EP-165 Spacelab

two illustrations of astronauts working aboard Spacelab.

"The purpose of the Agency shall be to provide for and promote, for exclusively peaceful purposes, cooperation among European States in space research and technology..."

- From the convention at which the European Space Agence (ESA) was organized.

 

"[the National Aeronautics and Space Administration shall]... plan, direct, and conduct aeronautical and space activities...arrange for participation by the scientific community in planning scientific measurements and observations....provide for the widest practical and appropriate dissemination of information concerning its activities and results thereof...."

From the U.S. National Aeronautics and Space Act which created NASA.

 

CHAPTER FOUR: Spacelab at Work

The Experiments (Part I)

 

Materials Science and Space Plasma Physics

 

[37] The treasures that astronauts bring to Earth from space are not of a material kind. They are far more precious because they are in the form of knowledge unobtainable elsewhere.

This statement, often heard in the early days of the space age, applies more appropriately to Spacelab than to an!! of its predecessors.

The quest for knowledge is Spacelab's only task. All of Spacelab's work is research. To extend the boundaries of science and technology is Spacelab's sole assignment.

This is essentially true even for Spacelab's early mission SL -1 and SL-2 - officially billed as "verification flights." Their prime objective is to check out Spacelab's systems in orbit, test their compatibility with those of the Orbiter in space, and to confirm Spacelab's suitability as host to the complicated experiments awaiting it. But these early flights are more than mere shakedown cruises or trial runs.

To give Spacelab the desired realistic tests, many complex experiments, from nearly every major scientific field, are aboard the very first flight.

 

Module-Pallet Configuration Flies First

SL-1 carries 38 separate scientific instruments* or "experiments packages," which the crew uses to perform more than 70 different experiments for more than 70 investigators who head research groups in 11 European countries** the United States, and Japan. SL- I will fly Spacelab in a basic configuration- the long module plus one pallet. Twenty-seven instruments are carried aboard the pallet, eight are installed inside the module, and three use both, with some components on the pallet and some inside the module.

Nearly all of these experiments have been in preparation for many years. For man! of the investigators an important aspect of their careers is riding into orbit with Spacelab.

 


Visible evidence of the tremendous energy arriving at and stored in the regions surrounding the Earth are sporadic occurrences of auroras, the ghostly northern and southern lights that dramatically illuminate the night sky.

Visible evidence of the tremendous energy arriving at and stored in the regions surrounding the Earth are sporadic occurrences of auroras, the ghostly northern and southern lights that dramatically illuminate the night sky. Spacelab instruments are seeking to learn more about these energy releases and their still little-understood effect on conditions on the Earth.

 

[38] Many have invested substantial portions of their professional lives and research resources in the design and construction of these experiments.

That is why it is not surprising that Ulf Merbold, the European payload specialist aboard SL-1 gave this pledge to his science colleagues when he addressed some of them at the International Astronautical Federation Congress in Paris on September 28, 1982:

"I promise, on behalf of the entire payload crew," said Merhold, ''that we all- be it in Spacelab or as backups or support crews on the ground- shall give our very best to assure good scientific return to the scientists who spent so much of their time, energy, and enthusiasm to develop their experiments."

Some SL-1 experiments require instruments to look down at the Earth for studies of lands, oceans, and the atmosphere. Others require instruments to look up at the Sun and stars. Some examine the immediate surroundings at Spacelab's orbital altitude. And still other experiments take place inside the Spacelab module without any reference to outside conditions.

This contrasts with the experiment lists for some later Spacelab missions when an entire flight may be devoted to research in a single scientific discipline. Such "discipline missions" make it possible to focus all of a flight's resources and research strategies on specific research objectives.

In a discipline mission dedicated to Earth resources observations, the Orbiter can maintain its upside-down position (as seen from Earth) throughout the flight so that Spacelab observation instruments can look toward Earth continuously. In a mission dedicated to experiments requiring long periods of weightlessness or near weightlessness, the Orbiter can restrict its movements and remain floating undisturbed at a constant velocity through most of the flight. In an astronomy mission the Orbiter's cargo bay can be kept facing outward toward the celestial objects which are the targets of Spacelab's research instruments.

In SL-1 the Orbiter intentionally engages in many maneuvers and position changes to satisfy the needs of the various experiments. The SL-1 list of experiments reads like a mailorder catalogue. The variety is deliberate. Some SL-1 experiments are designed to test Spacelab's abilities as a stable observation platform for studying distant research subjects as well as closer ones.

