Nasa Apollo 11 Lunar Surface Experiments - Easep

EASEP Press Backgrounder

?

¢

Aerospace Systems Division

Property of: Michigan Space & Science Center Donor: Lisa Neal Donation Date: IAug 1997

From

Daniel

Director The

H. Schurz

of Public

Bendix

Relations

Corporation

Aerospace

Systems

Ann

Arbor,

Michigan

April

1969

Division 48107

COVER ILLUSTRATION The _stronaut on the cover is adjusting a helical antenna on the Passive Seismic Experiment Package. passive seismometer contained in the large vertical cylinder below the antenna sends information through data system contained in the base of the package before transmission to earth.

A a

To the Astronaut's left is the Laser Ranging RetroReflector, already deployed and pointing toward the Earth. Scientists will use the reflector as a target for laser beams to develop a variety of accurate scientific interactions

data between

regarding the earth

distances and and the moon.

dynamic

ACKNOWLEDGMENTS The Apollo performed

design, integration and test of Scientific Experiments Package for the National Aeronautics

Administration by Bendix Corporation. Subcontractors

the

to

Experiment Package Ling-Temco-Vought substrate); Lockheed

Aerospace

Bendix

the is and

Systems

Division

for

Passive

the

Early being Space of

The

Seismic

are: Dynatronics (multiplexer) ; (PSE mounting plate and solar panel (second surface mirrors); Philco

(transmitters), and Spectro Labs (solar cells). Teledyne supplied the Passive Seismometer which was modified by Bendix for the Passive Seismic Experiment. The subcontractor Reflectors Perkin-Elmer.

Laser were

Ranging Retro~Reflector is Arthur D. Little, Inc. supplied to Arthur D. Little,

The

array RetroInc. by

INTRODUCTION This Division the Early

Backgrounder is published by the Aerospace Systems of The Bendix Corporation to familiarize the reader with Apollo Scientific Experiments Package (EASEP) , its

origins, be a quick statement examination

objectives reference of the of the

and operation. This source and the reader EASEP design followed component systems.

booklet will by

Additional copies of this publication and about EASEP may be obtained by contacting Mr. Director of Public Relations and Advertising, Systems

Division,

Ann

Arbor,

Michigan

48107.

is designed to find a general a more detailed

further Daniel Bendix

information H. Schurz, Aerospace

MISSION The moon

is

problem as

BACKGROUND

of deciding exacting as

AND OBJECTIVES

what man will do once he getting him there. While

gets the

to the primary

purpose of the first mission will be to demonstrate the capabilities for a lunar landing and return, the astronaut will gather maximum scientific information within the limited mobility and time he is allowed on his first lunar landing. In the summer of 1965, Science Board met at Woods most desirable areas of major

questions

which

the National Academy Hole, Massachusetts space study. This

would

guide

1.

What

is

the

internal

2.

What

is

the

geometric

3.

What

is

the

present

4.

What

is

the

composition

5.

What principal structure of

6.

What is tectonic

7.

What and

are

the

8.

What lunar

volatile surface?

9.

Are there moon?

10.

What is the stratigraphic

11.

What earth

of

on

of

the

the

moon?

energy the

regime

lunar

tectonic pattern the moon? processes

and/or

on

of

are

proto-organic

dynamic

for

moon?

the

present

distribution

erosion,

lunar

present

the

surface?

and

of the

the moon on the lunar of

moon?

are responsible surface?

material

age of units

is the history and the moon?

of

internal

substances

organic

of

shape

dominant

deposition

exploration:

structure

processes the lunar

the present activity

lunar

of Sciences Space to consider the board proposed 15

of

transport

surface? on

or

molecules

and the surface? interaction

age

near

the

on

the

range

of

between

the

12.

What

is

history

the of

13.

What moon

has and

14.

What acting

is

15.

What magnetic surface?

thermal, the

been how

the

tectonic,

and

possible

volcanic

moon?

the rate has that

the history on the moon?

of flux

of

fields

solid varied

cosmic

are

objects striking with time?

and

retained

solar

in

the

radiation

rocks

on

flux

the

lunar

In addition to these specific scientific questions regarding the moon, there are questions pertaining to space travel in general which may be answered during lunar voyages. Man's ability to do meaningful extra-terrestrial work is still an open question and the goals of early lunar operations must be constrained by this uncertainty. As our experience with men in space ability

was give

grows, these constraints to predict success for

become involved

more missions

From the list of questions from the Woods possible to design a complete geophysical the desired information about the moon

defined increases.

