sert 1 press kit

8/8/2019 SERT 1 Press Kit

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NATIONAL AERONAUTICS AND SPACE ADMINISTRATION TELS WO 2-41550 1Z Vj - WASHINGTON, D.C. 20546 WO 3-6925FOR RELEASE TUESDAY

RELEASE NO: 64-167 July 14, 1964NASA TO LAUNCH SERT I SPACECRAFT

The National Aeronautics and Space Administration willlaunch the 375-pound SERT I (Space Electric Rocket Test)spacecraft on a sub-orbital flight from Wallops Island, Va.,no earlier than July 18.

A four-stage solid-fuel Scout rocket will be the launch-ing vehicle.


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-2-If data from SERT I indicate that beam neutralization

is completely effective, the development of ion thrustorsfor space missions may continue in ground vacuum chambers withconfidence. If beam neutralization is of limited effective-ness, a new program of vacuum chamber and flight tests may beundertaken.

The SERT I flight test is part of the program being car-ried out by the NASA Headauarters Office of Advanced Researchand Technology. It is aimed at providing research informationand tecnnology required fo r future development of electric


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The engine, or "thrustor", is only part of the propulsionsystem which includes a power generating source, a control sys-tem and propellant.

The projected uses of electric engines for deep spacemissions depeni:s on the availability of light weight nuclearelectric power systems in the high kilowatts to multimegawattspower range and their ability to operate reliably for one tothree years.

A more immediate use probably will be for attitude con-


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A- 0o3. Electromagnetic (plasma) engines, in which the pro-

pellant is ionized into an electrically conducting gas and ac-celerated by electromagnetic forces.

The electrostatic (ion) engine is the only one that mustbe fully tested in a space environment to verify ground testresults.

SERT I SPACECRAFT

The SERT I spacecraft is spin-stabilized and contains twoion thrustor engines of different types driven by a single


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'0 -5-Other spacecraft and engine measurements will be taken for

a comparison between vacuum tank and flight data.SERT I will reach about 2,500 miles altitude to give about

ififty minutes of flight time. Trajectory inclina-tion is not critical. The payload will not be recovered.(Fig.l illustrates the trajectory).

About two minutes after launch just before third stageignition the 34-inch diameter heat shield is ejected. The thirdstage ignitesto spin the payload and fourth stage.

Spin rate at fourth stage burnout (about T plus 3 minutes)


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-6- 0A welded aluminum box frame is mounted on the top center

of the baseplate. In this structure and in the pedestal belowit are mounted the basic spacecraft gear: the programmer, thepower distributor, the telemetry signal conditioning and switch-ing gear, and the command receiver. The heavy components,such as batteries and power converters, are mounted on bothsides of the baseplate alongside the central frame and pedestal.

The engine mounting arms are hinged near the outer edge ofthe baseplate. The deployment linkage is locked to the centralpedestal and is released by an explosively actuated latch.The rate of engine deployment is limited by hydraulic dampers.


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ENGINE CHARACTERISTICSHUGHES LEWIS

Propellant cesium mercuryAccelerator volts 4500 2500Beam current 0.045 amps 0.275 ampsThrust 0.0011 pounds 0.00637 poundsSpecific impulse 8050 sec. 4900 sec.Exhaust velocity of ions 176,000 mph 107,000 mphPower output 193 watts 680 wattsPower input 600 watts 1400 wattsEngine efficiency 32.2% 48.5%


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-8-Regulating the boiler temperature provides propellant feed

control while a solenoid valve between the boiler and theionizer allows the propellant flow to be turned on or offrapidly.

There are three electrodes-- focus, accelerator and decelera-tor. The focus electrode is held at 4500 volts above space-craft potential, while the accelerator electrode is at 2000volts below spacecraft. The decelerator electrode is at space-craft potential.

The cesium ions created at the ionizer are drawn away andaccelerated by the difference


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-9-The Lewis engine will not encounter any outgassing problem

because it will be in space ar-ut 20 minutes before it beginsoperating.

THE LEWIS ELEChON-BOMBARDMENT ENGINEThe electron-bombardment engine, built by the NASA-Lewis

Resea~rch Center, uses mercury as a propellant. The mercury isvaporized in an electrically heated boiler and flows from thereto the ionization chamber as shown in the generalized schematicof Fig. 4. In the -hamber, electrons are emitted from a tanta-lum filament cathode or negative pole. These electrons move


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-10-

chamber and the screen electrode are at a potential of 2500volts above the spacecraft potential and the accelerator elec-trode is 2000 volts below. As in the Hughes engine, this po-tential difference accelerates the ions to a high exhaustvelocity. The ions accelerated out of the engine are neitra-lized by electrons from a tantalum neutralizer filament.