Other SL-1 experiments will check Spacelab for its performance as a "test bed" for calibrating and appraising the usefulness of new instruments and processes. Still other experiments examine Spacelab's utility as a laboratory for work in materials processing and life sciences investigations inside the module

 

Space Provides Unique Opportunities

Experiments planned for Spacelab take advantage of one or more of the five unique properties of space- attributes which cannot be duplicated on Earth:

Mission planners have divided SL-1 experiments into five major categories (figures in parentheses show the number of experiments in each category):

 


Experiment racks manufactured in Italy sit ready to be installed in the Spacelab module at the assembly plant in Bremen, West Germany, before shipment to the United States.

Experiment racks manufactured in Italy sit ready to be installed in the Spacelab module at the assembly plant in Bremen, West Germany, before shipment to the United States. Spacelab has been designed so that experiments can be placed in the racks before the racks are rolled into Spacelab.


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Typical Spacelab Configurations for Discipline Missions.

Typical Spacelab Configurations for Discipline Missions.

 

(Some experiments not counted above may straddle several categories. Several multiuse instruments provide data required for a variety of experiments. Conversely, some experiments may use data from more than one instrument.)

 

Materials Science

Thirty-five SL-1 1 experiments- nearly half of the total on board- are in the field of materials science. Thirteen of these come from investigators in West Germany, eight are from France, four from the United Kingdom, three from Italy, two each from Austria and the Netherlands, and one each from Belgium, Spain, and Sweden. Also, a technology experiment by the United States is in the same group.

The need for improved materials is universal. Engineers faced with a continuing trend toward miniaturization need alloys With changed conductivity and insulation characteristics for reliable, less costly communications and electronic equipment. Biomedical researchers seek lighter, stronger materials for sophisticated surgical instruments and new kinds of prostheses.

Automation of industrial machinery and household appliances calls for new kinds of alloys, plastics, ceramics, composites, and glasses with presently unavailable properties. Architects want structural materials that handle easily at reduced cost. They would be used for residential, commercial, industrial, and public works construction.

Whether any of these needs can be fulfilled with space technologies remains to be seen. Spacelab's materials science experiments are descendants of very promising, but relatively primitive preliminary investigations begun on Apollo flights in the early 1970s. More ambitious experiments with a materials processing chamber about the size of a large sewing machine were conducted aboard Skylab in 1973 and 1974. The new Spacelab explorations are more extensive and use more advanced and more sophisticated equipment. They may provide more definite answers.

All of these experiments share one premise: that in prolonged weightlessness or lower-than-normal gravity, materials can be manufactured with properties unobtainable [40] on Earth, where weightlessness can he achieved for no longer than seconds at a time.

When a heavy and a light metal are heated, melted, and mixed on Earth, the heavier components settle before the mixture can be cooled to a solid state. In weightlessness in space the mixture remains uniform. Formerly incompatible substances can be combined into consistent new kinds of materials. Unevenly heated fluids remain still until they harden, free from the disturbing convection currents that normally drive the hotter, and therefore lighter, portions to the top while the cooler portions sink.

 

Materials Studied Early

One of the earliest American hi-space experiments in materials science took place on Sunday evening, February 7, 1971, on the home-hound leg of the nine-day Apollo, 14 flight, history's third successful manned Moon-landing mission.

During a live color telecast from space, while the craft was nearing the Earth, the crew heated 18 sealed capsules containing a combination of ingredients, shook them briskly, then cooled them. One of the capsules contained paraffin, tungsten pellets, and sodium acetate. On Earth, gravity would have quickly separated the heated contents so that the heavier tungsten would have been on the bottom, the sodium acetate in the middle, and the lighter paraffin on top. In the nearly weightless environment of Apollo 14 the three ingredients retained their distribution to form a mixture never before achieved by civilization.

 

Results Prove Encouraging

Similarly encouraging results emerged from the other capsules. Among the Apollo 14 materials experiments were three to test materials-separation techniques in weightlessness. One of these processes, called electrophoresis, is based on the fact that most organic molecules become electrically charged when they are placed in a solution. When an electric field is applied (through an electrode in contact with the fluid), the charged particles move toward the electrode. Because molecules of different sizes and shapes move at different speeds, the faster molecules in a mixture "outrun" the slower ones as they move from one end of the solution to the other. Particles that are alike tend to form into layers.

