s-3b press kit

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NEWS RELEASENATIONAL AERONAUTICS AND SPACE ADMINISTRATION

k 400 MARYLAND AVENUE, SW, WASHINGTON 25, D C

IE.EPHONEES WORTH 2-4155 - WORTH 3- 1110

FOR RELEASE: Thursday PM'sOctober 25, 1962

RELEASE NO. 62-226

SATELLITE TO STUDY

ARTIFICIAL RADIATION BELT

The Nat:tonal Aeronautics and Space Administration plans to orbit

an Explorer satellite to study th e artificial radiation belt created

by the July 9 high altitude nuclear explosion over the Pacific,

By using a special satellite to study the location, composition

and decay rate of the artificial radiation, scientists also will have,

as a dividend, an unparalleled opportunity to better understand the

physi'al processes responsible for the natural (Van Allen) radiation

belts discovered in 1958.

If the first flight is not successful, another spacecraft will

be launched before the end of the year. The satellite, another in

the Explorer series0 was authorized on September 5 after coordination

with other interested government agencies. NASA's Goddard Space

Flight Center at Greenbelt, Md. was given the mission to design, build

and fly the spacecraft. The satellite is scheduled to be launched no

earlier. than October 26.

The spacecraft, named S-3b, is similar to Explorer XII and Ex-

plorer XIV which have successfully measured the energetic particles

in the natural radiation belt 0 It will be launched by a Delta rocket 0

If successful, this will be the 13th straight successful launch of

the Delta. The approximately 100-pound spacecraft will make an oval

orbit extending from 170 miles above the earth out to l10360 miles

every five hours0 Such a path will take it 17.8 degrees North and

South of the equator, permitting the study of the zone of trapped

fission electrons that was created more than 100 miles above the earth

and extending out to perhaps 10,000 miles0 Radiation at the lower

levels is not a hazard to spacecraft.



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It is believed that half of the electrons have energies of less

than a million electron volts, but that some have energies extending

up to as high as eight million electron volts. The spacecraft willcarry experiments to measure electrons in the range of 001 to 10 Mev

( million electron volts )O The total mass of all electrons in the

arta±ficial belt is less than 1/10 of an ounce.

It is important to future NASA programs that the high energy

artificial radiation be measured and understood as soon as possible,

before it decays appreciably. Such measurements will contribute to

she design of future spacecraft. An understanding of the phenomena

involved will contribute to the world scientific community's store-

house of knowledge0

Because of the desire to measure and understand these physical

processes quickly, it was decided that a spare flight unit of the

successful Explorer XIV could be made available with little modifica-

tion0

In addition, instruments were chosen that were already built

and tested and ready for flight0 It was decided that the spacecraft

should also carry redundant experiments to increase the total relia-

bility of the mission. In this same vein, experimenters were chosen

who had demonstrated competence in this field through previous suc-

cessful space flight,

The satellite also will carry spe.Lal solar cells having 60 mil

glass coatings to lessen their damage from energetic particles.

Dr0 Carl Mcllwain of the University of California at San Diego

has prepared an experiment to measure electron flux. A similar ex-periment has been furnished by Dr. Walter Brown of the Bell Telephone

Laboratories fBTL) and Dr0 Upendra D. Desai of Goddard0 Dr0 McIwain

and Dr. Brown also are contributing experiments to determine the dis-

tribution in pitch angle of the electrons0 Dr. Laurence Cahill of the

University of New Hampshire is providing a magnetometer0 Leo Davis of

Goddard has an ion-electron experiment, and James S. Albus of Goddard

has an optical aspect sensor to determine the satellite's orientation

to the sun0 Dr. H0 K0 Gummel of BTL is supplying a solar cell damage

experiment.

Dr. John W. Tbwnsend of Goddard is Project Manager0 Dr. Wilmot

FHess is Scientific Advisor.

Telemetry data from the spacecraft will be recorded on magnetic

tapes at the stations of the World-Wide Minitrack network0 These

tapes will be flown to Goddard for data reduction and processing.



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Processed data tapes will be forwarded to the scientific experimen-

ters for their analysis0 Results of experiments will be published

by the individual experimenters in NASA technical notes and scienti-

fic journals and made available to scientists around the world.

A "quick look" analysis of data will be made at Goddard. Pur-

pose of this analysis will be to determine the extent and spacing of

the artificial radiation belt, its intensity and the rate of decay

of the radiation.

ARTIFICIAL RADIATION BELT BACKGROUND

aThe Department of Defense, and the Atomic Energy Commission,

detonated a 1.4-megaton nuclear device 400 kilometers (250 miles)

over Johnston Island in the Pacific Ocean on July 9, 1962.

