# Mission characteristic velocity

Mission characteristic velocity

The mission characteristic velocity (also mission velocity or characteristic velocity) is an important parameter describing space missions. It is the total velocity change needed (the sum of all maneuvers) to accomplish the mission, typically given in km/s. To achieve low earth orbit it is approximately 8 km/s, while to escape from Earth needs 11.2 km/s, both ideal minimus figures for neglecting various inefficiencies that typically range from 10% to 20%. For the Apollo lunar landings with return to Earth it was of the order of 20 km/s.

Because the mass ratio required for a given mission is exponential in the mission velocity divided by the effective exhaust velocity of the rocket propulsion system, high mission velocities rapidly become extremely expensive for chemical rockets, so that the mission velocity, along with the payload, is a key parameter in assessing the overall difficulty of a given mission. Missions that would at first appear to be infeasible due to high mission velocity can sometimes be done by means of various tricks, such as gravity assist encounters with planets along the way, aerobraking, staging to intermediate bases, etc. Some of these have been described in the large literature of astronautics, e.g. Arthur C Clarke's Interplanetary Flight, and many others.

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• characteristic velocity — Aerospace. 1. a measure of the effectiveness with which the combustion in a rocket engine produces high temperature and pressure, equal to the exhaust velocity divided by the thrust coefficient. 2. the total of all velocities a space vehicle must …   Universalium

• characteristic velocity — Aerospace. 1. a measure of the effectiveness with which the combustion in a rocket engine produces high temperature and pressure, equal to the exhaust velocity divided by the thrust coefficient. 2. the total of all velocities a space vehicle must …   Useful english dictionary

• Characteristic energy — In astrodynamics a characteristic energy ( ), a form of specific energy, is a measure of the energy required for an interplanetary mission that requires attaining an excess orbital velocity over an escape velocity required for additional orbital… …   Wikipedia

• Space tether — Artist s conception of satellite with a tether Space tethers are cables, usually long and very strong, which can be used for propulsion, stabilization, or maintaining the formation of space systems by determining the trajectory of spacecraft and… …   Wikipedia

• Interstellar travel — Montage of fusion powered rocket concepts from 1987–2004, which could form the basis for an interstellar vehicle. Included are: VISTA (Lawrence Livermore National Laboratories,1987), Discovery II (NASA/GRC, 2002), Human Outer Planet Exploration… …   Wikipedia

• Tether propulsion — systems are proposals to use long, very strong cables (known as tethers) to change the velocity of spacecraft. The tethers may be used to initiate launch, complete launch, or alter the orbit of a spacecraft. Spaceflight using this form of… …   Wikipedia

• Non-rocket spacelaunch — Non rocket space launch (NRS) is a launch into space where some or all needed speed and altitude is provided by non rocket means, rather than simply using conventional chemical rockets from the ground. A number of alternatives to rockets have… …   Wikipedia

• Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics       Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity.       Computer scientist Manindra Agrawal of the… …   Universalium

• Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry       The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… …   Universalium

• Spacecraft propulsion — A remote camera captures a close up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is any method used to accelerate spacecraft and artificial… …   Wikipedia