THE DISCOVERER PROGRAM

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Col. C. L Battle, USAir

Alr Fares Specs Systems Division

Inglewood, California

and

AC J. W. Plummer

Lockheed Missiles and Spear Company

Sunnyvale, California

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SUCCESSFUL U.S. EARTH ORBITS

Of 47 satellites successfully orbited to date by U. B. Space Programs,

24 have been accomplished by Agana vehicles carrying a wide variety

of payloads. The Discoverer Program, using the Agana-Thor combi- nation, has accounted for 21 of the 24 successful orbits. The Agana B

has been the basic vehicle used by Discoverer since November, 1961.

Prior to that time a Brat generation vehicle, the Axons A, was successfully utilised to place divers* payloads in orbit.
U.S. ORBIT PAYLOADS

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Of the total 47 vehicles orbited by the II. 8. , the useful or functioning

portion of the vehicles amounts to 31,131 potands. This payload weight

does not include the vehicle structure, engine, stored propellants or

other components not directly used by the active orbiting experiment.

The umber Program at Lockheed, Sunnyvale has provided 25,297 pounds

with the Discoverer Program alone accounting for 52% of the total. Such a relatively large percentage of the total has resulted from the

large number of Waists rather than the sine of the functioning payload.

Per example .Discoverer Agena A and Agana /3 payloads averaged only about 600 pounds and 1000 pounds respectively.

These figures point up two important considerations: The Discoverer

has established a continuous and reliable weight - carrying ability, and

it has orbited payloads of all degrees of complexity and application

ranging from scientific-experimental modules to advanced systems

components.
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PAYLOAD RECOVERY FROM ORBIT

The United States, Discoverer 3011 was the first spacecraft to separate a payload while an orbit and re-enter it through the atmosphere to an

awaiting surface force. This event was successfully completed just Uhl* days before Sputnik V returned a biomedical payload, thus establishing

a "space first" which was much appreciated by the 'USAF Discoverer

Directorate and its team of contractors. right days later another precedent was set. The Discoverer XIV payload was recovered in mid-air

by a U. S. Mr Force C-119 aircraft. thereby completely iu1813iag the original design objectives.

The totals as of 30 September 1961 underscore the unions record of the

Discoverer Program — five mid-air recoveries and Woo successful •

surface recoveries by contrast with four surface recoveries attained by

Russian payloads.
PROGRAM EVOLUTION

LMSC Space Systems has taken its direction and assumed its present

responsibilities as a result of.combinad military, scientific and international political events.

Following the study and preliminary design period which started with

work at RAND, the first real development effort was initiated by the

awarding of a contract to Lockheed Aircraft Corporation. The normal

weapon system development process was greatly accelerated with the

successful orbit of Sputnik I, thereby providing the "birth" of the Discoverer Program.

A measure of the degree of acceleration of the program is shown by the

achievement of a successful orbit just 11 months after the establishment

of the program. Such a short development span resulted from the dedicated efforts of a large number of Air Force — contractor personnel,

and also by the establishment of a well defined and simplified set of

objectives.
PROGRAM OBJECTIVES

le DEVELOP TEST A BASIC SATELLITE VEHICLE

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The Discoverer, beginning as a general engineering program has

assumed a definite set of objectives directed toward proving feasibility

study assumptions, flight-testing hardware, linking ground and space

elements in an integrated world-wide network, establishing a platform

in space for advanced scientific and military experiments and performing ballistic re-entry. Through the course of 21 orbital mission, the

Discoverer — Agana propulsion system has been upgraded from the Bell

series 8001 to the current model 8096, a turbo-pomp fed, hypergolicallyfueled, restartible engine. Agana fuel capacity has been doubled since

the early configuration; space vehicle power has been sophisticated and

improved to the point where primary batteries now produce more than

85 watt hrs/lb., and guidance and communications and control units are

presently approaching third generation status. •

Beyond the research payloads which are flown for various government

agencies and their subcontractors, Discoverer derives a large percentage of its payload from the requirement for orbital testing of components

and equipments planned for use in other USAF satellite programs.

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PROGRAM MANAGEMENT

Overall responsibility for the Discoverer Program is vested in the

Space Systems Division of Air Force Systems Command. Lockheed Missiles and Space Company is prime contractor, responsible for technical direction of the program. Douglas Aircraft Company, an associate

contractor, provides the Thor first-stage booster together with necessary ground equipment and personnel. Philco Corporation, another associate contractor, is responsible for ground-space communications and satellite control. Some major subcontractors axe: Bell Asrosysterns, rocket engine; General Electric Company, recovery capsule; Minneapolis Honeywell,Advanced Technology Lab, and Fairchild Camera

and Instrument Company, guidance and control components.
space systems

FACILITIES

SPACE SYSTEMS FACILITIES

The headquarters for Lockheed's satellite and space programs is a 393,600 square foot building at Sunnyvale, California, where program

management, engineering, vehicle checkout and laboratory functions are

carried on. Manufacturing support is provided by the LMSC Central Manufacturing shops at Sunnyvale. Other major facilities are:

Santa Cm: Test Base - SCT3 is a 4,000 acre test area some 35 miles from Sunnyvale. Here static ftrings of the

Agana are conducted in one of the several

test stands.

