Soon after its launch in 1990, scientists realized that the Hubble Space Telescope’s large primary mirror was flawed. It distorted images and data, making everything blurry. Shuttle crews installed this corrective optics package, called COSTAR (Corrective Optics Space Telescope Axial Replacement), in 1993 and returned it to Earth in 2009.
The long box holds a clever device: tiny nickel-size mirrors that extended on short arms into the light path inside the telescope. These mirrors were precisely shaped to cancel the flaw in the large main mirror, and precisely positioned to send corrected, focused light into three instruments. A new fourth instrument, a wide-field camera, came with its own built-in corrective optics. COSTAR was an ingenious solution to the unexpected challenge of correcting the Hubble’s distorted vision.
Lent by NASA Goddard Space Flight Center
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