An interstellar probe is a

space probe A space probe is an artificial satellite that travels through space to collect scientific data. A space probe may orbit Earth; approach the Moon; travel through interplanetary space; flyby, orbit, or land or fly on other planetary bodies; or ent ...

that has left—or is expected to leave—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 "Solar S ...

and enter

interstellar space Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, predo ...

, which is typically defined as the region beyond the heliopause. It also refers to probes capable of reaching other star systems. There are five interstellar probes, all launched by the

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

space agency

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

: ''

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 interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...

'', ''

Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', o ...

'', ''

Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...

'', ''

Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...

'' and '' New Horizons''. As of 2019, ''Voyager 1'', ''Voyager 2'' and ''Pioneer 10'' are the only probes to have actually reached interstellar space. The other two are on interstellar trajectories. The

termination shock The heliosphere is the magnetosphere, astrosphere and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interst ...

is the point in the

heliosphere The heliosphere is the magnetosphere, astrosphere and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interstell ...

where the

solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...

slows down to subsonic speed. Even though the termination shock happens as close as 80–100 AU (

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits ...

s) the maximum extent of the region in which the Sun's gravitational field is dominant (the

Hill sphere The Hill sphere of an astronomical body is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit that lies within the planet's Hill sphere. That moon would, in turn, have a Hill sp ...

) is thought to be at around . This point is close to the nearest known star system, Alpha Centauri, located 4.36 light years away. Although the probes will be under the influence of the Sun for a long time, their velocities far exceed the Sun's

escape velocity In celestial mechanics, escape velocity or escape speed is the minimum speed needed for a free, non- propelled object to escape from the gravitational influence of a primary body, thus reaching an infinite distance from it. It is typically ...

, so they are leaving forever. Interstellar space is defined as the space beyond a magnetic region that extends about 122 AU from the Sun, as detected by ''Voyager 1,'' and the equivalent region of influence surrounding other stars. ''Voyager 1'' entered interstellar space in 2012. Currently, three projects are under consideration: Chinese ''

Interstellar Express ''Interstellar Express'' or ''Interstellar Heliosphere Probe'' (), is the current name for a proposed Chinese National Space Administration program designed to explore the heliosphere and interstellar space. The program will feature two space ...

'', NASA's ''

Interstellar Probe An interstellar probe is a space probe that has left—or is expected to leave—the Solar System and enter interstellar space, which is typically defined as the region beyond the heliopause. It also refers to probes capable of reaching other s ...

'', and '' StarChip'' from the

Breakthrough Initiatives Breakthrough Initiatives is a science-based program founded in 2015 and funded by Julia and Yuri Milner, also of Breakthrough Prize, to search for extraterrestrial intelligence over a span of at least 10 years. The program is divided into multiple ...

Overview

Planetary scientist G. Laughlin noted that with current technology a probe sent to Alpha Centauri would take 40,000 years to arrive, but expressed hope for new technology to be developed to make the trip within a human lifetime. On that timescale the stars move notably. As an example, in 40,000 years

Ross 248 Ross 248, also called HH Andromedae or Gliese 905, is a small star approximately from Earth in the northern constellation of Andromeda. Despite its proximity it is too dim to be seen with the naked eye. It was first catalogued by Fr ...

will be closer to Earth than Alpha Centauri. One technology that has been proposed to achieve higher speeds is an E-sail."Electric sail solar-wind space exploration"
Space.com By harnessing solar wind, it might be possible to achieve 20-30 AU per year without even using propellant.

List of interstellar probes

Functional spacecraft

''
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 interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...
'' (1977–)

''Voyager 1'' is a

launched by

on September 5, 1977. At a distance of about as of ,https://www.jpl.nasa.gov/voyager/mission/status/ , Voyager Mission Status it is the farthest manmade object from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. It was later estimated that ''Voyager 1'' crossed the termination shock on December 16, 2004 at a distance of 94 AU from the Sun. At the end of 2011, ''Voyager 1'' entered and discovered a stagnation region where charged particles streaming from the Sun slow and turn inward, and the Solar System's magnetic field is doubled in strength as interstellar space appears to be applying pressure. Energetic particles originating in the Solar System declined by nearly half, while the detection of high-energy electrons from outside increases 100-fold. The inner edge of the stagnation region is located approximately 113 astronomical units (AU) from the Sun. In 2013 it was thought ''Voyager 1'' crossed the heliopause and entered

on August 25, 2012 at distance of 121 AU from the Sun, making it the first known human-manufactured object to do so. , the probe was moving with a relative velocity to the Sun of about 16.95 km/s (3.58 AU/year). If it does not hit anything, ''Voyager 1'' could reach the

