Editing Interstellar travel (section)

=== Interstellar medium ===
A knowledge of the properties of the [[interstellar medium|interstellar gas and dust]] through which the vehicle must pass is essential for the design of any interstellar space mission.<ref name="ism" /> A major issue with traveling at extremely high speeds is that, due to the requisite high relative speeds and large kinetic energies, collisions with interstellar dust could cause considerable damage to the craft. Various shielding methods to mitigate this problem have been proposed.<ref>{{cite conference | url= http://www.nasa.gov/pdf/637131main_radiation%20shielding_symposium_r1.pdf | archive-url= https://web.archive.org/web/20140211144338/http://www.nasa.gov/pdf/637131main_radiation%20shielding_symposium_r1.pdf | url-status= dead | archive-date= 11 February 2014 | title= Active Radiation Shielding Utilizing High Temperature Superconductors | author= Westover, Shayne | conference= NIAC Symposium | date= 27 March 2012 }}</ref> Larger objects (such as macroscopic dust grains) are far less common, but would be much more destructive. The risks of impacting such objects and mitigation methods have been discussed in literature, but many unknowns remain.<ref>{{cite report | url= http://www.kiss.caltech.edu/workshops/systems2012/presentations/garrett.pdf | title= There and Back Again: A Layman's Guide to Ultra-Reliability for Interstellar Missions | author= Garrett, Henry | date= 30 July 2012 | url-status= dead | archive-url= https://web.archive.org/web/20140508062130/http://www.kiss.caltech.edu/workshops/systems2012/presentations/garrett.pdf | archive-date= 8 May 2014 }}</ref> An additional consideration is that, due to the non-homogeneous distribution of interstellar matter around the Sun, these risks would vary between different trajectories.<ref name=ism>{{cite journal|last1=Crawford|first1=I. A.|title=Project Icarus: A review of local interstellar medium properties of relevance for space missions to the nearest stars|journal=Acta Astronautica|date=2011|volume=68|issue=7–8|pages=691–699|doi=10.1016/j.actaastro.2010.10.016|arxiv=1010.4823|bibcode = 2011AcAau..68..691C |s2cid=101553}}</ref> Although a high density interstellar medium may cause difficulties for many interstellar travel concepts, [[Bussard ramjet|interstellar ramjets]], and some proposed concepts for decelerating interstellar spacecraft, would actually benefit from a denser interstellar medium.<ref name="ism" />