Interstellar probe

[3] Currently, three projects are under consideration: CNSA's Shensuo, NASA's Interstellar Probe, and StarChip from the Breakthrough Initiatives.

[10][11] 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.

[12] In 2013 it was thought Voyager 1 crossed the heliopause and entered interstellar space on August 25, 2012 at distance of 121 AU from the Sun, making it the first known human-manufactured object to do so.

[22] New Horizons was launched directly into a hyperbolic escape trajectory, getting a gravitational assist from Jupiter en route.

[23] 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).

In April 2016, Breakthrough Initiatives announced Breakthrough Starshot, a program to develop a proof of concept fleet of small centimeter-sized light sail spacecraft, named StarChip,[31] capable of making the journey to Alpha Centauri, the nearest star system, at speeds of 20%[32][33] and 15%[34] of the speed of light, taking between 20 and 30 years to reach the star system, respectively, and about 4 years to notify Earth of a successful arrival.

[35] A NASA funded study, led by the Applied Physics Laboratory, on possible options for an interstellar probe.

[36] A technology reference study published in 2006 with the ESA proposed an interstellar probe focused on leaving the heliosphere.

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 powered by standard radioisotope thermal generators.

[38] Studies suggest various technologies including americium-241-based RTG, optical communication (as opposed to radio), and low-power semi-autonomous electronics.

[39] The "next step" interstellar probe in this study suggested a 5 megawatt fission reactor utilizing 16 metric tonnes of H2 propellant.

[42] Project Orion was a proposed nuclear pulse propulsion craft that would have used fission or fusion bombs to apply motive force.

[44] 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.

[44][45][46] Project Daedalus was a proposed nuclear pulse propulsion craft that used inertial confinement fusion of small pellets within a magnetic field nozzle to provide motive force.

The design was studied during the 1970s by the British Interplanetary Society, and was meant to flyby Barnard's Star in under a century from launch.

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 explosions.

[54] AIMStar was a proposed antimatter catalyzed nuclear pulse propulsion craft that would use clouds of antiprotons to initiate fission and fusion within fuel pellets.

[60] In 2016, the Breakthrough Initiatives announced a program to develop a fleet of lightweight light-sail probes for interstellar travel, aiming to make the journey to Alpha Centauri.

This research program, with an initial funding of US$ 100 million imagines accelerating the probes to about 15% or 20% of the speed of light, resulting in a travel time of between 20 and 30 years.

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.

[64] Probe mass, power source, and propulsion systems are key technology areas for this type of mission.