Sunday, May 20, 2012

Spacecraft

A spacecraft is a vehicle or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters outer space but then returns to the planetary surface (such as Earth) without making a complete orbit. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflights carry people on board as crew or passengers. Spacecraft used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft that leave the vicinity of the planetary body are space probes. Robotic spacecraft that remain in orbit around the planetary body are artificial satellites. Starships, which are built for interstellar travel, are so far a theoretical concept only.

Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and space tourism. Spacecraft and space travel are common themes in works of science fiction.

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Spacecraft subsystems

A spacecraft system comprises various subsystems, dependent upon mission profile. Spacecraft subsystems may include: attitude determination and control (variously called ADAC, ADC or ACS), guidance, navigation and control (GNC or GN&C), communications (COMS), command and data handling (CDH or C&DH), power (EPS), thermal control (TCS), propulsion, structures, and payload.
Life support
Spacecraft intended for human spaceflight must also include a life support system for the crew.
Attitude control
Spacecraft need an attitude control subsystem to be correctly oriented in space and respond to external torques and forces properly. The attitude control subsystem consists of sensors and actuators, together with controlling algorithms. The attitude control subsystem permits proper pointing for the science objective, sun pointing for power to the solar arrays and earth-pointing for communications.
GNC
Guidance refers to the calculation of the commands (usually done by the CDH subsystem) needed to steer the spacecraft where it is desired to be. Navigation means determining a spacecraft's orbital elements or position. Control means adjusting the path of the spacecraft to meet mission requirements. On some missions, GNC and Attitude Control are combined into one subsystem of the spacecraft.
Command and data handling
The CDH subsystem receives commands from the communications subsystem, performs validation and decoding of the commands, and distributes the commands to the appropriate spacecraft subsystems and components. The CDH also receives housekeeping data and science data from the other spacecraft subsystems and components, and packages the data for storage on a solid state recorder or transmission to the ground via the communications subsystem. Other functions of the CDH include maintaining the spacecraft clock and state-of-health monitoring.
Power
Spacecraft need an electrical power generation and distribution subsystem for powering the various spacecraft subsystems. For spacecraft near the Sun, solar panels are frequently used to generate electrical power. Spacecraft designed to operate in more distant locations, for example Jupiter, might employ a Radioisotope Thermoelectric Generator (RTG) to generate electrical power. Electrical power is sent through power conditioning equipment before it passes through a power distribution unit over an electrical bus to other spacecraft components. Batteries are typically connected to the bus via a battery charge regulator, and the batteries are used to provide electrical power during periods when primary power is not available, for example when a Low Earth Orbit (LEO) spacecraft is eclipsed by the Earth.
Thermal control
Spacecraft must be engineered to withstand transit through the Earth's atmosphere and the space environment. They must operate in a vacuum with temperatures potentially ranging across hundreds of degrees Celsius as well as (if subject to reentry) in the presence of plasmas. Material requirements are such that either high melting temperature, low density materials such as Be and C-C or (possibly due to the lower thickness requirements despite its high density) W or ablative C-C composites are used. Depending on mission profile, spacecraft may also need to operate on the surface of another planetary body. The thermal control subsystem can be passive, dependent on the selection of materials with specific radiative properties. Active thermal control makes use of electrical heaters and certain actuators such as louvers to control temperature ranges of equipments within specific ranges.
Propulsion
Spacecraft may or may not have a propulsion subsystem, depending upon whether or not the mission profile calls for propulsion. The Swift spacecraft is an example of a spacecraft that does not have a propulsion subsystem. Typically though, LEO spacecraft (for example Terra (EOS AM-1) include a propulsion subsystem for altitude adjustments (called drag make-up maneuvers) and inclination adjustment maneuvers. A propulsion system is also needed for spacecraft that perform momentum management maneuvers. Components of a conventional propulsion subsystem include fuel, tankage, valves, pipes, and thrusters. The TCS interfaces with the propulsion subsystem by monitoring the temperature of those components, and by preheating tanks and thrusters in preparation for a spacecraft maneuver.
Structures
Spacecraft must be engineered to withstand launch loads imparted by the launch vehicle, and must have a point of attachment for all the other subsystems. Depending upon mission profile, the structural subsystem might need to withstand loads imparted by entry into the atmosphere of another planetary body, and landing on the surface of another planetary body.
Payload
The payload is dependent upon the mission of the spacecraft, and is typically regarded as the part of the spacecraft "that pays the bills". Typical payloads could include scientific instruments (cameras, telescopes, or particle detectors, for example), cargo, or a human crew.
Ground segment
The ground segment, though not technically part of the spacecraft, is vital to the operation of the spacecraft. Typical components of a ground segment in use during normal operations include a mission operations facility where the flight operations team conducts the operations of the spacecraft, a data processing and storage facility, ground stations to radiate signals to and receive signals from the spacecraft, and a voice and data communications network to connect all mission elements.
Launch vehicle
The launch vehicle is used to propel the spacecraft from the Earth's surface, through the atmosphere, and into an orbit, the exact orbit being dependent upon mission configuration. The launch vehicle may be expendable or reusable.

