This month's AE presenter: James Aubuchon
Date of presentation: 21-March-2022
Subject: Heat Pipes
Description: In this presentation from his "Space Systems" series, on the subject of heat management, Jim talked a bit about heat pipes - the structures designed to move heat energy generated by or radiated onto a system to another area where it is less likely to interfere with the proper operation of the system. Most of these seemed to involve the circulation of some sort of cooling fluid (not necessarily water) from Point A where they pick up heat to Point B where they get rid of it. Unlike a car radiator, however, there is virtually no air cooling in space, and vacuum is an excellent insulator, both of which make the actual heat transfer a bit more complex.
Showing posts with label Space Systems. Show all posts
Showing posts with label Space Systems. Show all posts
21 March 2022
07 February 2022
Presentation: February 2022
This month's AE presenter: James Aubuchon
Date of presentation: 7-Feb-2022
Subject: Space Systems: Heat Management (part 2)
Description: This week, Jim gave the second "half" of his Heat Management presentation. Since he had delivered most of the material in part 1, this became largely a question/answer session. But Jim did break part of the topic away and will talk solely about heat pipes in March.
Date of presentation: 7-Feb-2022
Subject: Space Systems: Heat Management (part 2)
Description: This week, Jim gave the second "half" of his Heat Management presentation. Since he had delivered most of the material in part 1, this became largely a question/answer session. But Jim did break part of the topic away and will talk solely about heat pipes in March.
31 January 2022
Presentation: January 2022
This month's AE presenter: James Aubuchon
Date of presentation: 31-Jan-2022
Subject: Space Systems: Heat Management (part 1)
Description: In this month's presentation, part of the "Space Systems" series, Jim talked about heat management on a space system - how heat has a number of sources, stemming from not only electronics, but also friction from moving parts, as well as radiation from the Sun and other sources. Since a space system cannot be expected to deal with steadily increasing heat indefinitely, pains must be taken not only to generate as little as possible, but also to route the heat energy away from sensitive areas.
Date of presentation: 31-Jan-2022
Subject: Space Systems: Heat Management (part 1)
Description: In this month's presentation, part of the "Space Systems" series, Jim talked about heat management on a space system - how heat has a number of sources, stemming from not only electronics, but also friction from moving parts, as well as radiation from the Sun and other sources. Since a space system cannot be expected to deal with steadily increasing heat indefinitely, pains must be taken not only to generate as little as possible, but also to route the heat energy away from sensitive areas.
Since Jim was unable to complete this presentation in the allotted time, it was continued the following week.
22 February 2021
Presentation: February 2021
This month's AE presenter: James Aubuchon
Date of presentation: 22 Feb 2021
Subject: The Major Subsystems of a Space System
Description: The presentation was an overview of the major subsystems that are a necessary part of any space system. The major subsystems (in this particular classification) are: Structures & Mechanisms, Power, Stabilization, Guidance, & Attitude Control, Orbit Control, Thermal, Communications, Payload (purpose of the spacecraft), Data Handling, Hardware, Software, Propulsion, and Telemetry & Monitoring.
Date of presentation: 22 Feb 2021
Subject: The Major Subsystems of a Space System
Description: The presentation was an overview of the major subsystems that are a necessary part of any space system. The major subsystems (in this particular classification) are: Structures & Mechanisms, Power, Stabilization, Guidance, & Attitude Control, Orbit Control, Thermal, Communications, Payload (purpose of the spacecraft), Data Handling, Hardware, Software, Propulsion, and Telemetry & Monitoring.
It was not possible to discuss each of these in detail. Most of the discussion was devoted to structures & mechanisms and the power subsystem. Several examples of interesting mechanisms were discussed as well as operational tradeoffs in the design of the power subsystem. It was noted that future presentations would discuss the thermal control subsystem and the communications subsystem in greater detail.
23 September 2019
Presentation: September 2019
This month's AE presenter: James AuBuchon
Date of presentation: 23 Sept 2019
Subject: How to Build a Space System III, Orbits
Description: Jim continued his series on how to build a space system with the third installment about orbits.
