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NASA FACTS (B-62) 1'63 16 700 Page 1
ORBITING SOLAR OBSERVATORY
First of the "Streetcar" Satellites
The mission of 050 - t h e Orbiti ng Solar
Observatory-is to gather scientific data about
the sun which cannot be obtained by observa
tion from the earth's surface.
The earth ' s atmosphere accepts certain types
of electromagnetic radiation, including visible
light, but screens out or distorts others. This
is fortunate for humans because it protects them
from ultraviolet radiation which would cause
bad sunburns, or even kill. But it is incon
venient fo r the scientist who wants to study
these radiations. Observations for his pur
poses have to come from th e other side of the
atmosphere.
Types of electromagnetic radiation in this
category include ultraviolet, X-rays and gamma
rays, al l of which are being observed and
counted by 050 - 1. launched on March 7, at
Cape Canaveral, aboard a three-stage Thor
Delta, the first Orbiting Solar Observatory de
lighted the team responsible for it by going into
an almost circular orbit. It then proceeded to
circle the earth at an altitude ranging from a
perigee of about 340 miles to an apogee of
370 miles, and to report most satisfactorily on
all the tasks assigned to it.
050-1 is called the first of the "streetcar"
satellites because it has a series of experiment
apparatuses aboard as "passengers " -thirteen
of them.
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Page 2
THE SUN
Despite obstacles, scientists have a great
deal of knowledge about th e sun, including
facts obtained by solar instruments on balloons
and rockets, and by telescopes on mountain
tops.
The sun is 93 million miles away, has a di
ameter of 864,000 miles (10 times the earth's).
Its core has a temperature of 35 million de-
grees. Sunspots, which are dark areas of vary
ing size on the surface, appear to be venting
valves fo r tremendous forces at work in the in-
terior. Periodically, there are enormous flares,
hurtling fa r out into space. The flares, and the
radiation accompanying them, are of special
interest to the scientists who are evaluating
data from OSO- l .
NASA FACTS (8-62)
The National Aeronautics and Space Admin
istration (NASA) now has inaugurated a scien-
tific research program, with OSO- l as one of
the early steps to "v iew" the sun with instru
ments circling beyond the earth's atmospheric
interference. This scientific program fulfills one
NASA object ive: "The expansion of human
knowledge of phenomena in the atmosphere
and space." OSO will also provide data to
insure the greater safety of America ' s manned
lunar landing during the 1960's.
The OSO as now instrumented is expected to
provide solar information through which solar
flare prediction techniques can be more ac-
curate. NASA hopes that improved flare fore
casting will precisely indicate th e periods of
relative safety and danger for space travel.
Manned lunar flights then can be scheduled ac-
cordingly.
Prominences beyond the limits of the sun's surface, taken by spectroheliokinematograph (motion
pictures of the sun in monochromatic light). The white do t at right near the sun's surface,
superimposed on the photograph, represents the earth, to scale.
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- - - - - - - - - - " ' - - - - - - " - ~ = " - ' - - - - - - ' - ' - - ' - ~ - ~ - " - - ' - - - - : - - - - - ' - - - ' - - ' - - - - - - - - - . -
NASA FACTS (8-62)
THE SATELLITE (OSO-1 )
The first 050 is a 458-pound spacecraft con
taining 13 scientific solar experiments, traveling
in a 350-mile high, 96-minute, earth orbit.
Spacecraft in the 050 series are basic carriers,
in which the number and type of experiments
can be interchanged and increased without any
change in the satellite's configuration-thus,
"streetcar" satellites. The 050-1 , as
launched, is 37 inches in height and its diam
eter is limited to 44 inches to fit th e Delta
booster. After launch three arms, each with
a nitrogen gas container with jets for stabilizing
the satellite, are extended, increasing diameter
to 92 inches and improving gyroscopic stability.
The 050 satellite technically is designated
as a "stabilized platform fo r solar oriented
scientific instruments."
The spacecraft has two main sections. There
is a wheel-like structure 44 inches in diameter
and 23 inches high consisting of 9 wedge
shaped compartments. Mounted on the wheel
is a rotating fan-shaped array containing five
continuously, sun-aligned experiments. Its sur
face is covered by 1860 solar cells, producing
27 watts of electric power. The satellite uses
1 6 watts: 9 for the experi ments and 7 for tele-
metry, data and control systems.
