German physicist Hans Wolter (1911-1978) conceived a series of designs for grazing-incidence telescopes, requiring photons to undergo two successive reflections from combinations of paraboloid-hyperboloid (particularly suited for extended field of view imaging) or paraboloid-ellipsoid surfaces (for spectroscopy requiring smaller field of view but higher spatial resolution).
The four innermost planets in the Solar System, which have solid rocky surfaces.
All the procedures, including the simulation of space environment, to ascertain that a spacecraft is ready for launch.
The rate at which the temperature changes with position.
The largest and most intriguing moon of Saturn. Titan is the second largest moon in the Solar System after Ganymede (one of Jupiter's moons), and is larger than the planet Mercury. Titan was discovered by the Dutch astronomer Christiaan Huygens on March 25 1655.
Ground facilities employed to follow the progress and to communicate with a satellite.