Oort cloud The Oort cloud (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from ...

in about 300 years

''
Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', o ...
'' (1977–)

''Voyager 2'' crossed the heliopause and entered interstellar space on November 5, 2018. It had previously passed the termination shock into the

heliosheath The heliosphere is the magnetosphere, astrosphere and outermost atmospheric layer of the Sun. It takes the shape of a vast, bubble-like region of space. In plasma physics terms, it is the cavity formed by the Sun in the surrounding interst ...

on August 30, 2007. As of ''Voyager 2'' is at a distance of from Earth. The probe was moving at a velocity of 3.25 AU/year (15.428 km/s) relative to the Sun on its way to interstellar space in 2013. It's moving at a velocity of relative to the Sun as of December 2014. ''Voyager 2'' is expected to provide the first direct measurements of the density and temperature of the interstellar plasma.

'' New Horizons'' (2006–)

''New Horizons'' was launched directly into a hyperbolic escape trajectory, getting a gravitational assist from

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

en route. By March 7, 2008, ''New Horizons'' was 9.37 AU from the Sun and traveling outward at 3.9 AU per year. It will, however, slow to an escape velocity of only 2.5 AU per year as it moves away from the Sun, so it will never catch up to either Voyager. As of early 2011, it was traveling at 3.356 AU/year (15.91 km/s) relative to the Sun. On July 14, 2015, it completed a flyby of Pluto at a distance of about 33 AU from the Sun. ''New Horizons'' next encountered 486958 Arrokoth on January 1, 2019, at about 43.4 AU from the Sun. The Heliosphere's termination shock was crossed by ''Voyager 1'' at 94 astronomical units (AU) and ''Voyager 2'' at 84 AU according to the IBEX mission. If ''New Horizons'' can reach the distance of , it will be traveling at about , around slower than ''Voyager 1'' at that distance.

Inactive missions

''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
'' (1972–2003)

The last successful reception of telemetry from ''Pioneer 10'' was on April 27, 2002, when it was at a distance of 80.22 AU, traveling at about 2.54 AU/year (12 km/s).

''
Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...
'' (1973–1995)

Routine mission operations for ''Pioneer 11'' were stopped September 30, 1995, when it was 6.5 billion km (approx 43.4 AU) from Earth, traveling at about 2.4 AU/year (11.4 km/s).

Probe debris

New Horizons' third stage, a STAR-48 booster, is on a similar escape trajectory out of the Solar System as ''New Horizons'', but will pass millions of kilometers from Pluto. It crossed Pluto's orbit in October 2015. The third stage rocket boosters for ''Pioneer 10'', ''Voyager 1'', and ''Voyager 2'' are also on escape trajectories out of the Solar System.

Proposed missions

; '' StarChip'' In April 2016,

announced

Breakthrough Starshot Breakthrough Starshot is a research and engineering project by the Breakthrough Initiatives to develop a Proof of concept, proof-of-concept fleet of light sail interstellar probes named ''Starchip'', to be capable of making the journey to the A ...

, a program to develop a

proof of concept Proof of concept (POC or PoC), also known as proof of principle, is a realization of a certain method or idea in order to demonstrate its feasibility, or a demonstration in principle with the aim of verifying that some concept or theory has prac ...

fleet of small centimeter-sized

light sail Solar sails (also known as light sails and photon sails) are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. A number of spaceflight missions to test solar propulsion and navigation have been p ...

spacecraft, named '' StarChip'', capable of making the journey to Alpha Centauri, the nearest star system, at speeds of 20% and 15% of the

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...

, taking between 20 and 30 years to reach the star system, respectively, and about 4 years to notify

of a successful arrival. ;''

'' (IHP) (2019–) A CNSA space mission first proposed in 2019 would be launched in 2024 with the intention to research the heliosphere. Both probes would use

gravity assist In orbital mechanics and aerospace engineering, a gravitational slingshot, gravity assist maneuver, or swing-by is the use of the relative movement (e.g. orbit around the Sun) and gravity of a planet or other astronomical object to alter the p ...

s at Jupiter and fly by

Kuiper belt object 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 time ...

s, and the second is also planned to fly by Neptune and Triton. The other goal is to reach 100 AU from the Sun by 2049, the centennial of the People's Republic of China's foundation. Interstellar_Probe_(2020s)

;''

Interstellar Probe (spacecraft) ''Interstellar Probe'' (''ISP'') is a proposed NASA space probe designed to explore and characterize the heliosphere and interstellar space. The study was originally proposed in 2018 by NASA for the Applied Physics Laboratory. It would have a ba ...

