Analytical Instrumentation in Space Expoloration - ACS Publications

REPORT FOR ANALYTICAL

CHEMISTS

Analytical Instrumentation in Space Expoloration by E d g a r L . S t e e l e , Activation Agricultural

r Ν 1961, this country launched one •*• of its greatest scientific and en­ gineering undertakings. At the spe­ cific recommendation of the Presi­ dent, with subsequent approval by the Congress, a m a n n e d lunar land­ ing, in this decade, was established as a national goal. T h u s , in less than three years from its creation, the N a t i o n a l Aeronautics and Space Administration assumed the largest scientific problem ever given to a government agency. T h e phenom­ enal growth of NASA would not have been possible in this time scale without the experience and staff of its forerunner, the N a t i o n a l Advi­ sory Committee for Aeronautics. T h e Committee, or N.A.C.A., as it was called, had its beginning in 1915. Operating its own research facilities a t the Langley Memorial Aeronautical L a b o r a t o r y and coor­ dinating the efforts of m a n y other interested parties, N.A.C.A. was charged by the Congress t o : 1. Furnish information, in regard to scientific or technical m a t t e r s r e ­ lating to aeronautics, to any de­ p a r t m e n t or agency of the govern­ ment. 2. Exercise these functions for any individual, firm, association, or corporation within the United States. 3. I n s t i t u t e research, investiga­ tion, and study of problems for the advance of the science and art of aeronautics. 4. Keep informed of the progress m a d e in research and experimental work in aeronautics in all p a r t s of the world. 5. Provide information, which is not confidential, to university lab­ oratories, aircraft manufacturers, and the public. 6. Be prepared to handle special problems which the President, the

and Mechanical

Analysis

Research

Laboratory,

College of Texas, College Station,

Congress, or the executive depart­ ments of the Government m a y re­ fer to it. I n October 1958, space research and development was added to these charges as a full time partner. There have been several smaller organizational changes since t h a t time to better fit the changing em­ phasis. At the present time, NASA is organized into five basic scientific divisions or program offices which report directly to the Office of the Associate Administrator (see Fig­ ure 1). T h e program offices have the direct responsibility for m a n ­ aging NASA's technical programs. T h e Office of Space Sciences, for example, is responsible for basic scientific investigations, develop­ ment of small and medium size launch vehicles, and life science studies not directly related to m a n n e d space missions. I n addi­ tion, this Office serves as the focal point for NASA relations with the Space Science Board, N a t i o n a l Sci­ ence Foundation and for contracts with universities. T h e Office of Applications has the m a n a g e m e n t responsibility for peaceful application of space tech­ nology. P r o g r a m s such as Tiros, Nimbus, and Aeros were designed to aid the science of meteorology. I n the area of communication, the passive satellite, such as Echo and Rebound, and the repeater satellites such as Relay, Telstar, and Syncom are proving a tremendous suc­ cess. The Office of M a n n e d Space Flight has three main programs. First, the Mercury, which was com­ pleted with the Cooper flight, was designed to study the medical ef­ fects and to develop technology of earth orbitors. Secondly, the Gem­

Texas

ini, which is designed to study long duration, two-manned earth orbitors and space-rendezvous. T h e third program is Apollo. I t is currently designed as a threem a n n e d earth orbitor by 1965, a circmnlunar by 1966, and a lunar landing by 1970. This Office also has the responsibility for the de­ velopment of large launch vehicles for the entire space program. T h e Office of Advanced Research and Technology is responsible for a wide range of activities. Its programs encompass the "conven­ t i o n a l " aeronautics as well as mis­ siles. Among other things, it is working with slow-speed aircraft, tactical aircraft, helicopters, and vertical takeoff and l a n d i n g / s h o r t takeoff and landing aircraft, super­ sonic transports, hypersonic air­ craft ( X - 1 5 ) , and gliders, as well as missiles. T h i s Office also works closely with the Atomic Energy Commission in the development of nuclear system technology. I n addition to its service in NASA flight programs, the Office of Tracking and D a t a Acquisition works closely with counterpart groups in the D e p a r t m e n t of D e ­ fense. Figure 1 also shows the relation­ ship of the field centers to the NASA H e a d q u a r t e r s . These cen­ ters provide the agency with inhouse technical competence to over­ see the national aeronautics and space programs. T h e y carry out in these areas, tasks and assign­ ments which have been approved by the program offices in terms of technical content, funding, and schedules. T h e centers also pro­ vide the administrative and techni­ cal direction of most NASA con­ tracts with industry and universiVOL. 35, NO. 9, AUGUST 1963

