Saturday, 1 November 2008

Indonesian Space Sciences Technology School,

Computational Methods

in Aerospace Engineering 


Staff

Instructor:
Prof. David Darmofal

Course Meeting Times

Lectures:
Three sessions / week
1 hour / session

Level

Undergraduate



Added & Edited

By: Arip Nurahman
Department of Physics Education, Faculty of Sciences and Mathematics
Indonesia University of Education

and

Follower Open Course Ware at Massachusetts Institute of Technology
Cambridge, USA
Department of Physics
http://web.mit.edu/physics/
http://ocw.mit.edu/OcwWeb/Physics/index.htm
&
Aeronautics and Astronautics Engineering
http://web.mit.edu/aeroastro/www/
http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/index.htm























Mach 2 inviscid flow simulation over a cylinder, from Project #1. (Image courtesy of Professor Darmofal.)

Course Highlights

This course features a complete set of lecture notes and assignments, and also a variety of study materials.

Course Description

This course serves as an introduction to computational techniques arising in aerospace engineering. Applications are drawn from aerospace structures, aerodynamics, dynamics and control, and aerospace systems. Techniques include: numerical integration of systems of ordinary differential equations; finite-difference, finite-volume, and finite-element discretization of partial differential equations; numerical linear algebra; eigenvalue problems; and optimization with constraints.

Technical Requirements

Special software is required to use some of the files in this course: .m, .mat.

Study Materials

The following materials are provided for preparation for the problem sets and final exam.

Sample Problems Sets

Problem Set 1 (PDF)
Solution Set 1 (PDF)
Problem Set 2 (PDF)
Solution Set 2 (PDF)

Final Exam Preparation

Preparation Materials (PDF)

Syllabus

Course Objectives

Students successfully completing 16.901 should have:
  1. A conceptual understanding of computational methods commonly used for analysis and design of aerospace systems.
  2. A working knowledge of computational methods including experience implementing them for model problems drawn from aerospace engineering applications.
  3. A basic foundation in theoretical techniques to analyze the behavior of computational methods.

Measurable Outcomes

The subject is divided into four sections:
  • Integration of Systems of Ordinary Differential Equations (ODE's)
  • Finite Volume and Finite Difference Methods for Partial Differential Equations (PDE's)
  • Finite Element Methods for Partial Differential Equations
  • Probabilistic Simulation Techniques
For each of these sections, the measurable outcomes are described below. Specifically, a student successfully completing 16.901 will be able to:

Integration Methods for ODE's

  1. (a) Describe the Adams-Bashforth, Adams-Moulton, and Backwards Differentiation families of multi-step methods;
    (b) Describe the form of the Runge-Kutta family of multi-stage methods; and
    (c) Explain the relative computational costs of multi-step versus multi-stage methods.
  2. (a) Explain the concept of stiffness of a system of equations, and
    (b) Describe how it impacts the choice of numerical method for solving the equations.
  3. (a) Explain the differences and relative advantages between explicit and implicit methods to integrate systems of ordinary differential equations; and
    (b) For nonlinear systems of equations, explain how a Newton-Raphson can be used in the solution of an implicit method.
  4. (a) Define a convergent method;
    (b) Define a consistent method;
    (c) Explain what (zero) stability is; and
    (d) Demonstrate an understanding of the Dahlquist Equivalence Theorem by describing the relationship between a convergent method, consistency, and stability.
  5. Determine if a multi-step method is stable and consistent.
  6. (a) Define global and local order of accuracy for an ODE integration method,
    (b) Describe the relationship between global and local order of accuracy, and
    (c) Calculate the local order of accuracy for a given method using a Taylor series analysis.
  7. (a) Define eigenvalue stability, and
    (b) Determine the stability boundary for a multi-step or multi-stage method applied to a linear system of ODE's.
  8. Recommend an appropriate ODE integration method based on the features of the problem being solved.
  9. Implement multi-step and multi-stage methods to solve a representative system of ODE's from an engineering application.

