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	Heat shield Info - Bored Net - Boredom (Site not responding. Last check: 2007-09-10)
		In aeronautics, a heat shield is a protective layer on a spacecraft or ballistic missile that is designed to protect it from high temperatures, usually those that result from aerobraking during entry into a planet's atmosphere.
		However the atmosphere between the heat shield and the shock wave is under very high pressure turning it from a gas to a very hot plasma.
		The simplest and cheapest type of heat shield is the ablative heat shield, which dissipates heat from the plasma by allowing its outer layers to vaporize.
	www.borednet.com /e/n/encyclopedia/h/he/heat_shield.html (593 words)

	Heat shield
		In aeronautics, a heat shield is a protective layer on a spacecraft designed to protect it from the high temperatures, usually those that result from aerobraking during entry into a planet's atmosphere.
		The simplest and cheapest type of heat shield is the ablative heat shield, which dissipates heat by allowing its outer layers to vaporize.
		Various advanced reusable spacecraft designs have been proposed recently that employ heat shields made from temperature-resistant metal alloys, some of them including active cooling systems in which water or cryogenic fuel is circulated over or through them.
	www.ebroadcast.com.au /lookup/encyclopedia/he/Heat_shield.html (287 words)

	Ablative heat shield
		Ablative heat shields have been used by spacecraft to allow safe re-entry into the Earth's atmosphere.
		They operate the same way ice cubes in a soda drink do: as the temperature rises from atmospheric friction kinetic energy is converted into heat and the ablative material undergoes a phase change[?] (vaporises from solid to gaseous).
		All of the early spacecraft used ablative technologies to assist with the transition from high orbital speeds down to aerodynamic regimes where a spacecraft can be flown or parachuted to safety.
	www.ebroadcast.com.au /lookup/encyclopedia/ab/Ablative_heat_shield.html (120 words)

	Structural Description
		The heat shield is a dish-shaped structure that forms the large end of the reentry module.
		The ablative substance of the Gemini heat shield is a paste-like material which hardens in standard atmosphere after being poured into a honeycomb form.
		A honeycomb blast shield between the two sections protects the equipment section and the dome of the Titan launch vehicle from excessive (explosion-causing) heat should it be necessary to fire the retrorockets in an abort condition.
	www.apollosaturn.com /geminiNR/sec1.htm (1844 words)

	reentry vehicle
		Clearly the problem of reentry to Earth's atmosphere was a significant challenge for the early spaceflight researchers, as they considered how best to overcome the heat generated by friction as a spacecraft slowed in the atmosphere.
		GE decided to use the heat-sink concept, whereby the heat of reentry was conducted from the surface of the vehicle to a mass of material that could soak it up quickly.
		Blunt body designs and improved ablative materials were also used on the Gemini and Apollo spacecraft, advancing rapidly during the 1960s.
	www.daviddarling.info /encyclopedia/R/reentry_vehicle.html (1461 words)

	Gemini Technical Description
		It was heated to a gaseous state by a heat exchanger, passed to a pressure reducing regulator, then on to the cabin pressure regulator which automatically maintained cabin pressure as desired for the mission.
		The Gemini spacecraft was brought to a "pilot heads-up" position causing it to impact the water at the edge of the heat shield.
		During orbit, the adapter section also served as a space radiator or heat exchanger for the dissipation of internally generated heat; therefore, the exterior surface of that part of the spacecraft had a very low solar absorption and a very high infrared thermal emittance to maintain its desired temperature characteristics.
	www.astronautix.com /articles/gemption.htm (16762 words)

	Mars Exploration Rover Mission: The Mission
		The heat shield protects the lander and rover from the intense heat from entry into the Martian atmosphere and aerodynamically acts as the first "brake" for the spacecraft.
		It was invented for the heat shields flown on the Viking Mars lander missions 25 years ago.
		Both the backshell and heat shield are made of the same materials, but the heat shield has a thicker (1/2 in) layer of the ablator.
	mars.jpl.nasa.gov /mer/mission/spacecraft_edl_aeroshell.html (533 words)

	Antenna window assembly for ablative heat shields - Patent 4006480
		In space and other vehicles utilizing ablative heat shielding, it is frequently necessary to transmit and receive information and data via radio frequency instruments aboard the vehicle.
		Varying density in the heat shield by the incorporation of windows or other devices necessarily tends to vary the ablation rate of the shield and in particular in those areas where substitute materials are used.
		The heat shield is constructed with an appropriately shaped aperture consistant with the requirement for the antenna or other device whose needs the window is intended to serve.
	www.freepatentsonline.com /4006480.html (1058 words)

