ENTROPY
(Launchspace Staff Writers)
Bethesda, MD - "Entropy" is defined as a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work. Many use this term to describe the degree of disorder or randomness in a system. A third definition is a lack of order or predictability with gradual decline into disorder. The second law of thermodynamics tells us that entropy always increases as available useful work decreases. Some managers in the space community use this term to represent a loss of productivity, innovation and enthusiasm within an organization.
Let's take the space program as an example. At the dawn of space flight in 1957, there was no entropy associated with space exploration excitement and interest. Almost all available energy was used to innovate, develop, experiment and test space systems. This was an ideal system for advancing space exploitation. A number of great and exciting things were accomplished in the beginning: the development of early communications satellites, the first planetary probes, men landing on the moon and returning safely, and the Space Shuttle. However, after the race to the Moon, enthusiasm and interest started to wane. Excitement and interest in the civil space arena started a long period of decline. At the same time the level of bureaucracy within civil space organizations began to increase. The rate of entropy increase grew, even though the Space Shuttle and ISS programs were successful. In the meantime, the growth rate of entropy within national security space and commercial space was kept a low levels.
National security space participants are highly challenged and dedicated. Entropy growth is kept low by the required high levels of focus on the contested space environment that has evolved over the past 20 years. Low earth orbits are extremely congested traffic zones. Individual satellites and constellation crowd the heavens between the altitudes of 600 km and 1200 km above Earth. There are probably over 100 active national security satellites in this zone that are operated by several nation states, some of which are allies and some are adversaries. Add to this the thousands of random, uncontrolled debris objects, each of which can cause catastrophic damage to very expensive spacecraft. Entropy levels are kept low, because focus, dedication and innovation all must be maintained at high levels.
In recent years commercial space has evolved into an area of high activity. Interest and innovation are intense. Applications such as space-based broad-band internet services are succeeding in attracting large investments and multiple players. Constellations with hundreds of satellite are being proposed and developed. Entropy is being kept at low levels and will be at these levels until, at least, some of these business plans are tested.
Some of the entropy trends will continued. For example, government-sponsored human space exploration may not see any new enthusiasm until we have a domestic crew launch capability. The national security space community will likely maintain low entropy levels for the indefinite future. And, commercial space activities should maintain high levels of interest and innovation for several years.
One takeaway from these observation: Bureaucracy and entropy tend to grow together.
Featured short course - available for customized presentation at your facility.
Space Vehicle Mechanisms: Elements of Successful Design
DURATION:THREE DAYS
LOCATION: YOUR FACILITY
LAUNCHSPACE COURSE NO.: 1135
COURSE SUMMARY
This course explores the technologies required for the successful design of moving mechanical assemblies in the space environment and offers a detailed look at many of the key components common to most mechanisms, such as ball bearings, motors and feedback devices. With this background, the high-performance materials required for operation in space are reviewed, emphasizing compatibility with the space environment and offering some background in the metallurgy, chemistry, and fabrication of those materials. Examples of some of the many types of mechanism will be included for illustration. In addition, the mechanisms relationship and interface with other vehicle systems will be explored, as a mechanism usually becomes an important part of the vehicles structural, thermal, contamination, survivability, and pointing subsystems. The course includes design and analysis examples to demonstrate principles involved in understanding how mechanisms should work, and how design margins should be evaluated during the evolution of a program. Finally, some important underlying techniques, such as reliability analysis and digital simulation, are covered.
WHO SHOULD ATTEND:
This course is intended for mechanisms engineers who wish to expand their knowledge and for system engineers and program managers who need a working knowledge of mechanism design and application.
WHAT YOU WILL LEARN:
Understanding a mechanism requires a working knowledge of dozens of specialties, such as motors, lubrication, structural metals, and feedback devices. You will acquire this knowledge and become conversant with the many components, materials, and technologies that go into a successful design. In addition, successful application of a mechanism requires a familiarity with the various vehicle subsystems of which a mechanism is often a crucial part, such as the pointing, contamination or structural system. The design and analysis of these subsystems, and their interfaces with the mechanism, are introduced.
