Polar bear

• 1. Introduction

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  Polar BEAR, which stands for Polar Beacon Experiment and Auroral Research, launched on the 13th of November 1986 from Vandenberg Air Force Base carrying a peculiar distinction: it was a satellite that had already been on public display. Before it ever reached orbit, this craft had spent nearly a decade inside the National Air and Space Museum, where visitors walked past it without knowing it would one day fly. How does a museum exhibit become a working spacecraft? And what scientific problem was so pressing that the U.S. military turned to a museum piece to solve it? Those are the questions that make Polar BEAR worth understanding.

• 2. From Museum to Orbit

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  Saving money drove one of the more unusual decisions in the history of American spaceflight. Rather than build an entirely new spacecraft, the Air Force and Johns Hopkins University's Applied Physics Laboratory retrieved a satellite that had been sitting on display at the National Air and Space Museum for almost a decade. The Applied Physics Laboratory, known as APL, was the organization tapped to build the mission for the Air Force. Pulling hardware out of a museum and returning it to flight-ready condition was the kind of cost-cutting measure that raises eyebrows, but it got Polar BEAR into the sky. The mission also carried the designations STP P87-1 and STP P87-A, placing it formally within the Space Test Program's catalog of military research payloads.

• 3. The Science of Solar Disruption

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  Solar flares and auroral activity can interfere with radio communications in the high-latitude regions of Earth, and that problem was precisely what Polar BEAR was sent to study. The concern is not abstract: military and civilian operators in polar regions depend on reliable communications links, and the charged particles and ionospheric disturbances that accompany solar and auroral events can degrade or sever those links. Polar BEAR did not arrive at this problem without precedent. Its science mission continued the work begun by an earlier effort called HILAT, an acronym for High Latitude, which had already been probing the same set of phenomena. The Polar BEAR mission represented a deliberate follow-on, designed to deepen the understanding that HILAT had started building.