·

23 A

REPORT FOR ANALYTICAL CHEMISTS ADMINI&TI'AIOH

DEI'UIY AUN'INItThA-OR

PROGRAMS

I U t i ' U r Y AHMINISTPATON

AC.MINIS] RADON

LJfci'UlY ASSUllATY ADMINMWWriK

TRACKING & DATA ACQUISITION

SPACE SCIFNChS

WAI ίϋΠΒ STATION

Figure 1. The NASA Operating Organization ties. All field centers are Govern­ ment-owned and, with the excep­ tion of the J e t Propulsion Labora­ tory ( J P L ) , are Governmentstaffed and managed. Goddard Space Flight Center and J P L have the major research roles in space science programs. JPL concentrates on lunar and plane­ tary phases and Goddard Space Flight Center concentrates on the earth, sun, and astronomical inves­ tigations. Goddard also provides major support for the Office of Ap­ plications. The Manned Space­ craft Center is responsible for de­ sign, fabrication and test of space­ craft, and for operations support of the manned flights. Marshall Space Flight Center is reponsible for development of large launch ve­ hicles required for future unmanned and manned exploration of space and their launch support. Langloy, Ames, Lewis, and Flight Research Centers carry out 24 A

·

ANALYTICAL CHEMISTRY

most of NASA's advanced research and development programs. Wal­ lops Station launches NASA's sci­ entific sounding rockets and other small-scale unmanned research flights. Other centers, such as Launch Operations and Tracking are not shown in the organizational structure since they report directly to one of the program offices. Space Science Programs All program offices have the usual analytical chemistry prob­ lems associated with high perform­ ance materials. However, the Office of Space Sciences is forced by the nature of some of its programs to m a k e analytical measurements in the hostile environment of outer space. These programs include studies of the earth's environment, geophysical investigations, solar studies, astronomical investiga­ tions, unmanned lunar and plane­

tary explorations, and the search for extraterrestrial life. Programs of these types are essential for sev­ eral reasons. First, they provide a source of technology which is sig­ nificant to the national growth. Secondly, they provide the neces­ sary engineering data for manned space flights in keeping with the na­ tional goals. Last, and most im­ portant, they provide basic scien­ tific data essential to a better understanding of the world and of the universe. Investigations of the earth, the sun, and the influence t h a t the sun exerts upon the earth are of pri­ mary importance. A sampling of these problems is shown pictorially in Figure 2. Satellites and sounding rockets are powerful new tools to investigate these phenom­ ena. Equipment can be sent aloft to study the atmosphere at all heights. The ionosphere, which lies in the upper reaches of the atmos-

REPORT FOR ANALYTICAL CHEMISTS

Edgar L. Steele is Associate Profesor of Chemistry and Associate Head and Chief Scientist of the Activation Analysis Research Laboratory at the Argicultural and Mechanical College of Texas, College Station. Since 1959, Dr. Steele has been extremely active in the field of nuclear activation analysis and has published about 20 papers in this area. He helped set up a number of activation analysis laboratories for Esso Research and Esso Standard Oil Co. The Activation Analysis Research Laboratory at Texas A. and M. is at present on its second NASA contract. The NASA work involves a feasibility study of activation analysis to determine the elemental composition of the lunar surface. The Laboratory is also currently engaged in a feasibility study of computercoupled automated activation analysis. Dr. Steele was born in Harrisonburg, Va., in 1927. He received the B.S. (1952) and M.S. (1954) in chemistry from Clemson Colege. Dr. Steele received the Ph.D. from the University of Virginia in 1957 where he worked with Professor John H. Yoe. He studied at the Oak Ridge Institute of Nuclear Studies in 1959 and later did postdoctoral work on activation analysis at the University of Michigan in 1960-61 with Professor W. W. Meinke. After a year as an instructor in radiochemistry at Louisiana State University, Dr. Steele worked as an analytical research chemist at Esso Standard Oil and Esso Research and Engineering Co. from 1958 to 1962, when he assumed his present position at Texas A. and M.

Figure 2.

Some Space Phenomena Being Investigated by Satellites

phcrc and consists of ions and electrons, can also be studied in this manner. A detailed knowledge of earth's atmosphere is important because it comprises the source and substance of everyday weather. The ionosphere is important particularly because it furnishes the means by which radio waves m a y be reflected beyond the horizon. Instability in the region seriously effects radio communications. Satellite-borne instruments plot the earth's magnetic field, and measure radiation to be found in •the Van Allen belt. They also provide a new method of study on the auroras. Satellites can be used to study the interior of the earth by observing the influence of the earth's shape and mass distribution

on the orbit. Sunspots, solar-flares, electromagnetic radiation from the sun, the solar corona, and energetic particles expelled from the solar surface can be studied above the interfering atmosphere of earth. Studies in interplanetary medium, where the particle density is 30 to 100 particles per cubic inch, yield information about the fundamental nature of the universe which cannot be matched with earth-bound systems. Lunar and planetary observations by satellite-borne instrumentation give a much more detailed view t h a n was previously available. Even these will be of secondary importance when instruments and men land on these bodies. Properties such as the structure,

EDGAR L. STEELE

composition, surface, atmosphere, magnetic field, radiation belt, and extraterrestrial life are just some of the problems for which there are no acceptable answers. The moon is particularly valuable as a scientific laboratory because it has no atmosphere to erase the history from its surface. Satellites open a new era in astronomy. With satellites, observations in wavelengths not available on earth are possible. Much information about stellar birth and evolution is to be found only in the ultraviolet region of the spectrum. The search for extraterrestrial life is important because of w h a t it m a y add to the question of the origin of physical life. I t may well be t h a t the Moon, Venus, Mercury, or the distant planets have no life but there is no evidence to indicate t h a t M a r s would not have some forms of primitive life. On the contrary, infrared radiations have been detected of the type t h a t would be emitted by certain biological m a terials. This, of course, is not proof of life on Mars, but it does raise the possibility. Space Environment and Its Effects on Instrumentation