As the 0 5 0 is put into orbit, small rocket
motors spin it so that th e vehicle maintains a
Page 3
spinning rate of 30 revolutions per minute.
05 0 thereby utilizes th e gyroscopic properties
of a spinning body to attain stability as a space
platform, and in addition, th e experiments in
the wheel portion point alternately at th e sun
and away from the sun, thus affording compari-
sons where wanted.
The top or fan-shaped portion, containing the
solar cells and the sun-pointed experi ments,
constantly faces the sun, despite the rotation of
the lower wheel. A torque motor dr ives the
upper portion at an equal but opposite rate to
that of the wheel and thereby keep s th e solar
cells an d the upper ex peri ments continuously
oriented to the sun.
Coarse and fine photodetectors located
around the spacecraft activate motors and jetsto keep 05 0 in proper relationship to th e sun.
Other detectors turn off and turn on th e elec
trical equipment as th e satellite enters and
emerges from the earth ' s shadow.
The useful lifetime of each 0 50 satellite is
estimated as 6 months, at which time the nitro
gen gas which positions it towards the sun will
have been expended. The machine will then
lose its sun-orientation and the solar cells will
be unable to provide the electric ity needed bythe experiments, the controls and the data trans
mission. The vehic le may continue in its earth
orbit for years but as a scientific information
source it will be dead, and successor OSO's
will be launched to continue some or all of
OSO-l 's experiments and / or others.
The scientific data obtained by OSO's 13 ex
periments are telemetered to earth by two in
dependent tape recorders and transmitters. For
90 minutes ofits
orbit, the experiments ' resultsare telemetered onto a continuous loop tape
recorder. During th e remaining five minutes,
the appropriate ground station directs th e re
corder to transmit the complex data by radio at
a rate 18 ti mes faster than it was recorded.
This process clears the tape so that as the
broadcasting ceases, it can record more data.
The ground station can order either transmitter
on or off; it can also turn on or off th e wheel
experiments and the sun-pointed tests.
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Page 4
050'5 SCIENTIFIC EXPERIMENTS
050 's 13 scientific experiments seek more
and new data about the sun by constantly count
ing and measuring the intensity of solar rays
trave l ing near the earth. The 050 utilizes avail
able sol ar properties to obtain data on the sun 's
origin, development and constantly changing
character. Knowing from optical and radio de
tectors on earth when solar storms and flares
are occurring, scientists can analyze and con
trast OSO ' s data, before, during and after the
known event, to discover laws ' and principles
about th e sun's composition, its solar storms
and flares, and their influence on the earth and
on spacecraft .
THE LAUNCH
050-1 was launched as the payload of a Thor-Delta launch
vehicle . It went into an almost circular orbit: perigee, 34 0
miles; apogee 370 miles . All reporting apparatus went
into action satisfactori Iy .
NASA FACTS (8-62)
The 13 experiments divide into two groups:
5 on the fa n shaped upper portion constantly
facing the sun, and 8 in the rotat in g wheel or
lower portion of the satellite. The former are
the sun-pointing tests, establishing standards
of solar activity during quiet an d turbulent
periods . The wheel experiments are sky-map
ping activities comparing radia ti ons directly
from the sun with those from othe r a reas of
space. A generalized summary of the 13 ex
periments follows :
THE SUN-POINTED EXPERIMENTS(Designed by NASA 's Goddard Space Fl ight Center)
1. SOLAR X-RAY SPECTROMETER measures
X-ray emissions in a range, now known only in
generalities, of 10 to 400 Angstroms (an Ang
strom is a measuring unit fo r the w ave lengths
of l ight, or on e ten-millionth of a mill i meter.
Red, the highest visible l ight, has a wave length
of 7600 Angstroms). Direct solar radiation is
dispersed by a prism into its wave lengths. Its
intensities are measured , coded an d recorded
on the tape.
2. GAMMA RAY MONITOR measures the
intensity of solar gamma rays and thereby pro
vides data about the thermonuc lea r processes
responsible fo r th e sun's hea t an d l i ght, sup
porting earth l ife . This test i s paralleled by a
similar wheel experiment.
