PUBLIC AFFAIRS CONTACTS Debra Rahn International Relations Division NASA Headquarters, Washington, D.C. (Phone: 202/453-8455) Michael Braukus Office of Space Science and Applications NASA Headquarters, Washington, D.C. (Phone: 202/453-1547) Jim Cast Office of Space Flight NASA Headquarters, Washington, D.C. (Phone: 202/453-8536) Randee Exler Goddard Space Flight Center, Greenbelt, Md. (Phone: 301/286-7277) George Diller/Dick Young Kennedy Space Center, Fla. (Phone: 407/867-2468) Wilfried Geist DLR ROSAT Project Office Cocoa Beach, Fla. (Phone: 407/784-8071) - i - CONTENTS GENERAL RELEASE............................................1 SCIENCE OBJECTIVES.........................................2 DIVISION OF TASKS..........................................4 MISSION TIMELINE...........................................5 ROSAT FLIGHT AND LAUNCH CONFIGURATION......................6 LAUNCH VEHICLE SCHEMATIC...................................7 MISSION BOOST PROFILE......................................8 THE INSTRUMENTS............................................9 X-RAY SKY SURVEY...........................................9 POINTED OBSERVATIONS......................................10 LAUNCH OPERATIONS.........................................10 LAUNCH VEHICLE............................................11 NASA ROLE... .............................................12 MISSION MANAGEMENT........................................13 - ii - RELEASE: 90-66 ROSAT SPACECRAFT TO EXPLORE HIGH ENERGY UNIVERSE Continuing a program in which it has been a pioneer, NASA will join with the U.S. Air Force and West Germany to launch the Roentgen Satellite (ROSAT) to expand human knowledge of the high-energy processes within the universe. ROSAT is scheduled for launch aboard a McDonnell Douglas Delta II expendable launch vehicle from Cape Canaveral Air Force Station, Fla., no earlier than May 31. ROSAT, a cooperative program between the United States and the Federal Republic of West Germany, originated from a 1975 proposal to the Bundesminister fur Forschung und Technologie (BMFT) from scientists at the Max-Planck-Institut fur Extraterrestrische Physik (MPE) in Garching, FRG. The mision will examine X-rays emitted by cosmic sources. The mission's objective is a detailed survey of X-ray sources across the sky, followed by studies of some 1,000 of the anticipated 50,000 to 100,000 sources that will be detected. X-rays from astronomical bodies cannot be observed from ground level because the Earth's atmosphere blocks them. Only instruments beyond the atmosphere can measure the X-ray sky, making X-ray astronomy a true product of the space program. Because X-ray emission is characteristic of very high temperatures, X-ray astronomy allows scientists to study high-energy processes in the universe. Such high-temperature processes represent a small fraction of the energy generated by ordinary stars like the sun, but they can dominate the output of supernova remnants, quasars and celestial systems containing neutron stars or black holes. NASA helped pioneer the development of X-ray astronomy, but the last NASA X-ray mission was the High Energy Astronomy Observatory (HEAO-2), nicknamed the Einstein Observatory because it was launched in 1979, the centennial year of physicist Albert Einstein's birth. A landmark in the development of astronomy, the Einstein Observatory provided the first true images of X-ray-emitting objects. - end general release - background information follows - 2 - ROSAT Science Objectives The ROSAT all-sky survey, which will take 6 months to complete, will use the imaging telescopes to measure positions of X-ray and extreme ultraviolet (XUV) sources to an accuracy of 0.5 arc minutes, while obtaining fluxes and spectral information. The second stage of the mission will consist of pointed observations of selected sources. Sources are chosen for the pointed phase based on proposals submitted by the astronomical community for peer review. Outlined below are some of the topics to be explored in the pointed phase of observations. Different types of normal stars apparently emit X-rays by different mechanisms. Relatively cool stars