There are three principal aspects to consider in the operation of analytical instrumentation in outer space: vacuum, particle radiation, and meteoroids. Problems with VOL. 3 5 , N O . 9, AUGUST 1 963

·

25

A

REPORT Table I. Cold Welding Effect on 1018 Steel in Vacuum Temperature °C. 500 150 25

ion pumping plus cryopumping Problem: Get the system d o w n to 10 s Torr in less time. Solution: Combine α VacIon®pump and a Varian Cryopump . . . letting e a c h do its o w n job in the most efficient w a y . Here's h o w it works. The Cryopump is simply a cold surface, chilled with (in this instance) liquid nitrogen. With this cold surface in the system, condensable g a s molecules such a s water vapor and C 0 2 simply strike and stick to the surface. Since the Cryopump will only pump condensable g a s e s , w e add another pump — the Vaclon pump. In this combination, the Vaclon pump is needed to pump the non-condensable g a s e s such a s N2 and O2 that won't freeze on the Cryopump. • In an unbaked vacuum system, a high percentage of the g a s adsorbed on surfaces is condensable. The addition of a high-speed Cryopump to such a system adds 25 times more pumping s p e e d at a modest 10 to 15 per cent increase in cost. Pumpdown time and b a s e pressure will be improved by a factor of 5 to 8 . . . a s s h o w n on the graph above. • This pumping combination is ideally suited to thin film deposition applications, since it is a low cost w a y to achieve and sustain l o w pressures during the evaporation process. For more information, write for the Varian Cryopump data sheet. • The Vacuum Products Division offers wide experience in this and other areas of high vacuum. W e also offer a wide variety of systems and components a s well a s an applications lab to assist y o u in solving your specific vacuum problem. M a y w e help you? Vaclon® is a registered trademark of Varian Associates

VARIAN

A S S O C I A T E S PALO ALTO, C A L I F . VACUUM PRODUCTS DIVISION

VARIAN A. G.: ZUG. SWITZERLAND Circle No. 21 on Readers' Service Card

26 A

·

ANALYTICAL CHEMISTRY

Maximum Cohesion, percent 96.0 35.9 18.9

earthbound equipment have gener­ ally been from a lack of vacuum. Here we have a case where the sit­ uation is reversed. Particle densi­ ties below 1000 per cm. 3 are the rule for most experiments (1). The best large vacuum chambers avail­ able have particle densities of 10" per cm. 3 Therefore, it is impossi­ ble to test equipment properly prior to flight. One of the things t h a t can happen in this environment is a materials loss due to evaporation or sublimation. Results of prelim­ inary studies indicate structural materials such as steel and alumi­ num alloys will not sublime rapidly enough to damage their load-carry­ ing ability (2). However, where materials are applied as thin coat­ ing, such as those used for thermal control, sublimation is more seri­ ous. Studies of the effect of a vacuum environment on three thermal control coatings t h a t are intended for use on the radiator of a space power plant {3, 4, 5) show t h a t the emittance can increase, re­ main the same, or decrease because of exposure to vacuum. A second problem arises due to the loss of adsorbed gas layers t h a t are normally present on the surface of all materials. After prolonged exposure to space-vacuum environ­ ment, a surface will lose all the surface gas and will become clean. As a result, it will behave differ­ ently when put in contact with another clean surface. Recent studies have shown t h a t cohesion or cold welding takes place (6). The studies were made by breaking a specimen in vacuum and then placing the broken faces into con­ tact again. Table I shows repre­ sentative results from this study for 1018 steel. T h e maximum co­ hesion is the percentage of the ini­ tial breaking force t h a t was re­ quired to break the specimen a second time.