 


Close-up (top) shows double rack used for materials-science experiments.

Diagram shows how this rack at far left fits into wall of module between other experiment racks. Small furnaces and process chambers in this rack liquefy, mix, and resolidify metals and other materials in weightlessness aboard Spacelab.

 

Close-up (top) shows double rack used for materials-science experiments. Diagram shows how this rack at far left fits into wall of module between other experiment racks. Small furnaces and process chambers in this rack liquefy, mix, and resolidify metals and other materials in weightlessness aboard Spacelab.


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Crystal Growth.

Solidification Casting.

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Crystal Growth.

Solidification Casting.

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Containerless Processes.

Chemical Processes.

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Containerless Processes.

Chemical Processes.

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Biological Separation.

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Biological Separation.

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Concept for Materials Science Configuration (Long Module).

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Concept for Materials Science Configuration (Long Module).

 

Unwanted substances can be removed by taking out the layer in which they have accumulated. The process has been particularly useful in filtering biological products to prepare purer medical preparations and vaccines with fewer adverse side reactions. On Earth such separation is difficult or inefficient because the pull of Earth's gravity overpowers the electrode attraction. Technical problems made results from two Apollo 14 samples inconclusive. The third, a mixture of red d and blue dyes, indicated the feasibility of obtaining sharper separations in space than is possible on Earth. Repetition of the experiments with improved demonstration apparatus during the Apollo 16 Moon-landing flight in April 1972 tended to confirm these findings.

 

Skylab Had Materials Facility

Materials processing in space made new strides aboard Skylab in 1973 and 1974 with a Materials Processing Facility that included a vacuum chamber 40 centimeters ( 16 inches) in diameter, inside which there was an electric furnace 29 centimeters ( 11.5 inches) long and 10 centimeters (4 inches) in diameter. With its ability to generate temperatures of up to 1,000 degrees C ( 1,832 degrees F) and to cool at controllable rates, the facility was used by astronauts to melt, weld, braze, and cast metals and alloys. This facility produced composite materials and formed them into spheres. The facility was also used for growing crystals in weightlessness. Several materials science experiments have already been conducted on Shuttle flights.

Spacelab's long module houses the Materials Science Double Rack Facility on the first flight. It stretches from the module's floor to the ceiling and accommodates four furnaces and processing chambers. After loading prepackaged cartridges containing sample materials into the processing chambers, crew [42] members operate the controls to apply heat for as many as 30 separate experiments.

One of the furnaces, the Isothermal Heating Facility, retains its temperature at a constant level through each experiment. Two cartridges can be processed simultaneously, one heating while the other cools. This furnace will he used for studies of the solidification of metals and alloys and for forming composites. Improved glasses and ceramics are additional possibilities for this unit.

The Gradient Heating Facility is designed for studies of crystal growth, and the Fluid Physics Module for studies of behavior of fluids in weightlessness. In the absence of gravity, liquids do not necessarily sink to the bottom of a tank or flow through its floor outlets. Nor are heated fluids disturbed by convection currents in their weightless state.

Two mirrors in the Mirror Heating Facility in the double rack concentrate heat from a filament on a single point or limited region- in contrast to the other furnaces which heat an entire processing chamber.

Besides SL-1 experiments accommodated by the four furnaces, six other experiments in this group require their own special instruments.

 

Lubricants Study Planned

One of these is a technology experiment, called Tribology in Zero Gravity, which is the only United States investigation in this group aboard SL-1. Jointly sponsored by Columbia University and NASA's Marshall Space Flight Center, this experiment seeks to find out how lubricants spread in the absence of gravity and how their changed behavior in weightlessness may affect friction and wearing of moving machine parts. Tribology is the study of the effect of moving surfaces on each other. A payload or mission specialist applies lubricants and then photographs their movement and distribution on stationary as well as on moving surfaces. Experiment findings could influence future machine designs, particularly equipment for use in space.

Two other SL-1 experiments deal with adhesion and diffusion of metals, and three others with crystal growth in weightlessness. The possibility of in-space growth of flawless crystals intrigues many scientists and engineers. Crystal formation, like metallurgy and other materials processing, is subject to three major forces- heat, pressure, and gravity. The first two are easily produced and controlled as desired. Adverse effects of gravity are beyond control on Earth except under certain special circumstances, such as in free tall or in certain flight paths in an airplane. On Earth, elimination of gravitational influence is possible for only seconds at a time.