like the sun emit X-rays from an outer corona of hot, low-density gas (visible when the bright chromosphere is masked, as in an eclipse). X-rays are thought to be produced in the stellar corona by interactions with the stellar magnetic field, heating gases to 1 million degrees or more. Scientists do not fully understand the corona phenomenon, but with ROSAT they can study the corona effect in the stars. Hot stars, which are 5 to 10 times hotter than the sun and 10 to 100 times more massive, also are X-ray emitters. In these stars it is believed that stellar winds carry shock-heated parcels of gas that emit X-rays. Very young stars are born in regions of contracting gas and dust that generally block astronomers view of X-rays. As a molecular cloud condenses, temperatures climb, nuclear reactions begin and a star bursts into life. The nature of X-ray emission from such young stars is a mystery that ROSAT will investigate. Supernova remnants, the remains of exploded massive stars, can tell scientists a great deal about the evolution of a star. The source of the explosion, the outward propagation, velocity and dynamics of the ejecta, the atomic composition of the debris and the evolution of the collapsed core are all questions of interest to astronomers. Supernova 1006, observed in the year 1006 AD, was the earliest recorded observation of a supernova in this galaxy. X-radiation detected in the constellation Lupus is thought to be the remnant of that explosion. ROSAT's high-resolution observations may show details of the distribution of material in this remnant. Compact objects such as white dwarfs, neutron stars and black holes evolve from dying stars when gravity has reduced them to the minimum possible volume for their mass. The gravitational fields around black holes are so strong that not even light can escape, and the existence of black holes is only established by their effects on objects close to them. - more - - 3 - The high spatial resolution of the ROSAT telescope will allow determination of the first accurate positions for compact X-ray sources. Many stars exist in binary systems, rotating around one another, with the compact member of the binary attracting a flow of X-ray emitting material from its companion. Detailed analysis of the X-ray data will give information about the size and shape of the system. Normal galaxies, both spiral and elliptical, produce X-rays. In spirals, the X-rays represent the accumulated emission from individual X-ray sources within the galaxy. ROSAT, with its improved sensitivity and spatial resolution, will allow detection of these individual sources in many galaxies. X-rays from elliptical galaxies, however, appear to originate in gas several millions of degrees in temperature. This gas is gravitationally confined, and a knowledge of its temperature and density will enable scientists to determine the mass of the galaxy. When comparing this mass with the mass of the stars comprising a galaxy, the difference will be a measure of dark matter associated with the galaxy. The effects of dark matter were detected by the Einstein Observatory for a few galaxies. The greater sensitivity, spatial and spectral resolution of ROSAT will increase the sample of galaxies studied and place stronger constraints on the determination of mass and distribution of dark matter in elliptical galaxies. Active Galactic Nuclei (AGN) make up a small percent of all galaxies. Very large amounts of energy are released from their nuclei, much more than can be accounted for by the stars they contain. The most well known class of AGN are quasars, which can be observed at very large distances because they are among the most luminous objects in the Universe. The large emissions from AGNs suggest they are powered by the release of gravitational potential energy as matter accretes onto a massive central object, thought to be a black hole. Current ideas favor the formation of a disc of accreting matter, heated by viscous forces as material is pulled inward onto the black hole. Soft X-rays may originate in the hypothesized accretion disk. ROSAT's soft-X-ray timing and spectral data may provide