REPORT FOR A N A L Y T I C A L CHEMISTS

Particle radiation in space orig­ inates from three sources: galactic cosmic radiation, solar cosmic r a d i ­ ation (solarfiares), and the earth's radiation belt or Van Allen r a d i a ­ tion. Galactic cosmic radiation consists of positive charged p a r t i ­ cles of very high energy. Eightyfive per cent of these particles are protons, thirteen per cent are alpha particles and the other two per cent are nuclei with masses u p to tin (Sn) (7,8). T h e particle flux from this source is small (2.5 particles/ cm.--sec.) and the most serious damage would be to photographic emulsions. Solar cosmic radiation is a much greater problem t h a n galactic cos­ mic radiation (7, 8, 9, 10, 11). These flares originate in chromospheric disturbances of the sun with a frequency related to the period of solar activity cycle. Low energy events (with particle energies to 400 ni.e.v.) and medium energy events (with particle energies to several b.e.v.) occurred with fre­ quencies between 5 and 13 times a y e a r from 1935 to 1959. During this same period, high energy events (with particle energies to 20 b.e.v.) occurred once or twice every 4 or 5 years. The discovery and definition of the earth's trapped radiation belt was one of the first scientific ac­ complishments of the satellite pro­ gram. It is by far the most serious radiation problem. Since the p a r ­ ticles are t r a p p e d in the earth's magnetic field, the intensities are highest near the equatorial plane and lowest a t the polar regions. High energy protons are con­ fined to the small inner contour of the belt. Fluxes up i;o 2 χ 10 4 pro­ tons/cm. 2 -sec. have been measured. Low energy protons are found throughout the whole belt. Fluxes for these particles are 10 8 to 10 9 protons/cm. 2 -sec. T h e r e is also a substantial flux of low and me­ dium energy electrons (45 kw. to 1.6 mw.) on the order 10 8 electrons/ cm. 2 -sec. throughout most of the region. The high energy electrons are largely confined to the outer contour with fluxes on the order of 10'"' to 10 6 electrons/cm. 2 -sec. A new electron component was added to the Van Allen belt due to the high altitude nuclear explosion

of J u l y 9, 1962 {12). T h e effect of such radiation is best seen by the fact t h a t , of those satellites in orbit at the time of the blast, three were inactivated by r a d i a ­ tion damage to their solar cells within a month. One failed within three days of the blast. D a m a g e to semiconductors and plastics is also of grave concern. Low fre­ quency transistors such as the 2N337, for example, undergo a se­ vere decrease in current gain in a a proton environment {13). The meteoroid h a z a r d in space is largely an unknown. In-flight measurements t a k e n with a micro­ phone t y p e dust particle sensor in­ dicate a cumulative influx rate of 1 0 1 2 particles per m. 2 per sec. T h e mass distribution of these particles is still in doubt, as is the extent to which they damage materials. At the present time the uncertainty in material thickness for meteoroid protection is 20 to 1. Flight Acceptance Test T h e last step in a long sequence of events, beginning with an experi­ mental idea and ending with an acceptable mechanism to obtain meaningful data, is the flight ac­ ceptance test. This test is not designed to determine whether the a p p a r a t u s will perform, but rather whether it will perform after going through each phase of its mission. E q u a l attention is given to insure t h a t the experiment will not inter­ fere with any others in the same area. Of necessity, each program will have its own set of acceptance tests. T h e Surveyor program, for example, which is designed to place a sci­ entific payload on the lunar surface, has a set of specifications for each instrument package or sub-assem­ bly as they are called. These tests consist of steady state accelera­ tion to six times the acceleration due to gravity (6g) for 5 minutes, a 6g variable frequency sine wave logarithmically swept from 5 to 1500 c.p.s. along through orthogonal directions for a total of 18 minutes, heating to lunar day (Ca. 300° F.) in a vacuum of 1 0 e m m . of H g for 2 hours, and cooling to lunar night (Ca. —200° F.) in a v a c u u m of 1 0 - 6 mm. of H g

N E W DATA

FOR HOT MELT AND HEAT SENSITIVE

ADHESIVES Comprehensive information, just now com­ ing off the press, is available on the versa­ tile, low molecular weight, styrene resin PICCOLASTIC® Among other characteristics, this low cost hydrocarbon resin exhibits the following: • high tensile strength •

flexibility

•

shock resistance

•

complete inertness

•

excellent heat stability

•

water and grease resistance

•

light color

•

wide compatibility

To find out more about how this versatile resin can solve some problems in your own adhesive application, mail the coupon below for your free copy of the new Piccolastic Resin Report.

PENNSYLVANIA INDUSTRIAL CHEMICAL CORPORATION 131 State Street · Clairton, Pennsylvania Please send free copy of Piccolastic Resins Report. Name Position Company . Type of business Address

Circle No. 121 on Readers' Service Card VOL. 3 5 , N O . 9, AUGUST 1 9 6 3

·

27

A

LABPOR

•

•

Filter Funnels

•

Extraction • Thimbles Filter Crucible • Filter Candles • Gas Dispersion • Tubes

• • •

REPORT

POROUS PLASTIC LABORATORY WARE

Immersion Filters Membrane Support Tubes

MATERIALS

Porous Tubes Coarse Porous Back-Up Sheets

Proposed Analytical Programs in Space

POREX

CORP.

Porous Sheets

348 Bay S t r e e t · Fairburn, Ga.

Circh No. 124 on Readers' Service Card

New design improves performance, reduces price

12

Λ I z , $70 . . . 12" χ 24", $105

(115 or 230 v)

THERMOLYNE

TYPE 2 2 0 0 HOT PLATES offer precision thermostatic a n d fast heat-υρ

control

over t h e

entire stepless r a n g e to 7 0 0 ° F Write for literature and name of nearest dealer. T H E R M O L Y N E C O R P O R A T I O N , Dept. 478, 2555 Kerper Blvd., Dubuque, Iowa

Circle No. 5 on Readers' Service Card 28 A

·

ANALYTICAL CHEMISTRY

for 2 hours. The subassembly must function after each test. Explosive atmosphere tests, using hydrogen and oxygen mixtures, are conducted to demonstrate t h a t t h e operating sub-assembly will not cause ignition of Centaur fuel boil off gases. I t also must n o t ignite ethylene oxide used in sterilization. Other tests such as electromagnetic interfer­ ence tests are used to verify t h a t there will be no interference with, or susceptability to, other assem­ blies on t h e spacecraft or a n y por­ tion of the launch vehicle. After each sub-assembly has been checked, the entire spacecraft is assembled and p u t through a test procedure.