Vandenberg AT Base - Pre-flight checkout of the satellite is performed in the large Missile Assembly Build- ing, where the Agena and Thor are first

mated.

Van Nuys - The Van Nuys, California plant was the original site of Lockheed missile and space

operations. The facility now serves primarily as the manufacturing center for Aerospace ground equipment and certain spacecraft components.

(over)
SPACE SYSTEMS FACILITIES (continued)

Satellite Teat Center - The STC is an Air Force owned banding at

Sunnyvale. Under direct control of the

USAF 6394th Teat Wing, the STC provides

for space operations of Discoverer and other

programs.
S PACE SYSTEMS TEST FAC I LITI ES

Ground testing facilities and equipment used in support of the Agena

programs and the Discoverer Program have been designed to a unique

advantage shared by few other space programs. Every calculation and

every flight component can be checked out fully on the ground with the

realisation thst the final and perhaps conclusive test under actual operating conditions in space is available through the capacity and capability

of an orbiting Discoverer vehicle.

Pending empirical data gathering on orbit, LIM= ground experiments

and checkouts are extended by means of these:

1. High Altitude Temperature Simulator,-An envirpnmental chaniber with a temperature range of -12e-r to + 320,r, and a maximum altitude simulation of 1 x 10-° mm Hg. The interior of

the chamber is so designed that cyclic temperature changes due

to spacecraft day - night cycles in space may be simulated. A

240-channel automatic data system collects test readings on

punched cards or an IBM typewriter.

Z. Environmental Laboratories - The environmental laboratories

also provide the full range of testing equipment necessary to

production of highly reliable spacecraft components. A large

(over)
SPACE SYSTEMS TEST FACILITIES (continued)

selection of equipments from the large machines required for

bating complete systems to the small ones for component testing are providsdto permit testing of all phases of standard military specifications.

3. High Vacuum Orbital Simulator - The MVOS is a. new 5,000 cubic foot chamber with a minimum pressure capability of

1 a 10'4 mm Ng. It can accommodate a complete Agena spear vehicle and can provide continuous test operation for one year.

A heat flux simulator can produce a thermal flint input of

1,000 BTII/sq. ft. /hr., while a cold wiLll liquid atropin crimp's:up can drop the temperature to -330-F. The MVOS will be

operational in early 196/.
SYSTEM NETWORK

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Discoverer satellite operations involve facilities located throughout

North America. Their. locations and functions are:

Vandenberg Air /Force Bass - Launch operations including initial

- launch tracking and telemetry readout. Subsequent orbital tracking and TIM readout are performed in line with mission requirements.

Downrange ships - Two ships operated by the Pacific Missile Range

are located some 1500 miles downrange during launch to moni- tor Agena engine burn and orbital injection.

Kodiak, Alaska - The Kodiak station is the first to acquire and track

the polar-orbiting Discoverer satellite as it completes its initial

complete orbit. This station also plays an important part in the recovery operation by recording the vital telemetry data of

vehicle and capsule functions in the recovery sequence.

New Hampshire Station - This station provides tracking and TIM readout coverage of the Discoverer satellite on its passes over the eastern United States and Canada.

Keene Point, Hawaii - The Keene Point station is the fourth of the

tracking and VIA station.. Its functions and equipment are

(over)
SYSTEM NETWORK (continued)

similar to thous of VATS, Kodiak and NewHampshire. Because

of its proximity to the recovery area, the Hawaiian station serves as a prime activity in tracking and recording of re-entry

data.

Recovery Control Center - The RCC is located at Mckam Air Force

Base, Hawaii. B is the point from which all air and surface recovery operations are coordinated.

Satellite Test Center The STC at Sunnyvale California is thanerve

canter of the tracking station. network. It is constantly in touch

with all the stations, the launch base and the Recovery Control Center. From the STC, Air Force and Lockheed personnel

command sad coordinate overall *yetis= operations.