	Strange Horizons Articles: Surfing Hell at Mach Twenty-Five: The Science and Speculation of Atmospheric Reentry, by ...
		A wide, rounded disk was found to be the most efficient shape for this type of heat shield, as it creates a shockwave just ahead of the vehicle that more readily deflects the heat away from the craft.
		These shields are usually made of heat-resistant polymer resins saturated with glass fibers or glass microspheres, and are designed to slough away millimeter by millimeter as they are charred or vaporized away by the heat.
		Heat sinks and refrigeration systems, spurned by designers early in the space age as too heavy, may see a resurgence on military dropships, in order for the vehicle to take advantage of steeper reentry angles to greatly reduce the amount of time it may be exposed to enemy fire.
	www.strangehorizons.com /2006/20060102/surfing-hell-a.shtml (3475 words)

	Apollo Expeditions to the Moon: Chapter 4
		The command module was compact, solid, and sturdy, designed with one overriding consideration: to survive the fiery heat of reentry as it abandoned the service module and slammed back into the atmosphere at the tremendous speed of 25,000 miles an hour.
		In fact, there is enough energy at reentry to melt and vaporize all the material in the command module several times over, so the spacecraft had to be protected by an ablative heat shield that charred and slowly burned away, thereby protecting all that it surrounded.
		The command module was also crammed with equipment and subsystems; and of course three men lived in it for most of the lunar journey, and one of them for all of it.
	www.solarviews.com /history/SP-350/ch-4-2.html (657 words)

	Method of coating with ablative heat shield materials - Patent 4112179
		Heretofore in the art of forming ablative heat shield coatings, one method utilized expensive pressure molds or dies into which batches of materials were placed and vacuum cured at 300.degree.
		This marked advance in the reduction of ablative heat shield coating density vastly improves the desired characteristics by lowering thermal conductivity, reducing the ablator weight and possibly increasing flexibility and elongation.
		The ablative composition of this invention may also be used as a peelable layer for use at locations other than the surface that had been sprayed.
	www.freepatentsonline.com /4112179.html (2994 words)

	Clavius: Bibliography - glossary
		An ablative heat shield is one in which the shield material itself vaporizes and takes the heat away with it as it goes.
		The Apollo command module used an ablative heat shield made of a resinous material held in an aluminum honeycomb.
		A technique for controlling the radiant heating of a spacecraft by slowly rotating it so that the sun does not always shine on the same side.
	www.clavius.org /bibdict.html (2374 words)

	Reentry Vehicle Technology
		Julian Allen is best known for his "blunt body theory" of aerodynamics, a design technique for alleviating the severe reentry heating problem that was then delaying the development of ballistic missiles.
		Julian Allen pioneered and developed the Blunt Body Theory that made possible the heat shield designs that were embodied in the Mercury, Gemini, and Apollo space capsules, enabling astronauts to survive the fiery reentry into the Earth's atmosphere.
		A blunt body produces a shockwave in front of the vehicle-visible in the photo-that actually shields the vehicle from excessive heating.
	www.centennialofflight.gov /essay/Evolution_of_Technology/reentry/Tech19.htm (1642 words)

	ESA - ESA Permanent Mission in Russia - Perfect landing of Soyuz TMA-3
		The Descent Module's computers oriented the capsule with its ablative heat shield pointing forward to repel the buildup of heat as it plunged into the atmosphere (at 23:48:18).
		Within minutes, at an altitude of a little more than 5 kilometers, the crew monitored the jettison of the Descent Module's heat shield, which was followed by the termination of the aerodynamic spin cycle and the dumping of any residual propellant from the Soyuz.
		With the jettisoning of the capsule's heat shield, the Soyuz altimeter was exposed to the surface of the Earth.
	www.esa.int /esaMI/ESA_Permanent_Mission_in_Russia/SEMPSS9DFZD_0.html (665 words)

	Ongoing H3 arc heater developmental testing hits major milestone, sets record
		The objective of this testing is to cause ablation, which is a burning away of the protective covering of a missile nose tip or the leading edge of a spacecraft, hypersonic aircraft or reentry vehicle.
		Ablation is a normal, expected re-entry phenomenon, and the use of an ablative heat shield is often the only way to protect a vehicle during reentry.
		Because energy is absorbed as the heat shield surface is vaporized, energy, which would have been absorbed by the craft is absorbed in the ablation process.
	www.blackanthem.com /scitech/military_2006041807.html (1236 words)

	NSSDC Master Catalog Display: Spacecraft (Site not responding. Last check: 2007-09-10)
		This was the second uncrewed Gemini test mission, consisting of a sub-orbital ballistic flight and reentry with the primary objectives being to demonstrate the adequacy of the spacecraft reentry module's heat protection during a maximum heating rate return, the structural integrity of the spacecraft, and the performance of spacecraft systems.
		Separating the reentry module from the retrorocket section of the adaptor at its base was a curved silicone elastomer ablative heat shield.
		Along with the ablative heat shield, thermal protection during reentry was provided by thin Rene 41 radiative shingles at the base of the module and beryllium shingles at the top.
	nssdc.gsfc.nasa.gov /database/MasterCatalog?sc=GEMINI2 (924 words)

