![An astronaut on the end of the robotic arm opens an equipment door on Hubble. The solar array and the blue earth are in the background.](https://science.nasa.gov/wp-content/uploads/2023/07/28024330075-0a0b725ce0-o.jpg?w=4096&format=jpeg)
Astronaut John M. Grunsfeld
John M. Grunsfeld, positioned on a foot restraint on the end of Discovery's Remote Manipulator System (RMS), prepares to replace a radio transmitter in one of the Hubble Space Telescope (HST) electronics bays. Steven L. Smith, STS-103 payload commander, was working to Grunsfeld's left.
Credits: NASA
Image CreditNASA
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