Each of these stations is tied to the Satellite Test Center in Sunnyvale,

California throw an extensive network of communications. All basic

orbital calculatioas are conducted by the computer center in the OTC

with each outlying station receiving' its acquisition messages and other

control data via the communications network.
INBOARD PROFILE

The Agana 8 space vehicle is of sesnimonocoque construction, 60 inches

in diameter and approximately 25 feet long, weighing 1350 pounds without fuel or payload. The largest single component is the integral aln- minum alloy fuel and oxidiser tanks, which serve the dual purpose of

containing the propellant and supplying a base from which the aft equip-.

meat rack is cantilevered. The aft equipment rack mounts the engine

and its auxiliary equipment; control actuators and associated hydraulic

system to control the direction of powered flight; reaction Jets on all axes and a store of compressed gas for • control of the vehicle the orbital phase; and equipment racks for attaching modular pat;g2 d

equipments. The forward equipment rack houses the connramications

equipment, programmers, guidance and control components, power conversion equipment, storage batteries, and the re-entry body.
LAUNCH TRAJECTORY

After the Agena has been boosted to an altitude a/approximately 70 miles

by the first-stage Thor, separation occurs and the satellite is oriented to a horizontal attitude for Arms engine firing. The many functions which must be performed to start the MguLd propellant engine in space are controlled•by a master timer. Discoverer tests have shown that the

engine can be reliably startedin space andthen restarted at* later time

without nozzle closure. All that is required for restart is the addition

of a second starter charge and additional tillage rockets to collect the

propellants at the tank outlets to the engine.

When the vehicle has Attained the required velocity as measured by the

accelerometer integrator the engine is shut down. Shortly thereafter, the Agena completes a 1500 yaw turn and orbits in atailifirst, horizontal

position. This maneuver exposes the research instrumentation to the

particles in space and simplifies the sequence required to separate the

re-entry body. Attitude control on orbit is provided by an IR sensing

device coupled to the inertial reference system and the guidance electron- ics, which command necessary reaction thrust from proportional gas

valves.
RE-ENTRY AND RECOVERY

Re-entry of the Discoverer capsuleis achieved in a ballistic mode without reliance on terminal guidance. By means of a retro rocket the re.

entry body is deflected to a new orbit which causes re•entry into the

earth's atmosphere. Prior to retro rocket ignition, the vehicle is

oriented to a nose down attitude at an angle which minimises re-entry

range and dispersion. The detailed retro sequence involves; capsule

spin up to provide stability during the retro phase; retro rocket firing

to impart approximately 1300 fps velocity; capsule de-spin to prevent

gyroscopic rotation when the capsule reorients by aerodynamic forces; and finally, separation of the spent rocket and attaching structure to

provide the necessary aerodynamic stability.

The capsule is protected during thermal re-entry by an ablative shield.

The ablative material pyrolises at peak surface temperatures of approx- imately 30007 while insulating the inner capsule to temperatures not

exceeding 100 F. At approximately 50, 000 feet, the parachute is de- ployed, simultaneously separating the ablative shield, and the capsule

descends at a rate consistent with aerial recovery requirements.
PRODUCTION FLOW

The basic componints of the Agena satellite are fabricated at 1./ASCos

central manufacturing shops in Sunnyvale and at the Van Nuys facility.

Final assembly, installation at wiring, engine and equipment is accomplished at Sunnyvale. as is vehicle checkout. Subsystems are first

tested and then the total integrated vehicle system is run through a. 24-

hour electronically simulated orbital mission. Selected vehicles, such as the first• of a new series, are sent to Santa Cron Test Base for a static firing. At Vandenberg Air Force Base, the Ass n& is again systemtested and sent to that launch pad, where it is mated with the Thor and

compatibility checks are performed. The long and thorough process of

checking and rechecking the vehicle continues until the, final checks are

completed in its final countdown. Consistent with the R&D nature of the

program, these checking procedures add materially to the reliability of

the program.
RESEARCH PROGRAM INFORMATION FLOW

One of the less publicised but very significant phases of the Discoverer

Program has been its contribution to space research in conjunction with other scientific agencies. Requirements and equipment for spice experiments are fmmeled through the Air Force Space Systems Division to

LMSC. while remits and findings are transmitted directly back to the originating agency by Lockheed.

Examples of Discoverer research efforts are: geophysical measurements

performed for Cambridge Research Center; biomedical experiments for

the Air Force School of Aviation Medicine such as the live tissue and embryonic culture carried on Discoverer X1rIli and space radiation ex- periments for the University of California's Lawrence Radiation Lsb.

Experimentation into the behavior of new materials and equipment in

space are performed for many scientific and government agencies including Lockheed's own research organisation.
MODULAR DESIGN

Discoverer research payloads have been Down for . t years. Currently

these modularised payloads are carried aboard the vehicle in both the

forward and aft equipmeut racks in I, variety of configurations and in accordance with any one of 3 basic experimental modes.

