Hubble’s Partners in Science

NASA's Hubble Space Telescope has a long history of working with other observatories to explore our universe.

Illustration of various space-based and ground-based telescopes.

Orbiting high above Earth's obscuring atmosphere, NASA's Hubble Space Telescope’s multiwavelength capabilities let it capture ultraviolet, visible, and near-infrared light. This unique ability allows astronomers to not only see a wide range of cosmic phenomena, but also lets them focus on a single phenomenon at different wavelengths. This is important, because the optical/visible light our eyes see is only a small fraction of what is available in the universe. Astronomers also use radio waves, microwaves, X-rays, gamma rays, gravity waves, and even subatomic particles like neutrinos to study the cosmos, and each one requires different instrumentation. No one telescope can see them all.

In that respect, Hubble is one in a fleet of telescopes across the globe and in space that study the universe, and it often collaborates with these other observatories to make discoveries. Those collaborations take many forms, from formal agreements to community-wide observations of an event.

Hubble observation time is generally proposed and won through the standard Hubble cyclical call for proposals. Proposals can request observing time on the James Webb Space Telescope, Chandra X-ray Observatory, the Transiting Exoplanet Survey Satellite (TESS), NOIRLab (formerly National Optical-Infrared Astronomy Research Laboratory) telescopes, National Radio Astronomy Observatory (NRAO) facilities, and the European Space Agency's XMM-Newton, in conjunction with requests for Hubble observations. Mid-cycle proposals may be submitted at any time, those received prior to a specified deadline receive consideration for execution beginning approximately two months later. Investigators may also request Director’s Discretionary Time, which is time set aside each cycle to observe scientifically compelling and unexpected phenomenon, or to support long observing programs that create data for the entire community (such as the Hubble Deep Field). Proposals for such work go to the Director of the Space Telescope Science Institute in Baltimore for selection.

Top: A spheroidal cloud. Its center holds colors of red and yellow with small areas of green and blue. Around the center is a ring of blue and green with a smattering of pink, purple, and white. Bottom, four small images (left to right): The first two are Chandra X-ray images in blue and green respectively. The third is a Hubble visible light image in yellow. The fourth is a Spitzer infrared image in red.
Three of NASA's Great Observatories work together to unravel the mysteries of Kepler's supernova.
NASA, ESA, R. Sankrit and W. Blair (Johns Hopkins University)
A colorful view of the Milky Way's center region. Colors of red, orange, yellow, blue, pink, and white form clouds and filaments against a dark backdrop.
In celebration of the International Year of Astronomy 2009, NASA's Great Observatories — the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory — collaborated to produce an unprecedented image of the central region of our Milky Way galaxy. Observations using infrared light and X-ray light see through the obscuring dust and reveal the intense activity near the galactic core. Note that the center of the galaxy is located within the bright white region to the right of and just below the middle of the image. The entire image width covers about one-half a degree, about the same angular width as the full moon. Each telescope's contribution is presented in a different color: ▪ Yellow represents the near-infrared observations of Hubble. These observations outline the energetic regions where stars are being born as well as reveal hundreds of thousands of stars. ▪ Red represents the infrared observations of Spitzer. The radiation and winds from stars create glowing dust clouds that exhibit complex structures from compact, spherical globules to long, stringy filaments. ▪ Blue and violet represent the X-ray observations of Chandra. X-rays are emitted by gas heated to millions of degrees by stellar explosions and by outflows from the supermassive black hole in the galaxy's center. The bright blue blob on the left side is emission from a double star system containing either a neutron star or a black hole. When these views are brought together, this composite image provides one of the most detailed views ever of our galaxy's mysterious core.

General-Purpose Observatories

The Hubble mission has formal agreements with other general-purpose, space-based observatories to award time for joint programs where Hubble science is the prime science, but multi-wavelength observations from another observatory are critical to the scientific goals of the proposal. The agreements also support the opposite direction, where Hubble is the ancillary observatory. In these scenarios, the two observatories may award time (up to an agreed upon limit) on the other to ensure that all the pertinent data are captured.