Hole station and its

and

our

meeting, it which would environment.

This station would be housed in a bay of the Lunar Module and be deployed by the astronauts on the moon. The Bendix design for this station was proposed as the Apollo Lunar Surface Experiments Package (ALSEP) , a contract awarded to The Bendix Corporation in 1966. ALSEP is a sophisticated geophysical station which is designed to return information about the moon's physical properties and the electromagnetic characteristics of the moon and deep space. Powered by a radioisotope thermoelectric generator, it is designed to return scientific data from the moon for up to two years. Its central station receives information from the various experiments and transmits it to the earth. The central station also receives earth commands and relays them to the individual experiments. This ambitious scientific lunar station requires approximately one-half hour for deployment by two astronauts. They carry the two experiment packages away from the Lunar _odule, set up the central station and power source,

align samples. While astronauts'

four

experiments,

it appears capabilities,

take

these it

now

photographs

tasks seems

and

are more

collect

all well desirable

within to set

soil

the more

conservative tasks for man's initial landing on the moon. The collection of soil samples and deployment of a simple scientific experiment package will be most in keeping with the purpose of the first mission, which is to prove that man can, indeed, land on the moon and return to earth safely. Initially, plans were made for the astronauts to leave the Lunar Module, collect soil samples, take photographs and then return to the module for an eight-hour sleep, after which they would deploy ALSEP. To keep the mission simple, the second trip outside the Lunar Module was cancelled. ALSEP deployment, then, will await the successful completion of the first lunar mission, deployment on the second lunar landing, with to be deployed on the following two missions. For the new mission which draws upon its experiment package would _odule as ALSEP, it pallets. central

Because station

requirements, broad ALSEP occupy the was decided

one of the electronics,

ALSEP it was

and two

is scheduled for similar packages

Bendix designed a package experience. Since the new same place in the Lunar to utilize the basic ALSEP pallets logical

housed to use

the

the ALSEP existing

electronics package. This has the additional virtue of havin_ been already fully integrated into the NASA communications and data processing facilities. The ALSEP experiment which would provide the most significant information traded off against ease of deployment is the Passive Seismic Experiment (PSE) which, in the

new

design,

is

mounted

permanently

on

the

central

The use of ALSEP-proved components allows the of a very reliable product at minimum cost. This Early Apollo Scientific Experiments Package (EASEP) by NASA on November 5, 1968.

station. rapid delivery design, the , was apprcved

The two EASEP packages can be removed and deployed by one astronaut within ten minutes during the astronauts' lunar excursion. They do not require deployment far from the Lunar Nodule and will operate satisfactorily with minimal emplacement and alignment. The PSE returns significant scientific data about

the solar which

interior

of

cell power carries

pallet, Experiment, Because

which or both

moon

by

measuring

by

which

EASEP, then, emphasize

the

astronauts,

consists simplicity

of

two and

to the Lunar and the return of expended.

The principal investigator is Dr. Gary Latham of Lamont Sutton of the University of Massachusetts Institute of

The Alley of Professor

principal investigator the University of Maryland. P.L. Bender, National J.E.

Chang

and

are

experiment deployment,

W.M.

R.H.

pallet other

scientists Currie and staff at H.

Kriemelmeir.

progress

of

packages proved

communication information

Passive Seismic Experiment Observatory. Dr. George Dr. Frank Press of the and Dr. Maurice Ewing of for the experiment. Engineer.

for

the LRRR is Professor C.O. The co-investigators are: Bureau of Standards, University

Dicke, Wesleyan

Kaula,

the

and NASA scientific

the co-investigators is Dr. Latham's Project

Professor Faller,

Professor

Mr.