3. X-RAY MONITOR measures the intensity
of emissions thought to be associated with fre
quency changes in solar radio activity so that a
comparison can be made with th e variations
recorded by the earth ' s radio observatories .
4. ION CHAMBER X-RAY MON ITOR sup
plements the X-ray spectrometer in Experiment
1, especially during a solar flare when X-ray
emissions increase so much that the wave lengths
and intensities of X-rays fall below the operat
ing level of that spectrometer.
5. DUST PARTICLE DETECTOR measures the
incoming rate, the momentum, and t h ~ kinetic
energy (energy resulting from motion) of the
microscopic dust moving away from the sun.
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NASA FACTS (8-62)
FLIGHT
SEQUENCE
o
\\
\ \
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Page 5
+800 SEC.-lOCK ON SUN
IN EI.EYATION ACTUATE
PITCH JETS (l.OCK ON SIIN
EACH SATELliTE MOIIN/Kt;
SHUTOFF EACHSATEURE1ItJIIT)
+400 SEC.- lOCK ON SUN
IN AZIMUTH AN D REMOVE
NUTATION
\+200 SEC.- DE-SPIN TO 30 !l.RN.
\\\
+/65 SEC.- 3 rd STAG-E SEPARATION\
+ /00 SEt:- ARMS OUT \
\
\+57SEC. - 3rtf STAGE BURNOUT
+IS SEC.-FIRE 31'd STAGE
0 ) ' 1 0 SEC - SPIN3,,( STMMAND SATELLffE TO 120 R.R/IIf.-START SATEUffE "ItfER
FLIGHT SEQUENCE
At launch , and during the ascent to orbital altitude, 050 ' s three arms are folded down on the Delta booster .
After separation they extend ta operating position and the satellite then adjusts to its position, an d
locks on to the sun, as indicated in the step-by-step diagram, showing the sequence from thi rd stage
separation, at a seconds, to " lock on sun," at plus 80 0 seconds.
THE WHEEL EXPERIMENTS
(Name in parentheses indicates institution design -
ing the experiment.)
6. SOLAR RADIATION DETECTOR (God
dard Space Flight Center) filters solar radiation
to restrict reception to the Blue Light level
(3800 to 4800 Angstroms), which is measuredto determine the total energy balance of the
sun and to learn how millions of tons of the
sun's hydrogen are converted into helium with
the excess transferred to the solar system in the
form of heat and light.
7. SOLAR ULTRA-VIOLET MONITOR (God
dard Space Flight Center) measures the most
fundamental line of the hydrogen spectrum, the
Lyman-Alpha emission l ine, to determine i f i t
5
remains constant during active and quiet solar
periods .
8, SOLAR GAMMA RAY MONITOR (God
dard Space Flight Center) is similar to Experi
ment 2, except that being in the wheel portion,
it scans Gamma ray emission across space.
This experiment also has a detector which de
termines if the satellite generates its own radiation from contact with space particles.
9. SOLAR GAMMA RAY DETECTOR (Uni
versity of Minnesota) measures rays in the
50,000 to 3 million electron volt ranges by use
of the "Compton Telescope. "
1O. NEUTRON MONITOR (University of
California) measures the output of neutrons
from the earth's atmosphere, produced by cos
mic rays striking oxygen and nitrogen nuclei.
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Page 6 NASA FACTS (B-62)
OSO IN ORBIT
The useful life anticipated fo r an Orbiting Solar Observatory is 6 months. After that time its nitrogen
gas will have been used and its jets cannot operate, so it cannot point the fan towards the sun and
rotate the wheel. But successor OSOs will be launched to continue the exper iments and to make
other types of observations.
11. PROTON-ELECTRON DETECTOR (University of California) distinguishes between pro
ton and electron ionization in the lower Van
Allen belt and provides data on the components
of that vital area.
12. EMISSIVITY STABILITY DETECTOR
(Ames Research Center) measures the variations
in temperature of several test surfaces on the
wheel during exposure to space conditions and
records the amount and the rate of change in
the thermal radiation characteristics of various
temperature-control materials used on the satel
lite.
