Interplanetary spaceflight or interplanetary travel is the crewed or uncrewed travel between stars and planets, usually within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System. Uncrewed space probes have flown to all the observed planets in the Solar System as well as to dwarf planets Pluto and Ceres, and several asteroids. Orbiters and landers return more information than fly-by missions. Crewed flights have landed on the Moon and have been planned, from time to time, for Mars, Venus and Mercury. While many scientists appreciate the knowledge value that uncrewed flights provide, the value of crewed missions is more controversial. Science fiction writers propose a number of benefits, including the mining of asteroids, access to solar power, and room for colonization in the event of an Earth catastrophe.
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry.
Solar sails are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The first spacecraft to make use of the technology was IKAROS, launched in 2010.
The Planetary Society is an American internationally-active non-governmental nonprofit organization. It is involved in research, public outreach, and political space advocacy for engineering projects related to astronomy, planetary science, and space exploration. It was founded in 1980 by Carl Sagan, Bruce Murray, and Louis Friedman, and has about 60,000 members from more than 100 countries around the world.
Nozomi was a Japanese Mars orbiter that failed to reach Mars due to electrical failure. It was constructed by the Institute of Space and Astronautical Science, University of Tokyo and launched on July 4, 1998, at 03:12 JST with an on-orbit dry mass of 258 kg and 282 kg of propellant. The Nozomi mission was terminated on December 31, 2003.
BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio. The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure. It was launched on an Ariane 5 rocket on 20 October 2018 at 01:45 UTC, with an arrival at Mercury planned for on 5 December 2025, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury. The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme; it is the last mission of the programme to be launched.
Space launch vehicle Volna, is a converted Submarine-launched ballistic missile used for launching satellites into orbit. It is based on the R-29R designed by State Rocket Center Makayev and related to the Shtil' Launch Vehicle. The Volna is a 3-stage launch vehicle that uses liquid propellant. The warhead section is used for the payloads that can be either put into orbit with the help of an additional boost engine or travel along a sub-orbital trajectory to be recovered at the landing site. Volna can be launched from Delta III-class submarine or from land based facilities.
New Millennium Program (NMP) was a NASA project with focus on engineering validation of new technologies for space applications. Funding for the program was eliminated from the FY2009 budget by the 110th United States Congress, effectively leading to its cancellation.
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 star systems.
"Sunjammer" is a science fiction short story by British writer Arthur C. Clarke, originally published in the March 1964 issue of Boys' Life,. The story has also been published under the title "The Wind from the Sun" in Clarke's 1972 collection of short stories with this title. It depicts a yacht race between solar sail spacecraft.
An electric sail is a proposed form of spacecraft propulsion using the dynamic pressure of the solar wind as a source of thrust. It creates a "virtual" sail by using small wires to form an electric field that deflects solar wind protons and extracts their momentum. The idea was first conceptualised by Pekka Janhunen in 2006 at the Finnish Meteorological Institute.
Field propulsion is the concept of spacecraft propulsion where no propellant is necessary but instead momentum of the spacecraft is changed by an interaction of the spacecraft with external force fields, such as gravitational and magnetic fields from stars and planets. Drives that use field propulsion are often called a propellantless drive. It is purely speculative and has not yet been demonstrated to be of practical use, or theoretically valid.
LightSail is a project to demonstrate controlled solar sailing within low Earth orbit using a CubeSat. The project was developed by The Planetary Society, a global non-profit organization devoted to space exploration. It consists of two spacecraft — LightSail 1 and LightSail 2. LightSail 1 was an engineering demonstration mission designed to test its new sail deployment method in space, it did not perform solar sailing. LightSail 2 was a fully functional spacecraft intended to demonstrate true solar sailing and incorporated the lessons learned from LightSail 1. LightSail is a follow-on project to Cosmos 1 — a solar-sail spacecraft designed by The Planetary Society in the early 2000s, which was destroyed during a launch failure in 2005.
IKAROS is a Japan Aerospace Exploration Agency (JAXA) experimental spacecraft. The spacecraft was launched on 20 May 2010, aboard an H-IIA rocket, together with the Akatsuki probe and four other small spacecraft. IKAROS is the first spacecraft to successfully demonstrate solar sail technology in interplanetary space. The craft's name is an allusion to the legendary Icarus, who flew close to the Sun on wings made of bird-feathers and wax.
The Near-Earth Asteroid Scout was a mission by NASA to develop a controllable low-cost CubeSat solar sail spacecraft capable of encountering near-Earth asteroids (NEA). NEA Scout was one of ten CubeSats launched into a heliocentric orbit on Artemis 1, the maiden flight of the Space Launch System, on 16 November 2022.
OKEANOS was a proposed mission concept to Trojan asteroids, which share Jupiter's orbit, using a hybrid solar sail for propulsion; the sail was planned to be covered with thin solar panels to power an ion engine. In situ analysis of the collected samples would have been performed by either direct contact or using a lander carrying a high-resolution mass spectrometer. A sample-return to Earth was an option under study.
Breakthrough Starshot is a research and engineering project by the Breakthrough Initiatives to develop a proof-of-concept fleet of light sail interstellar probes named Starchip, to be capable of making the journey to the Alpha Centauri star system 4.34 light-years away. It was founded in 2016 by Yuri Milner, Stephen Hawking, and Mark Zuckerberg.
CubeSail is a low-cost spacecraft propulsion demonstration mission using two identical 1.5U CubeSat satellites to deploy a 260 m (850 ft) long, 20 m2 (220 sq ft) solar sail ribbon between them. This mission is a first in a series of increasingly complex demonstrations leading up to a full-scale UltraSail heliogyro by the University of Illinois and CU Aerospace.
Solar Cruiser was a planned NASA spacecraft that would have studied the Sun while propelled by a solar sail. The mission would have supported NASA's Solar Terrestrial Probes program by studying how interplanetary space changes in response to the constant outpouring of energy and particles from the Sun and how it interacts with planetary atmospheres. It was expected to launch as a rideshare payload alongside IMAP in February 2025. However, the spacecraft was not selected for further development and project closeout efforts concluded in 2023.
Small Innovative Missions for Planetary Exploration (SIMPLEx) is a planetary exploration program operated by NASA. The program funds small, low-cost spacecraft for stand-alone planetary exploration missions. These spacecraft are intended to launch as secondary payloads on other missions and are riskier than Discovery or New Frontiers missions.