POWER SUPPLIESAlthough silver-zinc batteries provide the power needed

for the SERT I flight, these batteries could not be readilypackaged to provide the high voltages and circuit action needed


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-11-0 INSTRUMENTATIONAll data except thrust will be sampled rather than con-

tinuously measured. Except for the thrust detection system,all on-board and ground station requirements can be met by con-ventional FM/FM equipment.

Special instrumentation carried for diagnosis of thrustorperformance consists of a beam power probe that will sweepacross the discharge beam of the Lewis electron-bombardmentthrustor and an electric field meter that will give a qualita-tive indication of beam neutralization.


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The thrust of the contact ionization engine is expectedto cause the spacecraft spin rate to change about 0.14 percent per minute and that of the electron-bombardment engineabout 0.67 per cent per minute.

Only very low instrumentation accuracy would be necessaryif thrust were continuously produced for the whole time allotedto each engine. However; the SERT I spacecraft carries instru-mentation of the highest accuracy to assure thrust measure-ments in case of deviations from expected thrustor performanceor failure of engine or spacecraft after a short interval ofthrust.


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-13-

The third thrust detection system aboard the SERT I is anaccelerometer which senses acceleration due to spin. The SERTspacecraft is dynamically balanced for stable spin. When thearms deploy, and the pod cover is blown off the Hughes engine,the spacecraftts center of gravity will shift and its spin willchange. But, deploying the engine arms will cause a precessionor wobble of the spacecraft which will take some time to dampout. The accelerometer will provide information about thespacecraft's motion around all three principal axes. Thus,data from the accelerometer subsystem will describe any unex-pected, complex motions.


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-14-The sensitivity of the accelerometer and the precision of

the electronic counters at the receiving station ensure thatthrust from an engine burst of as little as 10 seconds couldbe measured within an accuracy of 0.00005 pounds.

SCOUT LAUNCH VEHICLEThe SERT I flight will mark first use at NASA's WallopsStation of an improved erector-launcher facility for Scout,

similar to one which is used at the Air Force Western TestRange. The new facility reduces the time the Scout must be inthe launcher from three weeks to less than a week.


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0 -15-The basic Scout launch vehicle is a multi-stage, guided

booster using four solid propellant rocket motors capable ofcarrying payloads of varying sizes on orbital, space probe orreentry missions. Developed by the Langley Research Center,the Scout is the only operational solid propellant launch ve-hicle with orbital experience.

The four Scout motors, Algol, Castor, Antares, and Altair,are interlocked with transition sections that contain the gui-dance, control-ignition, instrumentation systems, separationmechanisms, and the spin motors needed to orient the fourth


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TIE SERT I TEA4

The Spacecraft TDchnology Division of the Lewis ResearchCenter developed the con'I spacecraft. Harold Gold is headof the Spacecraft Branch. 7.aymaond J. Rulis is the SERT I pro-ject manager at Lewis, and James Lazar, chief of Electric Thrus-tor Systems at NASA Headquarters, is program manager. EugeneD. Schult, is head of the Scout Project Office, at LangleyResearch Center.

Lawrence Golden is project engineer for Radio Corp. of


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027:10 HUGHES ENG0:E OFF0,27:15 LEVIS ENGINE ON/ 05:06 HUGHES POD DOOR OPENS

05:04 ENGINES DEPLOYED05:02 FOURTH STAGE / PAYLOAD SEPARATION

-> 53:05 LEWIS' TESTING COMPLETE

p01:58 SHROUD EJECTED

/ 01:55 SECOND STAGE BURNOUT

ILAUNCH VEHICLE SCOUT

Ist STAGE ALGO Il-A2nd STAGE CASTOR I3rd STAGE (MOTOR) ANTARES X25941h STAGE (MOTOR) ALTAIR X258

MAXIMUM ALTITUDE 2500 MILESMAXIMUM RANGE 2000 MILES

LIFT-OFF ZERO-G TIME 53 MINUTES SPLASH DOWNHUGHES EXPERIMENT TIME 20 MINUTESLEWIS EXPERIMENT TIME 20 M)NUTES

Fig. I

- . - - - .-. - ~ - -- -- -


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,-HEAT SHIELDSERT PAYLOAD-%

I I '-SCOUT VEHICLE"FOURTH STAGE

SCOUT VEHIC~LETHIRD STAGE--,

QFigure .. spacecr~aft in launch configuration.Q


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HOTTUXG2TEN 45000

LEUTRAL -CESIU. IONS5BOILER CESIUML - _ATOS -ELECTRONS

HlTh SOLENOIDVALVE

ELECTRIC GENERATO

Fig. 3 - Schema tic drawing of contact -ionization thrustor.


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+2500 VOLTS-2000 VOLTS

PROPELLANT

* ~MERCURY IONS

IONIZER ELECTRONS

TANTALU MNEUTRALIZERAT SPACECRAFT

ELECTRIC- POTENTIALGENERATOR

Fig. 4 - Schematic drawing of electron bombardment thrustor.

sert 1 press kit

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