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.
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit (apoapsis) by flying the vehicle through the atmosphere at the low point of the orbit (periapsis). The resulting drag slows the spacecraft. Aerobraking is used when a spacecraft requires a low orbit after arriving at a body with an atmosphere, as it requires less fuel than using propulsion to slow down.
A gravity assist, gravity assist maneuver, swing-by, or generally a gravitational slingshot in orbital mechanics, is a type of spaceflight flyby which makes use of the relative movement and gravity of a planet or other astronomical object to alter the path and speed of a spacecraft, typically to save propellant and reduce expense.
The Interplanetary Transport Network (ITN) is a collection of gravitationally determined pathways through the Solar System that require very little energy for an object to follow. The ITN makes particular use of Lagrange points as locations where trajectories through space can be redirected using little or no energy. These points have the peculiar property of allowing objects to orbit around them, despite lacking an object to orbit, as these points exist where gravitational forces between two celestial bodies are equal. While it would use little energy, transport along the network would take a long time.
In astrodynamics, orbital station-keeping is keeping a spacecraft at a fixed distance from another spacecraft or celestial body. It requires a series of orbital maneuvers made with thruster burns to keep the active craft in the same orbit as its target. For many low Earth orbit satellites, the effects of non-Keplerian forces, i.e. the deviations of the gravitational force of the Earth from that of a homogeneous sphere, gravitational forces from Sun/Moon, solar radiation pressure and air drag, must be counteracted. For spacecraft in a halo orbit around a Lagrange point, station-keeping is even more fundamental, as such an orbit is unstable; without an active control with thruster burns, the smallest deviation in position or velocity would result in the spacecraft leaving orbit completely.
Martin Wen-Yu Lo is an American mathematician who currently works as a spacecraft trajectory expert at the NASA-owned Jet Propulsion Laboratory. Martin Lo is well known for discovering the Interplanetary Superhighway, also known as the Interplanetary Transport Network. The superhighway is created by combined gravitational forces of several planets that connects planets by a network of “tunnels” and is the most efficient way to navigate the solar system. This continues to be his main area of research.
In orbital mechanics, a free-return trajectory is a trajectory of a spacecraft traveling away from a primary body where gravity due to a secondary body causes the spacecraft to return to the primary body without propulsion.
A low-energy transfer, or low-energy trajectory, is a route in space that allows spacecraft to change orbits using significantly less fuel than traditional transfers. These routes work in the Earth–Moon system and also in other systems, such as between the moons of Jupiter. The drawback of such trajectories is that they take longer to complete than higher-energy (more-fuel) transfers, such as Hohmann transfer orbits.
DIDO is a MATLAB optimal control toolbox for solving general-purpose optimal control problems. It is widely used in academia, industry, and NASA. Hailed as a breakthrough software, DIDO is based on the pseudospectral optimal control theory of Ross and Fahroo. The latest enhancements to DIDO are described in Ross.
Kathleen Connor Howell is an American aerospace engineer known for her contributions to dynamical systems theory applied to spacecraft trajectory design which led to the use of halo orbit in multiple NASA space missions. She is currently the Hsu Lo Distinguished Professor at Purdue University in the School of Aeronautics and Astronautics. In acknowledgment of her many achievements, Discover magazine recognized her in 2002 as one of the 50 most important women in science.
Mason Peck is an associate professor at Cornell University and former NASA Chief Technologist. His immediate predecessor in the NASA position was Bobby Braun.
A rotating detonation engine (RDE) uses a form of pressure gain combustion, where one or more detonations continuously travel around an annular channel. Computational simulations and experimental results have shown that the RDE has potential in transport and other applications.
Amanda R. Hendrix is an American planetary scientist known for her pioneering studies of solar system bodies at ultraviolet wavelengths. She is a senior scientist at the Planetary Science Institute. Her research interests include moon and asteroid surface composition, space weathering effects and radiation products. She is a co-investigator on the Cassini UVIS instrument, was a co-investigator on the Galileo UVS instrument, is a Participating Scientist on the Lunar Reconnaissance Orbiter LAMP instrument and is a Principal Investigator on Hubble Space Telescope observing programs. As of 2019, she is also the co-lead of the NASA Roadmaps to Oceans World Group.
George Henry Born was an American aerospace engineer, Distinguished Professor, founder and Director Emeritus of the Colorado Center for Astrodynamics Research (CCAR) at the University of Colorado Boulder. He is known for his work in satellite navigation and precise orbit determination. He worked on various missions while at the Jet Propulsion Laboratory as well as navigation support for the Apollo program in the late 1960s while at Johnson Space Center.
Alejandro Miguel San Martín is an Argentine engineer of NASA and a science educator. He is best known for his work as Chief Engineer for the Guidance, Navigation, and Control system in the latest missions to Mars. His best known contribution is the Sky Crane system, of which he is coinventor, used in the Curiosity mission for the descent of the rover.
James Michael Longuski is an American scientist, inventor, writer, and educator known for his contributions to astrodynamics and space mission design. He worked as a space mission designer at Jet Propulsion Laboratory (JPL) for NASA starting in 1979. Longuski joined the faculty at Purdue University School of Aeronautics and Astronautics in 1988 and served until after the fall semester 2023.
Team Miles was a 6U CubeSat that was to demonstrate navigation in deep space using innovative plasma thrusters. It was also to test a software-defined radio operating in the S-band for communications from about 4 million kilometers from Earth. Team Miles was one of ten CubeSats launched with the Artemis 1 mission into a heliocentric orbit in cislunar space on the maiden flight of the Space Launch System (SLS), that took place on 16 November 2022. Team Miles was deployed but contact was not established with the spacecraft.
In mathematics, unscented optimal control combines the notion of the unscented transform with deterministic optimal control to address a class of uncertain optimal control problems. It is a specific application of tychastic optimal control theory, which is a generalization of Riemmann-Stieltjes optimal control theory, a concept introduced by Ross and his coworkers.
Moriba Kemessia Jah CorrFRSE is an American space scientist and aerospace engineer who describes himself as a "space environmentalist". He specializes in orbit determination and prediction, especially as related to space situational awareness and space traffic monitoring. He is currently a full professor of Aerospace Engineering and Engineering Mechanics at the University of Texas at Austin, a position he attained in 2024, and a National Geographic Explorer. Jah has co-founded Privateer Space x Orbital Insight, GaiaVerse, and Moriba Jah Universal. His work now broadly focuses on decision intelligence to improve the stewardship of the planet and beyond.
Swati Mohan is an Indian-American aerospace engineer and was the Guidance and Controls Operations Lead on the NASA Mars 2020 mission.