Finite Difference and Finite Volume Methods for PDE's

  1. (a) Define the physical domain of dependence for a problem,
    (b) Define and determine the numerical domain of dependence for a discretization, and
    (c) Explain the CFL condition and determine the timestep constraints resulting from the CFL conditions.
  2. Determine the local truncation error for a finite difference approximation of a PDE using a Taylor series analysis.
  3. Explain the difference between a centered and a one-sided (e.g. upwind) discretization.
  4. Describe the Godunov finite volume discretization of two-dimensional convection on an unstructured mesh.
  5. Perform an eigenvalue stability analysis of a finite difference approximation of a PDE using either Von Neumann analysis or a semi-discrete (method of lines) analysis.
  6. Implement a finite difference or finite volume discretization to solve a representative PDE (or set of PDE's) from an engineering application.

Finite Element Methods for PDE's

  1. (a) Describe how the Method of Weighted Residuals (MWR) can be used to calculate an approximate solution to a PDE,
    (b) Describe the differences between MWR, the collocation method, and the least-squares method for approximating a PDE, and
    (c) Describe what a Galerkin MWR is.
  2. (a) Describe the choice of approximate solutions (i.e. the test functions or interpolants) used in the Finite Element Method, and
    (b) Give examples of a basis for the approximate solutions in particular including a nodal basis for at least linear and quadratic solutions.
  3. (a) Describe how integrals are performed using a reference element,
    (b) Explain how Gaussian quadrature rules are derived, and
    (c) Describe how Gaussian quadrature is used to approximate an integral in the reference element.
  4. Explain how Dirichlet and Neumann boundary conditions are implemented for Laplace's equation discretized by FEM.
  5. (a) Describe how the FEM discretization results in a system of discrete equations and, for linear problems, gives rises to the stiffness matrix; and
    (b) Describe the meaning of the entries (rows and columns) of the stiffness matrix and of the right-hand side vector for linear problems.

Probabilistic Methods

Note: all students are expected to have a thorough understanding of probability, random variables, PDF's, CDF's, mean (expectation), variance, standard deviation, percentiles, uniform distributions, normal distributions, and x2-distributions from the prerequisite coursework.
  1. Describe how Monte Carlo sampling from multivariable, uniform distributions works.
  2. Describe how to modify Monte Carlo sampling from uniform distributions to general distributions.
  3. (a) Describe what an unbiased estimator is;
    (b) State unbiased estimators for mean, variance, and probability; and
    (c) State the distributions of these unbiased estimators.
  4. (a) Define standard error;
    (b) Give standard errors for mean, variance and probability;
    (c) Place confidence intervals for estimates of the mean, variance, and probability; and
    (d) Demonstrate the dependence of Monte Carlo convergence on the number of random inputs and the number of samples using the above error estimates.
  5. (a) Describe stratified sampling for single input and multiple inputs,
    (b) Describe Latin Hypercube Sampling (LHS), and
    (c) Describe the benefits of LHS for nearly linear outputs in terms of the standard error convergence of the mean with the number of samples.
  6. (a) Describe the Response Surface Method (RSM);
    (b) Describe the construction of a response surface through Taylor series, Design of Experiments with the least-square regression, and random sampling with least-squares regression; and
    (c) Describe the R2 -metric, its use in measuring the quality of a response surface, and its potential problems.

Homework Problems

A homework problem will be given at the end of most regular lectures and will be due at the beginning of the next class. These homework problems are intended to take 1-2 hours to complete. The individual homework sets will be graded on the following scale:
3: A complete solution demonstrating an excellent understanding of the concepts.
2: A complete solution demonstrating an adequate understanding of the concepts, though some minor mistakes may have been made.
1: A complete or nearly-complete solution demonstrating some understanding of the concepts, though major mistakes may have been made.
0: A largely incomplete solution or no solution at all.
Note: the individual homework grades will only be integer values. At the end of the semester, the highest 2/3's of the grades received in the homeworks will be averaged to determine an overall homework letter grade. Roughly, the following ranges will be used. A: 2.5-3; B: 2-2.5; C: 1.5-2; D: 1-1.5; F: 0-1.

