List Of Artificial Objects Leaving The Solar System
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space probes Space is a three-dimensional continuum containing positions and directions. In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless f ...
and the
upper stage A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own Rocket engine, engines and Rocket propellant, propellant. A ''tandem'' or ''serial'' stage is mounted on top of anoth ...
s of their launch vehicles are leaving the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...
, all of which were launched by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
. Three of the probes, ''
Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and the interstellar medium, interstellar space beyond the Sun's heliosphere. It was launched 16 days afte ...
'', ''
Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants (Jupiter and Saturn) and enabled further encounters with the ice giants (Uranus and ...
'', and ''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...
,'' are still functioning and are regularly contacted by radio communication, while ''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is a NASA space probe launched in 1972 that completed the first mission to the planet Jupiter. ''Pioneer 10'' became the first of five artificial objects to achieve the escape velocity needed ...
'' and ''
Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a NASA robotic space probe launched on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, the solar wind, and cosmic rays. It was the first probe to Exploration ...
'' are now derelict. In addition to these spacecraft, some upper stages and de-spin weights are leaving the Solar System, assuming they continue on their trajectories. These objects are leaving the Solar System because their velocity and direction are taking them away from the Sun, and at their distance from the Sun, its gravitational pull is not sufficient to pull these objects back or into orbit. They are not impervious to the gravitational pull of the Sun and are being slowed, but are still traveling in excess of
escape velocity In celestial mechanics, escape velocity or escape speed is the minimum speed needed for an object to escape from contact with or orbit of a primary body, assuming: * Ballistic trajectory – no other forces are acting on the object, such as ...
to leave the Solar System and coast into interstellar space.


Planetary exploration probes

*''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is a NASA space probe launched in 1972 that completed the first mission to the planet Jupiter. ''Pioneer 10'' became the first of five artificial objects to achieve the escape velocity needed ...
'' – launched in 1972, flew past
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...
in 1973 and is heading in the direction of
Aldebaran Aldebaran () is a star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent vis ...
(65 light years away) in the constellation of Taurus. Contact was lost in January 2003, and it is estimated to have passed 134
astronomical unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...
s (AU; one AU is roughly the average distance between Earth and the Sun: 150 million kilometers (93 million miles)). *''
Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a NASA robotic space probe launched on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, the solar wind, and cosmic rays. It was the first probe to Exploration ...
'' – launched in 1973, flew past Jupiter in 1974 and
Saturn Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth the average density of Earth, but is over 95 tim ...
in 1979. Contact was lost in November 1995, and it is estimated to be at 111 AU. The spacecraft is heading toward the constellation of Aquila, northwest of the constellation of Sagittarius. Barring any incident, ''Pioneer 11'' will pass near one of the stars in the constellation in about 4 million years. *''
Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, as a part of the Voyager program. It was launched on a trajectory towards the gas giants (Jupiter and Saturn) and enabled further encounters with the ice giants (Uranus and ...
'' – launched in August 1977, flew past Jupiter in 1979, Saturn in 1981,
Uranus Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile ( ...
in 1986, and
Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...
in 1989. The probe left the
heliosphere The heliosphere is the magnetosphere, astrosphere, and outermost atmospheric layer of the Sun. It takes the shape of a vast, tailed bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding ...
for interstellar space at 119 AU on November 5, 2018. ''Voyager 2'' is still active. It is not heading toward any particular star, although in roughly 40,000 years it should pass 1.7 light-years from the star
Ross 248 Ross 248, also called HH Andromedae or Gliese 905, is a small star approximately from Earth in the northern constellation of Andromeda (constellation), Andromeda. Despite its List of nearest stars, proximity it is too dim to be seen wit ...
. Ross 248 and the Sun currently approach each other. In about 36,000 years they will fly past each other at a distance of under 3 light-years. If undisturbed for 296,000 years, ''Voyager 2'' should pass by the star
Sirius Sirius is the brightest star in the night sky. Its name is derived from the Greek word (Latin script: ), meaning 'glowing' or 'scorching'. The star is designated  Canis Majoris, Latinized to Alpha Canis Majoris, and abbr ...
at a distance of 4.3 light-years. *''
Voyager 1 ''Voyager 1'' is a space probe launched by NASA on September 5, 1977, as part of the Voyager program to study the outer Solar System and the interstellar medium, interstellar space beyond the Sun's heliosphere. It was launched 16 days afte ...
'' – launched in September 1977, flew past Jupiter in 1979 and Saturn in 1980, making a special close approach to Saturn's moon
Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...
. The probe passed the heliopause at 121 AU on August 25, 2012, to enter interstellar space. ''Voyager 1'' is still active. In about 40,000 years the star Gliese 445 (AC +79 3888) and the Sun will fly past each other at a distance of 3.45 light-years, after being currently 17.6 light-years from each other, with ''Voyager 1'' coming as close as 1.6 light-years to Gliese 445 at that time. *''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...
'' – launched in 2006, the probe flew past Jupiter in 2007 and
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
on July 14, 2015. It flew past the
Kuiper belt The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...
object
486958 Arrokoth 486958 Arrokoth (Provisional designation in astronomy, provisional designation ; formerly nicknamed Ultima Thule) is a trans-Neptunian object located in the Kuiper belt. Arrokoth became the farthest and most primitive List of minor planet ...
on January 1, 2019, as part of the Kuiper Belt Extended Mission (KEM). On April 17, 2021, it reached a distance of 50 AU from the Sun. Although other probes were launched first, ''Voyager 1'' has achieved a higher speed and overtaken all others. ''Voyager 1'' overtook ''Voyager 2'' a few months after launch, on December 19, 1977. It overtook ''Pioneer 11'' in 1981, and then ''Pioneer 10''—becoming the probe farthest from the Sun—on February 17, 1998. ''Voyager 2'' is moving faster than all other probes launched before it; it overtook ''Pioneer 11'' in the late 1980s and then ''Pioneer 10'' — becoming the second-farthest spacecraft from the Sun — on July 18, 2023. Depending on how the " ''Pioneer'' anomaly" affects it, ''New Horizons'' will also probably pass the ''Pioneer'' probes, but will need many years to do so. It will overtake ''Pioneer 11'' in 2143, and will overtake ''Pioneer 10'' in 2314, but will never overtake the ''Voyagers''.


