Editing Navigation (section)

===Inertial navigation===
{{Further|Inertial navigation system}}

[[Inertial navigation system]] (INS) is a [[dead reckoning]] type of navigation system that computes its position based on motion sensors.<ref name="k075">{{cite book | last=Jekeli | first=Christopher | title=Inertial Navigation Systems with Geodetic Applications | publisher=Walter de Gruyter | publication-place=Berlin | date=2012-10-25 | isbn=978-3-11-080023-4 | page=113}}</ref> Before actually navigating, the initial latitude and longitude and the INS's physical orientation relative to the Earth (e.g., north and level) are established. After alignment, an INS receives impulses from motion detectors that measure (a) the acceleration along three axes (accelerometers), and (b) rate of rotation about three orthogonal axes (gyroscopes). These enable an INS to continually and accurately calculate its current latitude and longitude (and often velocity).

Advantages over other navigation systems are that, once aligned, an INS does not require outside information. An INS is not affected by adverse weather conditions and it cannot be detected or jammed. Its disadvantage is that since the current position is calculated solely from previous positions and motion sensors, its errors are cumulative, increasing at a rate roughly proportional to the time since the initial position was input. Inertial navigation systems must therefore be frequently corrected with a location 'fix' from some other type of navigation system.

The first inertial system is considered to be the V-2 guidance system deployed by the Germans in 1942. However, inertial sensors are traced to the early 19th century.<ref name="Tazartes">"An historical perspective on inertial navigation systems", Daniel Tazartes, ''2014 International Symposium on Inertial Sensors and Systems (ISISS)'',  Laguna Beach, CA</ref> The advantages INSs led their use in aircraft, missiles, surface ships and submarines. For example, the U.S. Navy developed the Ships Inertial Navigation System (SINS) during the [[Polaris missile]] program to ensure a reliable and accurate navigation system to initial its missile guidance systems. Inertial navigation systems were in wide use until [[satellite navigation]] systems (GPS) became available. INSs are still in common use on submarines (since GPS reception or other fix sources are not possible while submerged) and long-range missiles but are not now widely found elsewhere.<ref name="Jek296">{{cite book | last=Jekeli | first=Christopher | title=Inertial Navigation Systems with Geodetic Applications | publisher=Walter de Gruyter | publication-place=Berlin | date=2012-10-25 | isbn=978-3-11-080023-4 | page=296}}</ref>

==== Space navigation ====
Not to be confused with satellite navigation, which depends upon satellites to function, space navigation refers to the navigation of spacecraft themselves. This has historically been achieved (during the [[Apollo program]]) via a [[Apollo Guidance Computer|navigational computer]], an Inertial navigation system, and via celestial inputs entered by astronauts which were recorded by sextant and telescope. Space rated navigational computers, like those found on Apollo and later missions, are designed to be hardened against possible data corruption from radiation. Navigation in space has three main components: the use of a suitable reference trajectory which describes the planned flight path of the spacecraft, monitoring the actual spacecraft position while the mission is in flight (orbit determination) and creating maneuvers to bring the spacecraft back to the reference trajectory as required (flight path control).<ref name="r120">{{cite web | title=Chapter 13: Navigation | website=NASA Science | date=2023-07-20 | url=https://science.nasa.gov/learn/basics-of-space-flight/chapter13-1/ | access-date=2025-02-24}}</ref>

Another possibility that has been explored for deep space navigation is [[Pulsar-based navigation|Pulsar navigation]], which compares the X-ray bursts from a collection of known pulsars in order to determine the position of a spacecraft. This method has been tested by multiple space agencies, such as [[NASA]] and [[European Space Agency|ESA]].<ref>{{Cite web |title=GSP Executive Summary |url=https://gsp.esa.int/documents/10192/43064675/C4000106174ExS.pdf/8a26a304-9d5f-447d-aa75-bc0c955a4b78 |url-status=dead |website=gsp.esa.int |access-date=2022-12-07 |archive-date=2017-03-16 |archive-url=https://web.archive.org/web/20170316044511/http://gsp.esa.int/documents/10192/43064675/C4000106174ExS.pdf/8a26a304-9d5f-447d-aa75-bc0c955a4b78 }}</ref><ref>{{Cite web |author1=Rafi Letzter |date=2018-04-16 |title=NASA's Got a Plan for a 'Galactic Positioning System' to Save Astronauts Lost in Space |url=https://www.livescience.com/62309-galactic-positioning-system-nasa.html |access-date=2022-12-07 |website=livescience.com |language=en}}</ref>