Projects

Currently, three programming projects are planned for this semester (one for each section of the course except the ODE section). The projects will focus on applying numerical algorithms to aerospace applications. The programming is highly recommended to be done in Matlab®. The expected due dates for the projects are as follows.


PROJECTS DUE DATES
Project 1 Lecture 16
Project 2 Lecture 30
Project 3 Lecture 38

The project assignments will be distributed at least one week prior to the due dates. No homeworks will be given during the week the projects are due. Each project will be assigned a letter grade based on the standard MIT letter grade descriptions (see Course Grade).

Homework and Project Collaboration

While discussion of the homework and projects is encouraged among students, the work submitted for grading must represent your understanding of the subject matter. Significant help from other sources should be noted.

Oral Exams

There will be a mid-term and final oral exam. The mid-term oral exam will be held between Lecture 20 and Lecture 21. The final oral exam will be held during Final Exam Week. I will schedule the mid-term oral exam by the end of February based on preferences from each student. I will schedule the final oral exam once the final exam schedule for the institute has been published. Each oral exam will be assigned a letter grade based on the standard MIT letter grade descriptions (see Course Grade).

Course Grade

The subject total grade will be based on the letter grades from the homework, projects, and oral exams. Roughly, the weighting of the individual letters grade is as follows:


ACTIVITIES BREAKDOWN
Homework Letter Grades 1/8 of the Subject Total Grade
Project Letter Grades Each Project is 1/8 of the Total Grade
Oral Exam Letter Grades Each Exam is 1/4 of the Total Grade

For the subject letter grade, I adhere to the MIT grading guidelines which give the following description of the letter grades:
A: Exceptionally good performance demonstrating a superior understanding of the subject matter, a foundation of extensive knowledge, and a skillful use of concepts and/or materials.
B: Good performance demonstrating capacity to use the appropriate concepts, a good understanding of the subject matter, and an ability to handle the problems and materials encountered in the subject.
C: Adequate performance demonstrating an adequate understanding of the subject matter, an ability to handle relatively simple problems, and adequate preparation for moving on to more advanced work in the field.
D: Minimally acceptable performance demonstrating at least partial familiarity with the subject matter and some capacity to deal with relatively simple problems, but also demonstrating deficiencies serious enough to make it inadvisable to proceed further in the field without additional work.

Textbooks

Notes will be distributed. Reference texts will be recommended for specific topics as needed.


Citable URI: http://hdl.handle.net/1721.1/36877

Projects

Special software is required to use some of the files in this section: .m, .mat.
There are three programming projects for the class, one for each section of the course except the ODE section. They focus on applying numerical algorithms to aerospace applications.

Projects Supporting Files Solutions
Project 1 (PDF) CalcForces.m (M)

cyl_adaptmesh.m (M)

cyl_initmesh.m (M)

cylgeom.mat (MAT)

eulerflux.m (M)

FVM.m (M)

SetRefineList.m (M)

SetupEdgeList.m (M)

SetupMesh.m (M)

wallflux.m (M)		 (PDF - 1.4 MB)
Project 2 (PDF) bladeheat.m (M)

bladeplot.m (M)

hpblade_coarse.mat (MAT)

hpblade_fine.mat (MAT)

hpblade_medium.mat (MAT)

findloc.m (M)

Thgas.m (M)		 (PDF)

p2_matlabsol.txt (TXT)
Project 3 (PDF) calcblade.m (M)

DesignIntent.m (M)

hpblade_coarse.mat (MAT)

loadblade.m (M)

MCdriver.m (M)

Screen.m (M)

Thgas.m (M)

trirnd.m (M)		 (PDF)

