|
NASA's series of Great Observatories satellites were four large, powerful space-based telescopes. Each of the Great Observatories has/had a similar size and cost at program outset, and each has made a substantial contribution to astronomy. The four missions each had a region of the electromagnetic spectrum to which it was particularly suited. NASA logo Listen to this article · (info) This audio file was created from an article revision dated 2005-09-01, and does not reflect subsequent edits to the article. ...
A satellite is any object that orbits another object (which is known as its primary). ...
50 cm refracting telescope at Nice Observatory. ...
Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultrahigh frequency VHF = Very high frequency HF = High frequency...
Great Observatories - Hubble Space Telescope (HST) was called the Space Telescope (ST) before being named. It primarily observes visible light and near-ultraviolet. A 1997 servicing mission added capability in the near-infrared range. Launched in 1990 aboard the Space Shuttle Discovery STS-31
- Compton Gamma Ray Observatory (CGRO) was called the Gamma Ray Observatory (GRO), before being named. It primarily observed gamma rays, though it extended into hard X-rays as well. Launched in 1991 aboard the Space Shuttle Atlantis STS-37
- Chandra X-ray Observatory (CXO) was called the Advanced X-ray Astronomical Facility (AXAF), before being named. It primarily observes soft X-rays. Launched in 1999 aboard the Space Shuttle Columbia STS-93
- Spitzer Space Telescope (SST) was called the Space Infra-red Telescope Facility (SIRTF), before being named. It observes infrared. Launched in 2003 aboard a Delta II rocket.
Of these satellites, only the Compton is not operating; one of its gyroscopes failed, and NASA ordered it to be de-orbited on June 4, 2000. Parts which survived reentry splashed into the Pacific Ocean. Hubble was intended to be retreived and returned to Earth by the Space Shuttle in 2010. Although this has been officially abandoned, NASA officials are reconsidering. The Hubble Space Telescope (HST) is a telescope in orbit around the Earth. ...
The visible spectrum is the portion of the optical spectrum (light or electromagnetic spectrum) that is visible to the human eye. ...
Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ...
Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ...
Discovery prior to docking with the International Space Station. ...
The 35th Space Shuttle mission, STS-31 using Space Shuttle Discovery, launched April 24, 1990, and returned April 29. ...
Illustration of CGRO The Compton Gamma Ray Observatory(CGRO) was the second of the NASA Great Observatories to be launched to space, following the Hubble Space Telescope. ...
This article is about electromagnetic radiation. ...
In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...
The Space Shuttle orbiter Atlantis landing in 1997* Space Shuttle Orbiter Atlantis (NASA Orbiter Vehicle Designation: OV-104) is one of five NASA space shuttles. ...
// Crew Steven R. Nagel (flew on STS-51-G, STS-61-A, STS-37 & STS-55), Commander Kenneth D. Cameron (flew on STS-37, STS-56 & STS-74), Pilot Jerry L. Ross (flew on STS-61-B, STS-27, STS-37, STS-55, STS-74, STS-88 & STS-110), Mission...
For other uses, see Chandra (disambiguation). ...
An X-ray picture (radiograph), taken by Wilhelm Röntgen, of Albert von Köllikers hand. ...
Space Shuttle Columbia (NASA Orbiter Vehicle Designation: OV-102) was the first space shuttle in NASAs orbital fleet. ...
STS-93 marked the 95th launch of the Space Shuttle, the 26th launch of Columbia, and the 21st night launch of a Space Shuttle. ...
The Spitzer Space Telescope Facility launches from Cape Canaveral Air Force Station in Florida on Monday, Aug. ...
Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ...
A gyroscope is a device for measuring or maintaining orientation, based on the principle of conservation of angular momentum. ...
June 4 is the 155th day of the year in the Gregorian calendar (156th in leap years), with 210 days remaining. ...
This article is about the year 2000. ...
The Space Shuttle Columbia seconds after engine ignition, 1981 (NASA). ...
2010 (MMX) will be a common year starting on Friday of the Gregorian calendar. ...