valuable information on the size and physical conditions in this disk. Although extended optical and radio emitting regions have been found in many AGN, only a few cases of extended X-ray emission are known. ROSAT's high spatial resolution and sensitivity will allow a detailed study of such phenomena, giving scientists clues to their physical origin. - more - - 4 - The first X-ray astronomy experiments discovered that clusters of galaxies emit extensive X-rays. These emissions originate in the multi-million degree gas permeating each cluster, and the mass of this gas exceeds the mass of visible material. The total mass of a cluster can be measured in the same way as for elliptical galaxies. ROSAT will make it possible to estimate mass for lower temperature clusters emitting in the soft X-ray regime. The X-ray background comprises a uniform emission on which individual X-ray sources are superimposed. This background radiation may be either an intergalactic gas smoothly distributed throughout the Universe or a large number of individual sources too numerous and weak to be resolved by current instruments. The simplest way to resolve this question is to observe the background with increasingly sensitive and high spatial-resolution detectors to try to identify any individual sources resolved. Division Of Tasks Germany Spacecraft Dornier System (Prime Contractor) Messerschmitt-Boikow-Blohm Telefunken X-Ray Mirror Assembly Carl Zeiss Focal Plane Assembly MPE Garching Two Position Sensitive Proportional Counters MPE Garching Spacecraft Operations DLR-GSOC Oberpfaffenhofen USA Delta II Launch Vehicle McDonnell Douglas/USAF/NASA High Resolution Imager SAO/GSFC UK Wide Field Camera University Of Leicester and a Consortium of UK institutes - more - - 5 - ROSAT MISSION TIMELIME Activity Time Altitude Downrange Velocity (Min:Sec) Distance (MPH) Six solid rocket motors burnout 0:56 39,254 ft. 16,422 ft 1,220 Three solid rocket motors ignite 1:01 46,543 ft. 21,275 ft. 1,175 Jettison 3 solid motor casings 1:02 9.07 sm 4.21 sm 1,185 Jettison 3 solid motor casings 1:03 9.34 sm 4.41 sm 1198 Three solid motors burn out 1:56 28.7 sm 29.23 sm 3396 Jettison 3 solid motor casings 2:02 31.4 sm 34.14 sm 3517 Main engine cutoff (MECO) 4:25 86.9 sm 281.33 sm 11,663 1st separation 4:33 91.3 sm 306.29 sm 11,665 2nd stage ignition 4:38 94.3 sm 323.43 sm 11,646 Fairing jettison 4:43 96.8 sm 338.89 sm 11,671 2nd stage engine cutoff (SECO 1) 11:10 185.4 sm 1,753.7 sm 16,711 2nd stage ignition 38:02 360.7 sm 15,977 2nd stage engine cutoff (SECO 2) 38:14 360.8 sm 16,227 Spacecraft separation 43:00 359.8 sm 16,231 - more - - 9 - The Instruments The heart of the ROSAT spacecraft is the grazing-incidence X-ray telescope (XRT) developed in West Germany. The XRT focuses low energy or RsoftS X-rays in the energy range of 0.1 to 2 kilo electron volts (keV), corresponding to wavelengths of 100 to 6 Angstroms, onto detectors in XRTUs focal plane. This telescope consists of a four-fold nested Wolter type I mirror system with an 33-inch diameter and a 94-inch focal length, optimal with respect to survey sensitivity and on-axis collecting area at 1 keV. A carousel in the focal plane assembly carries two virtually identical West German Position Sensitive Proportional Counters (PSPC) and a single U.S.-supplied High Resolution Imager (HRI). As a result of a separate agreement between West Germany and the United Kingdom, ROSAT also will carry a longer wavelength telescope supplied by the U.K. called the Wide Field Camera (WFC). The WFC extends the measuring range to the extreme ultraviolet (XUV) region, with response over the energy range 0.04 to 0.2 keV (300 to 60 Angstroms). The WFC will view the sky simultaneously with the XRT, so that it can measure any XUV flux that might accompany X-ray emissions, in addition to discovering new sources that radiate primarily in the XUV during the survey. X-ray Sky Survey A 2-month instrument calibration period will follow ROSAT's launch. After calibration, the spacecraft will completely survey the celestial sphere. The sky survey is performed by continuously scanning great circles 2 degrees wide and