Gravity-induced convection in chemical solutions almost invariably causes defects and malformations during crystal growth. Mass produced crystals free of imperfections, apparently feasible in space, could lead to lower-cost and higher-performance communications and electronics instruments and set off another technological revolution in these already high-technology industries.

Similarly, the prospect of new kinds of glasses formed in weightlessness that would lend themselves to near-perfect, distortion free lenses has led experts to envision a new age of optical products for industry and consumers

 

Containerless Processing Foreseen

Optimistic forecasters foresee the possibility of containerless processing. Some experiments in that technology have already been conducted on hoard Shuttle flights and are planned for later Spacelab flights. Metals and other molten materials would cool and resolidify while floating weightlessly in a vacuum without touching any floor; wall, or other part of conventional containers.

Such a technique is foreseen as the ultimate in contamination-free processing,....

 


Familiarizing himself with the experiments in the laboratory racks in the Spacelab module is Payload Specialist Dr. Byron Lichtenberg, whose responsibility on the first Spacelab flight will be conducting many of these experiments.

Familiarizing himself with the experiments in the laboratory racks in the Spacelab module is Payload Specialist Dr. Byron Lichtenberg, whose responsibility on the first Spacelab flight will be conducting many of these experiments.

 

[43] ....because contact with any container, however slight, causes unwanted temperature changes and materials transfer.

As now envisioned for future Spacelab materials-science research, teardrop-size samples of metals and other materials will he held suspended without visible support and kept from drifting by sound waves trained on them from above, below, and the sides. If a sample tended to drift in any direction, the "accoustical levitator" in that area would automatically increase its output of sound waves to push the sample back into place. Also, varying the intensity of the sound is expected to make it possible to shape the liquid to desired forms. Sound waves on the Earth lack sufficient strength for such action against the force of the gravity pull, but they exert sufficient pressures to hold weightless specimens in their position in a vacuum. While suspended, the samples would be heated, mixed, or otherwise processed, cooled for resolidification, and returned to Earth for analysis.

 

Foamed Alloys a Possibility

Foreseen too are "foamed alloys" with bubble-like tiny pockets, like those in a sponge. Theoretically they could he stronger than steel, yet lighter than balsa wood. In any attempt to make such materials on Earth, the pockets would collapse before the material could solidify sufficiently during cooling.

If any of these prospects materialize, Spacelab could temporarily change its character as an exclusive research facility and become an interim manufacturing facility for small quantities of these valuable materials. Thus Spacelab could become a forerunner of our first factories in orbit, delivering the first commercial products stamped "Made in Space."

Of all Spacelab experiments, those in the materials science category are perhaps the most easily understood by nonscientists and are most likely to benefit large numbers of people in the near future. The space plasma physics experiments, which are discussed next, are among the most intricate Spacelab work from the point of view of nonscientists.

 

Space Plasma Physics

Six experiments aboard SL-1- two from West Germany, and one each from Austria, France, Japan, and the United States- will investigate the processes that occur around the Earth immediately above the atmosphere in the regions through which Spacelab is traveling. These experiments are grouped under the category of space plasma physics.

In the last 20 years scientists have radically changed their concepts about the environment of the Earth above the atmosphere. No longer do they visualize the Earth as traveling through a void, merely being warmed, as it turtle, by the visible radiations from the Sun.

 


Concept for Space Plasma Physics Configuration (Short Module and two pallets).

Concept for Space Plasma Physics Configuration (Short Module and two pallets).

 

[44] Observations by spacecraft in the last two decades show that the Earth is plowing through an active, energy-flooded environment in its annual orbit around the Sun. The near vacuum of space contains dynamic forces whose effects on our own environment at the Earth's surface are only beginning to he understood.

Magnetic fields envelop the Earth. Energetic particles strike the upper atmosphere. Visible and invisible radiations from the Sun and far more distant sources stream toward Earth. Electrified gases, called plasmas, flow past at speeds of up to 1,000 kilometers per second (625 miles per second).

The impact of these processes on our lives is only vaguely known, though there is evidence that these powerful forces so near the Earth generate important electrical and physical phenomena in our atmosphere and quite possibly influence our weather.

We know that bombardment of our upper atmosphere by charged particles from the Sun, guided along the Earth's magnetic force lines, can cause luminous hands called auroras, which can he seen sporadically in Earth's polar skies. Disturbances in these regions, caused by violent Sun behavior, can interfere with shortwave radio communications and interrupt electric power transmission on Earth.