Spitzer was the only one of the Great Observatories not launched by the Space Shuttle. It was originally intended to, but after the Challenger disaster, the Centaur LH2/LOX upper stage that would have been required to push it into a heliocentric orbit was banned from Shuttle use. Titan and Atlas rockets were cancelled for cost reasons. After redesign and lightening, it was launched by a Delta II rocket instead. STS-51-L was the 25th launch of a Space Shuttle and the tenth launch of the Challenger. ...
Model of Centaur with Surveyor as payload. ...
LH2 is an acronym used in the aerospace industry, which stands for liquid hydrogen. ...
Lox can stand for any of several things: Lox (salmon) - a type of salmon produce LOx (oxidizer) - liquid oxygen used as oxidizer in aerospace The Lox - was a Yonkers, NY-based rap trio This is a disambiguation page — a list of articles associated with the same title. ...
A heliocentric orbit is an orbit around the sun. ...
A Delta II rocket launches from Cape Canaveral carrying a GPS satellite The Boeing IDS Delta II family of launch vehicles has been in service since 1989. ...
Strengths Each observatory was designed to push the state of technology in its intended wavelength region. As x-rays, gamma-rays and far-infrared radiation do not pass through the Earth's atmosphere, space missions were essential for the Compton, Chandra and Spitzer observatories. ROSAT image of X-ray fluorescence of, and occultation of the X-ray background by, the Moon. ...
Gamma-ray astronomy is the astronomical study of the cosmos with gamma rays. ...
Far infrared astronomy is the branch of astronomy and astrophysics which deals with objects visible in far-infrared radiation (approximatively from 30μm to 300μm). ...
Hubble also benefits from being above the atmosphere, as the atmosphere blurs ground-based observations of very faint objects, decreasing spatial resolution (however brighter objects can be imaged in much higher resolution than Hubble from the ground using astronomical interferometers). Larger, ground-based telescopes have also recently matched Hubble in resolution for near-infrared wavelengths of faint objects. Being above the atmosphere eliminates the problem of airglow, allowing Hubble to make observations of ultrafaint objects. Ground-based telescopes cannot compensate for airglow on ultrafaint objects, and so very faint objects require unwieldy and inefficient exposure times. Hubble can also observe at ultraviolet wavelengths which do not penetrate the atmosphere. Diagram showing a possible layout for an astronomical interferometer, with the mirrors laid out in a parabolic arrangement (similar to the shape of a conventional telescope mirror). ...
The airglow is the very weak emission of visible light by the earths atmosphere, which means that the night sky is never completely dark. ...
Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. ...
Compton observed in gamma rays, which do not penetrate the atmosphere. It was dramatically larger than previous gamma-ray observatories, opening entirely new areas of observation. It also had four instruments, which complemented each other's sensitivities, resolutions, and fields of view. Gamma rays are emitted by ultrapowerful energy sources, such as black holes and supernovae.
Chandra, similarly, had no ground predecessors, and small orbital predecessors. Its spatial resolution was an order of magnitude better than previous missions (becoming comparable to some optical telescopes), and its large size, high orbit, and sensitive CCDs allowed observations of faint X-ray sources. These are also powerful objects, but with more visible details than in gamma rays. A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...
Spitzer is quite difficult or impossible to replicate with ground telescopes, and had few orbiting predecessors. Spitzer was not an order of magnitude larger than its latest predecessor, ISO (the Infrared Space Observatory). However, Spitzer's instruments took advantage of the rapid advances in infrared detector technology at the time. Combined with its slightly larger aperture, favorable fields of view, and longer life, science return will be unprecedented. Infrared observations are useful for distant astronomical objects where all the visible light is redshifted to infrared wavelengths, cool objects which do not emit much visible light, or objects obscured by dust at visible light wavelengths. The Infrared Space Observatory (ISO)is a space telescope for infrared light designed and operated by the European Space Agency (ESA). ...
Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared to that of the Sun (left). ...