The first type at research experiment is made possible by the Discoverer,

stability in spaces it is an experiment designed to make precise, com- parative measurements of phenomena associated with the earth below

the satellite and with deep space above.

The second variety, casing for a smaller module than the first, meas- ures such values as ler propagation for extended periods of time. The

:nodule incorporates its own power source so that it may continue to

operate long efts:* the Discoverer Agana has sent the re-entry **parlament

back to earth.

The third exPerimeatal mode is one requiring ejection from*. orbiting

Discoverer of the module. In this case, the unit is carried aloft, placed

in a predetermined orbit, jettisoned and, for its effective orbital life,

tracked and monitored by the originating agency of the experiment.
RESEARCH FM/FM TELEMETRY SYSTEM

Discoverer research experiments ass supplied with= independent communications link. Operating independently at the vehicle's other communication function and modularised to provide • capabilityf or necessary last minute changes without affecting the system integrity, the link provides the following capabilities:

Continuous recording for a complete snapping of the space environment at all latitudes and longitudes as well as during both night and day conditions. This is the function at a 200-minnte

tape recorder which records 60 samples of data/second sad has

a read-out to read-in ratio of 36 to I.

Periodic recording under control of the orbital programmer of

specific phenomena in specific areas. A 24 minute recorder serves this purpose.

• 3. Normal real time telemetry for readout while the vehicle is within range of the ground station system. •
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RESEARCH PROGRAM EXPERIMENTS

The results of the Discoverer recoverable and non-recoverable experiments have meaning for a broad span of space activities. Shielding

studies, high energy particle measurements and biological experiments

are obviously intimatelyrelatedtothe design of life-support systems and

ecological units. Discoverer HT carrying human tissue specimens late

in 1960 was subjected to an intense, heightened proton flux which was the

result of a class 3+ solar flare. Materials and equipments for advanced

systems can be better tested under actual operating conditions than they

can when subjected to theoretical extrapolations. Tor future flights, a

continuing series of experiments is planned. As research at Discoverer

altitudes is completed, emphasis will shift to testing of satellite components presently being designed for other programs.
FUONT I 2 3 4 5 6 7 3 II 1011121314151617188203222511252527282030

FLIGHT PERFORMANCE SUMMARY

An examination of the performance record of all the Discoverer flights

to date reveals some of the widely varying degrees of success that are encountered in an R&D space program. it may be seen that the tread

is toward increasingly greater reliability, as flight Ilesperioace provides &growing background of knowledge. Also wvidentis the fact that a great

deal of work is yet to be done to advance the state-of.the-art of such

fields as guidance and electrical power in space.

Conversion from the Agana A to the Amnia B, which represented introduction of many design improvements to the Agena, shows an expected

drop in reliability. Zack new system must apparently go through its

series of design-proving failures. In such mannerthe primary objective of the Discoverer Program is accomplished, namely to prove the basic

Agena equipments in an R&D atmosphere, and to reduce equipment and

system type failures in later USAF satellite programs.
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RELIABILITY/OPPORTUNITY TO PERFORM

A regrouping of the same basic data as the preceding chart compares

Agena A and Agena B.

Agena As Thirteen. of the fifteen Thor-boostedAg ena A vehicles had the opportunity to orbit, which produced an . 56 ra figure. Of these

thirteen, ten attained orbit while three did not, resulting in a . TT figure. Nine of tits ten or vehicles were actually programmed for orbital stability and re-entry, 01 not carrying this rewire:sent. The .66 reliability percentage at this pointwasattained bythe six vehicles out of

nine • fulfilling this requirement. Three of the six actually re-entered effecting a .50 reliability for this final event.

Agin' B: Fifteen Agena B vehiraes were given sufficient Thor-boost to orbit, one Agent not receiving the necessary initial velocity. Eleven

Agenas attained orbit, for a .73 reliability, and of these eleven, nine

were programmed for orbital stability and re-entry. Eleven stabilized on orbit which resulted in a . 77 reliability figure. Recovery of one of the

seven was prevented by a malfunction in the orbital programmer, thus re-entry has been successful in all six attempts.
RECOVERABLE PAYLOAD PERFORMANCE

PERCENTAGE OF

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Reliability percentages ars plotted herefor 3 separate, yet interrelated,

vents. Curve 1 is a running plot of orbital achievement as a function

of Thor performance. Curve 2 plots the reliability of achieving stability

and pitchdcrwn on orbit based upon the total number of achieved orbits

represented by Curve. 1. There are, as a matter of note, 21 orbital

achievements, 18 of these reviling stability and pitch.downfor re-entry. The 12 of the 18 which stabilised and re-oriented are marked along the

abscissa by squares. Curve 3 represents capsule separation and reentry reliability based on the 12 stabilised possibilities.