perpendicular to the Earth-sun line, which allows full-sky coverage in 6 months. The scan rate of one rotation per orbit will avoid wasted time due to Earth occultation. ROSAT's X-ray survey will be the first by a true imaging telescope, and scientists anticipate that there will be almost a 100-fold increase over the number of sources detected previously in surveys conducted with mechanically collimated counters. The X-ray sky survey will be performed with the PSPC at the focus of the XRT. Its relatively large field of view (2 degrees circular compared to the 1 degree per day change in the direction of the Earth-sun line) and high sensitivity are ideally suited to this aspect of the mission. The X-ray survey data will be analysed and published by the Max-Planck Institut fur Extraterrestrische Physik. - more - - 10 - The concurrent XUV survey, performed by the WFC with its 5-degree field, will be the very first conducted in its portion of the electromagnetic spectrum and will be capable of detecting sources at a level 1,000 times weaker than the brightest known XUV source, the white dwarf star HZ43. The results of the XUV survey will be analysed and published by the WFC consortium. Pointed Observations After the survey, the mission will be devoted to pointed observations. The nominal mission lifetime contains 1 year of pointed observations, but the spacecraft orbit has been chosen to guarantee at least 1 additional year of observations. The PSPC counter gas is the only consumable in the payload, and the gas should not be exhausted for at least 2 years of pointed operation. U.S. guest investigators have been allocated 50 percent of the time allotted for pointed observations with the XRT, with the remaining time being shared by the West Germans (38 percent) and the British (12 percent). Guest investigators can choose the pointing directions, instrument parameters and durations of the observations. After 1 year of proprietary ownership, all pointed-mode X-ray data enter the public domain and are available for archival research. ROSAT Launch Operations The 6555th Aerospace Test Group, U.S. Air Force Eastern Space and Missile Center, is responsible for the preparation and launch of the Delta II which will carry the 5333 lb. (2424 kg) ROSAT into a circular orbit of 359 statute miles (580 km) with an inclination of 53 degrees. ROSAT spacecraft pre-launch processing was accomplished by the West German Institute for Air and Space Flight cooperating with the Kennedy Space Center's Payloads Operations Directorate. Processing included functional testing, installation of the wide field camera and interface tests with the German mission control center at Oberpfaffenhofen, near Munich. Launch operations will be conducted from the Complex 17 blockhouse by a USAF/McDonnell Douglas team under the direction of the 6555th Aerospace Test Group. The hypergolic propellants for the second stage will be loaded approximately three days prior to launch. The RP-1 (kerosene) fuel for the first stage and the supercold liquid oxygen oxidizer for the first stage will be loaded during the terminal countdown. - more - - 11 - NASA will oversee the launch vehicle and support ROSAT flight preparations. A Kennedy Space Center launch manager will represent NASA during vehicle preparations and countdown and serve as liaison with the Air Force. The launch manager will be located in the Mission Director's Center on CCAFS to monitor launch countdown operations and will provide the final NASA concurrence for launch to the USAF launch director. DELTA II Launch Vehicle A United States Air Force Delta II 6920-10 expendable launch vehicle, featuring the largest payload fairing flown on a Delta to date, will lift ROSAT into low-Earth orbit. Based on the Titan fairing McDonnell Douglas Space System Company (MDSSC) has built for years, the 10-foot-diameter fairing will be the first three-section fairing used on a Delta vehicle. Fairings previously used on Deltas have consisted of two sections. This configuration accommodates ROSAT and other payloads requiring a larger volume than offered by the 9.5-foot and 8-foot fairings flown previously. NASA funded