Satellite maneuvering

Energy systems in space technology are devices that convert one kind of energy into another to ensure the functioning of automated and piloted satellites, interplanetary probes, and other kinds of spacecraft. Multiple functions of any spacecraft require two distinctly different energy sources propulsion for launch and maneuvers, and electricity supply to power the onboard equipment. 

Rocket engines arc also used for maneuvers in space. Some operations, such as a onetime transfer of a satellite from lower to higher orbit, could be performed by a solid-propellant engine. Yet many complex maneuvers, such as rendezvous and docking with another spacecraft, require multiple engine firings and variable power impulses. Hence modern spacecraft are equipped with an assortment of attitude control engines that usually use liquid storable propellant. 

System Hazards (1) Ihe satellite does not reach a useful geosynchronous orbit (2) the satellite is damaged during orbit insertion maneuvers and cannot provide its intended function. 

Propulsion System. The propulsion system performs occasional maneuvers required to keep Earthorbiting satellites on station or interplanetary probes on course. The propulsion system consists of rocket thrusters, propellant, pumps, valves, and pressure vessels. Attitude control thrusters control the rotational dynamics of the spacecraft. Course correction thrusters change the speed or direction of motion of the spacecraft. The propellant must be storable for long periods of time under the harsh conditions of space. Special pressurization techniques are necessary to move liquid propellants from tanks to thrusters in zero gravity. The spacecraft must carry enough propellant for the planned mission lifetime plus a reserve necessary for deorbit at end of life. 

This satellite also only required small station keeping maneuvers, which were easily achievable with the vane. The HS 601 Block n satellite design completed in 1997 used a simple four vane arm PMD in its main propellant tank (Tam et al., 1998). This design was similar to its predecessor, except the longer cylindrical tank required longer vane arms and a slightly more complex trap assembly. 

Compared with the case of the satellite, the main additional constraint is therefore the first phase, the success of which determines the following phase, the success of which must obey the reliability targets similar to those of a satellite (often over shorter periods, for example from 2 to 5 years, but with a system that already had the opportunity to fail and lose some redundancy in an environment often more aggressive than in the Earth s orbit, and with the constraints of mass, consumption and ground-onboard liaisons often stronger than in the Earth s orbit). The difficulties of the additional transport phase, besides the abovementioned constraints, come from the fact that there are often periods with very strong requirements for instantaneous availability (see section 7.4.2 below), for example, maneuvers for gravitational attraction or oibit insertion. 

March 1965 NASA Gemini 3 First attempt to maneuver satellite in space (V. Grisson and J. Young, three orbits). 

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