June 13, 2001 The Microwave Anisotropy Probe (MAP), scheduled for launch June 30, will journey into deep space on a voyage to explore some of the deepest mysteries of the cosmos.
Scientists hope to determine the content, shape, history, and the ultimate fate of the universe, by constructing a full-sky picture of the oldest light. MAP is designed to capture the afterglow of the Big Bang, which comes to us from a time well before there were any stars, galaxies or quasars. Patterns imprinted within this afterglow carry with them the answers to mysteries such as: What happened during the first instant after the Big Bang? How did the Universe evolve into the complex patterns of galaxies that we see today? Will the Universe expand forever or will it collapse?
To answer these questions, MAP's measured pattern of the Big Bang's afterglow, like a fingerprint, will be compared against the unique fingerprint pattern predicted by each cosmic scenario to find the right match. "We are tremendously excited about this mission because it will help answer basic questions that people have been asking for ages," said Dr. Charles L. Bennett, Principal Investigator for the MAP mission at NASA's Goddard Space Flight Center, Greenbelt, MD. "MAP's unprecedented accuracy and precision will allow us to determine the nature and destiny of the universe."
According to the Big Bang theory, the universe began about 14 billion years ago as an unimaginably hot and dense fog of light and exotic particles. The Universe has since continuously expanded and cooled. The whole Universe is bathed in the afterglow light from the Big Bang. The light that is now reaching us has been traveling for about 14 billion years, thus allowing us a look back through time to see the early Universe.
"The cosmic microwave light is a fossil," says Professor David T. Wilkinson, Princeton University, Princeton, NJ. "Just as we can study dinosaur bones and reconstruct their lives of millions of years ago, we can probe this ancient light and reconstruct the Universe as it was about 14 billion years ago."
MAP views the infant universe by measuring the tiny temperature differences within the extraordinarily evenly dispersed microwave light, which now averages a frigid 2.73 degrees above absolute zero temperature. MAP will resolve the slight temperature fluctuations, which vary by only millionths of a degree. These temperature differences point back to density differences in the young Universe, where denser regions gave way to the vast web-like structure of galaxies that we see today.
A great deal of effort over the past 35 years has gone into measurements of the afterglow light from the Big Bang. In 1992, NASA's Cosmic Background Explorer satellite discovered tiny patterns, or "anisotropy," in its full-sky picture of the light. Balloon-borne and ground-based experiments have further advanced our knowledge. The upcoming MAP full-sky picture, to be made with unprecedented accuracy and precision, will dramatically revolutionize our view of the Universe. MAP required an extraordinary design to achieve its accurate and precise measurement capability. "Nothing has ever been built like it before," said Dr. Edward Wollack, a science team member at Goddard. "To measure the cosmic glow reliably to a part in a million, to millionths of a degree has been the grand challenge. That's like measuring the weight of a cup of sand down to the resolution of a single grain."
About a month after its launch on a Delta II rocket from Cape Canaveral, FL, MAP will swing past the Moon, boosting its orbit to the second Lagrange Point, or L2. This is the first time a spacecraft will be in orbit around the L2 point. The Italian-French mathematician Josef Lagrange discovered five special points in the vicinity of two orbiting masses where a third, smaller mass can orbit at a fixed distance from the larger masses. L2 is four times further than the Moon in the direction away from the Sun and requires very little fuel to maintain orbit.
After a three month journey, MAP will begin to chart the faint microwave glow from the Big Bang. It will take about 18 months to build up a full-sky picture and perform the analysis. The MAP hardware and software were produced by Goddard and Princeton. Science team members are also located at the University of Chicago, IL; the University of California, Los Angeles; Brown University, Providence, RI; and the University of British Columbia, Vancouver. MAP, an Explorer mission, cost about $145 million. More information is available on the Internet at: http://www.gsfc.nasa.gov/gsfc/spacesci/map/map.htm
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