Hubble’s primary observing partners naturally include its NASA sibling space missions like Webb, Chandra, TESS, and the now retired Spitzer Space Telescope. In fact, a special program for preparatory observations was executed for several years to support the Webb mission before it launched. These observations provided potential targets, initial multi-wavelength data, and other science for Webb to further explore when it came online. Hubble also has collaborative agreements with the European Space Agency for cooperative time on their X-ray telescope, XMM-Newton. Combining data from each of these telescopes lets us see objects in X-ray, ultraviolet, visible, and infrared light. 

Hubble data are also combined with ground-based data collected by observatories that look at wavelengths outside of Hubble’s sensitivity range. Collaborative agreements exist with the NRAO and NOIRLab's Gemini Observatories. But Hubble data are often used with other ground-based observatories to advance science including the Laser Interferometer Gravitational-Wave Observatory (LIGO), the W. M. Keck Observatory, and others.

One of the highest priority ways Hubble will be working in complement with other observatories is in the study of some sources of gravitational waves. Hubble cannot detect gravitational waves (LIGO and other facilities can). But some sources of gravitational waves, such as merging neutron stars, also create visible explosions like kilonovae. Hubble can view the radiation from such explosions and therefore help characterize the source and impacts and products created from these events that also produce gravitational waves. We anticipate Hubble will be a major player in this “multi-messenger astronomy” in future years, providing important follow-up and complementary observations to gravitational wave detections from observatories like LIGO. Hubble has already demonstrated this, by highlighting the location and radiation and aftermath composition of a kilonova explosion in 2017 that was incited by a merger of neutron stars, a source of gravitational waves detected by LIGO.

Top: Large composite image of M82 in colors of pink, red, green, white, yellow, and blue on a black background. Bottom: Three smaller image taken by Hubble (left), Chandra (center), and Spitzer (right).
Composite of multi-wavelength images of the active galaxy M82 from three of NASA's Great Observatories.
NASA, ESA, CXC, JPL-Caltech, JHU, D. Strickland, and C. Engelbracht (University of Arizona)

Solar System Probes

NASA’s program to explore the solar system includes spacecraft that have studied the inner and outer solar system and have traveled well beyond the realm of the Sun's influence. Unlike Hubble, these probes leave Earth’s orbit and travel to the solar system object of interest. At times, it is advantageous to use Hubble to help find targets for these probes, or do collaborative observations of a specific event.

A prime example of such a collaboration involved NASA’s New Horizons spacecraft. Hubble observed Pluto before New Horizons made its flyby of the dwarf planet, capturing the first details of its surface and discovering four new moons around Pluto. Hubble's Pluto observations shaped the observing plan of New Horizons by helping the mission chart its flyby and capture images of these moons and avoid collisions with these same objects. Hubble also looked for and identified targets that New Horizons could visit after its flyby of Pluto.

Hubble similarly helped NASA's LUCY mission by studying the composition of Trojan asteroids. Because Hubble can detect small, dim satellites orbiting larger asteroids — something an Earth-bound telescope might miss — the LUCY team also used Hubble to search for Trojan satellites. Hubble observations revealed a small satellite, subsequently named Queta, orbiting the asteroid Eurybates. Hubble's observations gave the LUCY team the opportunity to better plan their exploration of these Trojan asteroids.

Pluto and its largest moon, Charon, are at image center appearing as a large and small white dot. Hydra, Nix, and P4 (a very small white dot that has a green circle around it) are to the left of Pluto and Charon. P4 is to the right of Pluto and Charon.
This Hubble image shows five moons orbiting the distant, icy dwarf planet Pluto. The green circle marks the newly discovered moon, designated P5, as photographed by Hubble's Wide Field Camera 3 on July 7, 2012. The observations helped scientists plan the flyby of Pluto by NASA's New Horizons spacecraft.
NASA; ESA; M. Showalter, SETI Institute
Dr. Keith Noll, project scientist for NASA's LUCY Mission, explains how Hubble observations benefited the LUCY and New Horizons missions. Credit: NASA's Goddard Space Flight Center; Lead Producer: James Leigh

NASA’s DAWN mission also benefited from Hubble observations. Hubble captured images of the large asteroids Vesta and Ceres that helped scientists refine their plans for the Dawn spacecraft's rendezvous with these two large asteroids.