See also


References

  1. ^ “IEEE Standard Glossary of Software Engineering Terminology,” IEEE std 610.12-1990, 1990, quoted at the beginning of Chapter 1: Introduction to the guide "Guide to the Software Engineering Body of Knowledge" (February 6, 2004). Retrieved on 2008-02-21.
  2. ^ Pecht, Michael (1995). Product Reliability, Maintainability, and Supportability Handbook. CRC Press. ISBN 0-8493-9457-0.
  3. ^ Pehrson, Ronald J. (January 1996). "Software Development for the Boeing 777". CrossTalk: the Journal of Defense Software Engineering. http://www.stsc.hill.af.mil/crosstalk/1996/01/Boein777.asp. , "The 2.5 million lines of newly developed software were approximately six times more than any previous Boeing commercial airplane development program. Including commercial-off-the-shelf (COTS) and optional software, the total size is more than 4 million lines of code."
  4. ^ Randell, Brian (10 Aug 2001). "The 1968/69 NATO Software Engineering Reports". Brian Randell's University Homepage. The School of Computer Sciences, Newcastle University. Retrieved on 2008-10-11. "The idea for the first NATO Software Engineering Conference, and in particular that of adopting the then practically unknown term "software engineering" as its (deliberately provocative) title, I believe came originally from Professor Fritz Bauer."
  5. ^ Table 1 in Chapter 1,"Guide to the Software Engineering Body of Knowledge" (February 6, 2004). Retrieved on 2008-02-21.
  6. ^ Ian Sommerville (2004). Software Engineering. 7th edition. Chapter 1. Bezien 20 Okt 2008.
  7. ^ Table 2 in Chapter 1,"Guide to the Software Engineering Body of Knowledge" (February 6, 2004). Retrieved on 2008-02-21.
  8. ^ Bureau of Labor Statistics, U.S. Department of Labor, USDL 05-2145: Occupational Employment and Wages, November 2004, Table 1.
  9. ^ "Software Engineering". Retrieved on 2008-02-01.
  10. ^ Cowling, A. J. 1999. The first decade of an undergraduate degree programme in software engineering. Ann. Softw. Eng. 6, 1-4 (Apr. 1999), 61-90.
  11. ^ "ABET Accredited Engineering Programs" (April 3, 2007). Retrieved on 2007-04-03.
  12. ^ McConnell, Steve (July 10, 2003. Professional Software Development: Shorter Schedules, Higher Quality Products, More Successful Projects, Enhanced Careers. ISBN 978-0321193674.
  13. ^ Actually the ACM made an explicit decision not to continue with certification. 1
  14. ^ IEEE Computer Society. "2006 IEEE computer societe report to the IFIP General Assembly". Retrieved on 2007-04-10.
  15. ^ Canadian Information Processing Society. "I.S.P. Designation". Retrieved on 2007-03-15.
  16. ^ As outsourcing gathers steam, computer science interest wanes
  17. ^ Computer Programmers
  18. ^ Software developer growth slows in North America | InfoWorld | News | 2007-03-13 | By Robert Mullins, IDG News Service
  19. ^ Hot Skills, Cold Skills
  20. ^ Dual Roles: The Changing Face of IT

Further reading


External links

Sister project Wikimedia Commons has media related to: Software engineering
Retrieved from "http://en.wikipedia.org/wiki/Software_engineering"

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Saturday, 25 October 2008

Indonesian Space Sciences & Technology School

Indonesian Space Sciences & Technology School

 Added & Edited


By: Arip Nurahman
Department of Physics Education, Faculty of Sciences and Mathematics
Indonesia University of Education

and

Follower Open Course Ware at Massachusetts Institute of Technology
Cambridge, USA
Department of Physics 
http://web.mit.edu/physics/
http://ocw.mit.edu/OcwWeb/Physics/index.htm
&
Aeronautics and Astronautics Engineering
http://web.mit.edu/aeroastro/www/
http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/index.htm
















Space manufacturing

Space manufacturing is the production of manufactured goods in an environment outside a planetary atmosphere. Typically this includes conditions of microgravity and hard vacuum. Manufacturing in space has several potential advantages over Earth-based industry.

  1. The unique environment can allow for industrial processes that cannot be readily reproduced on Earth.
  2. Raw materials can be collected and processed from other bodies within the solar system at a relatively low expense compared to the cost of lifting materials into orbit.
  3. Potentially hazardous processes can be performed in space with minimal risk to the environment of the Earth or other planets.
Comparison of insulin crystal growth in outer space (left) and on Earth (right). NASA image.