Speed and distance from the Sun

To put the distances in the table in context,
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
's average distance (
semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...
) is about 40 AU. Note: Data above as of November 21, 2024. Source: JPL, NASA SSD Simulator, and for New Horizons. Solar
escape velocity In celestial mechanics, escape velocity or escape speed is the minimum speed needed for an object to escape from contact with or orbit of a primary body, assuming: * Ballistic trajectory – no other forces are acting on the object, such as ...
is a function of distance (r) from the Sun's center, given by :v_e = \sqrt, where the product '' G'' '' Msun'' is the heliocentric gravitational parameter. The initial speed required to escape the Sun from its surface is , and drops down to at Earth's distance from the Sun (1 AU), and at a distance of 100 AU. File:Voyager speed and distance from Sun.svg, Voyager 1 and 2 speed and distance from the Sun File:Pioneer speed and distance from Sun.svg, Pioneer 10 and 11 speed and distance from the Sun File:New Horizons Speed and distance from Sun.svg, New Horizons speed and distance from the Sun. In order to leave the Solar System, the probe needs to reach the local escape velocity. Escape velocity from the sun without the influence of Earth is 42.1 km/s. In order to reach this speed, it is highly advantageous to use as a boost the orbital speed of the Earth around the Sun, which is 29.78 km/s. By later passing near a planet, a probe can gain extra speed from a
gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...
.


Propulsion stages

Every planetary probe was placed into its escape trajectory by a
multistage rocket A multistage rocket or step rocket is a launch vehicle that uses two or more rocket ''stages'', each of which contains its own engines and propellant. A ''tandem'' or ''serial'' stage is mounted on top of another stage; a ''parallel'' stage is ...
, the last stage of which ends up on nearly the same trajectory as the probe it launched. Because these stages cannot be actively guided, their trajectories are now different from the probes they launched (the probes having been guided with small thrusters that allowed course changes). However, in cases where the spacecraft acquired escape velocity because of a
gravity assist A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby (spaceflight), flyby which makes use of the relative movement (e.g. orbit around the Sun) and gra ...
, the stages may not have a similar course and there is the extremely remote possibility that they collided with something. The stages on an escape trajectory are: * ''Pioneer 10 third stage'', a TE364-4 variant of the Star-37 solid fuel rocket. * ''Voyager 1 fourth stage'', a Star 37E solid fuel rocket. * ''Voyager 2 fourth stage'', a Star 37E solid fuel rocket. * ''New Horizons third stage'', a Star 48B solid fuel rocket, is on a similar escape trajectory out of the Solar System to ''New Horizons'', even arriving at Jupiter six hours before ''New Horizons''. On October 15, 2015, it passed Pluto's orbit at a distance of 213 million kilometers (over 1 AU) distant from
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
. This was four months after ''New Horizons Pluto flyby. In addition, two small
yo-yo de-spin A yo-yo de-spin mechanism is a device used to reduce the spin of satellites, typically soon after launch. It consists of two lengths of cable with weights on the ends. The cables are wrapped around the final stage and/or satellite, in the manne ...
weights on wires were used to reduce the spin of the ''New Horizons'' probe prior to its release from the third-stage rocket. Once the spin rate was lowered, these masses and the wires were released, and so are also on an escape trajectory out of the Solar System. None of the above objects are trackable – they have no power or radio antennas, spin uncontrollably, and are too small to be detected. Their exact positions are unknowable beyond their projected Solar System escape trajectories. The third stage of ''Pioneer 11'' is thought to be in solar orbit because its encounter with Jupiter would not have resulted in escape from the Solar System. ''Pioneer 11'' gained the required
velocity Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical q ...
to escape the Solar System in its subsequent encounter with Saturn. On January 19, 2006, the ''
New Horizons ''New Horizons'' is an Interplanetary spaceflight, interplanetary space probe launched as a part of NASA's New Frontiers program. Engineered by the Johns Hopkins University Applied Physics Laboratory (APL) and the Southwest Research Institut ...
'' spacecraft to Pluto was launched directly into a solar-escape trajectory at from Cape Canaveral using an
Atlas V Atlas V is an expendable launch system and the fifth major version in the Atlas (rocket family), Atlas launch vehicle family. It was developed by Lockheed Martin and has been operated by United Launch Alliance (ULA) since 2006. Primarily used to ...
and the Common Core Booster,
Centaur A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...
upper stage, and Star 48B third stage. ''New Horizons'' passed the Moon's orbit in just nine hours. The subsequent encounter with Jupiter only increased its velocity, and enabled the probe to arrive at Pluto three years earlier than without this encounter. Thus the only objects to date to be launched ''directly'' into a solar escape trajectory were the ''New Horizons'' spacecraft, its third stage, and the two de-spin masses. The ''New Horizons''
Centaur A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...
(second) stage is not escaping; it is in a 2.83-year heliocentric (solar) orbit. The ''Pioneer 10'' and ''11'', and ''Voyager 1'' and ''2'' Centaur (second) stages are also in heliocentric orbits.


