Editing Spacecraft propulsion (section)

==Research==

Development of technologies will result in technical solutions that improve thrust levels, [[specific impulse]], power, [[specific mass]], (or [[Power-to-weight ratio|specific power]]), volume, system mass, system complexity, operational complexity, commonality with other spacecraft systems, manufacturability, durability, and cost. These types of improvements will yield decreased transit times, increased payload mass, safer spacecraft, and decreased costs. In some instances, the development of technologies within this technology area will result in mission-enabling breakthroughs that will revolutionize space exploration. There is no single propulsion technology that will benefit all missions or mission types; the requirements for in-space propulsion vary widely according to their intended application.{{Sfn|Meyer|2012|p=5}}<ref name=leone/>

One institution focused on developing primary propulsion technologies aimed at benefitting near and mid-term science missions by reducing cost, mass, and/or travel times is the [[Glenn Research Center]] (GRC).{{citation needed|date = July 2023}} [[Electric propulsion]] architectures are of particular interest to the GRC, including [[Ion thruster|ion]] and [[Hall thruster]]s.{{citation needed|date = July 2023}} One system combines [[solar sail]]s, a form of propellantless propulsion which relies on naturally-occurring starlight for propulsion energy, and Hall thrusters. Other propulsion technologies being developed include advanced chemical propulsion and aerocapture.<ref name="leone" /><ref name="grcspace">[https://www1.grc.nasa.gov/space/sep/ Solar Electric Propulsion (SEP)]. Glenn Research Center. NASA. 2019</ref><ref name="glenion">[http://www.grc.nasa.gov/WWW/ion/ Ion propulsion system research] {{Webarchive|url=https://web.archive.org/web/20060901214224/http://www.grc.nasa.gov/WWW/ion/|date=2006-09-01}}. Glenn Research Center. NASA. 2013</ref>

===Defining technologies===
The term "mission pull" defines a technology or a performance characteristic necessary to meet a planned NASA mission requirement. Any other relationship between a technology and a mission (an alternate propulsion system, for example) is categorized as "technology push." Also, a space demonstration refers to the spaceflight of a scaled version of a particular technology or of a critical technology subsystem. On the other hand, a space validation would serve as a qualification flight for future mission implementation. A successful validation flight would not require any additional space testing of a particular technology before it can be adopted for a science or exploration mission.{{Sfn|Meyer|2012|p=5}}

===Testing===
Spacecraft propulsion systems are often first statically tested on Earth's surface, within the atmosphere but many systems require a vacuum chamber to test fully.<ref>{{Cite journal |last1=Rafalskyi |first1=Dmytro |last2=Martínez |first2=Javier Martínez |last3=Habl |first3=Lui |last4=Zorzoli Rossi |first4=Elena |last5=Proynov |first5=Plamen |last6=Boré |first6=Antoine |last7=Baret |first7=Thomas |last8=Poyet |first8=Antoine |last9=Lafleur |first9=Trevor |last10=Dudin |first10=Stanislav |last11=Aanesland |first11=Ane |date=November 2021 |title=In-orbit demonstration of an iodine electric propulsion system |journal=Nature |language=en |volume=599 |issue=7885 |pages=411–415 |doi=10.1038/s41586-021-04015-y |pmid=34789903 |issn=1476-4687|pmc=8599014 |bibcode=2021Natur.599..411R }}</ref> Rockets are usually tested at a [[rocket engine test facility]] well away from habitation and other buildings for safety reasons. [[Ion drive]]s are far less dangerous and require much less stringent safety, usually only a moderately large vacuum chamber is needed.{{Citation needed|date=April 2024}} Static firing of engines are done at [[Rocket engine test facility#Rocket ground test facilities|ground test facilities]], and systems which cannot be adequately tested on the ground and require launches may be employed at a [[rocket launch site|launch site]].