Comparison of insulin crystal growth in outer space (left) and on Earth (right). NASA image.
The space environment is expected to be beneficial for production of a variety of products. Once the heavy capitalization costs of assembling the mining and manufacturing facilities is paid, the production will need to be economically profitable in order to become self-sustaining and beneficial to society. The most significant cost is overcoming the energy hurdle for boosting materials into orbit. Once this barrier is significantly reduced in cost per kilogram, the entry price for space manufacturing can make it much more attractive to entrepreneurs.
Economic requirements of space manufacturing imply a need to collect the requisite raw materials at a minimum energy cost. The economical movement of material in space is directly related to the delta-v, or change in velocity required to move from the mining sites to the manufacturing plants. Near-earth asteroids, Phobos, Deimos and the lunar surface have a much lower delta-v compared to launching the materials from the surface of the Earth to Earth orbit.

Contents

History

During the Soyuz 6 mission, Russian astronauts performed the first welding experiments in space. Three different welding processes were tested using a hardware unit called Vulkan. The tests included welding aluminum, titanium, and stainless steel.

The Skylab mission, launched in May, 1973, served as a laboratory to perform various space manufacturing experiments. The station was equipped with a materials processing facility that included a multi-purpose electric furnace, a crystal growth chamber, and an electron beam gun. Among the experiments to be performed was research on molten metal processing; photographing the behavior of ignited materials in zero-gravity; crystal growth; processing of immiscible alloys; brazing of stainless steel tubes, electron beam welding, and the formation of spheres from molten metal. The crew spent a total of 32 man-hours on materials science and space manufacturing investigation during the mission.

The Space Studies Institute began hosting a bi-annual Space Manufacturing Conference in 1977.
Microgravity research in materials processing continued in 1983 using the Spacelab facility. This module has been carried into orbit 26 times aboard the Space Shuttle, as of 2002. In this role the shuttle has served as an interim, short-duration research platform in lieu of the upcoming International Space Station.

The Wake Shield Facility is deployed by the Space Shuttle's robotic arm. NASA image.

The Wake Shield Facility is deployed by the Space Shuttle's robotic arm. NASA image.
In February 1994 and September 1995, the Wake Shield Facility was carried into orbit by the Space Shuttle. This demonstration platform used the vacuum created in the orbital wake to manufacture thin films of gallium arsenide and aluminum gallium arsenide.

On May 31, 2005, the recoverable, unmanned Foton-M2 laboratory was launched into orbit. Among the experiments were crystal growth and the behavior of molten-metal in weightlessness.

ISS

The completion of the International Space Station is expected to provide expanded and improved facilities for performing industrial research. These will lead to improvements in our knowledge of materials sciences, new manufacturing techniques on Earth, and potentially some important discoveries in space manufacturing methods. The completion of this facility has been delayed due to safety problems with the Space Shuttle.
The Material Science Laboratory Electromagnetic Levitator (MSL-EML) on board the Columbus Laboratory is a science facility that can be used to study the melting and solidification properties of various materials. The Fluid Science Laboratory (FSL) will be used to study the behavior of liquids in microgravity.[1]

Environment

There are several unique differences between the properties of materials in space compared to the same materials on the Earth. These differences can be exploited to produce unique or improved manufacturing techniques.
  • The microgravity environment allows control of convection in liquids or gasses, and the elimination of sedimentation. Diffusion becomes the primary means of material mixing, allowing otherwise immiscible materials to be intermixed. The environment allows enhanced growth of larger, higher-quality crystals in solution.
  • The ultraclean vacuum of space allows the creation of very pure materials and objects. The use of vapor deposition can be used to build up materials layer by layer, free from defects.
  • Surface tension causes liquids in microgravity to form perfectly round spheres. This can cause problems when trying to pump liquids through a conduit, but it is very useful when perfect spheres of consistent size are needed for an application.
  • Space can provide readily available extremes of heat and cold. Sunlight can be focused to concentrate enough heat to melt the materials, while objects kept in perpetual shade are exposed to temperatures close to absolute zero. The temperature gradient can be exploited to produce strong, glassy materials.