An orbit is the path taken by a celestial body under the gravitational influence of another body. They may be open or closed. The orbital characteristics of man-made space systems may be selected to best serve the mission of the space system. Closed orbits in a two-body system are ellipses with each body orbiting the barycenter (center of gravity) of the system. If one of the two objects is extremely massive (in comparison to the other), the barycenter may be within the more massive body. Such is the case in the Solar System, the Earth-moon system, and man-made satellites orbiting a planetary body.
Six parameters are required to describe an orbit. The six Newtonian parameters are equivalent to the six Keplerian parameters. Either parameter set can be used. Orbits may be perturbed by a long list of factors, hence the need for station-keeping in man-made satellites. Perturbations can be deliberately introduced to change the orbit for operational reasons. Orbits of man-made satellites are selected to optimize altitude, inclination, and synchronicity with the rotational period of the central body, and eccentricity. These choices represent various operational trade-offs and are selected to suit the mission of the satellite. Some of these trade-offs are discussed in greater detail. Satellites can be caused to orbit about Lagrange points.
Date of presentation: 23 Sept 2019
Subject: How to Build a Space System III, Orbits
Description: Jim continued his series on how to build a space system with the third installment about orbits.
An orbit is the path taken by a celestial body under the gravitational influence of another body. They may be open or closed. The orbital characteristics of man-made space systems may be selected to best serve the mission of the space system. Closed orbits in a two-body system are ellipses with each body orbiting the barycenter (center of gravity) of the system. If one of the two objects is extremely massive (in comparison to the other), the barycenter may be within the more massive body. Such is the case in the Solar System, the Earth-moon system, and man-made satellites orbiting a planetary body.
Six parameters are required to describe an orbit. The six Newtonian parameters are equivalent to the six Keplerian parameters. Either parameter set can be used. Orbits may be perturbed by a long list of factors, hence the need for station-keeping in man-made satellites. Perturbations can be deliberately introduced to change the orbit for operational reasons. Orbits of man-made satellites are selected to optimize altitude, inclination, and synchronicity with the rotational period of the central body, and eccentricity. These choices represent various operational trade-offs and are selected to suit the mission of the satellite. Some of these trade-offs are discussed in greater detail. Satellites can be caused to orbit about Lagrange points.
31 May 2019
Presentation: May 2019
This month's AE presenter: James Aubuchon
Date of presentation: May 2019 (exact date uncertain)
Subject: How to Build a Space System II, the Space Environment Proper
Description: Space is by its nature a difficult environment in which to place and operate any kind of system. The space environment is characterized by high vacuum, temperature extremes, thermal cycling, and low gravity.
Though a small speck can damage a satellite, over 500,000 pieces of orbital debris larger than 10 cm are currently tracked by NASA. There are over 40 known meteor showers that pass through Earth’s upper atmosphere. There are also cosmic rays, micrometeoroids, and other particulates. The chemical environment includes very reactive atomic oxygen and the Van Allen radiation belts. There is an induced environment as the result of venting and outgassing from the space system itself which can interact with the space system.
Space weather variations, due mainly to the Sun, make the environment more challenging. While visible light is approximately constant, X-ray and ultraviolet light are highly variable in time and space.
Solar wind, solar flares, coronal mass ejections, solar energetic particles, x-ray flares, solar radio bursts, & solar proton events are unpredictable and are sometimes huge to monumental. These can react directly with the space system or with the Earth’s magnetosphere to cause geomagnetic storms. They can energize the ionosphere and the Van Allen radiation belts.
Direct effects on the space system may include radiation damage which can cause single event upset, latchup, loss of orientation, execution of phantom commands, and degradation of solar panels. They may result in spacecraft charging with subsequent spark discharge and possible damage. Effects on the atmosphere may result in scintillation of satellite to ground communication.
These are some of the factors which make space a difficult environment. Taken individually, any one might prove hazardous to endurance, navigation, or general operation of a space system. Taken collectively, they make operating any such system in space a massive and yet delicate undertaking.
