X

X Ray Astrophysics Facility

   (NASA Thesaurus)

Free-flying x ray observatory that is shuttle-launched, maintainable in orbit, and retrievable. Used for Advanced X Ray Astrophysics Facility and AXAF.

x ray binaries

   (NASA Thesaurus)

Bright galactic x ray sources consisting of a compact star (neutron star or black hole) accreting matter from a close companion star.

x ray fluorescence spectroscopy

   (Global Land Information System Glossary - USGS)

This non-destructive analytical technique is used to determine concentrations of specific chemical elements. The procedure is based on the artificially induced absorption, atomic excitation, and emission of electromagnetic radiation at characteristic wavelengths.

x ray imagery

   (NASA Thesaurus)

Reproduction of an object by means of focusing penetrating electromagnetic radiation (wavelengths ranging from 10-5 to 103 angstroms) coming from the object or reflected by the object. Analogous to infrared imagery, radar imagery and microwave imagery using the IR, radar and microwave frequencies.

x ray optics

   (NASA Thesaurus)

The study and application of x ray properties and phenomena that are similar to the optical characteristics of visible light.

x ray stars

   (NASA Thesaurus)

Stars with strong emission in the x ray portion of the electromagnetic spectrum. Used for extars.

X Ray Timing Explorer

   (NASA Thesaurus)

An Explorer satellite planned for late 1993 or 1994 to consist of three experiments: a large area proportional counter, an all sky monitor, and a high energy x ray timing experiment. The package is designed to measure the time variability of x ray sources and broad band spectra.

x ray tubes

   (NASA Thesaurus)

Vacuum tubes designed to produce x rays by accelerating electrons to a high velocity by means of an electrostatic field, then suddenly stopping them by collision with a target.

x rays

   (NASA Thesaurus / NASA SP-7, 1965)

Nonnuclear electromagnetic radiation of very short wavelength, lying within the interval of 0.1 to 100 angstroms (between gamma rays and ultraviolet radiation). Also called X-radiation, Roentgen ray .
X-rays penetrate various thickness of all solids and they act upon photographic plates in the same manner as light. Secondary X-rays are produced whenever X-rays are absorbed by a substance; in the case of absorption by a gas, this results in ionization.

x wing rotors

   (NASA Thesaurus)

A new VTOL concept utilizing the stopped rotor X-wing aircraft.

X-31 aircraft

   (NASA Thesaurus)

A research aircraft (single-engine, delta-wing/canard configuration) designed to demonstrate enhanced fighter maneuverability (EFM) and post-stall controllability through the use of thrust vector control at very high angle-of-attack.

X-32 aircraft

   (NASA Thesaurus)

Experimental supersonic strike fighter developed to be configured as a conventional or short takeoff/vertical landing vehicle. Developed as part of the Joint Strike Fighter (JSF) program.

X-35 aircraft

   (NASA Thesaurus)

Experimental strike fighter incorporating a vertical lift fan for short takeoff/vertical landing capability. Developed as part of the Joint Strike Fighter (JSF) program.

X-43 vehicle

   (NASA Thesaurus)

The experimental research vehicle of the NASA Hyper-X program designed to flight validate key propulsion and related technologies for air-breathing hypersonic aircraft.

X-band

   (NASA SP-7, 1965)

A frequency band used in radar extending approximately from 5.2 to 10.9 kilomegacycles per second.

X-radiation

   (NASA SP-7, 1965)

= x rays.

xenon chloride lasers

   (NASA Thesaurus)

Rare gas-halide lasers using XeCl as the active material.

xenon fluoride lasers

   (NASA Thesaurus)

Lasers using XeF as the active material.

XV-15 aircraft

   (NASA Thesaurus)

Experimental model of a tilt-rotor aircraft built by Bell Aircraft Company.

xylene

   (NASA Thesaurus)

A mixture of Carbon 8 aromatic hydrocarbons.