Materials processing

For most manufacturing applications, specific material requirements must be satisfied. Mineral ores need to be refined to extract specific metals, and volatile organic compounds will need to be purified. Ideally these raw materials are delivered to the processing site in an economical manner, where time to arrival, propulsion energy expenditure, and extraction costs are factored into the planning process. Minerals can be obtained from asteroids, the lunar surface, or a planetary body. Volatiles could potentially be obtained from a comet or the moons of Mars or other planets. It may also prove possible to extract hydrogen from the cold traps at the poles of the Moon.

Another potential source of raw materials, at least in the short term, is recycled orbiting satellites and other man-made objects in space. Some consideration was given to the use of the Space Shuttle external fuel tanks for this purpose, but NASA determined that the potential benefits were outweighed by the increased risk to crew and vehicle[citation needed].

Unless the materials processing and the manufacturing sites are co-located with the resource extraction facilities, the raw materials will need to be moved about the solar system. There are several proposed means of providing propulsion for this material, including solar sails, magnetic sails, mini-magnetospheric plasma propulsion (which uses a cloud of ionized gas as a magnetic sail), electric ion thrusters, or mass drivers (this last method uses a sequence of electromagnets mounted in a line to accelerate a conducting material).

At the materials processing facility, the incoming materials will need to be captured by some means. Maneuvering rockets attached to the load can park the content in a matching orbit. Alternatively, if the load is moving at a low delta-v relative to the destination, then it can be captured by means of a mass-catcher. This could consist of a large, flexible net or inflatable structure that would transfer the momentum of the mass to the larger facility. Once in place, the materials can be moved into place by mechanical means or by means of small thrusters.

Materials can be used for manufacturing either in their raw form, or by processing them to extract the constituent elements. Processing techniques include various chemical, thermal, electrolitic, and magnetic methods for separation. In the near term, relatively straightforward methods can be used to extract aluminum, iron, oxygen, and silicon from lunar and asteroidal sources. Less concentrated elements will likely require more advanced processing facilities, which may have to wait until a space manufacturing infrastructure is fully developed.

Some of the chemical processes will require a source of hydrogen for the production of water and acid mixtures. Hydrogen gas can also be used to extract oxygen from the lunar regolith, although the process is not very efficient. So a readily available source of useful volatiles is a positive factor in the development of space manufacturing.

One proposed method of purifying asteroid materials is through the use of carbon monoxide (CO). Heating the material to 500 °F (260 °C) and exposing it to CO causes the metals to form gaseous carbonyls. This vapor can then be distilled to separate out the metal components, and the CO can then be recovered by another heating cycle. Thus an automated ship can scrape up loose surface materials from, say, the relatively nearby 4660 Nereus (in delta-v terms), process the ore using solar heating and CO, and eventually return with a load of almost pure metal. The economics of this process can potentially allow the material to be extracted at one-twentieth the cost of launching from Earth, but it would require a two-year round trip to return any mined ore.[citation needed]

Manufacturing

Due to speed of light constraints on communication, manufacturing in space at a distant point of resource acquisition will either require completely autonomous robotics to perform the labor, or a human crew with all the accompanying habitat and safety requirements. If the plant is built in orbit around the Earth, or near a manned space habitat, however, telecheric devices can be used for certain tasks that require human intelligence and flexibility.

Solar power provides a readily available power source for thermal processing. Even with heat alone, simple thermally-fused materials can be used for basic construction of stable structures. Bulk soil from the Moon or asteroids has a very low water content, and when melted to form glassy materials is very durable. These simple, glassy solids can be used for the assembly of habitats on the surface of the Moon or elsewhere. The solar energy can be concentrated in the manufacturing area using an array of steerable mirrors.

The availability and favorable physical properties of metals will make them a major component of space manufacturing. Most of the metal handling techniques used on Earth can also be adopted for space manufacturing, but a few will need significant modifications. The microgravity environment of space will necessitate modifications to some metal handling techniques.