The major analytical chemistry efforts in space are mainly con­ nected with lunar and planetary programs. Since the moon is the first space island to which a manned spacecraft can venture, it h a s be­ come the focal point of much of the scientific endeavor. Early, u n ­ manned flights, will provide a de­ tailed survey of t h e lunar surface. The determination of its chemical and mineralogical composition, and its physical properties by re­ mote analytical techniques will re­ quire t h e combined knowledge of the analytical community. At t h e present time, these un­ manned flights are grouped in three main programs. I n 1963-64 the Ranger program will attempt to m a k e a rough lunar landing. The Ranger program was designed to capitalize on t h e capability of the Atlas-Agena B . This is t h e first U. S. vehicle capable of launch­ ing a payload sufficiently heavy t o m a k e possible t h e survivable land­ ing of a scientific package on t h e moon. Since it w a s obvious t h a t no one flight could carry all of t h e various scientific instruments, t h e Ranger spacecraft w a s designed in t h e " b u s " concept. Approxi­ mately 70 per cent of t h e major system of the spacecraft, as re­ lated to cost, is the same for all Rangers. T h e remaining 30 per cent is appended scientific pack­ ages. When t h e launch vehicle, which is common to all flights, is

REPORT FOR ANALYTICAL CHEMISTS considered, the number becomes 85 per cent. T h e increase in savings and reliability is obvious. Problems, such as long-range communications, guidance, and maintaining acceptable instrument temperatures associated with space flight, were solved by designing an a t t i t u d e controlled spacecraft capable of maintaining a fixed orientation relative to the sun and earth. Flights of long duration have been m a d e to check this spacecraft concept. T h e next step in the R a n g e r program will be the rough lunar landing with a capsule designed to survive the impact and return d a t a to earth for a period of approxim a t e l y one month. T V pictures, lunar radiation and lunar r a d a r reflectivity will be obtained on a p proach. T h e capsule will contain seismographic equipment. The last picture prior to i m p a c t should have a resolution of 6 inches or better. The Ranger program is scheduled to phase out as the more advanced Surveyor spacecraft becomes operational. This will be possible when the C e n t a u r launch vehicle is operational. Two closely related sets of missions are scheduled in 1964—65 for the Surveyor program. These missions arc designed to place a relatively complex instrument package in a lunar orbit a n d on t h e lunar surface. Surveyor-orbitor and Surveyor-lander, as t h e y are called, are directed toward developing the technology for future operation on the moon and obtaining scientific d a t a for a better understanding of the universe. T h e a d v a n t a g e of this program to the planners of m a n n e d flights is obvious. Surveyor-lander will carry 100— 300 pounds of instruments to provide detailed information on the character of the moon. I t s multiple-camera television system, for example, will provide panoramic viewing of the local lunar landscape. I t s telescopic optics will permit examination of the nearby terrain, craters, rubble, cracks, and fissures in the surfaces. I t s downward-looking cameras will permit examinations of the texture of the surface material. Its drill and sample transport system, observed by the TV cameras, will provide in-

formation on the hardness of the surface and the subsurface and provide samples of lunar material for its chemical analysis experiments. Its soil mechanics experiments will provide d a t a on surface bearing capacity and shear strength. Its radiation detectors, temperature, and atmospheric gages will reveal the properties of the enviroment on the surface. I t s magnetometers and seismometers will provide information of the structure and body properties of the moon. T h e surveyor soft landing missions will obtain several such spot samples of data. The Surveyor lunar orbiting missions will provide a longlife space platform in a stable orbit about 100 kilometers above the lunar surface. Principal objective of these missions is broad area reconnaissance of the total visible and hidden faces of the moon. These d a t a will be used to select landing sites for subsequent Surveyor-landers and the Apollo mission. T h e orbitor will also monitor the radiation environment and other physical parameters in the immediate vicinity of the moon. Knowledge of the moon's gravitational field and the anomalies therein, are required for accurate guidance for Apollo landing and return missions. Surveyor orbitor missions will begin in 1965 and extend through Apollo in 1970. I n addition to its scientific investigations, the orbitor will serve as a communication satellite for the relay of radio transmissions between the lunar surfaces and earth, and it will serve as a navigation aid in lunar explorations. A third program in lunar exploration is Prospector. This spacecraft, which will use a launch vehicle of the Saturn class, will consist of a landing platform, an ejectable retrorocket, and the scientific instrument package. Landing platforms will be designed to accommodate various payloads and would not share systems with the instrument payload. T h e principle difference between Prospector and Surveyor is in size, scope, and versatility. Since Prospector will proceed to t h e l u n a r surface from a lunar orbit, a n y position on the moon can be selected. Surveyor can land a t slant angles u p to 45° and hence, would be limited to