Spacecraft Impactors

More recently, Hubble worked with NASA's Double Asteroid Redirection Test (DART), the first mission to slam an object into an asteroid and alter its motion in space. Hubble and Webb both captured detailed views of the DART impact. After the impact, Hubble continued to monitor the asteroid and provided information about the impact's debris field.

Left: mottled spheroid in colors of white, grey, and tan. Left: mottled spheroid mainly bluish-grey and white with a slight some tan areas.
To prepare for Dawn's visit, astronomers used Hubble's Wide Field Planetary Camera 2 to snap new images of the asteroids Ceres and Vesta.
Vesta: NASA; ESA; L. McFadden and J.Y. Li (UM, College Park); M. Mutchler and Z. Levay (STScI); P. Thomas (Cornell); J. Parker and E.F. Young (SwRI); and C.T. Russell and B. Schmidt (UCLA); Ceres: NASA; ESA; J. Parker (SwRI); P. Thomas (Cornell); L. McFadden (UM, College Park); and M. Mutchler and Z. Levay (STScI)

This was not the first time Hubble observed a spacecraft collision. In 2005, Hubble captured images and spectra of a collision with a comet.  The Deep Impact Mission released a penetrator to collide with the nucleus of Comet Tempel 1 to determine the make-up of a comet.  Hubble supported with images and spectra of the aftermath.

Planetary Probes

Beyond missions to the smaller, rocky worlds of our solar system, Hubble's observations supplement missions to the outer gas giant planets like NASA's Juno and the retired Cassini-Huygens missions as well.

Hubble regularly images the outer planets (Jupiter, Saturn, Uranus, and Neptune) to track changes in each planet's atmosphere over time. Some of its Jupiter observations are also designed to build upon data collected by the Juno spacecraft in its mission to study this large gas giant. Joint observations are planned such that Hubble takes data at the same time as Juno to get different perspectives of phenomena on that planet.

Hubble observations, combined with those from the Gemini Observatory and the Juno spacecraft, have helped scientists interpret cloud structures and atmospheric circulation on Jupiter. The collective data allows researchers to see that lightning flashes are clustered in turbulent regions that hold deep water clouds where moist air is rising to form tall convective towers similar to cumulonimbus clouds (thunderheads) on Earth. The combined observations were used to map the cloud structure in three dimensions and infer details of Jupiter's atmospheric circulation.

While Cassini traveled toward a July 1, 2004 rendezvous with Saturn, Hubble captured stunning images of this ethereal planet and its rings. The Hubble images were so sharp that many individual ringlets were visible in Saturn's ring plane. At the time the images were taken, Hubble was nearly a billion miles farther from Saturn than Cassini, which was still approaching the planet. Yet, Hubble's exquisite optics, coupled with the high resolution of its Advanced Camera for Surveys, allowed it to take pictures of Saturn that were nearly as sharp as Cassini's wide-angle views of the full planet. Those images marked the first time astronomers were able to compare views of Saturn with equal sharpness from two very different perspectives.

Various images of jupiter's great red spot
These images of Jupiter's Great Red Spot, taken by Hubble and the Gemini Observatory, provided a wide-view context for Juno’s 12th pass of the planet.
NASA, ESA, and M.H. Wong (UC Berkeley) and team
Saturn and its rings. The planet appears as though it is tilted backward, appearing to reveal the underside of its rings. Overall Saturn is yellow with bands of red, yellowish-brown, light orange, pink, and blue.
As NASA's Cassini spacecraft hurtled its way toward Saturn, Hubble snapped breathtaking images from its orbit around Earth. For the first time, astronomers were able to compare views of Saturn with equal sharpness from two very different perspectives.
NASA, ESA and E. Karkoschka (University of Arizona)
Three images of Jupiter, from left to right: Infrared Jupiter holds bright yellow, deep red, orange and marron stripes. The Great Red Spot is a deep maroon. The middle image is in the visible light our eyes are sensitive to. It reveals horizontal stripes in muted tones of red and orange along with wide white bands. The Great Red Spot is deep orange with bands of dark red. The final image is in ultraviolet. Here Jupiter's cloud bands are in tones of blue, pink and purple. The Great Red Spot appears as a dark blue.
Three images of Jupiter show the gas giant in three different types of light — infrared, visible, and ultraviolet. The image on the left was taken in infrared by the Near-InfraRed Imager (NIRI) instrument at Gemini North in Hawaii, the northern member of the international Gemini Observatory, a Program of NSF’s NOIRLab. The center image was taken in visible light by the Wide Field Camera 3 on the Hubble Space Telescope. The image on the right was taken in ultraviolet light by Hubble’s Wide Field Camera 3. All of the observations were taken on January 11, 2017.
International Gemini Observatory/NOIRLab/NSF/AURA/NASA/ESA, M.H. Wong and I. de Pater (UC Berkeley) et al.; Acknowledgments: M. Zamani