The

scientific ease of

Princeton University,

University

Angeles; Professor G.J.F. MacDonald, Santa Barbara; Dr. H.tt. Plotkin, Professor D.T. Wilkinson,

Participating Professor D.G. the technical

The

same

on

for the Geological Hawaii, Technology,

University VanHemelrijck

Los at and

to the equipment.

depending

Module maximum

Columbia Mr. Ludo

Connecticut;

activity.

carries the Laser Ranging Retro-Reflector LRRR, will become a target for earth-based lasers. pallets are completely independent, either or both

be deployed mission.

of Colorado; Professor

seismic

supply is attached directly the PSE and electronics

may the

acceptability requirements, for effort

the

of

University Goddard Space Princeton

University; Middletown, California

at

of California Flight Center University.

at the University of Maryland include Professor S.K. Poultney. Members of the University of Maryland are Dr. S.K.

EASEP SYSTEM DESCRIPTION PASSIVE SEISMIC EXPERIMENT PACKAGE The purpose of the Passive Seismic Experiment Package (PSEP) is to measure lunar seismic activity. These measurements will indicate the structure, strain regime and physical properties of the interior of the moon as well as record meteoroid impacts and tectonic disturbances. The basic unit of operation of the experiment is a suspended weight which will tend to remain immobile as the experiment package moves with the motions of the moon. This relative motion between the weight and the rest of the experiment causes an electrical change which becomes a reading of amount and frequency of motion. These measurements are taken by three units which, between vertical

them, report and horizcntal

longaxes.

DATA

and

short-period

along

SUBSYSTEM

The PSEP measurements are sent to the earth which shares the PSEP helical antenna with the An earth command is selected and transmitted to phase modulated decoded, and The information, data processing special format helical antenna

vibrations

by a command the

transmitter receiver. PSEP as

a

signal in digital form. The message is received, directed to the experiment as a discrete command. or science, from the experiment is sent to the unit and combined with other PSEP data in a which is transmitted, in digital form, through the back to earth.

LASER RANGING RETRO-REFLECTOR EXPERIMENT The other section of EASEP, the Laser Ranging Retro-Reflector Experiment, is wholly passive and has no electronics nor is it connected in any way to the first EASEP Package. The retroreflector unit will be a target for earth-based laser beams. The LRRR experiment will precisely measure earth-moon distance over a period of several years from which fluctuations in the earth's rotation rate, measurements of gravity influences on the moon and other astronomical information can be derived. The unit is functionally the moon, the angle

a reflecting however, would of incidence

beam would relative

be reflected depending on to the earth-moon direction,

the earth or even EASEP experiment

surface. A flat be useless because equals the angle

reflecting surface on with a flat mirror of reflection; a laser

the alignment and could

in space. The reflector array uses retro-reflectors manufactured

of fall

the mirror anywhere on

used with

for the extreme

precision from selected high-quality fused silica. These reflectors have the property that the angles of incidence and reflection coincide independent of the reflector's position, and for this reason have been used here on earth in such things as bicycle and highway reflectors. A corner reflector on the moon will permit a laser ray to be reflected along the same path with which it strikes the reflector: a laser ray from Hawaii is reflected to Hawaii; a ray from Washington, D.C. is reflected to Washington,

D.C.

PASSIVE SEISMIC EXPERIMENT SUBSYSTEM DETAILS PASSIVE SEISMIC EXPERIMENT PACKAGE The

Passive

Seismic the PSEP The experiment held it

Seismic

Experiment in its stowed

Experiment (PSE) and

PSEP

also includes during the survive the cold

The electricity

solar and

panels have

operate only durin? is inoperative. power conditioning

Package

and data deployed the lunar (-300

carries

system. Figures configurations.

solar panels, day and isotope degree F) lunar

convert an output

the

the of

energy 33 to

43

which heaters night. of watts.

the lunar day; during the lunar The output of the solar panels unit and supplies all the

requirements resistors.

of

the

PSEP;

excess

The isotope fueled with a

survival heaters small amount of Pu

of radiation. radioactivity controls for day and night.

They are completely escapes to the lunar the heaters and they

current

is

produce 15 watts 238 which emits shielded environment. operate both

1

Passive and

2

power which

sunlight The

show

the will

to panels

night, PSEP is fed to the electrical dissipated

a

each very

so

that There during

by

and are low level no stray are no the lunar

DUST DETECTOR Also

mounted

on

the

PSEP

is

a

dust

detector

which

reports

through the Data System the buildup of dust particles on the surfaces of the PSEP. The detector measures in two planes and consists of photocells which will sense dust as an apparent decrease in the intensity of the sun. The unit measures one and three-quarters inches scuare by two and two-thirds inches high.