While it was predicted that this test would temporarily increasethe electron density of the natural radiation belts, the intensity of

the artificial radiation proved much greater than expected, based on

( urrent information. The zone of fission electrons, trapped by the

earth's magnetic field, is believed to lie between 100 and 100000

nautical miles above the surface of the earth. The electrons were

created by fission reactions in the atomic bomb that detonated the

main explosion. The high intensity region of the belt extends roughly

1e500 nautical miles on either side of the equator and at low alti-

tudes is more intense over the South Atlantic Ocean than at low alti-

tudes in other regions of the belt,

It has been theoretically calculated that the core of the belt,

which lies about 2,000 miles overhead at the geomagnetic equator,

may last many years. However, some scientists feel that a major

solar event, possibly at the next peak of the 12-year sunspot cycle,

might disturb the earth's magnetic field enough to eliminate this

core,

In the core, it is estimated that one billion electrons strike

a square centimeter in space every second. Further, other scientists

feel that most of the belt, below 500 miles will vanish within a year

because of absorption by the denser atmosphere near earth.

There is scientific disagreement on how far out the belt extends.

,One difficulty has been to distinguish between the artificially-

reated electrons and those that form the natural belt. The S-3b

spacecraft will carry special detectors to make these measurements.



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Scientists feel that the project affords them a unique oppor-

tunity to learn more about the behavior of these fundamental build-

ing blocks of the universe.

By observing how the artificial belt changes with time, theyfeel they will get a better understanding of the dynamics of the

natural radiation belts. Since the artificial belt is considerablymore intense at low altitudes than the natural belt, scientists willbe able to watch its decay. This could provide a detailed under-

standing of the processes responsible for removal of particles, be-

l.eved to be "dumped" into the atmosphere, plus data on their energychanges, in different portions of space at different times.

In the past year, for example, estimates of the lifetime ofelectrons in the natural radiation regions have differed by a factorof one hundred thousand. Scientists feel this problem could besettled by a study of the artificial belt. They want to observe what

changes are produced in the artificial belt because of magnetic storms.They would like answers to such questions as:

lo Is the energy spectrum of the particles changed by magnetic

field acceleration?

2. Are electrons "dumped" into the atmosphere by magnetic storms0or

3. Does nothing occur?

Deterioration of solar-cell power supplies (which convert thesunes ultra-violet energy into usable electricity) due to electrondamage caused the Transit IV-B and TRASC satellites to cease trans-mitting. Severe solar-cell damage to th e U.S.-U.K. Ariel satellitehas resulted in intermittent transmissions of data. Some deteriorationhas been sustained by Telstar but its power supply was designed towithstand considerable amounts of radiations, and it is expected tocontinue working well for some time. Observed degradiation agrees withthat predicted prior to th e Starfish test.

A review several months ago determinedthat satellites presentlyin orbit or planned would not provide the required data because none

of the experiments was specifically designed to study electrons of theflux and energy of the fission electrons. Also, none would give adirect measure of the pitch-angle distribution, o- how the particle

intensities vary in angles to the magnetic field,



Only Explorer XIV, launched October 2, has an orbit of sufficient

eccentricity to measure radiation as a function of distance from the

center of the earth. However, the Explorer XIV experiments were de-signed for the natural radiation belts and interplanetary space and

will not provide detailed measurements of the artificial environment.

It was determined that a near equatorial. orbit satellite projectshould be established for the specific purpose of studying the arti-ficial radiation belt.

PRCJECT PARTICIPANTS

The project is under the overall direction of the NASA Head-

quarters Office of Space Sciences, headed by Dr. Homer E. Newell.Dr. John Naugle is the Program Chief and Eugene Ehrlich is the Pro-

ject Officer.

NASA's Goddard Space Flight Center, Greenbelt, Md., has project

management responsibility. in addition to project management respon-

(4 ibility, GSFC has systems management responsibility for the experi-

ments0 :he spacecraft, the tracking and data system, th e Delta launch

vehicle system, and launch operations.

Dr. John W. Townsend, Jr., the Assistant Director for Space

Science and Satellite Applications at Goddard, is Project Manager.

Robert C. Baumann of Goddard is project coordinator. He is respon-

sible for coordinating the activities of the various individuals and

organizations concerned with the project; overall project schedulingand acts for the project manager in his absence.

Dr. Wilmot N. Hess, Chief of the Theoretical Division, is

scientific advisor. He keeps the project manager informed of thelatest data available concerning the artificial radiation belt and

provides 'liaison with the scientific community. Environmental testing

of the spacecraft was performed by the Test and Evaluation Division

of Goddard. John C. New, Chief of that Division, is test coordinator.

