Orbit insertion

Orbit insertion is the spaceflight operation of adjusting a spacecraft’s momentum to allow for entry into a stable orbit around a planet, moon, or other celestial body.[1] This maneuver involves either deceleration from a speed in excess of the respective body’s escape velocity, or acceleration to it from a lower speed.

Contents

Deceleration

The first kind of orbit insertion is used when capturing into orbit around a celestial body other than Earth, owing to the excess speed of interplanetary transfer orbits relative to their destination orbits. This shedding of excess velocity is typically achieved via a rocket firing known as an orbit insertion burn. For such a maneuver, the spacecraft’s engine thrusts in its direction of travel for a specified duration to slow its velocity relative to the target body enough to enter into orbit.[2] Another technique, used when the destination body has a tangible atmosphere, is called aerobraking, which uses the friction of atmospheric drag to slow a spacecraft. Generally aerobraking is used to circularize a highly elliptical capture orbit while minimizing the use of on board fuel. To date, only a handful of aerocapture maneuvers have been attempted by NASA.[3]

Acceleration

The second type of orbit insertion is used for newly launched satellites and other spacecraft. The majority of space launch vehicles used today can only launch a payload into a very narrow range of orbits. The angle relative to the equator and maximum altitude of these orbits are constrained by the rocket and launch site used. Given this limitation, most payloads are first launched into a transfer orbit, where an additional thrust maneuver is required to circularize the elliptical orbit which results from initial space launch. The key difference between this kind of maneuver and powered trans-planetary orbit insertion is the significantly lesser change in velocity required to raise or circularize an existing planetary orbit, versus canceling out the considerable velocity of interplanetary cruise.

Alternatives to rockets

Although current orbit insertion maneuvers require precisely timed burns of conventional chemical rockets, some headway has been made towards the use of alternative means of stabilizing orbits, such as ion or plasma thrusters to achieve the same result using less fuel over a longer period of time. In addition, research into the use of electrically conducting space tethers to magnetically repel the Earth’s magnetic field has shown some promise, which would virtually eliminate the need for fuel altogether.

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Lunar Orbit Insertion — (LOI) is an orbital maneuver by means of which a spacecraft in placed on a selenocentric orbit …   Wikipedia

  • insertion — Synonyms and related words: Earth insertion, LEM, LM, access, admission, apogee, aside, attitude control rocket, ballistic capsule, booking, burn, capsule, cataloging, chronicling, deep space ship, docking, docking maneuver, enlistment,… …   Moby Thesaurus

  • orbit — Synonyms and related words: Earth insertion, LEM, LM, O, air lane, ambit, annular muscle, annulus, aphelion, apogee, area, arena, areola, astronomical longitude, attitude control rocket, aureole, autumnal equinox, bailiwick, ball, ballistic… …   Moby Thesaurus

  • insertion — n. 1 the act or an instance of inserting. 2 an amendment etc. inserted in writing or printing. 3 each appearance of an advertisement in a newspaper etc. 4 an ornamental section of needlework inserted into plain material (lace insertions). 5 the… …   Useful english dictionary

  • Geostationary transfer orbit — A Geosynchronous Transfer Orbit or Geostationary Transfer Orbit (GTO) is a Hohmann transfer orbit around the Earth between a low Earth orbit (LEO) and a geosynchronous orbit (GEO). It is an ellipse where the perigee is a point on a LEO and the… …   Wikipedia

  • Single-stage-to-orbit — The VentureStar was a proposed SSTO spaceplane. A single stage to orbit (or SSTO) vehicle reaches orbit from the surface of a body without jettisoning hardware, expending only propellants and fluids. The term usually, but not exclusively, refers… …   Wikipedia

  • Air launch to orbit — is the method of launching booster rockets at altitude from a horizontal takeoff turbojet aircraft, either subsonic or supersonic. This method, when employed for orbital payload insertion, presents significant advantages over conventional… …   Wikipedia

  • List of artificial objects in heliocentric orbit — Below is a current list of artificial objects currently in heliocentric orbit. These do not include man made objects which are escaping from the Solar System (Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, and New Horizons), Agena, Centaur, or IUS …   Wikipedia

  • Transfer orbit stage — The Transfer Orbit Stage (TOS) was an upper stage rocket developed by Martin Marietta on a subcontract to Orbital Sciences Corporation during the late 1980s and early 1990s. Orbital Sciences was the prime contractor for NASA for TOS. TOS was… …   Wikipedia

  • MESSENGER — This article is about the NASA space mission. For other uses, see Messenger. MESSENGER Artist s rendering of MESSENGER orbiting Mercury. Operator NASA / APL Major contractors APL …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.