PASSIVESEISMIC EXPER IMENT ANTENNA

SOLARPANELS

'JT HANDLE

ISOTOPE HEATER

SOLARPANEL DEPLOYMENT LINKAGE

ANTENNA POSITIONING MECHANISM CARRYINGHANDLE

Figure

1 Passive

Seismic

Experiment

Package

Stowed Configuration

I--

z

_ _-

z _

0

rZ I--(,/3

_ _

<

_

_

0

<

E

'1-

m _

>-

._

·cC

U

,¥

§

._ Z Z

'-a _ o

Z

.._

_J

u ct

Z

0. x I.IJ u

E

-$ >

__

0

(,/3

__

"I"

10

PASSIVE The measures

PSE

exterior inches

11

pounds. It is covered

SEISMIC

EXPERIMENT

is a cylindrical in diameter by

is secured to with a highly

subpallet reflective

DETAILS

beryllium 15 inches No.

1 at surface

container which high and weighs 25 four for

points thermal

and it control

during the lunar day. This cylinder contains four seismic sensors and associated electronics; three long-period (LP) sensors are mounted on a leveling assembly with a short-period (SP) sensor attached beneath. (Figure 3). The 0.004 the

LP

cycle ends

horizontal moving which

sensors

arcs

masses produces

vertical

measure

per second of three and

the

measuring

motions consists seismic and the and the

SP

The

swings

which

is

a

of

approximately of a magnet activity, the coil moves in

mass

to

part to

on

a

boom

single-axis

approximately masses two masses

swing of a their

for

device

one

vertically.

from

the

detects

on in The

circuit The its

weight

which

to

mounted to swing

capacitance displacement.

suspended

compensates

which

associated

outputs until

from

1.65-pound allow

frame

of

the

vertical

20 to 0.05 cycles per second. It suspended in a coil. For high frequency magnet behaves as the mass in the LP sensor relation to it, cutting its magnetic field

a voltage motion.

electronics

filter the are stored

remaining

mass

sensor

inducing relative

contain which

are electrically an output proportional

by a Lacoste spring, boom/mass assembly. The

frequencies

and booms

and the

is

proportional

with

convert them PSE receives

to

each

the

sensor

to 10 bit a signal

velocity

of

amplify

digital from the

words Data

and which System

that it is ready to accept the information for transmission to the Earth. The digital data is then fed to the Data System where it is placed in the data format and transmitted to earth as eight distinct measurements: six signals for the three LP seismic outputs; the the sensor.

SP

output;

and

Fifteen commands may be These commands are sequential "on-off" commands, so that

a

measurement

of

the

temperature

of

addressed to the PSE from the earth. (take the next step) as well as more than fifteen functions may be

11

HORIZONTAL

VERTICAL LACOSTESPRING

SENSOR BOOM

_ CAPACITOR MOTI

"_

CAPAC ITOR PLATI

_so_ _oo_ MOT ION ·

·

'ELECTROMA(

BELLOWS (RETRACTFORUNCAGE)

WORMDR IVER SPRlNG ADJUST.

CAGING BELLOWS (RETRACTFORUNCAGE)

Figure 3 Passive Seismic Experiment Details

12

commanded from earth. Additionally, there are automatic leveling modes which control the leveling motors without specific earth commands. Three commands control the gain of the sensors, two provide calibration, five are directed to leveling the and one command each controls the heater and the uncage These commands are selected, converted to digital form in the command data format which is transmitted to the

the

The PSE sensor masses are held immobile moon by pins. These pins are mounted

inflated placed bellows, free.

on

during their on bellows

experiment function. and placed PSEP. trip which

to hold the pins in the masses. After the experiment the moon, an earth command fires a scuib venting collapsing it and retracting the pins so the masses

to are is the are

DATA SUBSYSTEM DETAILS Mounted the PSEP reception and control (moon to

on the same pallet as the PSE, the Data Subsystem is central control unit. The system is responsible for: and decoding of uplink (earth to moon) commands; timing of the PSEP; collection and transmission of downlink earth) scientific and engineering data. The Data

Subsystem

(DSS),

Figure

4,

is

composed

of

the

following

parts:

