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Subject: SPACE Digest V11 #400

SPACE Digest                                     Volume 11 : Issue 400

Today's Topics:
             ROSAT Press Kit (Forwarded)
----------------------------------------------------------------------

Date: 14 May 90 17:39:50 GMT
From: trident.arc.nasa.gov![e-mail]  (Peter E. Yee)
Subject: ROSAT Press Kit (Forwarded)

pages 6-8 are line art not transmitted via telemail.  These
pages wil be faxed to Centers.











    PUBLIC AFFAIRS CONTACTS


Debra Rahn
International Relations Division
NASA Headquarters, Washington, D.C.
(Phone:  [phone])

Michael Braukus
Office of Space Science and Applications
NASA Headquarters, Washington, D.C.
(Phone:  [phone])

Jim Cast
Office of Space Flight
NASA Headquarters, Washington, D.C.
(Phone:  [phone])

Randee Exler
Goddard Space Flight Center, Greenbelt, Md.
(Phone:  [phone])

George Diller/Dick Young
Kennedy Space Center, Fla.
(Phone:  [phone])

Wilfried Geist
DLR ROSAT Project Office
Cocoa Beach, Fla.
(Phone:  [phone])
















    - 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 of SPACE Digest V11 #400
*******************