Editing Solar sail (section)

== Projects proposed or cancelled or not selected ==
Despite the losses of ''Cosmos 1'' and NanoSail-D (about 23cm x 23cm x 34cm) which were due to failure of their launchers, scientists and engineers around the world remain encouraged and continue to work on solar sails. While most direct applications created so far intend to use the sails as inexpensive modes of cargo transport, some scientists are investigating the possibility of using solar sails as a means of transporting humans. This goal is strongly related to the management of very large (i.e. well above 1&nbsp;km<sup>2</sup>) surfaces in space and the sail making advancements. Development of solar sails for crewed space flight is still in its infancy.

===Sunjammer 2015===
{{Main|Sunjammer (spacecraft)}}
A technology demonstration sail craft, dubbed [[Sunjammer (spacecraft)|''Sunjammer'']], was in development with the intent to prove the viability and value of sailing technology.<ref>{{cite web |url=http://www.nasa.gov/mission_pages/tdm/solarsail/solarsail_overview.html |title=Nasa Solar Sail Demonstration |publisher=www.nasa.gov |date=2013-10-28 |access-date=2013-03-25 |archive-date=2015-12-24 |archive-url=https://web.archive.org/web/20151224180251/http://www.nasa.gov/mission_pages/tdm/solarsail/solarsail_overview.html |url-status=dead }}</ref> ''Sunjammer'' had a square sail, {{convert|38|m}} wide on each side, giving it an effective area of {{convert|1200|m2}}.  It would have traveled from the Sun-Earth {{L1}} [[Lagrangian point]] {{convert|1.5|e6km|mi|abbr=off}} from Earth to a distance of {{convert|3|e6km|e6mi|abbr=off}}.<ref>{{cite web|url=http://www.space.com/19565-worlds-largest-solar-sail-sunjammer.html|title=NASA to Launch World's Largest Solar Sail in 2014|author=Leonard David|publisher=Space.com|date=January 31, 2013|access-date=June 13, 2013}}</ref> The demonstration was expected to launch on a [[Falcon 9]] in January 2015.<ref name="Yahoo">{{cite web|url=https://news.yahoo.com/worlds-largest-solar-sail-launch-november-2014-214450113.html|title=World's Largest Solar Sail to Launch in November 2014|author=Mike Wall|publisher=Space.com|date=June 13, 2013|access-date=June 13, 2013}}</ref> It would have been a secondary payload, released after the placement of the [[Deep Space Climate Observatory|DSCOVR]] climate satellite at the L1 point.<ref name="Yahoo"/> Citing a lack of confidence in the ability of its contractor [[LGarde|L'Garde]] to deliver, the mission was cancelled by NASA in October 2014.<ref>{{cite news|url=http://www.spacenews.com/article/civil-space/42227nasa-nixes-sunjammer-mission-cites-integration-schedule-risk|archive-url=https://archive.today/20141018025439/http://www.spacenews.com/article/civil-space/42227nasa-nixes-sunjammer-mission-cites-integration-schedule-risk|url-status=dead|archive-date=October 18, 2014|title=NASA Nixes Sunjammer Mission, Cites Integration, Schedule Risk|last=Leone|first=Dan|work=spacenews.com|date=October 17, 2014}}</ref>

===OKEANOS===
{{main|OKEANOS}}
OKEANOS (Outsized Kite-craft for Exploration and Astronautics in the Outer Solar System) was a proposed mission concept by Japan's [[JAXA]] to Jupiter's [[Jupiter Trojan|Trojan asteroids]] using a hybrid solar sail for propulsion; the sail would have been covered with thin [[Solar panels on spacecraft|solar panels]] to power an [[ion engine]]. ''In-situ'' analysis of the collected samples would have been performed by either direct contact or using a lander carrying a high-resolution mass spectrometer. A lander and a sample-return to Earth were options under study.<ref name="Matsumoto 2015">[http://www.hayabusa.isas.jaxa.jp/kawalab/astro/pdf/2015A_16.pdf Sampling Scenario for the Trojan Asteroid Exploration Mission] {{Webarchive|url=https://web.archive.org/web/20171231155341/http://www.hayabusa.isas.jaxa.jp/kawalab/astro/pdf/2015A_16.pdf |date=2017-12-31 }} (PDF). Jun Matsumoto, Jun Aoki, Yuske Oki, Hajime Yano. 2015.</ref> The OKEANOS Jupiter Trojan Asteroid Explorer was a finalist for Japan's [[Institute of Space and Astronautical Science|ISAS]]{{'}} 2nd Large-class mission to be launched in the late 2020s. However, it was not selected.

===''Solar Cruiser''===
{{main|Solar Cruiser}}

In August 2019, NASA awarded the ''Solar Cruiser'' team $400,000 for nine-month mission concept studies. The spacecraft would have a {{cvt|1672|sqm}} solar sail and would orbit the Sun in a polar orbit, while the [[coronagraph]] instrument would enable simultaneous measurements of the [[Sun#Magnetic field|Sun's magnetic field]] structure and velocity of [[coronal mass ejection]]s.<ref name='PR Helio'>[https://www.nasa.gov/press-release/nasa-selects-proposals-to-demonstrate-smallsat-technologies-to-study-interplanetary NASA Selects Proposals to Demonstrate SmallSat Technologies to Study Interplanetary Space.] NASA press release, 15 August 2019.</ref> If selected for further development, it would have launched in 2025. However, ''Solar Cruiser'' was not approved to advance to phase C of its development cycle and was subsequently discontinued.<ref>{{cite web |last=Christe |first=Steve |url=https://hesto.smce.nasa.gov/2023/08/02/solar-cruiser-enabling-new-vistas-for-heliophysics-science/ |title=Solar Cruiser: Enabling new vistas for Heliophysics Science |work=Heliophysics Strategic Technology Office |publisher=[[NASA]] |date=2 August 2023 |access-date=5 December 2023}}</ref>