CAHN RECORDING VACUUM BALANCES are ideal for research in SPACE MATERIALS THIN FILMS SURFACE CHEMISTRY THERMOGRAVIMETRY and other problems

• A wide choice of models from $1495. • Sensitivity to 10—7g • Capacity to 200g • For high vacuum, corrosive atmospheres and room air • Proved in hundreds of installations

WRITE FOR FULL DETAILS:

CAHN

instrument company

15505 Minnesota Ave., Paramount, Calif., U.S.A. Circle No. 7 on Readers' Service Card

VOL. 35, NO. 9, AUGUST 1963

·

29 A

REPORT

BUGHLER

FLASH EVAPORATORS FOR EVERY APPLICATION UNIVERSAL MODELS . . . for Batch or Continuous Operation in permanent installations,

from $215.50

roughly one half of the visible surface. P l a n e t a r y investigations are also being conducted a t the present time. The recent Venus fly-by was accomplished as p a r t of the Mariner program. A fly-by mission is a scientific instrument package designed to acquire information on a single pass by a planet and transmit the data to the earth. I n the 1964-68 time period, M a r iner spacecraft will fly-by Venus and M a r s . Launched by the AtlasCentaur, these spacecraft will eject small capsules to enter the planets' atmospheres. Observations by the capsules and the spacecraft will be transmitted back to earth by the spacecraft. By 1968 a Saturn-class launch vehicle will phase in the Voyager program. This spacecraft will be considerably more advanced t h a n the Mariner, plus, it will carry a propulsion model for orbiting about the planet M a r s . A n a l y t i c a l Instruments in S p a c e

( A ) PORTABLE MODEL Rigid balanced design. Evaporation within glass and teflon prevents contamination.

$174.40 (B) PORTABLE MODEL with DEWAR Condenser to perform evaporation of heat-sensitive materials.

$197.00 (C) PORTABLE MODEL with SPIRAL Condenser—eliminates the setting up of a separate cooling arrangement.

$199.10 Available also with temperature-controlled water bath. To evaporate aqueous solutions, high-boiling-point solvents, strong acids, alkalis and radioactive materials without contaminating back-drip.

GLASS-TO-GLASS A N D TEFLON CONNECTIONS

THROUGHOUT!

Prevent contamination—Distillation occurs only within glass and t e f l o n — B a l a n c e d design permits smooth rotation without d r a g and l a r g e r output without loss of material—Continuous f e e d of solution or inert gas. Components and accessories a v a i l a b l e a t low cost t o convert easily f r o m one model t o another. M a d e in U.S.A. and a v a i l a b l e for immediate d e l i v e r y .

SEND T O D A Y FOR NEW BULLETIN A-FE1000 w i t h complete information and prices on all models and all components and accessories LABORATORY

APPARATUS

BUCHLER INSTRUMENTS, INC. 1 3 2 7 16th Street, Fort Lee, N e w Jersey P h o n e 2 0 1 - 9 4 5 - 1 1 8 8 or c a l l N . Y . C . d i r e c t LO 3 - 7 8 4 4 PRECISION

INSTRUMENTS Circle No. 148 on Readers' Service Card

30 A

·

ANALYTICAL CHEMISTRY

Any analytical instrument which will provide useful information within the scope of the problems outlined above, is , or will be, considered for space applications. Major considerations in design are analytical integrity, weight, power requirements, size, reliability, and spacecraft compatibility. As in most analytical solutions, there is a compromise with the first five criteria, but spacecraft compatibility is rigidly maintained. No experiment is allowed to jeopardize the success of other experiments aboard a given flight. I n a real sense then, each experiment must compete with all other experiments. Final decisions on flyable instruments are made technically by NASA's in-house experts a t their field centers and administratively by NASA's program offices. Analytical instrumentation m a y originate with NASA's field centers, private industries, universities, nonprofit research laboratories, or with private individuals. Once approved by the program office a t NASA Headquarters, the experimenter proceeds with a feasibility study with NASA funding. If the study looks promising, a second

REPORT FOR ANALYTICAL CHEMISTS

Handle your high vacuum on a LOW BUDGET... Figure 3. Alpha Scattering Spectrum of Potassium Carbonate

You can —providing you have a

Nevaco 911, the lowest priced highvacuum pump available today. Its patented open stage design makes it lightweight, but it does heavy duty work, and does it well. It has a guaranteed blank-off vacuum of 10 microns on McLeod gauge . . . a free air capacity of .85 C.F.M. at its recommended operating speed of 3 34 R.P.M. Pump and >/3 hp, 115 volt AC, 60 cycle, single phase m o t o r are mounted on a steel base equipped with shock-absorbing feet. Highly portable, the unit's easy-tolift base ends are safe handholds free from sharp edges. Its dimensions are only 10Vi" by 13" by 12"; its shipping weight only 40 lbs. Be budget-minded. Write for complete details.