Planet Hunters

Hubble regularly teams up with ground-based and space-based telescopes to better understand the composition, environment, and formation of planets beyond those in our solar system, called extrasolar planets or exoplanets. Building on exoplanet discoveries made by TESS and the retired Kepler spacecraft, astronomers use Hubble to take measurements of the atmospheric composition of these worlds. Its observations have identified atmospheres that contain sodium, oxygen, carbon, hydrogen, carbon dioxide, methane, helium, and water vapor. These Hubble observations demonstrate that we can detect and measure the basic organic components for life on planets orbiting other stars.

A graph showing brightness along the Y-axis and wavelength along the X-axis. They upper left corner holds an artists illustration of the WASP-121b system. The graph shows spectrum of water absorption by the brown dwarf in purple and the spectrum of water emission by the planet in red.
This diagram presents evidence for the existence of a stratosphere on a planet orbiting another star. As on Earth, the stratosphere increases in temperature with altitude. The water emissions from the Jupiter-sized planet's upper atmosphere show this. The results are in marked contrast to the spectrum of a failed star, a brown dwarf, which shows water absorption because the atmosphere is cooling with altitude increase.
NASA, ESA, and A. Feild (STScI)

In the age of multiwavelength and multi-messenger astronomy, Hubble's sensitivity to ultraviolet, visible, and infrared wavelengths makes it an invaluable tool for researchers trying to unravel the mysteries of the universe. Hubble's three decades of operation also provides researchers with a wealth of data taken over many years. By comparing Hubble's older observations with newer ones from Hubble and other observatories, astronomers can better understand how an object, like Jupiter's atmosphere, changes over time. As new space and ground-based telescopes continue to come online, Hubble's current observations and extensive archive will continue to expand our understanding of the universe.

An orange-red-yellow star s
This artist's illustration compares two scenarios for how an Earth-sized exoplanet might pass in front of its host star. The bottom path shows the planet just grazing the star. Studying the light from such a transit could lead to an inaccurate estimate of the planet's size, making it seem smaller than it really is. The top path shows the optimum geometry, where the planet transits the full disk of the star. Hubble's accuracy can distinguish between these two scenarios, yielding a precise measurement of the planet's diameter.
NASA, ESA, Elizabeth Wheatley (STScI)
illustration of WASP-121b exoplanet
This artist's illustration shows an alien world losing magnesium and iron gas from its atmosphere. Hubble observations of the system represent the first time that elements more massive than hydrogen and helium were detected escaping from a hot Jupiter, a large gaseous exoplanet orbiting very close to its star.
NASA, ESA, and J. Olmsted (STScI)
This illustration shows the ball of a red dwarf star. It is mottled with dark spots and finger-like filamentary outbursts. In front is a much smaller black circle representing the silhouette of a planet passing in front of the star. The red dwarf's furious activity is causing the planet's atmosphere to escape into space. This appears as wispy blue filaments along the planet’s straight horizontal orbital path. The star is colored a rich red because it is cooler than our Sun.
This artist's illustration shows a planet (dark silhouette) passing in front of the red dwarf star AU Microscopii. The planet is close to the eruptive star, and its blasts are heating the planet's hydrogen atmosphere, causing the atmosphere to escape into space. The illustration is based on measurements made by Hubble after NASA's Spitzer and TESS space telescopes discovered the planet in 2020.
NASA, ESA, and Joseph Olmsted (STScI)
Until the 20th century, astronomers learned virtually all they knew about sources in the sky from only the tiny fraction of electromagnetic radiation that is visible to the eye. In this video, Dr. Padi Boyd explains the exciting future of multiwavelength astronomy and how important Hubble is to exploring the mysteries of the universe. Credit: NASA's Goddard Space Flight Center; Producer and Director: James Leigh