Impact All four telescopes have had a substantial impact on astronomy. The opening up of new wavebands to high resolution, high sensitivity observations by the Compton, Chandra and Spitzer has revolutionized our understanding of a wide range of astronomical objects, and has lead to the detection of thousands of new, interesting objects. In comparison, at optical wavelengths Hubble has provided a more modest improvement in sensitivity and resolution over existing instruments. Hubble's capability for uniform high-quality imaging of any astronomical object at any time has allowed accurate surveys and comparisons of large numbers of astronomical objects. The Hubble Deep Field observations have been very important for studies of distant galaxies, as they provide rest-frame ultraviolet images of these objects with a similar number of pixels across the galaxies as previous ultraviolet images of closer galaxies, allowing direct comparison. The James Webb Space Telescope will provide an even greater step forward, providing rest-frame visible light images of even more distant galaxies which can be directly compared with images of nearby galaxies at (more familiar) visible light wavelengths. The Hubble Deep Field The Hubble Deep Field (HDF) is the result of a series of observations by the Hubble Space Telescope of a small region of the northern celestial hemisphere. ...
The James Webb Space Telescope (JWST) is a planned orbital infrared observatory, intended (in part) to replace the aging Hubble Space Telescope. ...
Hubble has had a much larger public and media impact, partly because it operates at wavelengths which are familiar to us, and partly because of a lack of appreciation of the importance of other wavebands in modern astronomy.
Synergies Aside from inherent mission capabilities (particularly sensitivities, which cannot be replicated by ground observatories), the Great Observatories program allows missions to interact for greater science return. Different objects shine in different wavelengths, but training two or more observatories on an object allows a deeper understanding.
High-energy studies (in X-rays and gamma rays) have had only moderate imaging resolutions so far. Studying X-ray and gamma-ray objects with Hubble, as well as Chandra and Compton, gives accurate size and positional data. In particular, Hubble's resolution can often discern whether the target is a standalone object, or part of a parent galaxy, and if a bright object is in the nucleus, arms, or halo of a spiral galaxy. Similarly, the smaller aperture of Spitzer means that Hubble can add finer spatial information to a Spitzer image. A spiral galaxy is a type of galaxy in the Hubble sequence which is characterized by the following physical properties: Spiral Galaxy M74 presents a face-on view of its spiral arms. ...
Ultraviolet studies with Hubble also reveal the temporal states of high-energy objects. X-rays and gamma rays are harder to detect with current technologies than visible and ultraviolet. Therefore, Chandra and Compton needed long integration times to gather enough photons. However, objects which shine in X-rays and gamma rays can be small, and can vary on timescales of minutes or seconds. Such objects then call for followup with Hubble or the Rossi X-ray Timing Explorer, which can measure details in seconds or fractions of a second, due to different designs. The Rossi X-ray Timing Explorer (RXTE) satellite observes the fast-moving, high-energy worlds of black holes, neutron stars, X-ray pulsars and bursts of X-rays that light up the sky and then disappear forever. ...
The ability of Spitzer to see though dust and thick gases is good for galactic nuclei observations. Massive objects at the hearts of galaxies shine in X-rays, gamma rays, and radio waves, but infrared studies into these clouded regions can reveal the number and positions of objects.
Hubble, meanwhile, has neither the field of view nor the available time to study all interesting objects. Worthwhile targets are often found with ground telescopes, which are cheaper, or with smaller space observatories, which are sometimes expressly designed to cover large areas of the sky. Also, the other three Great Observatories have found interesting new objects, which merit diversion of Hubble. The field of view is the part of the observable world that is seen at any given moment. ...
One example of observatory synergy is solar system and asteroid studies. Small bodies, such as small moons and asteroids, are too small and/or distant to be directly resolved even by Hubble; their image appears as a diffraction pattern determined by brightness, not size. However, the minimum size can be deduced by Hubble through knowledge of the body's albedo. The maximum size can be determined by Spitzer through knowledge of the body's temperature, which is largely known from its orbit. Thus, the body's true size is bracketed. Further spectroscopy by Spitzer can determine the chemical composition of the object's surface, which limits its possible albedos, and therefore sharpens the low size estimate. Moons of solar system scaled to Earths Moon A natural satellite is a moon (not capitalized), that is, any natural object that orbits a planet. ...
An asteroid is a small, solid object in our Solar System, orbiting the Sun. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
Albedo is the measure of reflectivity of a surface or body. ...
Extremely high resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines) Spectroscopy is the study of spectra, that is, the dependence of physical quantities on frequency. ...