the development of the 10-foot fairing for the Delta rocket. The fairing uses the MDSSC contamination-free thruster joints to separate into three sections. MDSSC fairings, which are manufactured at the MDSSC plant in Pueblo, Colo., have a 100 percent success record. The ROSAT launch will be the 10th flight for the Delta II. Delta's origins reach back to the mid-1950s, when the U. S. Air Force developed the Thor intermediate-range ballistic missile. NASA later modified the Thor, a single-stage, liquid-fueled missile, for the Delta launch vehicle. The two-stage Delta II carrying ROSAT consists of four major assemblies: the first stage, including nine strap-on solid rocket motors, the interstage, the second stage and the payload fairing. Initial system improvements incorporated into the Delta II include a 12-foot extension in the first-stage tanks for added propellant capacity and the use of Morton-Thiokol Caster IVA solid rocket boosters. The Delta II is 123.4 feet tall and 8 feet in diameter. The payload fairing is 26 feet tall and 10 feet in diameter. The first-stage main engine has a liftoff thrust of 207,000 pounds, and each of the nine solid strap-on motors has a sea-level thrust of 97,070 pounds. The main engine and six of the nine solid motors are burning at liftoff, providing a total liftoff thrust of 789,420 pounds. The second set of three solid strap-on motors is ignited during the first stage burn. The second-stage engine has a vacuum-rated thrust level of 9,645 pounds. - more - - 12 - Several major subcontractors contribute to the Delta vehicle built by MDSSC: The Rocketdyne Division of Rockwell International in Canoga Park, Calif., is responsible for the first-stage main engine; Aerojet TechSystems Co. in Sacramento, Calif., builds the second-stage engine; Morton Thiokol of Huntsville, Ala., manufactures the solid rocket boosters; and Delta Systems of Goleta, Calif., produces the guidance computer. NASA's Role The Goddard Space Flight Center (GSFC), Greenbelt, Md., is the lead NASA center for the U.S. portion of ROSAT. GSFC managed the development and delivery of the High Resolution X-ray Imager fabricated at the Smithsonian Astrophysical Observatory, Cambridge, Mass., and assured the instrument's integration into the XRT focal plane. GSFC also managed all aspects of launch vehicle preparation and its mating to the spacecraft. NASA will provide initial spacecraft tracking and orbit determination until these tasks can be assumed by West Germany at its ground station at Weilheim and Operations Control Center at Oberpfaffenhofen a few hours after launch. NASA also is prepared to provide, on request, spacecraft engineering data capture and transmission to Germany in case of an emergency during the life of the spacecraft. GSFC is developing a comprehensive U.S. ROSAT Science Data Center (USRSDC), and is responsible for providing all U.S. guest investigators with their data and the software necessary for analysis. Data centers will be established at both the GSFC and at the Smithsonian Astrophysical Observatory for the convenience of guest investigators, but investigators also will be able to perform most of their analyses at their home institutions. GSFC also is establishing an accessible ROSAT data archive that can be used in conjunction with data sets from other missions. The USRSDC supports astronomers in their preparation of proposals for pointed phase observations through the Mission Information and Planning System (MIPS). MIPS is a software system that provides a proposer with information such as observation times appropriate for a given source. It was used by 137 different astronomers across the U.S. for the first round of proposals. Following the results of a questionnaire distributed to users, the USRSDC staff is making improvements in preparation for the second round of proposals. In the first round, 354 proposals were received by NASA. The USRSDC assisted NASA Headquarters in the review and selection of these investigations by performing technical evaluations and organizing the independent peer review. USRSDC staff were on hand during the peer review to answer technical