(1) the antenna, a ribbon wound helically around a fiberglas cylinder 23 inches long by 1 1/2 inches in diameter. This gives a directional (35 degree beam width) and highly sensitive unit (15.2 db gain) which must be aimed at the earth by the astronaut. It operates for both reception and transmission (2) the transmitters

diplexer to the

(3) the diplexer operates to receive input and transmitter (4)

the

transmitter,

(5)

the

command

switch, antenna

which

may

connect

filter, which selects or transmit information output to the antenna a

receiver,

1-watt which

phase

whether the and connects

modulated

detects

either

uplink

of

two

antenna receiver

unit signals

13

(COMMAND) UPLINK

NNA //

._ -;_

i iDlyU. Xt.K

& SWITCH RECEIVER I _

t

I

_Z___

DOwNLINK

(SC IENTIFIC DATA)

i i

I

(A ANDB)

_I

POWER

J TIMERj

DISTRIBUTION UNIT

j

!

DECODER

i

PROCESSOR CELLS

I

I

=

I

PASSIVE SEISMIC

i l

J EXPERIMENT

Figure 4 Data Subsystem Block Diagram

14

(6) the command command receiver "executive" on printed circuit and issue 100 the astronauts (7)

the

timer,

(8)

the

data

and analog the PSEP transmission (9) the

the units

decoder, which processes information from the and issues commands to the PSEP. This is the board PSEP, and is constructed using multilayer

boards. commands. leave, a

clock

processor

multiplexer and places

power of the

a

which is

a

relatively

provides

backup

combination

converter it in

distribution PSEP.

Physically, the DSS PSE and solar panels is interconnected by connectors which make components

It can understand 128 different Immediately after deployment it issues the "UNCAGE" command timing

digital

commands before the PSE

signals data

processor

which collects information from the EASEP format for downlink

unit

(PDU)

,

which

controls

is contained in the pallet are mounted. Each component a wire harness ending removal and replacement simple

and to

on is in of

power

to

which the boxed, and multi-pin individual

operation.

PSEP DEPLOYMENT The grasps PSEP; PSEP the

astronaut opens the $EQ bay door on the Lunar Module a deployment lanyard which is attached to a boom and pulling the lanyard extends the boom and then allows to be drawn from the scientific equipment bay and lowered Lunar surface in a continuous motion. The lanyard

restowed, and feet from the lunar surface

the astronaut picks up the PSEP and Lunar Module (Figure 5). He lowers on an East-West axis, walks around

and the the to is

walks about the PSEP to the package

30 the and

extends deployment handle to its working height. Usin 9 this handle to steady himself, he removes a series of retainer pins and lanyards. He then grasps the carrying handle and, rotating the unit, aligns it using the shadow cast by an indicator on top of the PSE. _{hen he is satisfied with the alignment, the astronaut pulls a lanyard attached to the deployment handle and the spring loaded solar panels pivot to their deployed position (Figure 6). The astronaut then adjusts the antenna to correspond to the landing site, completing the deployment (Figure 7). The total time required is approximately six minutes.

15

Figure 5 Astronaut Carrying the PSEP

16

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to ¥

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18

LASER RANGING RETRO-REFLECTOR SUBSYSTEM DETAILS LASER RANGING RETRO-REFLECTOR The Laser pallet and the astronaut

Ranging Retro-Reflector is mounted has provisions for alignment ±5 degrees when it is placed on the lunar surface

The reflector each containing retro-reflectin? synthetic fused light the

shining three

parallel The Little, structure

to

unit fused prism silica. a

into faces the

the of

indicent

The

own by 8).

is an array of 100 cylindrical cavities silica retro-reflecting prism. The is a corner cut from a perfect cube of A corner has the unique property that

corner will the corner

be sequentially and come out

reflected from a path that is

in

light.

array structure, designed and Inc., supports and aligns provides passive thermal

appropriate insulation, reflectors

on its or better (Figure

fabricated by the retro-reflectors. control by

selection of cavity geometry, to minimize temperature and thereby assure satisfactory retro-reflectors

are

surface gradients optical

mounted

in

the

Arthur means

D. This of

properties, and in the retroperformance.

array

with

Teflon

rings as shown in Figure 9. They are installed with the apex of the finished prism pointing down the cylinder and secured in the cylinder by a retaining ring. Total weight of the experiment assembly is about 65 (11 lunar) pounds and its structure and thermal design will permit survival and functional utility for up to ten years.