	Ablative heat shield: Definition and Links by Encyclopedian.com
		They were Tom and Boston, two half-brothers, Harry Armstrong Reed, a nephew and a brother-in-law, James Calhoun.
		...Ablative heat shield Ablative heat shield Ablative heat shields have been used...into heat and the ablative material undergoes a Phase-change Phase change phase change (vaporises...solid to gaseous).
		...cheapest type of heat shield is the ablative heat shield, which dissipates heat by allowing its outer layers to...able to survive multiple reentries with only minor repairs between missions.
	www.encyclopedian.com /ab/Ablative-heat-shield.html (275 words)

	MOOSE (Site not responding. Last check: 2007-09-10)
		It consisted of a small twin-nozzle rocket motor sufficient to deorbit the astronaut, a mylar bag six feet (1.8 metres) long with a flexible quarter-inch-thick ablative heat shield on the back, two pressurized canisters to fill it with polyurethane foam, and a parachute, radio Equipment and a survival kit.
		The foam heat shield would serve a final role as cushioning when the astronaut touches down, and as a flotation device should he land on water.
		General Electric performed preliminary testing on some of the components of the MOOSE system, including flying samples of heat shield material on a Mercury mission, inflating a foam-filled bag with a human subject embedded inside, and test-dropping dummies in MOOSE foam shields short distances.
	moose.iqnaut.net (420 words)

	Space Cowboy Saloon
		One other side-effect of this extreme aerodynamic heating is that the air around the capsule becomes so hot that it ionizes, making communications between the capsule and the ground impossible for a few minutes, until the capsule has slowed down and the air around it cools.
		These were attached to the heat shield end of the capsule with metal straps.
		An inflatable device known as a landing bag would be deployed between the heat shield and the capsule, and the capsule would slowly descend to the sea on its main parachute.
	groups.msn.com /SpaceCowboySaloon/howdy.msnw (1198 words)

	NASA - The Fiery Return of NASA's Space Dust Cargo
		The special carbon-based heat shield material designed to protect the Stardust capsule is a candidate for potential inclusion on NASA's next planned spaceship, the Crew Exploration Vehicle (CEV), NASA engineers say.
		"Our main interest is the performance of the heat shield and the chemistry that takes place in it as it vaporizes and erodes during the descent and re-entry," said Dave Jordan, a NASA Ames engineer and project manager for the capsule observation mission.
		The trail may form a thin line behind the capsule, especially near the point of peak brightness where ablation (erosion of the heat shield and dissipation of the heat that results from the friction of the heat shield with the atmosphere) is most intense.
	www.nasa.gov /centers/ames/research/exploringtheuniverse/stardust.html (2069 words)

	:: NASA Quest > Archives :: (Site not responding. Last check: 2007-09-10)
		The total weight of the forebody heat shield is 335 pounds, of which 193 pounds are expected to be vaporized during entry.
		Additional detailed technical information on the heat shield is available at the end of this section.
		When the heat shield has slowed the Probe to a speed of 1,800 mph explosive nuts fire to release the aft cover, which in turn pulls out the bag of the main parachute.
	quest.arc.nasa.gov /galileo/features/probesquash.html (4666 words)

	Mission 2004: Team One Propulsion Systems
		At the start of the IPP's descent to the Martian surface, a heat shield will be employed to ensure that the package will not burn up in the Martian atmosphere.
		At an altitude of 110 km, the heat shield will jettison, uncovering a liquid propellant rocket and landing legs.
		Six landing legs, previously tucked behind the ablative heat shield, will deploy to softly land the descent configuration on the Martian surface.
	web.mit.edu /12.000/www/finalpresentation/DARTS/landsolution.html (426 words)

	The Space Shuttle Orbiter and Ceramic Tiles - Some History and Information (Site not responding. Last check: 2007-09-10)
		The ablative heat shields used on Apollo command modules returning astronauts from the Moon were priced at $30,000 per square foot, and were used only once.
		HRSI or FRCI tiles are used to protect the forward fuselage from the heat radiated from the hot inside surface of the RCC.
		In ablative technology, the surface of the heat shield melts and vaporizes, and in the process, it carries away heat.
	www.freerepublic.com /focus/news/834596/posts (3983 words)

	Howstuffworks "How Project Mercury Worked"
		On the blunt end of the spacecraft there was a heat shield, which protected the capsule from the heat of re-entry, and a retro-pack, which were small rocket thrusters that slowed the spacecraft down for re-entry.
		The structure of the shield was honeycombed aluminum with many layers of glass-fiber material.
		As the spacecraft descended, the material of the heat shield boiled away, taking the heat away with it.
	science.howstuffworks.com /project-mercury2.htm (674 words)

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