Sumber:
1. Wikipedia
2. http://astrophysicsblogs.blogspot.com/2008/09/25.html
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Friday, May 18, 2012

Aeronautics and Astronautics Engineering Course from MIT




Professors, students, and researchers come to MIT from all corners of the globe to explore their passion for air and space travel and to advance the technologies and vehicles that make such travel possible.

We build on our long tradition of scholarship and research to develop and implement reliable, safe, economically feasible, and environmentally responsible air and space travel.

Our industry contributions and collaborations are extensive. We have graduated more astronauts than any other private institution in the world. Nearly one-third of our current research collaborations are with MIT faculty in other departments, and approximately one-half are with non-MIT colleagues in professional practice, government agencies, and other universities. We work closely with scientists and scholars at NASA, Boeing, the U.S. Air Force, Stanford University, Lockheed Martin, and the U.S. Department of Transportation.

Our educational programs are organized around three overlapping areas:

Aerospace information engineering

Focuses on real-time, safety-critical systems with humans-in-the-loop. Core disciplines include autonomy, software, communications, networks, controls, and human-machine and human-software interaction.

Aerospace systems engineering

Explores the central processes in the creation, implementation, and operation of complex socio-technical engineering systems. Core disciplines include system architecture and engineering, simulation and modeling, safety and risk management, policy, economics, and organizational behavior.

Aerospace vehicles engineering

Addresses the engineering of air and space vehicles, their propulsion systems, and their subsystems. Core disciplines include fluid and solid mechanics, thermodynamics, acoustics, combustion, controls, computation, design, and simulation.

Department of Aeronautics and Astronautics links

Visit the MIT Department of Aeronautics and Astronautics home page at:
http://web.mit.edu/aeroastro/www/
Review the MIT Department of Aeronautics and Astronautics curriculum at:
http://ocw.mit.edu/OcwWeb/web/resources/curriculum/index.htm#16
Learn more about MIT Engineering:
http://engineering.mit.edu/
Sumber:
1.  MIT Department of Aeronautics and Astronautics
2.  http://astrophysicsblogs.blogspot.com/2008/09/7.html
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Saturday, May 5, 2012

Aerospace Engineering Topics

 

Overview

Modern flight vehicles undergo severe conditions such as differences in atmospheric pressure and temperature, or heavy structural load applied upon vehicle components. Consequently, they are usually the products of various technologies including aerodynamics, avionics, materials science and propulsion. These technologies are collectively known as aerospace engineering. Because of the complexity of the field, aerospace engineering is conducted by a team of engineers, each specializing in their own branches of science., The development and manufacturing of a flight vehicle demands careful balance and compromise between abilities, design, available technology and costs.

Elements

See also: List of aerospace engineering topics
Some of the elements of aerospace engineering are:
  • Fluid mechanics - the study of fluid flow around objects. Specifically aerodynamics concerning the flow of air over bodies such as wings or through objects such as wind tunnels (see also lift and aeronautics).
  • Astrodynamics - the study of orbital mechanics including prediction of orbital elements when given a select few variables. While few schools in the United States teach this at the undergraduate level, several have graduate programs covering this topic (usually in conjunction with the Physics department of said college or university).
  • Statics and Dynamics (engineering mechanics) - the study of movement, forces, moments in mechanical systems.
  • Mathematics - because aerospace engineering heavily involves mathematics.
  • Electrotechnology - the study of electronics within engineering.
  • Propulsion - the energy to move a vehicle through the air (or in outer space) is provided by internal combustion engines, jet engines and turbomachinery, or rockets (see also propeller and spacecraft propulsion). A more recent addition to this module is electric propulsion and ion propulsion.
  • Control engineering - the study of mathematical modeling of the dynamic behavior of systems and designing them, usually using feedback signals, so that their dynamic behavior is desirable (stable, without large excursions, with minimum error). This applies to the dynamic behavior of aircraft, spacecraft, propulsion systems, and subsystems that exist on aerospace vehicles.
  • Aircraft structures - design of the physical configuration of the craft to withstand the forces encountered during flight. Aerospace engineering aims to keep structures lightweight.
  • Materials science - related to structures, aerospace engineering also studies the materials of which the aerospace structures are to be built. New materials with very specific properties are invented, or existing ones are modified to improve their performance.
  • Solid mechanics - Closely related to material science is solid mechanics which deals with stress and strain analysis of the components of the vehicle. Nowadays there are several Finite Element programs such as MSC Patran/Nastran which aid engineers in the analytical process.
  • Aeroelasticity - the interaction of aerodynamic forces and structural flexibility, potentially causing flutter, divergence, etc.
  • Avionics - the design and programming of computer systems on board an aircraft or spacecraft and the simulation of systems.
  • Risk and reliability - the study of risk and reliability assessment techniques and the mathematics involved in the quantitative methods.
  • Noise control - the study of the mechanics of sound transfer.
  • Flight test - designing and executing flight test programs in order to gather and analyze performance and handling qualities data in order to determine if an aircraft meets its design and performance goals and certification requirements.
The basis of most of these elements lies in theoretical mathematics, such as fluid dynamics for aerodynamics or the equations of motion for flight dynamics. However, there is also a large empirical component. Historically, this empirical component was derived from testing of scale models and prototypes, either in wind tunnels or in the free atmosphere. More recently, advances in computing have enabled the use of computational fluid dynamics to simulate the behavior of fluid, reducing time and expense spent on wind-tunnel testing.
 
