| BEYOND THE UNIVERSE:
NEXT GENERATION SPACE TELESCOPE TO INVESTIGATE THE BEGINNING OF THE COSMOS
| G02-023 | 9/10/02 | 00:19:14 | NASA has selected TRW to build the Next Generation Space Telescope (NGST) spacecraft which has the goal of observing the formation of the first stars and galaxies in the universe, just a few hundred million years after the big bang. They will design and fabricate the NGST observatory and will be responsible for integrating the science instrument module onto the spacecraft as well as performing the pre-flight testing and on-orbit checkout of the telescope.
NGST will replace the highly successful Hubble Space Telescope (HST) when it retires near the end of this decade. Scheduled to launch in 2010, the telescope will carry cameras and spectrographs sensitive to infrared radiation. Over the telescope's 5-10 year lifetime astronomers hope to observe the farthest and deepest reaches of the Universe. NGST will look back to an extremely important period in the early history of the Universe when the first stars and galaxies began to form. While scientists have a fairly good understanding of the Universe in other periods, there are no observations during this time when the Universe was between 1 million and a few billion years old. NGST's studies will help us understand the shape and chemical composition of the Universe, the evolution of galaxies, and the nature of unseen "dark matter."
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ITEM (2): Unlocking The Mystery of The Cosmic Dark Zone
a) Birth of the Very First Stars - Primordial matter in the early universe consisted of just hydrogen and helium gas. These gas clouds were the seeds of future clouds, stars, galaxies, and clusters of galaxies that populated the universe. In these primordial conditions, stars formed from denser condensations in the clouds.
Under the action of its own gravity, the gas in one of these dense knots starts falling toward its center. Attracted by the stellar seed, more material starts falling, forming a swirling disk of gas. The disk collects the falling gas and funnels it onto the surface of the growing star. The star grows quickly and gains the energy released by the falling gas, and in the process, dissipates any excess of material and energy by ejecting polar jets.
With time, the stellar body grows in mass and shrinks in size, becoming denser and hotter. Eventually, the temperature at the center of the star becomes so high that hydrogen atoms can effectively merge together to form helium, releasing large amounts of energy (light and heat). The swirling disk is dissipated by the action of the increased luminosity, and no more gas falls on the star.
These primordial stars are big and very bright, and have short lifetimes: in just a few million years they consume all their nuclear fuel and end their lives in catastrophic supernova explosions, leaving a black hole behind. These explosions eject a large quantity of gas that has been enriched in heavier elements, such as carbon, oxygen, and silicon. These elements are essential for the formation of Earth-like planets and, eventually, the birth of life on them.
b) Supernova and Exploding Starfield - Clouds of gas and stars are swirling together, forming the basis of proto-galaxies. At the center of a proto-galaxy so much gas, stars, black holes and other stellar remnants clump together that a massive black hole starts to form. The central massive black will accrete most of its surrounding material falling in, but a small fraction is ejected along two very energetic jets. If one of these energy beams is pointed at us, we may be seeing it as a quasar. Quasars will be among the furthest objects NGST will be able to see, and astronomers will be able to study all intervening gas clouds against these background light beacons.
c) The Building Blocks of the Universe - Many proto-galaxies are forming, drawn together by their mutual gravitational attraction. They start to collide and merge together, building larger and larger galaxies. Disk like spiral galaxies will form if the inflow of material is smooth and consists mainly of gas, rounder elliptical galaxies will form if the collisions are more violent and head-on.
On even larger scales, gravity has been pulling galaxies together over the last 13 billion years in structures resembling a sort of foam; we have large voids nearly devoid of galaxies, large sheets and filaments of galaxies where two bubbles meet and we have galaxies streaming along these filaments toward galaxy clusters, the points where several bubbles meet.
NGST will look past all these foreground galaxies, looking deep into space and back in time, to find the earliest star formation, galaxy formation and quasars. The treasure we are looking for will be hidden as a needle in a haystack of foreground galaxies.
Courtesy: NASA
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Space Science Gallery