Future

Given the huge emptiness of interstellar space, all the objects listed here are likely to continue into deep space in timelines that, barring the exceptionally unlikely chance of their colliding with (or being collected by) another object, could outlast even the
main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...
existence of the Sun's life, billions of years hence. One estimated timescale as to the likelihood of the Pioneer or Voyager spacecraft colliding with a star (or stellar remnant) is 1020 (100 quintillion) years. They are very unlikely, however, to gain enough velocity to escape the
Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...
galaxy (or its future merger with the Andromeda galaxy) into intergalactic space.


''Ulysses''

In 1990, the
solar Solar may refer to: Astronomy * Of or relating to the Sun ** Solar telescope, a special purpose telescope used to observe the Sun ** A device that utilizes solar energy (e.g. "solar panels") ** Solar calendar, a calendar whose dates indicate t ...
probe '' Ulysses'' was launched towards Jupiter in order to reach a high-inclination heliocentric orbit over the Sun's poles; the spacecraft was shut down in 2008. ''Ulysses'' is currently in a 79° inclination orbit around the Sun with its
apoapsis An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...
crossing the orbit of Jupiter. In November 2098, it will have another close fly-by with Jupiter, crossing between the orbits of Europa and Ganymede. After this slingshot maneuver, it will possibly enter a
hyperbolic trajectory In astrodynamics or celestial mechanics, a hyperbolic trajectory or hyperbolic orbit is the trajectory of any object around a central body with more than enough speed to escape the central object's gravitational pull. The name derives from the ...
around the Sun and eventually leave the Solar System. ''Ulysses'' is now switched off as its RTG power supply has run down, and so is uncontactable and cannot be tracked or guided in any way since 2009. Its exact trajectory is therefore unknowable as factors such as solar
radiation pressure Radiation pressure (also known as light pressure) is mechanical pressure exerted upon a surface due to the exchange of momentum between the object and the electromagnetic field. This includes the momentum of light or electromagnetic radiation of ...
could significantly alter its encounter path.


Gallery

File:Voyager.jpg, Photograph of ''Voyager 1'' / ''Voyager 2'' File:Pioneer10-11.jpg, Artist's concept of ''Pioneer 10'' / ''Pioneer 11'' File:Pioneer 10 at Jupiter.gif, Artist's concept of ''Pioneer 10'' near Jupiter File:15-011a-NewHorizons-PlutoFlyby-ArtistConcept-14July2015-20150115.jpg, Artist's concept of ''New Horizons'' approaching
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
. File:PIA19703-PlutoFlyby-NewHorizons-ArtistConcept-20150709.jpg, Artist's concept of ''New Horizons'' near
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
.


See also

*
Interstellar probe An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar medium, interstellar space, which is typically defined as the region beyond the Heliopause (astronomy), heliopause. It also r ...
*
Intergalactic travel Intergalactic travel is the hypothetical travel between galaxies. Because the Milky Way and its closest neighbors are separated by millions of light-years, any such venture would also require millions of years based on our current understanding o ...
* List of interplanetary voyages * List of missions to the outer planets * List of extraterrestrial orbiters * List of artificial objects on extraterrestrial surfaces * List of spacecraft intentionally crashed into extraterrestrial bodies *
Oberth effect In astronautics, a powered flyby, or Oberth maneuver, is a maneuver in which a spacecraft falls into a gravitational well and then uses its engines to further accelerate as it is falling, thereby achieving additional speed. The resulting maneuve ...


References


External links


Spacecraft escaping the Solar System
in heavens-above.com
NASA = Explaining planetary gravity assists
{{Portal bar, Astronomy, Stars, Spaceflight, Outer space, Solar System Artificial leaving Leaving solar system