apparent thermal inertia (ATI) - An approximation of thermal inertia calculated as one minus albedo divided by the difference between daytime and nighttime
achromatic vision - The perception by the human eye of changes in brightness, often used to describe the perception of monochrome or black and white scenes.
angular resolving power -Minimum separation between two resolvable targets, expressed as angular separation.
atmospheric correction - Image-processing procedure that compensates for effects of selectivity scattered light in multispectral images.
forward overlap - The percent of duplication by successive photographs along a flight line.
geostationary orbit - An orbit at 41 000 km in the direction of the Earth’s rotation, which matches speed so that a satellite remains over a fixed point on the Earth’s surface.
"That so few now dare to be eccentric, marks the chief danger of the time. I have said that it is important to give the freest scope possible to uncustomary things, in order that it may in time appear which of these are fit to be converted into customs. But independence of action, and disregard of custom, are not solely deserving of encouragement for the chance they afford that better modes of action, and customs more worthy of general adoption, may be struck out. No one can be a great thinker who does not recognise that as a thinker it is his first duty to follow his intellect to whatever conclusions it may lead. Truth gains more even by the errors of one who, with due study and preparation, thinks for himself, than by the true opinions of those who only hold them because they do not suffer themselves to think. Not that it is solely, or chiefly, to form great thinkers that freedom of thinking is required. On the contrary, it is as much, and even more indispensable to enable average human beings to attain the mental stature which they are capable of. There have been, and may again be, great individual thinkers in a general atmosphere of mental slavery. But there never has been, nor ever will be, in that atmosphere, an intellectually active people. Where any people has made a temporary approach to such a character, it has been at a period when the dread of heterodox speculation was for a time suspended. Where there is a tacit convention that principles are not to be disputed; where the discussion of the greatest questions which can occupy humanity is considered to be closed, we cannot hope to find that generally high scale of mental activity which has made some periods of history so remarkable. Never when controversy avoided the subjects which are large and important enough to kindle enthusiasm, was the mind of a people stirred up from its foundations, and the impulse given which raised even persons of the most ordinary intellect to something of the dignity of thinking beings. Of such we have had an example in the condition of Europe during the times immediately following the Reformation; another, though limited to the Continent and to a more cultivated class, in the speculative movement of the latter half of the eighteenth century; and a third, of still briefer duration, in the intellectual fermentation of Germany during the Goethian and Fichtean period. These periods differed widely in the particular opinions which they developed; but were alike in this, that during all three, the yoke of authority was broken. In each, an old mental despotism had been thrown off, and no new one had yet taken its place. The impulse given at these three periods has made Europe what it now is. Every single improvement which has taken place either in the human mind or in institutions, may be traced distinctly to one or other of them. Appearances have for some time indicated that all three impulses are well-nigh spent; and we can expect no fresh start until we again assert our mental freedom."
achromatic vision - The perception by the human eye of changes in brightness, often used to describe the perception of monochrome or black and white scenes.
angular resolving power -Minimum separation between two resolvable targets, expressed as angular separation.
atmospheric correction - Image-processing procedure that compensates for effects of selectivity scattered light in multispectral images.
forward overlap - The percent of duplication by successive photographs along a flight line.
geostationary orbit - An orbit at 41 000 km in the direction of the Earth’s rotation, which matches speed so that a satellite remains over a fixed point on the Earth’s surface.