'' (ISP) (2018–) A NASA funded study, led by the

Applied Physics Laboratory The Johns Hopkins University Applied Physics Laboratory (Applied Physics Laboratory, or APL) is a not-for-profit university-affiliated research center (UARC) in Howard County, Maryland. It is affiliated with Johns Hopkins University and emplo ...

, on possible options for an interstellar probe. The nominal concept would launch on a SLS in the 2030s. It would perform either a fast Jupiter flyby, a powered Jupiter flyby, or a very close perihelion and propulsive maneuver, and reach a distance of 1000–2000 AU within 50 years. Possibilities for planetary, astrophysical and exoplanet science along the way are also being investigated.https://www.space.com/interstellar-probe-science-of-solar-system.html NASA's Voyager Missions Were Amazing. Now Scientists Want a True Interstellar Probe ;''Interstellar Heliopause Probe'' (IHP) (2006) A technology reference study published in 2006 with the ESA proposed an interstellar probe focused on leaving the heliosphere. The goal would be 200 AU in 25 years, with traditional launch but acceleration by a solar sail. The roughly 200–300 kg probe would carry a suite of several instruments including a plasma analyzer, plasma radio wave experiment, magnetometer, neutral and charged atom detector, dust analyzer, and a UV-photometer. Electrical power would come from an RTG. ;'' Innovative Interstellar Explorer'' (2003) NASA proposal to send a 35 kg science payload out to at least 200 AU. It would achieve a top speed of 7.8 AU per year using a combination of a heavy lift rocket, Jupiter gravitational assistance, and an

ion engine An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. It creates thrust by accelerating ions using electricity. An ion thruster ionizes a neutral gas by extracting some electrons out of ...

radioisotope thermal generator A radioisotope thermoelectric generator (RTG, RITEG), sometimes referred to as a radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioacti ...

s. The probe suggested a launch in 2014 (to take advantage of Jupiter gravitational assist), to reach 200 AU around 2044. ;''Realistic Interstellar Explorer'' and ''Interstellar Explorer'' (2000–2002) Studies suggest various technologies including

americium-241 Americium-241 (, Am-241) is an isotope of americium. Like all isotopes of americium, it is radioactive, with a half-life of . is the most common isotope of americium as well as the most prevalent isotope of americium in nuclear waste. It is com ...

-based RTG, optical communication (as opposed to radio), and low-power semi-autonomous electronics. Trajectory uses a Jupiter

and Solar Oberth maneuver to achieve 20 AU/year, allowing 1000 AU within 50 years, and a mission extension up to 20,000 AU and 1000 years. Needed technology included advanced propulsion and solar shield for perihelion burn around the Sun. Solar thermal (STP), nuclear fission thermal (NTP), and nuclear fission pulse, as well as various RTG isotopes were examined. The studies also included recommendations for a solar probe (see also

Parker Solar Probe The Parker Solar Probe (PSP; previously Solar Probe, Solar Probe Plus or Solar Probe+) is a NASA space probe launched in 2018 with the mission of making observations of the outer corona of the Sun. It will approach to within 9.86 solar radii ...

), nuclear thermal technology, solar sail probe, 20 AU/year probe, and a long-term vision of a 200 AU/year probe to the star

Epsilon Eridani Epsilon Eridani ( Latinized from ε Eridani), formally named Ran, is a star in the southern constellation of Eridanus, at a declination of 9.46° south of the celestial equator. This allows it to be visible from most of Earth's surf ...

.Ralph L. McNutt, et al - Interstellar Explorer (2002) - Johns Hopkins University
The "next step" interstellar probe in this study suggested a 5 megawatt fission reactor utilizing 16 metric tonnes of H₂ propellant. Targeting a launch in the mid-21st century, it would accelerate to 200 AU/year over 4200 AU and reach the star

after 3400 years of travel in the year 5500 AD. However, this was a second-generation vision for a probe and the study acknowledged that even 20 AU/year might not be possible with then current (2002) technology. For comparison, the fastest probe at the time of the study was ''