Additionally, aerospace engineering addresses the integration of all components that constitute an aerospace vehicle (subsystems including power, communications, thermal control, life support, etc.) and its life cycle (design, temperature, pressure, radiation, velocity, life time).
 
  1. ^ a b Stanzione, Kaydon Al (1989). "Engineering". Encyclopædia Britannica (15) 18. 563–563.
  2. ^ "Career: Aerospace Engineer". Career Profiles. The Princeton Review. Retrieved on 2006-10-08. "Due to the complexity of the final product, an intricate and rigid organizational structure for production has to be maintained, severely curtailing any single engineer's ability to understand his role as it relates to the final project."
  3. ^ Kermit Van Every (1988). "Aeronautical engineering". Encyclopedia Americana 1. Grolier Incorporated.
  4. ^ A Brief History of NASA
  5. ^ "Science: Engineering: Aerospace". Open Site. Retrieved on 2006-10-08.
  6. ^ a b Gruntman, Mike (September 19, 2007). "The Time for Academic Departments in Astronautical Engineering" in AIAA SPACE 2007 Conference & Exposition. AIAA SPACE 2007 Conference & Exposition Agenda, AIAA.
  7. ^ USNews.com: America's Best Colleges 2008: Aerospace / Aeronautical / Astronautical
  8. ^ USNews.com: America's Best Colleges 2008: Aerospace / Aeronautical / Astronautical
 Sources:
2.Wikipedia
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Tuesday, May 1, 2012

Aerospace Engineering

Photo by: NASA

Aerospace engineering is the branch of engineering behind the design, construction and science of aircraft and spacecraft. Aerospace engineering has broken into two major and overlapping branches: aeronautical engineering and astronautical engineering. The former deals with craft that stay within Earth's atmosphere, and the latter deals with craft that operate outside of Earth's atmosphere. While "aeronautical" was the original term, the broader "aerospace" has superseded it in usage, as flight technology advanced to include craft operating in outer space. Aerospace engineering is often informally called rocket science.

Contents

Aerospace engineering is a complex, rapidly changing field whose primary application is the design and development of flight vehicles such as aircraft, missiles, spacecraft and satellites.


Aerospace engineering is also important and applicable to other vehicles and systems such as submarines, automobiles, trucks and rapid transit, and can include advanced robotics, exotic materials and computational simulations.


The goals of Indonesia Aerospace Engineering School, aerospace engineering program are to:

(a) using a high quality faculty, provide a comprehensive aerospace engineering education that develops in students the fundamental skills necessary for the design, synthesis, analysis and research development of aircraft, spacecraft and other high technology flight systems; and

(b) prepare students for the aerospace engineering profession and related fields by developing in them the attributes needed so that they can contribute successfully to society and the engineering profession now and in the future.

The curriculum includes

(a) sciences and mathematics to provide a foundation for engineering, aerospace engineering and design; and

(b) humanities, social sciences, visual and performing arts, and international and cultural diversity topics to ensure an awareness of cultural heritage.

In the junior and senior years, coursework includes aerodynamics, structures and materials, propulsion, dynamics and control, and astrodynamics. These studies provide a strong fundamental basis for specialization and advanced study, while technical electives allow exploration of special interests.

Advanced courses emphasize new technologies and skills, and a senior-level design-build-fly sequence requires students to work in teams to design an aerospace system, such as an aircraft, rocket, or spacecraft.
All courses utilize modern computational tools. The department has an extensive array of computing resources including PCs and workstations.

Studies are supported by well-equipped laboratories: water and wind tunnels for aerodynamic analysis, a jet engine test facility, research aircraft, a flight simulator, and a state-of-the-art materials and structures testing facility. 
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