was designed to reach and study Alpha Centauri. Starwisp (1985)Starwisp is a hypothetical unmanned interstellar probe design proposed by Robert L. Forward.Landis, Geoffrey A. (July 17–19, 2000). "Microwave Pushed Interstellar Sail: Starwisp Revisited," paper AIAA-2000-3337, presented at the AIAA 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 (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 explosions. The design, published by the British Interplanetary Society, 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 (1990s-2000s)AIMStar was a proposed antimatter catalyzed nuclear pulse propulsion craft that would use clouds of antiprotons 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 craft was designed to reach a distance of 10,000 AU from the Sun 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 (TZF) and the British Interplanetary Society (BIS), and was motivated by Project Daedalus, 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 (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 Project Dragonfly. Four student teams worked on concepts for such a mission in 2014 and 2015 in the context of a design competition.Breakthrough Starshot (2016+) 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 twenty and thirty years. Geoffrey A. Landis proposed for interstellar travel future-technology project interstellar probe with supplying the energy from an external source (laser of base