degree: a position or space on the earth or in the heavens as measured by degrees of latitude.

inclination: the degree of deviation from a horizontal or vertical.

kg (kilogram): the basic metric unit of mass and weight equal to the mass of a platinum-iridium cylinder kept at the International Bureau of Weights and Measures near Paris and nearly equal to 1000 cubic centimeters of water at the temperature of its maximum density.

km (kilometer): one thousand meters (the basic metric unit of length).

minute: the 60th part of a degree.

orbit: a path described by one body or object in its revolution about another.

perigee: the point in the orbit of a satellite of the earth that is nearest to the earth.

period: the interval of time required for a satellite to complete an orbit.

torque: a turning or twisting force.

uhuru: the Swahili word for "freedom." The SAS-1 was nicknamed "Uhuru" because it was launched off the coast of Kenya on Kenya's independence day.

X-ray: a relatively high-energy photon with wavelength in the approximate range from 0.05 angstroms to 100 angstroms. b. Often x-rays. A stream of such photons, used for their penetrating power in radiography, radiology, radiotherapy, and research.