COURSE OUTLINE:
Overview of how all types of mechanisms are used in spacecraft.
2. Pointing Subsystems.
Design and requirements considerations common to pointing systems. High and low precision consideration for bearings, motors and feedback devices.
3. Motors.
Stepper motors, DC brush and brushless motor characteristics and behavior. Different motors for suitability against various mechanism applications.
4. Feedback Devices.
Optical encoder, inductosyn, resolver and potentiometer characteristics and precision. Selection of feedback devices for suitability against various mechanism applications.
5. Bearings and Gears.
Fundamentals of high-precision ball bearings and proper lubrication techniques for long life. Overview of gears with a focus on harmonic drives.
6. Lubrication Fundamentals.
Wet and Dry Lubricants. Fundamental behavior, performance and life characteristics of liquid and dry lubricants for space. Different lubrication choices for suitability against various mechanism applications.
7. Release Systems and Deployment Systems.
Pyrotechnic and non-pyrotechnic release mechanisms operation and characteristics. Deployment system elements and basics.
8. Rotating Signal and Power Transfer Systems.
Slip ring characteristics, operation and behavior.
9. Electrical Interfaces.
Interfaces between mechanisms and the spacecraft to give the mechanism designer insight into the implications of important interfaces.
10. Structural Dynamics.
Spacecraft and general structural dynamics to give the mechanism designer insight into the structural aspect of mechanisms and into interfaces with larger spacecraft structure developments.
11. Structural Metals.
Common structural metals for mechanisms including stainless steel, titanium, beryllium and others. Characteristics of most interest for mechanisms. Materials for springs and bearings.
12. Composite Materials.
Common composite materials for mechanisms and characteristics of interest.
13. Reliability and Simulation Techniques.
Mechanism simulation techniques and reliability assessment methods.
14. Contamination.
Contamination considerations between mechanism and satellite.
15. Radiation and Survivability.
Radiation environment and survivability implications for the mechanisms.
Instructor: Bill Purdy
Bill Purdy has 22 years of hands-on experience in the space engineering field with wide-ranging involvement in both spacecraft mechanisms and systems engineering disciplines. Mr. Purdy has been one of the leaders of the space mechanism industry's transition from explosive release mechanisms to non-explosive devices. His involvement in numerous space endeavors includes key roles on over 25 successfully flown spacecraft, work on over 30 flown mechanisms including gimbals, release mechanisms, deployables and many other types of mechanisms. As an educator and space industry consultant to both government and industry, Mr. Purdy applies this broad experience to bring out a clear understanding of the space mechanisms, definition, resolution and integration of mechanism requirements and their relationship to the overall system program success. Mr. Purdy was the Associate Editor of the industry-standard handbook
Space Vehicle Mechanisms - Elements of Successful Design and the author of the chapter on non-explosive release mechanisms. He has published seven Aerospace Mechanisms Symposia Papers and was the 1999 winner of the Herzl Award. Mr. Purdy holds a BSME from the University of Maryland.
since 1970. Early in his career, Dr. Marshall H. Kaplan realized that space professionals had limited resources in advancing their own space-related knowledge base and on-the-job training options. Over the last few decades this company has created and delivered hundreds of focused courses to thousands of engineers, managers and support personnel in the space community. All training subject matter and supporting materials are designed to increase knowledge and improve productivity associated with space technologies, systems and operations. These topics are not offered in a university setting.
Over the past 20 years, Launchspace has been offering company-specific courses that are tailored to the requirements of any given company to train its own personnel. These courses are presented on-site by experts in the particular subject areas. Such offerings have proven to be very cost-effective and efficient. Every major space organization in North America and Europe has taken advantage of Launchspace's Training programs. This includes government agencies such as NASA, USAF and several other offices of the Department of Defense.Course topics cover almost every aspect of space flight from launch vehicle technologies to orbital mechanics to spacecraft design. Our customized courses are offered at client locations in support of mission requirements and to expand the expertise of professional staff members. In addition, a few high-demand public classes are presented for open registration at selected conference locations. Contact us to discuss a customized training program for your professionals:info@launchspace.com
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