb Space Telescope. Chandra enables scientists around the world to obtain X-ray images of exotic environments to help understand the structure and evolution of our Universe. NASA has centers across the country from Florida to California and works with institutions and organizations around the world. Its headquarters are located in Washington, DC.