'' at about 3.6 AU/year (17 km/s), relative to the Sun. ;'' Interstellar Probe (1999)'' ''Interstellar Probe'' was a proposed solar sail propulsion spacecraft planned by NASA Jet Propulsion Laboratory. It was planned to reach as far as 200 AU within 10 years at a speed of 14 AU/year (about 70 km/s, and function up to 400+ AU). A critical technology for the mission is a large 1 g/m² solar sail. ;'' TAU mission'' (1987) ''TAU mission'' (Thousand Astronomical Units) was a proposed

nuclear electric rocket A nuclear electric rocket (more properly nuclear electric propulsion) is a type of spacecraft propulsion system where thermal energy from a nuclear reactor is converted to electrical energy, which is used to drive an ion thruster or other electrica ...

craft that used a 1 MW fission reactor and an

ion drive An ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion. It creates thrust by accelerating ions using electricity. An ion thruster ionizes a neutral gas by extracting some electrons out of ...

with a burn time of about 10 years to reach a speed of 106 km/s (about 20 AU/year) to achieve a distance of 1000 AU in 50 years. The primary goal of the mission was to improve parallax measurements of the distances to stars inside and outside our galaxy, with secondary goals being the study of the heliopause, measurements of conditions in the

interstellar medium In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...

, and (via communications with Earth) tests of

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

Mission concepts

; '' Project Orion'' (1958–1965) Project Orion was a proposed

nuclear pulse propulsion Nuclear pulse propulsion or external pulsed plasma propulsion is a hypothetical method of spacecraft propulsion that uses nuclear explosions for thrust. It originated as Project ''Orion'' with support from DARPA, after a suggestion by Stanislaw ...

craft that would have used fission or fusion bombs to apply motive force. The design was studied during the 1950s and 1960s in the

United States of America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...

, with one variant of the craft capable of

interstellar travel Interstellar travel is the hypothetical travel of spacecraft from one star system, solitary star, or planetary system to another. Interstellar travel is expected to prove much more difficult than interplanetary spaceflight due to the vast diffe ...

. ;''

Bracewell probe A Bracewell probe is a hypothetical concept for an autonomous interstellar space probe dispatched for the express purpose of communication with one or more alien civilizations. It was proposed by Ronald N. Bracewell in a 1960 paper, as an alter ...

'' (1960)

Interstellar communication Interstellar communication is the transmission of signals between planetary systems. Sending interstellar messages is potentially much easier than interstellar travel, being possible with technologies and equipment which are currently available. Ho ...

via a probe, as opposed to sending an electromagnetic signal. ;''Sanger Photon Rocket'' (1950s-1964) Eugene Sanger proposed a spacecraft powered by antimatter in the 1950s. Thrust was intended to come from reflected gamma-rays produced by electron- positron annihilation. ; ''

Enzmann starship The Enzmann starship is a concept for a crewed interstellar spacecraft proposed in 1964 by Dr. Robert Enzmann. A three million ton ball of frozen deuterium would fuel nuclear fusion rocket engines contained in a cylindrical section behind that ...

'' (1964/1973) Proposed by 1964 and examined in an October 1973 issue of ''

Analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...

'', the ''Enzmann Starship'' proposed using a 12,000 ton ball of frozen deuterium to power thermonuclear powered pulse propulsion.Duncan-Enzmann, Robert, "Enzmann Starship"
archived version
; from
Enzmann Starship
' blog. About twice as long as the Empire State Building and assembled in-orbit, the spacecraft was part of a larger project preceded by large interstellar probes and telescopic observation of target star systems. ;

Project Daedalus Project Daedalus (named after Daedalus, the Greek mythological designer who crafted wings for human flight) was a study conducted between 1973 and 1978 by the British Interplanetary Society to design a plausible uncrewed interstellar probe.Pro ...

(1973–1978) Project Daedalus was a proposed

craft that used

inertial confinement fusion Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion reactions by compressing and heating targets filled with thermonuclear fuel. In modern machines, the targets are small spherical pellets about the size of ...

of small pellets within a magnetic field nozzle to provide motive force. The design was studied during the 1970s by the

British Interplanetary Society The British Interplanetary Society (BIS), founded in Liverpool in 1933 by Philip E. Cleator, is the oldest existing space advocacy organisation in the world. Its aim is exclusively to support and promote astronautics and space exploration. Str ...

, and was meant to flyby

Barnard's Star Barnard's Star is a red dwarf about six light-years from Earth in the constellation of Ophiuchus. It is the fourth-nearest-known individual star to the Sun after the three components of the Alpha Centauri system, and the closest star in t ...

in under a century from launch. Plans included mining Helium-3 from Jupiter and a pre-launch mass of over 50 thousand metric tonnes from orbit. ;

Project Longshot Project Longshot was a conceptual interstellar spacecraft design. It would have been an uncrewed starship (about 400 tonnes), intended to fly to and enter orbit around Alpha Centauri B powered by nuclear pulse propulsion. History Developed ...