LASER RANGING

RETRO-REFLECTOR

DEPLOYMENT

To deploy the reflector array, the astronaut removes the unit from the SEQ bay of the Lunar Module using a boom and lanyard as in removing the PSEP. The astronaut then walks about 30 feet from the lunar module and sets the array on the lunar surface approximately 10 feet from the PSEP and rough aligns it on an EW axis. Using both the array tilting handle and the deployment handle, he aligns the unit to suit the particular lunar landing site, lowers the package to the surface, and aligns the experiment. approximately

Total four

deployment minutes.

time

for

the

reflector

is

19

Figure 8 Astronaut Deploying and Aligning I. RRR

2O

RETRO-REFLECTOR ARRAY

REARSUPPORT-M-ANGLEBRACKET HMEN7 SUNCOMPASS PLATE AIM-ANGLE HANDLE

LEVEL

PALLE_ ALIGNMENTHANDLE

RETAINERRING (ALUMINUM)

SIMPLIFIED LASER

MOUNTING _, SEGMENTS (TEFLON)

PANEL STRUCTURE ,/ (ALUMINUM)

,x/RETRO-REFLECTOR _

RAY PATH

_-__

TYPICAL FRONT

VIEW

· PARALLEL

Figure 9 LRRR Details

21

UTILIZATION The prospect not carry with undertaking. The providing

most a

OF THE LASER RANGING

of reflecting it a clear

obvious specific

value of reflective

very precise measurements earth to the moon. measure in nanoseconds possible to measure to the moon and return with

of

an

uncertainty

Such earth

of

precision distances

a laser suggestion

the

of

from the

the

the value

array moon

moon does of such an

is it

that, in will allow

of the point-to-point distance from the Since we know the speed of light and can (one billionth of a second), it is the time required for a beam of light to go and from it find the earth-moon distance 15

centimeters.

will also between

give two

much more transmitting

scientists about

Primarily, unmeasurable

will orbit

scientists variations in

the

accurate laser

measurements stations,

will be able to the earth as well. be and

looking rotation

for of

and

develop

previously the earth

moon. Variations

interactions a greater clarify diminishing, _anginq increase

in

of the understanding whether

the

orbit

earth, or

of

Wobble is circumstance.

moon

reveal

the

This study gravity and of gravity

the moon as a reference point, the its axis may be studied; this _iobble. Scientists have observed not The

constant, earth's

but seems rotation

axis only to be excited again by significance is the fact that Chandler's wobble, and it may be _obble may allow scientists to predict

the

moon and sun. of the nature of not the force

gravitational will will is

allow help to slowly

a theory which may be proved if, using the Laser Retro-Reflector, the moon's orbit is discovered to by an extremely small ratio (2-6 x 10 -11) each year.

Using earth on Chandler's

now

beam

reflector surface on

from this type of information a large body of new information

and

RETRO-REFLECTOR

the

to be gradually

wobblin_ motion that

caused by returns

this unknown force. earthquakes seem that an understanding predict earthquakes

of the is called Chandler's

some to

a

unknown stable

Of great relate to of the much as they to

weather.

22

The

measurement

measurement continental

using about

a single ten years,

points Again, a the

wobbling accurately greater answer homogenous gravity) of masses heating

Chandler's

Wobble

to track any continental drift holds that Africa,

were once of about that

of

on

the

continent scientists,

that

continents

are

is

similar

drift. South America

"drifted" using the slowly

to

This and

apart. reflector, drifting

another

theory Antarctica

Over may

of

a period discover

apart.

because of the laser reflector lunar orbit will

ability to make precision measurements on the moon, very accurate information be made available. Similarly, the

motion of measured,

moon this

the and

about its center of information will

gravity give

a

may be much

understanding of the internal structure of the moon. The to the moon's origin may be found in whether it is an mass (formed in outer space and caught in the earth's or, like the earth, composed of various concentrations caused by large scale differentiation from thermal and volcanic activity.

Thus, the about earth-moon knowledge about of the moon and

ability to make extremely precise measurements distances will produce a great body of new the size of the earth, the structure and origin even our understanding of gravity.

23