13 . HIGH ENERGY SOLAR GAMMA RAY
DETECTOR (University of Rochester) counts the
high energy (100-500 mill ion electron volt
range) gamma rays originating particularly
during solar flares bu t also in quiet periods, not
only directly from the sun but from the whole
spacial area, as the rotating satellite wheel
sweeps the whole sky.
ADDITIONAL SATELLITE OBSERVATORIES
NASA plans to launch a similar OSO in
1963, so that the sun will be under constant
scientific surveillance. Thereafter, it is expected
that improved OSOs will have been developed
to discover other solar secrets which will be the
basis fo r planning of lunar flights. NASA plans
to maintain non-atmospheric scientific investiga
tion of the sun fo r the full eleven years com
prising a solar cycle. The types and the objectives of the scientific satellites will be altered
as successful OSOs provide increasing solar data
which may raise new and unforeseen problems
requiring new testing techniques ta provide
needed answers.
NASA has also developed other orbiting ob
servatories, such as lunar and geophysical observ
atories, which, during 1962 and 1963, will be
collecting additional data.
~ - - - - --
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NASA FACTS (8-62) Page 7
ORBITING ASTRONOMICAL
OBSERV ATORY
OAO
MISSIONS OF OAO
The Orbiting Astronomical Observatory is designed fo r a wide variety of astronomical experiments,
making observations of the solor system, of the stars (stellar radiations) tenuous material be-
tween the stars (interstellar gas) and fa r distant galaxies (galactic radiations) .
A satellite capable of making astronomical
observations from space above the atmosphere,
thus avoiding atmospheric distortions which
plague astronomers using telescopes on the
earth's surface, is th e Orbit ing Astronomical
Observatory.
The first OAO is scheduled fo r launching into
orbit in late 1963. Others ar e planned fo r
yearly launchings thereafter.
OAO is described as a "stabil ized space
platform." Its launch vehicle is the Atlas
Agena B, capable of inserting the 3,300 pound
OAO into a 500-mile high circular orbit. In-
cluded in the 3,300 pounds are 1,000 pounds
of experimental gear.
7
OAO has self-contained stabilization, com
munications and power equipment. It is
equipped with solar cell paddles to convert sun-
l ight into electrical energy.
For astronomical observations, the satellite
has scientific apparatus and instruments en-
abling it to perform a wide variety of scientific
experiments in a single mission. Included are
telescopes with mirrors up to 36 inches; spec-
trometers fo r measuring spectral wave lengths;
photometers to measure th e intensity of l ight;
and image-detecting tubes.
OAO will be able to point instruments at a
given star with an accuracy of a fraction of a
second of an arc, equivalent to focusing within
one-third inch of a point a mile away.
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.....
Page 8 NASA FAC'FS (B-62)
r - - - "ORBITING GEOPHYSICAL
OBSERVATORIES
OGO: EGO AND POGO
OGO IN ORBIT
The Orbiting Geophysical Observatory uses its " sensors" to acquire the information it has been put into orb it to
collect (see below) an d transmits the data to earth for study an d evaluation by the scientists who ore con
ducting the experiments.
These satellites, with the colorful short names
of EGO and POGO, are Orbiting Geophysical
Observatories. OGO refers to the basic de
sign. EGO's full name is Eccentric Geophysi
cal Observatory, so-called because it is intended
for launching into an eccentric orbit with an
apogee of about 70,000 miles from the earth
and a perigee of about 175 miles. POGO is
the Polar Orbiting Geophysical Observatory,
which will have a planned apogee and perigee
of 570 and 160 miles, respectively, passing
over the poles of the earth, and giving partic
ular attention to the unexplored regions of the
polar atmosphere.
There also ar e differences in the assigned
experiments.
For EGO, the main purpose is the study of
energetic particles, an d other geophysical phe
nomena requiring th e type of orbit planned
for it.
POGO will be instrumented chiefly to study
the atmosphere and ionosphere, especially over
the North and South Poles.
An Atlas-Agena B will be used to launch
EGO and insert it into orbit. POGO will be
launched for its polar orbit by a Thor-Agena B.
U. S. GO VERHMENT PRIN TI NG OFFICE : 19620'-64 0489
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