true orbit
121Ganymede (moon) — Ganymede Image of Ganymede s anti Jovian hemisphere taken by the Galileo probe. Lighter surfaces, such as in recent impacts, grooved terrain and the whitish north polar cap at upper right, are enriched in water ice. Discovery …
122Project Orion (nuclear propulsion) — An artist s conception of the NASA reference design for the Project Orion spacecraft powered by nuclear propulsion. Project Orion was a study of a spacecraft intended to be directly propelled by a series of explosions of atomic bombs behind the… …
123Orbital station-keeping — In astrodynamics orbital station keeping is a term used to describe the orbital maneuvers made by thruster burns that are needed to keep a spacecraft in a particular assigned orbit. For many Earth satellites the effects of the non Keplerian… …
124Mars — This article is about the planet. For other uses, see Mars (disambiguation) …
125particle accelerator — accelerator (def. 7). [1945 50] * * * Device that accelerates a beam of fast moving, electrically charged atoms (ions) or subatomic particles. Accelerators are used to study the structure of atomic nuclei (see atom) and the nature of subatomic… …
126physical science — physical scientist. 1. any of the natural sciences dealing with inanimate matter or with energy, as physics, chemistry, and astronomy. 2. these sciences collectively. [1835 45] * * * Introduction the systematic study of the inorganic world …
127Retrograde motion — This article is about retrograde motions of celestial bodies relative to a gravitationally central object. For the apparent motion as seen from a particular vantage point, see Apparent retrograde motion. Retrograde orbit: the satellite (red)… …
128List of natural satellites — This article is about the moons of planets and dwarf planets. For asteroid or minor planet moons, see Minor planet moon. Objects in the Solar System By orbit …