The production of hardened steel in space will introduce some new factors. Carbon only appears in small proportions in lunar surface materials and will need to be delivered from elsewhere. Waste materials carried by humans from the Earth is one possible source, as are comets. The water normally used to quench steel will also be in short supply, and require strong agitation.

Casting steel can be a difficult process in microgravity, requiring special heating and injection processes, or spin forming. Heating can be performed using sunlight combined with electrical heaters. The casting process would also need to be managed to avoid the formation of voids as the steel cools and shrinks.

Various metal-working techniques can be used to shape the metal into the desired form. The standard methods are casting, drawing, forging, machining, rolling, and welding. Both rolling and drawing metals require heating and subsequent cooling. Forging and extrusion can require powered presses, as gravity is not available. Electron beam welding has already been demonstrated on board the Skylab, and will probably be the method of choice in space. Machining operations can require precision tools which will need to be imported from the Earth for some duration.

New space manufacturing technologies are being studied at places such as Marshall's National Center for Advanced Manufacturing. The methods being investigated include coatings that can be sprayed on surfaces in space using a combination of heat and kinetic energy, and free-form fabrication of parts. Approaches such as these, as well as examination of material properties that can be investigated in an orbiting laboratory, will be studied on the International Space Station.

Products

There are thought to be a number of useful products that can potentially be manufactured in space and result in an economic benefit. Research and development is required to determine the best commodities to be produced, and to find efficient production methods. The following products are considered prospective early candidates:
As the infrastructure is developed and the cost of assembly drops, some of the manufacturing capacity can be directed toward the development of expanded facilities in space, including larger scale manufacturing plants. These will likely require the use of lunar and asteroid materials, and so follow the development of mining bases.

Rock is the simplest product, and at minimum is useful for radiation shielding. It can also be subsequently processed to extract elements for various uses.

Water from lunar sources, Near Earth Asteroids or Martian moons is thought to be relatively cheap and simple to extract, and gives adequate performance for many manufacturing and material shipping purposes. Separation of water into hydrogen and oxygen can be easily performed in small scale, but some scientists[1] believe that this will not be performed on any large scale initially due to the large quantity of equipment and electrical energy needed to split water and liquify the resultant gases. Water used in steam rockets gives a specific impulse of about 190 seconds; less than half that of hydrogen/oxygen, but this is adequate for delta-v's that are found between Mars and Earth[citation needed]. Water is useful as a radiation shield and in many chemical processes.

Ceramics made from lunar or asteroid soil can be employed for a variety of manufacturing purposes. These uses include various thermal and electrical insulators, such as heat shields for payloads being delivered to the Earth's surface.

Metals can be used to assemble a variety of useful products, including sealed containers (such as tanks and pipes), mirrors for focusing sunlight, and thermal radiators. The use of metals for electrical devices would require insulators for the wires, so a flexible insulating material such as plastic or fiberglass will be needed.
A notable output of space manufacturing is expected to be solar panels. Expansive solar energy arrays can be constructed and assembled in space. As the structure does not need to support the loads that would be experienced on Earth, huge arrays can be assembled out of proportionately smaller amounts of material. The generated energy can then be used to power manufacturing facilities, habitats, spacecraft, lunar bases, and even beamed down to collectors on the Earth with microwaves.

Other possibilities for space manufacturing include propellants for spacecraft, some repair parts for spacecraft and space habitats, and, of course, larger factories. Ultimately, space manufacturing facilities can hypothetically become nearly self-sustaining, requiring only minimal imports from the Earth. The microgravity environment allows for new possibilities in construction on a massive scale, including megascale engineering. These future projects might potentially assemble space elevators, massive solar array farms, very high capacity spacecraft, and rotating habitats capable of sustaining populations of tens of thousands of people in Earth-like conditions.

See also


References

  1. ^ Staff (July 18, 2007). "Columbus laboratory". ESA. Retrieved 2007-07-18.
  2. ^ Eric Cardiff of NASA's Goddard Space Flight Center, as quoted at http://www.physorg.com/news66314743.html
  3. ^ http://www.popsci.com/military-aviation-amp-space/article/2009-09/iss-could-get-its-own-electron-beam-fabrication-3d-printer


External links

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