Date of presentation: May 2019 (exact date uncertain)
Subject: How to Build a Space System II, the Space Environment Proper
Description: Space is by its nature a difficult environment in which to place and operate any kind of system. The space environment is characterized by high vacuum, temperature extremes, thermal cycling, and low gravity.
Though a small speck can damage a satellite, over 500,000 pieces of orbital debris larger than 10 cm are currently tracked by NASA. There are over 40 known meteor showers that pass through Earth’s upper atmosphere. There are also cosmic rays, micrometeoroids, and other particulates. The chemical environment includes very reactive atomic oxygen and the Van Allen radiation belts. There is an induced environment as the result of venting and outgassing from the space system itself which can interact with the space system.
Space weather variations, due mainly to the Sun, make the environment more challenging. While visible light is approximately constant, X-ray and ultraviolet light are highly variable in time and space.
Solar wind, solar flares, coronal mass ejections, solar energetic particles, x-ray flares, solar radio bursts, & solar proton events are unpredictable and are sometimes huge to monumental. These can react directly with the space system or with the Earth’s magnetosphere to cause geomagnetic storms. They can energize the ionosphere and the Van Allen radiation belts.
Direct effects on the space system may include radiation damage which can cause single event upset, latchup, loss of orientation, execution of phantom commands, and degradation of solar panels. They may result in spacecraft charging with subsequent spark discharge and possible damage. Effects on the atmosphere may result in scintillation of satellite to ground communication.
These are some of the factors which make space a difficult environment. Taken individually, any one might prove hazardous to endurance, navigation, or general operation of a space system. Taken collectively, they make operating any such system in space a massive and yet delicate undertaking.
25 March 2019
Presentation: March 2019
This month's AE presenter: James Aubuchon
Date of presentation: 25-Mar-2019
Subject: How to Build a Space System I, Dealing with the Earth’s Atmosphere
Description: A space system must ascend (and possibly descend) through the atmosphere. We must communicate with that system through the atmosphere. Some very small portion of the atmosphere remains even at the altitude of man-made satellites. The atmosphere has layers determined not by arbitrary boundaries, but by physical characteristics. Still, there is more than one layering system.
The best known (Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere) is determined by temperature gradient (not temperature). For example, temperature decreases with altitude in the troposphere and increases with altitude in the stratosphere.
The atmosphere is also layered by chemical composition. The atmosphere can be divided into the lower homosphere in which the atmosphere is well stirred and the higher heterosphere where chemical layering is more pronounced. There is also an ozone layer, and an ionosphere (which, itself, has layers).
There is a lower acoustic zone and a higher anacoustic zone in which sound will not propagate. These classifications schemes overlap one another.
The physical characteristics of the various layers were discussed. The exosphere blends smoothly into outer space where the gravity of the Earth is no longer strong enough to prevent the solar radiation from removing particles from the Earth’s atmosphere.
Date of presentation: 25-Mar-2019
Subject: How to Build a Space System I, Dealing with the Earth’s Atmosphere
Description: A space system must ascend (and possibly descend) through the atmosphere. We must communicate with that system through the atmosphere. Some very small portion of the atmosphere remains even at the altitude of man-made satellites. The atmosphere has layers determined not by arbitrary boundaries, but by physical characteristics. Still, there is more than one layering system.
The best known (Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere) is determined by temperature gradient (not temperature). For example, temperature decreases with altitude in the troposphere and increases with altitude in the stratosphere.
The atmosphere is also layered by chemical composition. The atmosphere can be divided into the lower homosphere in which the atmosphere is well stirred and the higher heterosphere where chemical layering is more pronounced. There is also an ozone layer, and an ionosphere (which, itself, has layers).
There is a lower acoustic zone and a higher anacoustic zone in which sound will not propagate. These classifications schemes overlap one another.
The physical characteristics of the various layers were discussed. The exosphere blends smoothly into outer space where the gravity of the Earth is no longer strong enough to prevent the solar radiation from removing particles from the Earth’s atmosphere.
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