questions. - more - - 13 - GSFC is responsible for processing and distributing ROSAT pointed-phase data. Initially all data are processed at the German Space Operation Center (GSOC) in Oberpfaffenhofen, West Germany. Video tapes containing master data records are then shipped to the Max Plank Institute in Garching, West Germany, and to GSFC, where they are processed to create the files for distribution to guest investigators. These files also are archived by the USRSDC and will be made generally available 1 year after calibrated data has been delivered to the investigator. ROSAT/DELTA TEAM Bundesministerium fuer Forschung und Technologie Dr. Jan B. Mennicken, Director, General Aerospace Research and Technology, Geosciences, Transportation Dr. Ing. H. Strub, Director, General Aerospace Research and Technology, Transporation and Marine Technology Dr. Herbert Roemer, Head, Section Space Research and Astronomy Manfred Otterbein, Program Director/Manager/Scientist Deutsche Forschungsgsgesellschaft fur Luft-und Raumfahrt, Oberpfaffenhofen Wilfried Geist, Project Manager Dr. Volker Kaltenbach, Deputy Project Manager Friedrich Guckenbiehl, ROSAT Manager Ground Operations Max-Planck-Institut fur Extraterrestrische Physik, 8046 Garching, West Germany Prof. J. Truemper, ROSAT Project Scientist Dr. B. Aschenbach, Deputy ROSAT Project Scientist Dr. H. Brauninger, ROSAT Fl Project Manager H. Hippmann, ROSAT Fl Project Engineer Dr. H. U. Zimmermann, German ROSAT Data Center Coordinator - more - - 14 - NASA Headquarters Dr. Lennard A. Fisk, Associate Administrator, Office of Space Science and Applications Alphonso V. Diaz, Deputy Associate Administrator, Office of Space Science and Applications Dr. Charles J. Pellerin Jr., Director, Astrophysics Division John A. Lintott, Program Manager Dr. Alan N. Bunner, Program Scientist Dr. Louis Kaluzienski, Deputy Program Scientist Dr. William B. Lenoir, Associate Administrator, Office of Space Flight Joseph B. Mahon, Deputy Associate Administrator, Office of Space Flight Charles R. Gunn, Director, Unmanned Launch Vehicles and Upper Stages Peter T. Eaton, Chief, Small and Medium Launch Vehicles Branch Charles T. Force, Associate Administrator, Office of Space Operations Goddard Space Flight Center Dr. John W. Townsend Jr., Director Gilbert W. Ousley, Sr. Project Manager Dr. Stephen S. Holt, Project Scientist Dr. Robert Petre, Deputy Project Scientist Dr. Robert Price, Director, ROSAT Science Data Center John Beckham, Delta Project Manager - more - - 15 - Kennedy Space Center, Fla. Forrest S. McCartney, Center Director John T. Conway, Director of Payload Management and Operations J. L. Womack, Director, Expendable Vehicles, NASA Launch Manager William R. Fletcher, ROSAT Launch Site Support Manager USAF Eastern Space and Missile Center, Patrick AFB, Fla. Col. John R. Wormington, Commander Col. Robert B. Bourne, Commander, 6555th Aerospace Test Group Lt. Col. Harold Donald, Acting Chief, Medium Launch Vehicle Division Test Director Harvard-Smithsonian Astrophysical Observatory John Gerdes, Project Manager Dr. Stephen R. Murray, HRI Project Scientist McDonnell Douglas Space Systems Co., Huntington Beach, Calif. Don Tutwiler, Director, NASA and Commercial Programs Lyle Holloway, Director, Launch Sites Jerry Winchell, Program Manager, NASA Programs Jay Witzling, Senior Manager, Spacecraft Integration Jack Dodds, Launch Conductor - end - TO: MDS/PRA Group 1615 L Street, N.W. - Suite 100 Washington, D.C. 20036 DATE & TIME: May 18, 1990 4:00pm ORDERED BY: Edward Campion NASA Headquarters/LMD 400 Maryland Avenue, SW Washington, DC 20546 PHONE: 202/453-8400 PROJECT TITLE: Release No: 90-66/ROSAT PRESS KIT PRINT ORDER: 2253 PRINTING: Camera Ready, lst pg on NASA logo, other pages plain ENCLOSE & MAIL: 1 PRESS KIT PER ENVELOPE MAIL DATE: UPON RECIEPT OF PRESS KIT EXTRA COPIES: DELIVEER TO THE NASA NEWSROOM 50 copies 275 copies 75 copies -------------------- ------------------- ----------------- National Press Club NASA Mailroom NASA Newsroom 13th floor newsrack NASA Headquarters NASA Headquarters National Press Building 600 Independ. 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