Nelson Vacuum Pump Company

jievaco

2133 Fourth Street Berkeley 10, California THornwall 8-2277 Area Code 415

Representatives in all Principal Cities

NEVACO VACUUM

PUMPS

circle No. 126 on Readers' Service Card 32 A · ANALYTICAL CHEMISTRY

step is negotiated and the experimental· agrees to deliver a working breadboard model, (not flight-hardware) to the cognizant NASA technical authority, for testing. Analytical integrity, operating life, reproducibility, and reliability are examined in various environments. Next step in the chain of events leading to space, is the construction of a prototype of the flyable instrument. This is basically an engineering step to "space-harden" and reduce weight of the instrument. The experimenter may submit a proposal to handle this phase of the operation, but because of the specialized techniques involved, this step is generally contracted to a "space hardware" firm. Prototype instruments are space tested as outlined above. If everything is satisfactory, NASA contracts with industry to provide a specified number of units and they are placed in ready. The last step is an administrative decision from the cognizant program office. This is where the compromise in desired information is made to conform to weight and power limitation of a given flight. At the present time, there are a variety of analytical instruments, at one stage of development or another, being actively considered. A fair sampling of these instruments is listed below. Alpha Particle Scattering Alpha particle scattering

for

chemical analysis of lunar surfaces was proposed to NASA by Professor A. Turkcvich at the University of Chicago (74). On the basis of this proposal, Professor Turkevich received a NASA grant to develop the technique and build a breadboard model for testing by the Jet Propulsion Laboratory. Dr. E. Franzgrote at J P L is NASA's in-house cognizant authority for this program. Professor Turkevich has also been supported by the personnel of the University of Chicago, Laboratory for Applied Science, Argonne National Laboratory, and J P L . The scientific objective of this experiment is to determine the amounts of all major elements present (greater t h a n a few per cent) except hydrogen. Individual elements through atomic number 20 will be determined. Elements with triasses above 40 will be identified in mass groups. For example, iron, copper, and nickel will be reported as one group. Expected accuracy is roughly the reciprocal of the percentage observed. Instrumentally, the experiment contains a source of 6 m.e.v. alpha particles, solid-state surface barrier detectors, amplifiers, and two 128 channel pulse height analyzers. Principle of operation involves bombardment of the sample material by the alpha particles with the subsequent detection and measurement of the scattered alpha par-

REPORT FOR ANALYTICAL CHEMISTS

SEALED IR CELLS

Table II.

Functional Test Performace of the Lunar X-Ray Diffractometer (1011 Quartz Peak Characteristics) Specification P-3 Performance Parameter < 0.22 0.19 Peak width at », 2 Max., deg. (20) < 0.43 0.36 Peak width at l/"io Max., deg. (20) Asvmmetrv (x/'v) < 1.12 1.08 42 Peak/background > 27 Peak intensity, pps >2300 4326 0.6 Reproducibility of peak intensity, % < 3

t i d e s and l a , p) induced protons. A typical spectrum from the breadboard model is shown in Figure 3. Complex samples containing six elements have been analyzed. H o w ever, these data have not been made available as yet. T h e electronic package is 7 X 8 X 4}/2 inches and weighs 5.0 pounds. Power requirement for operation is approximately one watt. X-Ray Diffractomeier The feasibility of using x-ray diffraction for petrological analysis was demonstrated in 1961 a t Philips Space Development Company of Mt. Vernon, N e w Y o r k (I4). Dr. A. Metzger of .IPL worked with this group. The space objectives are to identify the types of minerals present on the moon's surface, the relative quantities of each t y p e , and the composition of complex minerals. Basically, the diffractometer is similar in configuration to standard commercial units except the lunar instrument is inverted and employs a shorter focus-to-specimen distance. Functional acceptance tests for the P-3 unit are compared with designed specifications in Table I I . Total weight for the head, electronics, and power supply is approximately 20 pounds. Gas Chromatography A gas chromatograph will be used as p a r t of the Surveyor scientific mission to provide an analysis of the volatile constituents in lunar crust material (I4). Samples will be collected by Surveyor sampling devices and delivered to an oven in the G.C. unit. After sealing, the volatile material is released by heat as a tight slug into the-helium carrier gas. The sample gas will then be divided and swept through packed analytical columns. Surveyor gas chromatography is

being built by B e c k m a n I n s t r u ments, Inc., with technical support provided by D r . L. E. Wilhite at J P L . S. R. Lipsky, Yale University, and J. E. Lovelock, University of Houston, are working closely with these groups and the a p p a r a t u s reflects much of the advice and guidance by these consultants. Figure 4 shows a schematic diagram of the Surveyor gas chromatograph. Three parallel columns in this G . C a r e : a 7-ft. molecular sieve 5A column for separating fixed gases; a 15-ft. column with C'arbowax 1540 on T-6 Teflon particle support, for separating water and most hydrocarbons; and a 12-ft. column with Apiezon L, Carbowax 20M, and phosphoric acid on a Chromosorb support. The entire column package is thermostated a t 105° C. The three detectors used in the Surveyor G.C. are glow discharge type devices. T h e y act electrically similar to gas-filled voltage regulator tubes. Detector signal processing consists mainly of three chopper stabilized electrometer amplifiers. X-Ray Spectrometer T h e object of the Surveyor x-ray spectrometer is to provide data on the elemental composition of the lunar surface (14)· The instrument package is being developed a t Philips Space Development, M t . Vernon, New York, with technical assistance by D r . R. Speed of .IPL and Professor Harrison Brown of the California I n s t i t u t e of Technology. X - r a y s are produced by irradiating the sample with 25 kv. electrons from a self-biased electron gun. Eleven Geiger counters and four proportional counters are used to detect the x-rays diffracted into different channels corresponding to each of the elements of inter-

