Editing Sub-orbital spaceflight (section)

===Sub-orbital transportation===
Research, such as that done for the [[X-20 Dyna-Soar]] project suggests that a semi-ballistic sub-orbital flight could travel from Europe to North America in less than an hour.

However, the size of rocket, relative to the payload, necessary to achieve this, is similar to an ICBM. ICBMs have delta-v's somewhat less than orbital; and therefore would be somewhat cheaper than the costs for reaching orbit, but the difference is not large.<ref>{{cite web|url=http://www.thespacereview.com/article/1118/1|title=The Space Review: Point-to-point suborbital transportation: sounds good on paper, but...|website=www.thespacereview.com|access-date=4 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170801074751/http://www.thespacereview.com/article/1118/1|archive-date=1 August 2017}}</ref>

Due to the high cost of spaceflight, suborbital flights are likely to be initially limited to high value, very high urgency cargo deliveries such as [[courier]] flights, [[military]] fast-response operations or [[space tourism]].{{opinion|date=April 2012}}

The [[SpaceLiner]] is a hypersonic [[suborbital spaceplane]] concept that could transport 50 passengers from [[Australia]] to [[Europe]] in 90 minutes or 100 passengers from Europe to [[California]] in 60 minutes.<ref>{{Cite journal|doi=10.1016/j.actaastro.2010.01.020| author = Sippel, M. | title = Promising roadmap alternatives for the SpaceLiner |journal = Acta Astronautica |issue = 11–12 |volume = 66 |date = 2010| pages = 1652–1658 | bibcode = 2010AcAau..66.1652S | url = https://elib.dlr.de/64605/1/AA3731.pdf }}</ref> The main challenge lies in increasing the reliability of the different components, particularly the engines, in order to make their use for passenger transportation on a daily basis possible.

[[SpaceX]] is potentially considering using their [[SpaceX Starship|Starship]] as a sub-orbital point-to-point transportation system.<ref name=trati20190530>{{cite news |last=Ralph|first=Eric |url=https://www.teslarati.com/spacex-elon-musk-wants-starship-spaceliners/ |title=SpaceX CEO Elon Musk wants to use Starships as Earth-to-Earth transports |work=Teslarati |date=30 May 2019 |access-date=31 May 2019 }}</ref>