(1987–1988) Project Longshot was a proposed

craft that used

of small pellets within a magnetic field nozzle to provide motive force, in a manner similar to that of Project Daedalus. The design was studied during the 1990s by

and the

US Naval Academy The United States Naval Academy (US Naval Academy, USNA, or Navy) is a federal service academy in Annapolis, Maryland. It was established on 10 October 1845 during the tenure of George Bancroft as Secretary of the Navy. The Naval Academy is ...

. The craft was designed to reach and study Alpha Centauri. ; ''

Starwisp Starwisp is a hypothetical unmanned interstellar probe design proposed by the late Robert L. Forward. It is propelled by a microwave sail, similar to a solar sail in concept, but powered by microwaves from a human-made source. It would fly through ...

'' (1985) ''Starwisp'' is a hypothetical unmanned interstellar probe design proposed by

Robert L. Forward Robert Lull Forward (August 15, 1932 – September 21, 2002) was an American physicist and science fiction writer. His literary work was noted for its scientific credibility and use of ideas developed from his career as an aerospace engineer. He ...

.Landis, Geoffrey A. (July 17–19, 2000). "Microwave Pushed Interstellar Sail: Starwisp Revisited," paper AIAA-2000-3337, presented at the

AIAA The American Institute of Aeronautics and Astronautics (AIAA) is a professional society for the field of aerospace engineering. The AIAA is the U.S. representative on the International Astronautical Federation and the International Council of t ...

36th Joint Propulsion Conference and Exhibit, Huntsville AL.
abstract
It is propelled by a microwave sail, similar to a solar sail in concept, but powered by microwaves from an artificial source. ; ''

Medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

'' (1990s) ''Medusa'' was a novel spacecraft design, proposed by Johndale C. Solem, using a large lightweight sail (spinnaker) driven by pressure pulses from a series of

nuclear explosion A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, tho ...

s. The design, published by the

, was studied during the 1990s as a means of interplanetary travel. ;'' Starseed launcher'' (1996) ''Starseed launcher'' was concept for launching microgram interstellar probes at up to 1/3 light speed. ; ''

AIMStar AIMStar was a proposed antimatter-catalyzed nuclear pulse propulsion craft that uses clouds of antiprotons to initiate fission and fusion within fuel pellets. A magnetic nozzle derives motive force from the resulting explosions. The design was stud ...

'' (1990s-2000s) ''AIMStar'' was a proposed

antimatter catalyzed nuclear pulse propulsion Antimatter-catalyzed nuclear pulse propulsion (also antiproton-catalyzed nuclear pulse propulsion) is a variation of nuclear pulse propulsion based upon the injection of antimatter into a mass of nuclear fuel to initiate a nuclear chain reaction fo ...

craft that would use clouds of

antiproton The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy. The exis ...

s to initiate fission and fusion within fuel pellets. A magnetic nozzle derived motive force from the resulting explosions. The design was studied during the 1990s by

Penn State University The Pennsylvania State University (Penn State or PSU) is a public state-related land-grant research university with campuses and facilities throughout Pennsylvania. Founded in 1855 as the Farmers' High School of Pennsylvania, Penn State became ...

. The craft was designed to reach a distance of 10,000 AU from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

in 50 years. ; Project Icarus (2009+) Project Icarus is a theoretical study for an interstellar probe and is being run under the guidance of the

Tau Zero Foundation The Breakthrough Propulsion Physics Project (BPP) was a research project funded by NASA from 1996-2002 to study various proposals for revolutionary methods of spacecraft propulsion that would require breakthroughs in physics before they could be r ...

(TZF) and the

(BIS), and was motivated by

, a similar study that was conducted between 1973 and 1978 by the BIS. The project is planned to take five years and began on September 30, 2009. ; ''

Project Dragonfly Project Dragonfly may refer to * Project Dragonfly (space study) - the first conceptual design study that assesses the feasibility of a laser-propelled interstellar probe. * Google's development of the Dragonfly search engine intended for us ...

'' (2014+) The Initiative for Interstellar Studies (i4is) has initiated a project working on small interstellar spacecraft, propelled by a laser sail in 2014 under the name of

. Four student teams worked on concepts for such a mission in 2014 and 2015 in the context of a design competition. Geoffrey A. Landis proposed for

future-technology project interstellar probe with supplying the energy from an external source (

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fir ...

of base station) and ion thruster.