Late 1991: Operation of both Hubble and Compton
Late 1999: Operation of Hubble, Compton, and Chandra
Mid 2000: Operation of both Hubble and Chandra
Late 2003-2008???: Operation of Hubble, Chandra, and Spitzer
Successors to the original GO program - James Webb Space Telescope (JWST) - the JWST, previously known as the NGST (Next Generation Space Telescope) is projected to replace Hubble (HST) around 2013. Its segmented, deployable mirror will be over twice as large, increasing angular resolution noticeably, and sensitivity dramatically. Unlike Hubble, JWST will observe in the infrared, in order to penetrate dust at cosmological distances. This means it will continue some Spitzer capabilities, while some Hubble capabilities will be lost (as currently planned). New advances in ground telescopes will take over some visible observations, but fewer in ultraviolet.
- Constellation-X - A mission to perform extremely sensitive X-ray observations, beginning around 2016. This is not a direct replacement for Chandra; Chandra is optimized for high angular resolution. Constellation-X is more of a follow-on to the XMM-Newton mission, which trades resolution for sensitivity. Constellation-X may be several times to several dozen times more sensitive than Compton. It will also extend further into the hard-X-ray regions, giving it some abilities of Compton.
- GLAST, the Gamma Ray Large Area Space Telescope, is a follow-on to Compton scheduled for 2007. GLAST will be more narrowly defined, and much smaller; it will carry only one main instrument and a secondary experiment. Other missions, such as HETE-2, launched in 2000, and Swift, launched in 2004, will complement GLAST. The Ramaty High-Energy Solar Spectroscopic Imager (RHESSI), launched in 2002, observes in some Compton and Chandra wavelengths, but is pointed at the Sun at all times. Occasionally it observes high-energy objects which happen to be in the view around the Sun.
- Another large, high-energy observatory is INTEGRAL, Europe's INTErnational Gamma Ray Astrophysics Laboratory, launched in 2002. It observes in similar frequencies to Compton. But INTEGRAL uses a fundamentally different telescope technology, coded-aperture masks. Thus, its capabilities are complementary to Compton and GLAST, not a direct replacement.
- Spitzer has no direct successor planned. However, JWST will exceed its performance in near-infrared, and the European Space Agency's Herschel Space Observatory will exceed it in the far-infrared when launched around 2007. The SOFIA (Stratospheric Observatory For Infrared Astronomy) airborne platform will observe in near- and mid-infrared. SOFIA will have a larger aperture than Spitzer, but at lower relative sensitivities in restricted duty cycles. Also, smaller space missions will perform specialized infrared observations.
Note that none of these missions are designed for Shuttle launch, or manned servicing. Most are in orbits beyond the Shuttle's capability, to allow new observing modes. GLAST will have no appreciable instrument upgrades after launch. The James Webb Space Telescope (JWST) is a planned orbital infrared observatory, intended (in part) to replace the aging Hubble Space Telescope. ...
Constellation-X, the Constellation X-ray Mission (formerly HTXS, the High Throughput X-ray Spectroscopy program) is a Next Generation X-ray Observatory dedicated to observations at high spectral resolution, providing as much as a factor of 100 increase in sensitivity over currently planned high resolution X-ray spectroscopy missions. ...
This article is about XMM-Newton. ...
The Gamma-ray Large Area Space Telescope, or GLAST, is future space-based gamma-ray telescope, designed to explore the high-energy Universe. ...
The High Energy Transient Explorer is an American astronomical satellite. ...
The Swift Gamma-Ray Burst Mission consists of an unmanned spacecraft called Swift, which was launched into orbit on November 20, 2004, at 17:16:00 UTC (12:16 PM, EST) by a Delta 2 7320-10C expendable launch vehicle. ...
Reuven Ramaty High Energy Solar Spectroscopic Imager (or RHESSI) is a NASA sixthSmall Explorer, launched on 5 February 2002. ...
In calculus, the integral of a function is a generalization of area, mass, volume and total. ...
This article is about the European Space Agency. ...
The Herschel Space Observatory is a mission of the European Space Agency. ...
The 747 which will house NASAs Stratospheric Observatory for Infrared Astronomy (SOFIA) on a test flight in 1997. ...
See also |
Feeds |
Contact