 

Instruments to Study Auroras

Six instruments, each designed for investigations studying forces related to auroras, are mounted on the SL-1 pallet. One of these instruments consists of two units, one of them in the scientific airlock. Scientists hope to coordinate the data obtained from these instruments with the results from collaborative studies now in progress.

A large instrument, known as SEPAC (Space Experiment with Particle Accelerators), developed for this mission by Japan's Institute of Space and Astronautical Science in Tokyo, injects gas streams and high intensity electrons from its position on the pallet into Sun-ejected plasmas trapped in Earth's magnetic field. The results of SEPAC injections m space are analogous to radioactive tracers in medical research. They trigger radiant emissions that are essentially man-made auroras. SEPAC and other SL-1 instruments observe these illuminated beams that tend to travel along magnetic field lines, the normal route for energy entering the atmosphere.

The SEPAC instrument, controlled from the Spacelab module by payload and mission specialists, is the only SL-1 experiment by a Japanese research team.****

A French experiment, called Phenomena Induced by Charged Particle Beams, sends moderate-intensity particle beams into the....

 


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The regions surrounding the Earth were once considered a void, with only visible sunlight warming the atmosphere and the surface.

The regions surrounding the Earth were once considered a void, with only visible sunlight warming the atmosphere and the surface. That view has changed as scientists in recent decades have discovered magnetic fields which trap electrified gases called plasmas, emitted by the Sun and enveloping the Earth beyond the denser portions of the atmosphere. Experiments aboard Spacelab will examine these phenomena, which are not readily detectable or measurable from lower altitudes.

 


Diagram shows Earth's Magnetosphere and other near-Earth phenomena.

Diagram shows Earth's Magnetosphere and other near-Earth phenomena.

 

....plasma. These beams, generated by the instrument's "active" unit on the pallet, trigger a reaction from the plasma, which is measured by the instrument's "passive" unit mounted in the module's scientific airlock. Payload and mission specialists install the passive unit in the airlock and operate the experiment for the French National Center of Scientific Research.

A passive experiment from the Max Planck Institute for Aeronautics in West Germany, called Low Energy Electron Flux, uses a pallet-mounted detector to trace "echoes" reflected from electric fields by the electrons fired by the above two active instruments.

Among three other passive experiments on the SL-1 pallet is the Atmospheric Emission Photometric Imaging instrument from the Lockheed Palo Alto Research Laboratories. It uses television and a photometer to observe the artificial auroras. Spacelab's onboard computer controls most of the operation of this largely automated experiment.

Another passive experiment analyzes the magnetic field around the Orbiter. This experiment, called the DC Magnetic Field Vector Measurement, is from the Space Research Institute of the Austrian Academy of Sciences. The experiment uses three magnetometers to measure different aspects of the motions of particles along the lines of Earth's magnetic field. From these motions the instrument calculates the strength and direction of the magnetic field.

The last of the passive experiments in the plasma physics series on board SL-1 is the Isotope Stack Measurement of Heavy Cosmic Ray Isotopes. It is a detector made up of a series of plastic sheets stacked on top of each other behind a thin shield. Cosmic rays passing through the sheets or being stopped by them leave tracks, revealed after chemical processing of the sheets following the flight. From analysis of these tracks scientists can determine the strength, speed, composition, and even the source of these particles. The experiment is from the Institute for Basic and Applied Nuclear Physics of the University of Kiel, West Germany.

Though some of the research appears intricate and complex, the bottom line for Spacelab investigators is simple: To what extent is the research expanding human knowledge? How well is Spacelab helping to put knowledge to work for human betterment and progress? Spacelab's payoff ultimately lies in the answers to these questions.

 


* NASA and ESA agreed to divide Spacelab's weight capacity equally among themselves for their instruments. ESA's instruments are smaller and lighter. Thus ESA has 24 instruments and NASA 13 aboard SL-1. One instrument in plasma physics is being carried on SL-1 for Japanese researchers.

** The 10 European nations who jointly designed, built, and financed Spacelab plus Sweden.

*** One of these is a "technology experiment".

**** Japan is also planning for a partial Spacelab mission in 1988 for material and life sciences experiments. This mission will be on a cost-reimbursable basis- Japan pays NASA for the applicable expenses of operating the flight-and Japan may perhaps send its own payload specialist along.


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