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 difference in the scale of the involved distances. Whereas the distance between any two planets in the Solar System is less than 30 astronomical units (AU), stars are typically separated by hundreds of thousands of AU, causing these distances to typically be expressed instead in light-years. Because of the vastness of these distances, non-generational interstellar travel based on known physics would need to occur at a high percentage of the speed of light; even so, travel times would be long, at least decades and perhaps millennia or longer.
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.
In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters are sometimes referred to as Hall thrusters or Hall-current thrusters. Hall-effect thrusters use a magnetic field to limit the electrons' axial motion and then use them to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume. The Hall-effect thruster is classed as a moderate specific impulse space propulsion technology and has benefited from considerable theoretical and experimental research since the 1960s.
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.
The Alcubierre drive is a speculative warp drive idea according to which a spacecraft could achieve apparent faster-than-light travel by contracting space in front of it and expanding space behind it, under the assumption that a configurable energy-density field lower than that of vacuum could be created. Proposed by theoretical physicist Miguel Alcubierre in 1994, the Alcubierre drive is based on a solution of Einstein's field equations. Since those solutions are metric tensors, the Alcubierre drive is also referred to as Alcubierre metric.
A warp drive or a drive enabling space warp is a fictional superluminal spacecraft propulsion system in many science fiction works, most notably Star Trek, and a subject of ongoing physics research. The general concept of "warp drive" was introduced by John W. Campbell in his 1957 novel Islands of Space and was popularized by the Star Trek series. Its closest real-life equivalent is the Alcubierre drive, a theoretical solution of the field equations of general relativity.
A starship, starcraft, or interstellar spacecraft is a theoretical spacecraft designed for traveling between planetary systems. The term is mostly found in science fiction. Reference to a "star-ship" appears as early as 1882 in Oahspe: A New Bible.
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 realized. The project ended in 2002, when the Advanced Space Transportation Program was reorganized and all speculative research was cancelled. During its six years of operational funding, this program received a total investment of $1.2 million.
The NASA Institute for Advanced Concepts (NIAC) is a NASA program for development of far reaching, long term advanced concepts by "creating breakthroughs, radically better or entirely new aerospace concepts". The program operated under the name NASA Institute for Advanced Concepts from 1998 until 2007 (managed by the Universities Space Research Association on behalf of NASA), and was reestablished in 2011 under the name NASA Innovative Advanced Concepts and continues to the present. The NIAC program funds work on revolutionary aeronautics and space concepts that can dramatically impact how NASA develops and conducts its missions.
A reactionless drive is a hypothetical device producing motion without the exhaust of a propellant. A propellantless drive is not necessarily reactionless when it constitutes an open system interacting with external fields; but a reactionless drive is a particular case of a propellantless drive that is a closed system, presumably in contradiction with the law of conservation of momentum. Reactionless drives are often considered similar to a perpetual motion machine. The name comes from Newton's third law, often expressed as: "For every action, there is an equal and opposite reaction."
Spacecraft electric propulsion is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generate thrust to modify the velocity of a spacecraft in orbit. The propulsion system is controlled by power electronics.
The EmDrive is a concept for a thruster for spacecraft, first written about in 2001. It is purported to generate thrust by reflecting microwaves inside the device, in a way that would violate the law of conservation of momentum and other laws of physics. The concept has been referred to at times as a resonant cavity thruster.
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.
The Advanced Space Transportation Program (ASTP) is a NASA program to intentionally advance current space transportation system technologies, and innovate novel technologies, through intense research efforts that are intended to culminate in regularizing the outer space environment decades from now. The intense efforts aim to accelerate scientific and technological breakthroughs.
Busek Co. Inc. is an American spacecraft propulsion company that builds thrusters, electronics, and various systems for spacecraft.
Harold G. "Sonny" White is a mechanical engineer, aerospace engineer, and applied physicist who is known for proposing new Alcubierre drive concepts and promoting advanced propulsion projects.
The Asteroid Redirect Mission (ARM), also known as the Asteroid Retrieval and Utilization (ARU) mission and the Asteroid Initiative, was a space mission proposed by NASA in 2013; the mission was later cancelled. The Asteroid Retrieval Robotic Mission (ARRM) spacecraft would rendezvous with a large near-Earth asteroid and use robotic arms with anchoring grippers to retrieve a 4-meter boulder from the asteroid.
IXS Enterprise is a conceptual interstellar superluminal spacecraft designed by NASA scientist Dr. Harold G. White, revealed at SpaceVision 2013, designed for the goal of achieving warp travel. The conceptual spacecraft would make use of a modified version of the Alcubierre drive. Dr. White is currently running the White–Juday warp-field interferometer experiment in order to develop a proof of concept for Alcubierre-style warp travel, when possible. The Alcubierre drive uses exotic matter to travel faster than light.
Advanced Electric Propulsion System (AEPS) is a solar electric propulsion system for spacecraft that is being designed, developed and tested by NASA and Aerojet Rocketdyne for large-scale science missions and cargo transportation. The first application of the AEPS is to propel the Power and Propulsion Element (PPE) of Gateway, to be launched in 2024. The PPE module is built by Maxar space solutions in Palo Alto, California. Two identical AEPS engines would consume 25 kW being generated by the roll-out solar array (ROSA) assembly, which can produce over 60 kW of power.
Alec Damian Gallimore is an American aerospace engineer, currently serving as Provost of Duke University as of July 2023. Prior to assuming the role of provost at Duke, Gallimore served as the Robert J. Vlasic Dean of Engineering and the Richard F. and Eleanor A. Towner Professor of Engineering of the University of Michigan College of Engineering. He founded the Plasmadynamics and Electric Propulsion Laboratory in 1992.
