Editing Voyager program (section)

=== Mission details ===
[[File:Transitional regions.jpg|thumb|right|350x350px|This diagram about the heliosphere was released on 28 June 2013 and incorporates results from the Voyager spacecraft.<ref>{{Cite web|url=http://voyager.jpl.nasa.gov/news/transitional_regions.html|archive-url=https://web.archive.org/web/20130708092850/http://voyager.jpl.nasa.gov/news/transitional_regions.html|url-status=dead|title=NASA – Transitional Regions at the Heliosphere's Outer Limits|archive-date=8 July 2013}}</ref>]]
By the start of VIM, ''Voyager 1'' was at a distance of 40 [[Astronomical unit|AU]] from the Earth, while ''Voyager 2'' was at 31 AU. VIM is in three phases: termination shock, heliosheath exploration, and interstellar exploration phase. The spacecraft began VIM in an environment controlled by the Sun's magnetic field, with the plasma particles being dominated by those contained in the expanding supersonic solar wind. This is the characteristic environment of the termination shock phase. At some distance from the Sun, the supersonic solar wind will be held back from further expansion by the interstellar wind. The first feature encountered by a spacecraft as a result of this interaction – between interstellar wind and solar wind – was the termination shock, where the solar wind slows to subsonic speed, and large changes in plasma flow direction and magnetic field orientation occur. ''Voyager 1'' completed the phase of termination shock in December 2004 at a distance of 94 AU, while ''Voyager 2'' completed it in August 2007 at a distance of 84 AU. After entering into the heliosheath, the spacecraft were in an area that is dominated by the Sun's magnetic field and solar wind particles. After passing through the heliosheath, the two Voyagers began the phase of interstellar exploration. The outer boundary of the heliosheath is called the heliopause. This is the region where the Sun's influence begins to decrease and interstellar space can be detected.<ref>{{cite web|url=http://voyager.jpl.nasa.gov/mission/interstellar.html|title=Voyager – The Interstellar Mission|last=JPL.NASA.GOV|website=voyager.jpl.nasa.gov|access-date=2016-05-27|archive-date=15 October 2009|archive-url=https://web.archive.org/web/20091015172229/http://voyager.jpl.nasa.gov/mission/interstellar.html|url-status=live}}</ref> 

''Voyager 1'' is escaping the Solar System at the speed of 3.6 AU per year 35° north of the [[ecliptic]] in the general direction of the [[solar apex]] in [[Hercules (constellation)|Hercules]], while ''Voyager 2''{{'}}s speed is about 3.3 AU per year, heading 48° south of the ecliptic. The Voyager spacecraft will eventually go on to the stars. In about [[Timeline of the far future#Spacecraft and space exploration|40,000 years]], ''Voyager 1'' will be within 1.6 [[Light-year|light years]] (ly) of AC+79 3888, also known as [[Gliese 445]], which is approaching the Sun. In 40,000 years ''Voyager 2'' will be within 1.7 ly of [[Ross 248]] (another star which is approaching the Sun), and in [[Timeline of the far future#Spacecreaft and space exploration|296,000 years]] it will pass within 4.6 ly of [[Sirius]], which is the brightest star in the night-sky.<ref name="JPL.NASA">{{cite web |author=Jpl.Nasa.Gov |url=http://www.jpl.nasa.gov/interstellarvoyager/ |title=Voyager Enters Interstellar Space – NASA Jet Propulsion Laboratory |publisher=Jpl.nasa.gov |access-date=14 September 2013 |archive-date=13 April 2020 |archive-url=https://web.archive.org/web/20200413080732/https://voyager.jpl.nasa.gov/mission/interstellar-mission// |url-status=live }}</ref> The spacecraft are not expected to collide with a star for 1 sextillion (10<sup>20</sup>) years.<ref name=lavender>{{Cite journal|title = Future stellar flybys of the Voyager and Pioneer spacecraft|journal = Research Notes of the American Astronomical Society|volume= 3|pages = 59|number=4|doi=10.3847/2515-5172/ab158e|date = 3 April 2019|author = Coryn A.L. Bailer-Jones, Davide Farnocchia|arxiv = 1912.03503|bibcode = 2019RNAAS...3...59B|s2cid = 134524048 | doi-access=free }}</ref>

In October 2020, astronomers reported a significant unexpected increase in density in the [[Outer space|space]] beyond the [[Solar System]], as detected by the Voyager [[space probe]]s. According to the researchers, this implies that "the density gradient is a large-scale feature of the [[Interstellar medium#Structures|VLISM]] (very local [[interstellar medium]]) in the general direction of the [[Heliosphere#Edge structure|heliospheric nose]]".<ref name="SA-20201019">{{cite news |last=Starr |first=Michelle |title=Voyager Spacecraft Detect an Increase in The Density of Space Outside The Solar System |url=https://www.sciencealert.com/for-some-reason-the-density-of-space-is-higher-just-outside-the-solar-system |date=19 October 2020 |work=[[ScienceAlert]] |access-date=19 October 2020 |archive-date=19 October 2020 |archive-url=https://web.archive.org/web/20201019133221/https://www.sciencealert.com/for-some-reason-the-density-of-space-is-higher-just-outside-the-solar-system |url-status=live }}</ref><ref name="AJL-20200825">{{cite journal |last1=Kurth |first1=W.S. |last2=Gurnett |first2=D.A. |title=Observations of a Radial Density Gradient in the Very Local Interstellar Medium by Voyager 2 |date=25 August 2020 |journal=[[The Astrophysical Journal Letters]] |volume=900 |number=1 |pages=L1 |doi=10.3847/2041-8213/abae58 |bibcode=2020ApJ...900L...1K |s2cid=225312823 |doi-access=free }}</ref>