Paul Butler of the Spacecraft Technology Division, is Goddard

spacecraft system manager. He was responsible for the necessary de-sign modifications to adapt the spare flight unit of th e Explorer XIV

spacecraft. Mr. Butler is assisted by J. Madely and E. Travis for the

mechanical subsystems, F. C. Yagerhofer for power subsystem, R. E.

.idwell for thermal subsystems, and D. A. Krueger for spacecraft inte-gration.



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Dr, Frank B. McDonald of the Space Sciences Division is theexperimnrcts system manager. He is responsible for coordinating the

activi ties of the experimenters.

John To Mengel, the Assistant Director for Tracking and DataSystems. GSF.C is tracking and data systems manager. Jeremiah J.

Madden is Mr. Mengel's alternate as well as operations coordinator.They are assisted by Ralph Stroble for station and network preparation

'Hc, Turnbull, alternate), Edmund Habib for data processing (Dr. RobertCoates alternate!, and Dr. Joseph W. Siry for orbital computation.

Program Manager for the Delta is T0 B. Norris of NASA Headquarters.

The Goddard Delta vehicle manager is William R. Schindler. Robert H.

Gray heads the Goddard Field Projects Branch at Cape Canaveral.

The spacecraft was fabricated from Explorer XIV flight spares,parts and components diverted from other projects, stock items, off-

the shelf purchases, and issuance of work orders on existing contracts.The only major spacecraft procurement was for nine solar padddles with

Positive on Negative cells and 60 mil glass0

The Spectrolab Company of Los Angeles was selected to provide thesolar cells, The contract has an estimated value of $275,000.

Another contract with Electro-Mechanical Research, IncOe wasissued for integration services0

Experimentse other than those by Goddard, were provided under

new contracts with the Western Electric Company (Bell Telephone

Laboratories!, the University of Califcrnia at San Diego, and theUniversity of New Hampshire. The contract with Western Electric hasan approximate value of $200OOOO The contract with the Universityof California at San Diego and th e University of New Hampshire arefor an estimated $2500O00 and.$50,00 0 , respectively0

The first stage (Thor) of the Delta launch vehicle is supplied

through an Air Force Space Systems Division contract with the Dougla.sAircraft Company0 NASA Headquarters arranged for the third stage

(X-248) rocket to be supplied as government furnished equipment bythe Naval Propellant Plant. Douglas subcontracts the propulsion

system of the second stage from the Aerojet General Corporation.

Launch support is also supplied by Douglas.



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THE DELTA LAUNCH VEHICLE

The launch vehicle for the S-3b is the NASA-developed Delta

a three-stage rocket which has performed flawlessly in the last

12 out of its 13 launch attempts. Delta is nine stories high and

weighs 57 tons. The prime contractoris

theDouglas Aircraft Co.

The vehicle's first stage is a 60-foot modification of the

Air Force developed Thor (SM-75) and generates 170,000 pounds of

thrust during the two and one-half minutes its 50 tons of pro-

pellant burn.

The DM-l9 Thor booster was replaced on the last launch with

the model DMI-21 which will be used on this attempt, The DM-21

differs primarily in that the thrust is increased from 150,000

pounds to 170,000 pounds by substitution of the Rocketdyne Block II

engine.

The second stage is 17 feet tall and weighs a little more

than two and one-half tons, It is powered by an Aerojet-General

liquid engine which develops 7,500 pounds of thrust and burns

slightly less than two minutes,

Delta's 500-pound. solid propellant third stage is five feet

high and uses an Allegany Ballistics Laboratory ABL 248 engine

with a thrust of 3,000 pounds. Its burning time is 40 seconds.

For a minute and a half after lift-off, Delta is guided by

its Thor auto-pilot. After burn-out of the Thor booster, a Bell

Telephone Laboratories radio guidance system makes refined velocity

and steering corrections as needed. Shortly after first stage

burn-out separation and after ignition of the second stage, the

fairing--covering the third stage and the S-3b payload--is jettisoned

Second stage burning ends about four and one-half minutes

after lift-off. The vehicle, with second and third stages still

attached, is now at an altitude of about 125 miles. At this point

a 10-minute coasting period occurs. During this period, guidance

is provided by a 42-pound flight control system contained in the

second stage. The satellite and the third stage are spin stabilized

by small rockets mounted on a "spin table" between the second and

third stages. At the end of the coast period--about 14 minutes

after launch--the second stage separates and third stage ignition

occurs. Soon the required orbital velocity of about 20,000 miles

an hour is reached and the satellite, trailed by the third stage

is infected into orbit_



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Prograin Manager for the Delta is T. 1B. Norris of NASA

Headquarters. The Goddard Delta vehicle manager is William R.

Schindler. Robert H. Gray heads the Goddard Field Projects

Branch at Cape Canaveral.

s-3b press kit

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