THE BASIC TOOLS FOR IR ANALYSIS

Good spectroscopists deserve good accessories. Take these sealed IR cells for instance. Nothing fancy about them — just accuracy, precision and reliability. Path lengths from 7 microns upwards, in either sealed or demountable forms. Available fitted with most IR transmitting window materials. Immediate delivery of NaCI and KBr cells. F-05 suitable for Perkin-Elmer, Beckman, Unicam and Cary-White instruments— F-04 for Infracord only. Interested? Call or write for more details.

LIMIT R E S E A R C H

C O R P O R A T I O N

Box 8 5 2 , Darien, Conn. Phone ( 2 0 3 ) 6 5 5 - 3 9 9 1 Circle No. 22 on Readers' Service Card

VOL. 35, NO. 9, AUGUST 1963

·

35 A

REPORT FOR ANALYTICAL CHEMISTS est. Figure 5 shows a schematic diagram of a Surveyor x-ray spectrometer. T h e first three prototype models failed to pass the acceptance tests and the experiment is not scheduled to fly on an early Surveyor. Aside from crystal alignment problems, electrical cross talk and R F pickup have prevented successful operation. Model D has been ordered and this unit will receive considerable testing.

•,&'t

Figure 4. Schematic Diagram of Surveyor G. C.

Figure 5. Surveyor X-Ray Spectrometer

Figure 6. Schematic Diagram of Neutron Inelastic Scattering Instrument 36 A

·

ANALYTICAL CHEMISTRY

Soil Mechanics Experiment The soil mechanics instrument is designed to determine the load bearing strength and the shear strength of the lunar surface adjacent to the Surveyor spacecraft (14)· Other properties such as structure, composition, and particle size m a y possibly be deduced by interpretation of the measured parameters. Bearing strength will be determined by using two axially loaded, circular flat plates of different areas. Penetration measurements as a function of applied load provide data for calculating the cohesive modulus, the Motional modulus, and the bearing stability. Shear strength will be determined by means of a spudded aunular ring. Measurement of the torque required to rotate the rings as a function of various constant axial loads will be used to compute the cohesion coefficient and the M o tional angle of the soil. Defense Research Laboratories of General Motors Corp. developed the instrument package with technical assistance by D r C. Thorman of J P L . I t is approximately 25 inches in height and weighs 9.0 pounds. Nuclear Activation Analysis Remote lunar elemental analysis by nuclear activation analysis was first proposed by Drs. E. F. M a r tina and C. D . Schrader in 1960 (15). The technique employed in this investigation and in succeeding investigations (16, 17) was neutron inelastic scattering. Dr. R. E. Wainerdi proposed to NASA in 1961 study of the feasibility of remote lunar analysis using any nuclear reaction available within the weight and power limits of space exploration. The inelastic scattering device,

Table III. Run 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Precision of Oxygen Determination:

Lunar Analysis System

%o

%o

A1203 A1203 Fe 2 O s SiO, MgO

Density 1.339 1.339 0.759 0.937 0.587

Flux 1.164 1.000 1.245 1.007 1.107

A° 17,088 18,020 6,558 13,457 6,161

A°/g 2712 2860 2876 2691 2644

Added 47.06 47.06 30.06 53.33 39.69

Found 45.68 48.18 30.95 51.37 37.56

A1,03 A1203 + Si0 2 A1203 + Si0 2

1.339 1.193 1.193

1.143 1.154 1.064

17,656 16,508 16,906

2803 2808 2875

47.06 49.30 49.30

47.20 49.54 50.77

Fe 2 0 3 A1203 A1203 Ai2Oa Si0 2 A1..0a A120, Fe 2 0 3

1.077 1.174 1.296 1.193 0.937 1.174 1.339 1.077

1.009 0.927 1.000 0.938 1.066 0.905 0.854 0.902

10,173 12,218 16,169 16,667 13,822 12,390 14,830 9,272

2842 2783 2668 2835 2764 2822 3131 2590

33.27 37.39 46.78 49.30 53.33 37.39 47.06 33.27

33.84 37.24 44.67 50.01 52.76 37.77 52.74 30.84

Sample

+ + + +

MgO Fe 2 0 3 + MgO Fe 2 0 3 + MgO + Si02 SiO's

+ Fe 2 0 3 + MgO + MgO

as proposed by D r . Schrader, is essentially a small Cockcroft-Walton, [H :l (