Paula Cleggett-Haleim Headquarters, Washington, D.C. January 13, 1990 (Phone: 202/453-1547) Embargoed for 9:30 a.m. EST Carolynne White Goddard Space Flight Center, Greenbelt, Md. (Phone: 301/286-8956) RELEASE: 90-5 EARLY COBE RESULTS IN ACCORD WITH BIG BANG THEORY A major advance in cosmology was revealed today as early results from NASA's Cosmic Background Explorer (COBE), launched last fall, were presented at the American Astronomical Society meetings held at Crystal City, Va. Preliminary results are in accord with the predictions of the Big Bang theory, which traces the origin of the universe to a primordial explosion some 15 billion years ago. The universe today shows that sometime after the Big Bang additional release(s) of energy must have occurred. COBE's new results severely limit the magnitude and character of such a release. Limited COBE data now indicate a smooth, uniform Big Bang. However, small deviations from a blackbody spectrum -- the characteristic signature of radiation from an opaque object of uniform temperature -- would reveal energetic processes in the early universe. COBE scientists reported that the instruments onboard the spacecraft are performing exquisitely with precision never before achieved. Such precision puts new constraints on theories to explain the present universe. Over the 2-year mission, COBE will continue to collect much more data. Scientists expect the final data to be ten times more sensitive than these early results. These early results were reported to the American Astronomical Society by the principal investigators for the three instruments: the Far Infrared Absolute Spectrophotometer (FIRAS), the Differential Microwave Radiometer (DMR) and the Diffuse Infrared Background Experiment (DIRBE). -more- -2- Dr. John Mather, Principal Investigator for FIRAS and Project Scientist, reported that the spectrum measurement of the cosmic microwave background (a relic of the Big Bang) is highly accurate and heralds a major advance in observational cosmology. Based on a small sample of data, FIRAS measurements show no deviation from a blackbody spectrum as large as one percent of the peak brightness of the cosmic microwave background over the wavelength range 500 microns to 5 millimeters. When FIRAS captured these data, it was pointed toward the North Galactic Pole, where emissions from our own galaxy, the Milky Way, are expected to be low. Using only 9 minutes of sky observations, FIRAS already has produced the most precise cosmic microwave background spectrum measurement ever made. Much more exposure time will be obtained during the mission. Dr. George Smoot, Principal Investigator for the DMR, presented the first COBE maps of the variation in brightness of the cosmic background radiation over the sky. The maps, taken at frequencies of 31, 53 and 90 GHz, indicate that the cosmic background radiation is equally bright in all directions. The question of what and where are the progenitors of galaxies and large clusters of galaxies is still open. The preliminary results from DMR are based on only about 20 days of data and also indicate the extraordinary smoothness of the universe. This instrument will continue to take data for two years, which will improve its sensitivity to search for anisotropies, or "lumpiness," in the early universe well beyond the present limits. Dr. Michael Hauser, Principal Investigator for DIRBE, showed maps of half the sky taken at wavelengths of 1.2, 12, and 240 microns (never before achieved for the 1.2 and 240 micron wavelengths). Final maps from this experiment will enable COBE scientists to search for radiation from the first stars and galaxies. These initial maps, taken over a one-week period, clearly reveal bright foreground radiation from stars, dust in our own Solar System, and interstellar dust. DIRBE maps half the entire sky every day at 10 different wavelengths and it covers the entire sky in 6 months. At the AAS meeting, Dr. Nancy W. Boggess, Deputy Project Scientist, gave an overview of the mission, reporting that COBE has met or exceeded all design goals. At launch, all systems deployed as planned. The RF/Thermal Shield, which protects all three instruments from solar and terrestrial radiation, is more spectacular than hoped. -more- -3- This efficient shield results in a lower than anticipated temperature of the dewar, the giant thermos bottle that maintains the FIRAS and DIRBE at operating temperatures below 2 degrees K. The dewar now operates at 1.4 degrees K, though designed for 1.6 degrees K less. The lower temperature will enable the detectors of the COBE instruments to be more sensitive. It also makes the lifetime of the liquid helium, which keeps the dewar cryogenically cooled, longer than the original 12 to 14 months. It is now expected to last 430 days. COBE was launched Nov. 18, 1989, aboard the last NASA-owned Delta rocket, from the Vandenberg Air Force Base, Calif. COBE is managed by NASA's Goddard Space Flight Center, Greenbelt, Md., for the Office of Space Science and Applications. GSFC is responsible for the design, development and flight operations, as well as for the development of the analysis software and for the production of the final mission data sets. The COBE science team consists of Drs. Charles L. Bennett, Nancy W. Boggess, Edward S. Cheng, Eli Dwek, Michael G. Hauser, Thomas Kelsall, John C. Mather, S. Harvey Moseley, Jr., Richard A. Shafer and Robert F. Silverberg, all of the Goddard center; Drs. Samuel Gulkis and Michael A. Janssen of the Jet Propulsion Laboratory; Dr. Philip M. Lubin of the University of California at Santa Barbara; Drs. Stephan S. Meyer and Rainer Weiss of the Massachusetts Institute of Technology; Dr. Thomas L. Murdock of the General Research Corporation; Dr. George F. Smoot of the University of California, Berkely; Dr. David T. Wilkinson of Princeton University; and Dr. Edward L. Wright of the University of California at Los Angeles. -end- NOTE TO EDITORS: Photographs to complement this release are available from the NASA Headquarters Audio-Visual Branch by calling 202/453-8383 or the Goddard Space Flight Center Public Affairs Office at 301/286-6256. Ask for: Color: 90-HC-20 90-HC-21 90-HC-22 B&W 90-H-20 90-H-21 90-H-22 TO: MDS/PRA Group 1615 L Street, N.W. - Suite 100 Washington, D.C. 20036 DATE & TIME: JANUARY 16, 1990... 3:00 P.M. 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