Trans-Neptunian probes at precursor distances

In the early 2000s many new, relatively large planetary bodies were found beyond Pluto, and with orbits extending hundreds of AU out past the heliosheath (90–1000 AU). The NASA probe ''New Horizons'' may explore this area now that it has performed its Pluto flyby in 2015 (Pluto's orbit ranges from about 29–49 AU). Some of these large objects past Pluto include 136199 , 136108 , 136472 , and 90377 Sedna. Sedna comes as close as 76 AU, but travels out as far as 961 AU at aphelion, and minor planet goes out past 1060 AU at aphelion. Bodies like these affect how the Solar System is understood, and traverse an area previously only in the domain of interstellar missions or precursor probes. After the discoveries, the area is also in the domain of interplanetary probes; some of the discovered bodies may become targets for exploration missions, an example of which is preliminary work on a probe to Haumea and its moons (at 35–51 AU). Probe mass, power source, and propulsion systems are key technology areas for this type of mission. In addition, a probe beyond 550 AU could use the Sun itself as a

gravitational lens A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...

to observe targets outside the Solar System, such as planetary systems around other nearby stars, although many challenges to this mission have been noted.A Space Mission to the Gravitational Focus of the Sun
''MIT Technology Review,'' April 2016 (access date 28 April 2016)

Interstellar messages

Pioneer plaque.svg, The

Pioneer plaque The Pioneer plaques are a pair of gold-anodized aluminum plaques that were placed on board the 1972 ''Pioneer 10'' and 1973 ''Pioneer 11'' spacecraft, featuring a pictorial message, in case either ''Pioneer 10'' or ''11'' is intercepted by inte ...

s are a pair of gold-anodized aluminium plaques placed on board the 1972 ''

'' and 1973 ''

'' spacecraft, featuring a pictorial message in case they are rediscovered The Sounds of Earth - GPN-2000-001976.jpg, The

Voyager Golden Record The Voyager Golden Records are two phonograph records that were included aboard both Voyager spacecraft launched in 1977. The records contain sounds and images selected to portray the diversity of life and culture on Earth, and are intended for ...

, as included aboard the ''Voyager 1'' and ''Voyager 2'' spacecraft, features audio recordings and encoded pictures

References

External links

Spacecraft escaping the Solar SystemNASA - Interstellar Probe
(2002 era Study)
Voyager mission website
(NASA) {{DEFAULTSORT:Interstellar Probe Interstellar travel, *Probe Space probes Spacecraft escaping the Solar System, *

Overview

List of interstellar probes

Functional spacecraft

''
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 interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...
'' (1977–)

''
Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', o ...
'' (1977–)

'' New Horizons'' (2006–)

Inactive missions

''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
'' (1972–2003)

''
Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...
'' (1973–1995)

Probe debris

Proposed missions

Mission concepts

Trans-Neptunian probes at precursor distances

Interstellar messages

See also

References

Further reading

External links

Overview

List of interstellar probes

Functional spacecraft

''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 interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...'' (1977–)

''Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', o ...'' (1977–)

'' New Horizons'' (2006–)

Inactive missions

''Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...'' (1972–2003)

''Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...'' (1973–1995)

Probe debris

Proposed missions

Mission concepts

Trans-Neptunian probes at precursor distances

Interstellar messages

See also

References

Further reading

External links

''
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 interstellar space beyond the Sun's heliosphere. Launched 16 days after its twin ''Voyager 2'', ''Voya ...
'' (1977–)

''
Voyager 2 ''Voyager 2'' is a space probe launched by NASA on August 20, 1977, to study the outer planets and interstellar space beyond the Sun's heliosphere. As a part of the Voyager program, it was launched 16 days before its twin, '' Voyager 1'', o ...
'' (1977–)

''
Pioneer 10 ''Pioneer 10'' (originally designated Pioneer F) is an American space probe, launched in 1972 and weighing , that completed the first mission to the planet Jupiter. Thereafter, ''Pioneer 10'' became the first of five artificial objects to ach ...
'' (1972–2003)

''
Pioneer 11 ''Pioneer 11'' (also known as ''Pioneer G'') is a robotic space probe launched by NASA on April 5, 1973, to study the asteroid belt, the environment around Jupiter and Saturn, solar winds, and cosmic rays. It was the first probe to encounter ...
'' (1973–1995)