Posted on 08/22/2003 3:33:40 PM PDT by demlosers
SIRTF set to scour skies for infrared traces of galaxy formation.
NASA's Space Infrared Telescope Facility (SIRTF) is scheduled to launch early on Monday morning, after more than 20 years of planning.
The orbiting observatory will look for infrared traces of the Universe's history. It will peer through shrouds of cosmic dust and gas deep into the murky cradles of star birth in our own and distant galaxies.
"It's tremendously exciting, having been working on the project for 20 years - now its time to get it launched and do the science," says Tom Soifer, director of the SIRTF Science Center at the California Institute of Technology in Pasadena.
SIRTF is the last of NASA's four Great Observatories. It joins the Hubble Space Telescope and the Chandra X-ray Observatory in mapping the heavens' light spectrum from vantage points high above the Earth's wet and blurry atmosphere. The Compton Gamma Ray Observatory splashed into the Pacific at the end of its life in June 2000.
"SIRTF will see the epochs at which most of the heavy elements in the Universe were made," explains survey team leader Michael Rowan-Robinson of Imperial College, London.
NASA decided to build
SIRTF in 1979.
© NASA/JPL-Caltech
From its quickly-released data, astrophysicists hope to learn more about galaxy evolution, massive black holes, stars' life cycles, planet formation and the centre of our own Milky Way. "We are looking forward to seeing galaxies at the time they formed most of their stars," says survey team member Seb Oliver of the University of Sussex, UK.
Conceived by NASA in 1979, the observatory has been plagued by setbacks1. Redesigns, cost-cutting and abandoned launch attempts had left some wondering if it would ever take off. "To be involved in a project for so long takes either no imagination or great imagination," says Soifer.
Three of a kind
SIRTF is actually the third orbiting infrared telescope. The revolutionary US-Dutch-British Infrared Astronomical Satellite (IRAS) launched in 1983, and more recently the European Space Agency's Infrared Space Observatory (ISO) flew between 1995 and 1998. SIRTF will be faster and much more sensitive than either of its predecessors.
Its weakness is that it won't cover the important 7-80 micron wavelength Michael Rowan-Robinson Imperial College
"SIRTF's weakness is that it won't cover the important 7-80-micron [thousandths of a millimetre] wavelength range which is rich in spectral features," says Rowan-Robinson. Understanding the detailed chemistry of the objects that SIRTF detects may therefore be a challenge.
Two more infrared satellites are hot on SIRTF's heels. The Japanese-led ASTRO-F mission, which will map the sky's extreme infrared wavelengths even faster than SIRTF, is expected to launch in February 2004. And ESA's Herschel satellite, slated for launch in February 2007, should provide the first clear view of the infrared sky between 60 and 680 microns, opening an entirely new window onto the Universe.
SIRTF should blast off on a Boeing Delta 2 rocket from Cape Canaveral, Florida, at 05:35 GMT on 25 August. It will be renamed after launch
"There's many a slip 'tween cup and lip." Let's hope there's no slips this time.
I second that in spades!
"We are extremely proud of our decades of work on behalf of NASA, and such a key role in NASA's newest space observatory," said John Straetker, Lockheed Martin SIRTF program manager. "It is particularly satisfying for our team to see SIRTF off on its way into deep space to begin its historic mission."
SIRTF is a cryogenically cooled space observatory that will conduct infrared (IR) astronomy during a two and one-half-to-five year mission. SIRTF completes NASA's family of Great Observatories, which also includes the Hubble Space Telescope, the Chandra X-Ray Observatory and the Compton Gamma Ray Observatory. The SIRTF program, a cornerstone of NASA's Origins Program, is managed by JPL for NASA's Office of Space Science in Washington DC.
The spaceborne SIRTF observatory comprises a 0.85-meter diameter telescope and three scientific instruments capable of performing imaging and spectroscopy in the 3-180 micron wavelength regime. Incorporating the latest in large-format infrared detector array technology, SIRTF will provide more than a 100-fold increased in scientific capability over previous IR missions. Cornell University, University of Arizona, and the Harvard-Smithsonian Center for Astrophysics have provided the instruments for SIRTF.
