nasa facts orbiting solar observatory first of the streetcar satellites

8/7/2019 NASA Facts Orbiting Solar Observatory First of the Streetcar Satellites

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NASA FACTS (B-62) 1'63 16 700

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.



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

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.



- = ~ ~ ~ ~ - - - - ~ - - ~ ~ ~ ~ - - ~ - - - - ~ ------------------------------------

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.



NASA FACTS (8-62)

FLIGHT

SEQUENCE

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+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.

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+/65 SEC.- 3 rd STAG-E SEPARATION\

+ /00 SEt:- ARMS OUT \

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\+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.



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.

~ - - - - --



NASA FACTS (8-62)

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.



.....

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

nasa facts orbiting solar observatory first of the streetcar satellites

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