Payloads

In the following section, we briefly describe payload and the principles of dependability, before focusing primarily on the platform, which is more generic with operating principles that are also more generally used for the dependability of the payload. 

The payload of a satellite depends on its mission. We can mainly distinguish satellites scientifics on observation and telecommunications satellites. 

Scientific or observation satellites include one or more instruments (cameras, telescopes, spectrometers, etc.) with associated electronic systems for power, control, or direction of the instruments, and preliminaiy data processing (e g., compression). Given their size and cost, instruments are usually provided without spares on board as there is no redundancy at that level. In contrast the electrical elements and associated electronics usually are redundant. Most often a cold redundancy of two degrees (one active element and an available backup) is set up with a switch (telecommanded from the ground). 

The payload of the telecommunications satellites is different in nature, consisting of a set of electronic processing and signal amplification systems. The desired dependability properties are obtained not by one-for-one redundancy of the elements but by a few additional elements kept in reserve (not powered, in cold redundancy) to replace faulty elements during the mission. The replacement is done using connection matrices to estabhsh the desired paths. When there are no more resources available in reserve, the continuation of the mission is possible in degraded operation (number of channels below the nominal specification) until the capacity of the satellite is considered inadequate in terms of its operating costs and the use of orbital position. 

However, the management of faults on the payload does not remain limited to these local solutions due to interactions with the rest of the satellite  

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After 12-24 hours of reflux the reaction is, for the most part, complete. The reaction mix will be a dark brown. So what does one do about all those brown particles and junk. Well, usually there aren t any. The solution should be uniformly dark. If any solids can be seen it means that they are insoluble in ethanol and can be removed from solution by gravity or vacuum filtration through a coffee filter or some paper towels. If it takes a day to drip through the filter then so-be-it. The ethanol with its payload of isosafrole will... 

The cooled reaction mixture can be induced to crystallize its p-nitropropene payload by simply dumping the whole thing in a large volume of ice water [40],... 

Many terms have been used to describe the contents of a microcapsule active agent, actives, core material, fill, internal phase (IP), nucleus, and payload. Many terms have also been used to describe the material from which the capsule is formed carrier, coating, membrane, shell, or wall. In this article the material being encapsulated is called the core material the material from which the capsule is formed is called the shell material. 

A majority of the fasteners used in automobiles in the United States are coated with microcapsules loaded with an adhesive. When the fastener is installed, a fraction of the capsules in the coating mpture releasing the adhesive payload. The adhesive essentially glues the fasteners in place preventing them from becoming loose and causing rattles. The capsules are designed so that only a fraction of them break each time a fastener is taken off and put back. The on/off cycle can be repeated three or four times. 

Upon the advent of high performance jet-powered aircraft, the fire bomb became obsolete. When deUvered at speeds approaching Mach one (345 m/s), the design characteristics were often grossly exceeded and many units broke up or functioned while stiU on the aircraft. DeHvery from high altitude created craters and deposited most of the flame agent payload in those craters. 

Weight savings can also mean the difference between whether the structure we design can perform its mission or not. The current Space Shuttle payload is limited to 60,000 lb (27,200 kg). If we have an object that we wish to carry up into space that weighs 65,000 lb (29,500 kg), then we are out of luck. That object does not satisfy the Shuttle s weight limit. We must wait for a new-generation Space Shuttle, or sufficient weight in the object to be carried must be saved to fit within the current Space Shuttle limitations. 

For a space structure of any kind, the main concern will probably be with the coefficients of thermal expansion and the various stiffnesses. Most readers are probably aware from various Space Shuttle problems that the Shuttle gets heated more on one side than the other if it does not keep turning around relative to the sun. During one mission, the payload-bay doors were opened, but could not be closed again. The television commentator said that the doors had expanded and were warped so much that they would not fit back into the opening to be locked... 

In order to evaluate one of the issues that is very pertinent to this material selection, the cost to get the truss elements up into space must be known. In 1985, a Shuttle flight cost 90 million. If the Shuttle is capable of carrying a payload of 60,000 lb (27,000 kg), then for every... 

Aiiciah Payload Capacity Top Speed Cruising Speed Fuel Consumption (1000 mile flight) 4D Ratio... 

Payload capacity for civil transports is given in number of passengers for the C-17 it is in pounds. Payloads and cruising speeds were unavailable for the fighter planes. 

It weighs roughly nnc-fifth of Its payload weight. (By comparison, even a small motorcycle weighs more than the rider.)... 

Designafion Numhei o/ Stages Launch Payload PM/LM Comments... 

One of the seemingly obvious ways to cut down the cost is a reusable launch vehicle, such as the Space Shuttle. NA.SA hoped that the enormous cost of the Space Shuttle development would have been compensated by the expected tenfold reduction in the price of putting a payload in orbit. Unfortunately, that goal was not achieved. Despite the Shuttle s unique capabilities, the cost of its payload deliveiy... 

The most advanced among today s projects is the future American reusable launch system known as Venture Star. It utilizes two new concepts that are expected to boost efficiency and cut down the cost of a payload. The first is the single stage-to-orbit concept—the launch vehicle carries the entire propellant load and does not have any expendable parts. The latter is planned to be achieved by a revolutionary rocket engine design called Aerospike. The bell-shaped noz-... 

A block train consists of a series of rail tank cars of either 45 tons glw or 100 tons glw (or a mixture of both) coupled for movement from source to destination and back as a unit. The size of the trains will be determined by contractual agreement, but will never be less than 300 tons payloads, and will normally be 500 tons. 

Missile payload varies from nuclear, through HE fitted with proximity fuzes, to chemical warheads. Electronic countermeasures equip-... 

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