An important feature of the SIRTF mission is the adoption of a solar orbit. To reach this orbit, the spacecraft was launched on a Delta 7920 launch vehicle with slightly greater than terrestrial escape velocity. The resulting orbit will have SIRTF trailing the Earth in its orbit around the Sun. This orbit makes better use of launch capability than would many possible alternate orbits that would have kept SIRTF in orbit around the Earth. It permits excellent, uninterrupted viewing of a large portion of the sky without the need for Earth-avoidance maneuvers. In addition, the absence of heat input from the Earth provides a stable thermal environment and allows the exterior of the telescope to reach a low temperature via radiative cooling.
A one meter-diameter transmitting antenna fixed to the bottom of the spacecraft will be used twice each day to transmit 12 hours of stored science data to stations of NASA's Deep Space Network. In this manner, an adequate average data rate of 85 kbps -- corresponding to one image from SIRTF's largest array every 10 seconds -- can be maintained over the lifetime of the mission.
SIRTF's scientific potential is rooted in four basic physical principles that define the importance of infrared investigations for studying astrophysical problems:
-- Infrared observations reveal cool states of matter: Solid bodies in
space -- ranging in size from sub-micron-sized interstellar dust grains
to giant planets -- have temperatures spanning the range from 3K to
1500K (above which nearly all solids evaporate). Most of the energy
radiated by objects in this temperature range lies in the infrared part
of the spectrum. Infrared observations are therefore of particular
importance in studying low-temperature environments such as dusty
interstellar clouds where stars are forming and the icy surfaces of
planetary satellites and asteroids.
-- Infrared observations explore the hidden universe: Cosmic dust
particles effectively obscure parts of the visible universe and block
the view of many critical astronomical environments. This dust becomes
transparent in the infrared, where observers can probe optically
invisible regions such as the center of the Milky Way (and other
galaxies) and dense clouds where stars and planets may be forming. For
many objects -- including dust-embedded stars, active galactic nuclei,
and even entire galaxies -- the visible radiation absorbed by the dust
and re-radiated in the infrared accounts for virtually the entire
luminosity.
-- Infrared observations access unique spectral features: Emission and
absorption bands of virtually all molecules and solids lie in the
infrared, where they can be used to probe conditions in cool celestial
environments. Many atoms and ions have spectral features in the
infrared that can be used for diagnostic studies of stellar atmospheres
and interstellar gas, exploring regions that are too cool or too
dust-enshrouded to be reached with optical observations.
-- Infrared observations reach back to the early life of the cosmos: The
cosmic redshift which results from the general expansion of the
universe inexorably shifts energy to longer wavelengths in an amount
proportional to an object's distance. Because of the finite speed of
light, objects at high redshift are observed as they were when the
universe and those objects were much younger. As a result of the
expansion of the universe, much of the optical and ultraviolet
radiation emitted from stars, galaxies, and quasars since the beginning
of time now lies in the infrared. How and when the first objects in
the universe formed will be learned in large part from infrared
observations.
Apart from a few windows at short wavelengths, all of the infrared radiation emitted by the above objects is absorbed by Earth's atmosphere. Worse, the infrared emission of the atmosphere itself blinds astronomers peering through those windows. Hence the need for a cooled space-based infrared observatory with high sensitivity -- SIRTF.
NASA's Origins Program follows the chain of events that began with the birth of the universe at the Big Bang. It seeks to understand the entire process of cosmic evolution from the formation of chemical elements, galaxies, stars and planets, through the mixing of chemicals and energy that cradles life on Earth, to the earliest self-replicating organisms and the profusion of life. In short, Origins hopes to answer the fundamental questions: Where did we come from? Are we alone?
Lockheed Martin Space Systems Company is one of the major operating units of Lockheed Martin Corporation. Space Systems designs, develops, tests, manufactures, and operates a variety of advanced technology systems for military, civil and commercial customers. Chief products include a full-range of space launch systems, including heavy-lift capability, ground systems, remote sensing and communications satellites for commercial and government customers, advanced space observatories and interplanetary spacecraft, fleet ballistic missiles and missile defense systems.
For additional information, visit our website: http://www.lockheedmartin.com.
CONTACT: Media, Buddy Nelson, +1-510-797-0349, or buddynelson@mac.com, for Lockheed Martin Space Systems Company.
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