NASA's latest mission to ferret out the secrets of the cosmos is the Microwave Anisotropy Probe, or MAP. The satellite will measure is the afterglow of the Big Bang, -the first light, the oldest light that exists. It will map tiny fluctuations in temperature of the Cosmic Microwave Background temperature over the whole sky.
MAP is designed to test the Big Bang theory, which makes definite predictions for the structure and evolution of the universe that depend on the nature and the amount of matter in the universe. This information will reveal answers to fundamental questions that both scientists and philosophers have pondered for millennia.
Scientists currently believe the universe is older than 10 billion years and younger than 17 billion years. Most cite 14 billion year as the best guess. MAP should be able to nail it down for us.
What is the universe made of?
Ideas about the stuff that comprises the universe have been turned upside down recently and astronomers are prepared to have it happen again with the MAP results.
About ten years ago, scientists believed that "baryonic matter" or ordinary material made up of protons, neutrons and electrons (like you and me) made up almost the entire universe. Since then, in measuring the mass of galaxies, astronomers have found they weigh about ten times more than can be accounted for by all the stars, gas and dust that we can see.
So evidence has been accumulating for the existence of something we can't see, some mysterious, "dark matter," that exerts a gravitational pull, but does not emit nor absorb light. There are candidates for the missing mass, like brown dwarfs, but there aren't enough of them. This leads some scientists to conjecture the missing mass is an exotic, or non-baryonic material.
If our ideas about the origin and evolution of galaxies and large-scale structures are correct, then MAP should be able to measure the density of ordinary and weird matter to great accuracy. It will also be able to determine some of the properties of the non-baryonic stuff.
What is the shape of the universe?
Granted you probably spend more time thinking about the shape you're in, but the truth is that scientists can't doodle a picture of the universe. MAP's accurate measurement of the density of matter in the universe can answer this one for us, too.
According to theory, the universe might be closed, and curved like a sphere. It could be open and shaped like the surface of a saddle. Most scientists believe the evidence points to the notion that our universe is as flat as a sheet of paper.
How will the universe end?
Though the fate of the universe is not so close or important in our thoughts as our own personal fortunes, it is a thought-provoking topic for animated debate over coffee, or on lazy Saturday afternoons with a tall, cold drink.
The universe evolved from its beginning, through a struggle between the momentum of expansion and the pull (or push) of gravity. The strength of gravity depends on the density and pressure of the matter in the universe.
Once again, MAP's careful measuring of temperature differences should give scientists data on matter and density in the universe needed to tell us whether the cosmos will expand endlessly, whether it collapse in a "Big Crunch," or whether its end will be something as yet unimagined.
More than the Big Bang
The Big Bang theory is incomplete, it doesn't explain a number of things important to our understanding of the universe. It doesn't explain how structures like stars and galaxies came to exist. Nor why there are fluctuations in the temperature of the Cosmic Microwave Background Radiation. Another idea, called "inflationary theory" may offer answers to these questions, and, again, MAP will gather key evidence.
On June 30, 2001, when the MAP satellite is lofted into space atop a Delta II rocket, it will briefly rock our world. By the end of its two-year mission, our understanding of the universe, will be changed forever.
To learn more about the MAP spacecraft, its mission and cosmology, visit the following sites:
Microwave Anisotropy Home Page
The Explorer's Program
Cosmology 101
Frontiers of Cosmology