The Chief of Research and Exploration was a position at Starfleet Command that supervised Starfleet's myriad science endeavors.
Many departments reported to it, such as Research and Development, Starfleet Medical, Astronomical Operations, Starfleet Diplomatic Corps, and Planetary Science Operations.
The position was normally held by a Fleet Admiral and, had a seat on the Joint Chiefs, reporting directly to the Commander in Chief.
In 2371 Fleet Admiral Stenn held the position. He ordered the USS Lionheart to host a trio of experimental devices to detect cloaked vessels. ("Blinded by Science")