NASA has picked a longtime solar scientist who heads its heliophysics division to become the U.S. space agency's science chief - the first woman named to serve in the role, according to two people familiar with the decision.

Nicola Fox, the former top scientist on the Parker Solar Probe mission studying the sun, will be named this week as NASA's associate administrator for the agency's Science Mission Directorate, said the two sources, who spoke on condition of anonymity ahead of the official announcement.

Fox will lead NASA's science directorate, a unit with an annual budget of roughly $7 billion that oversees some of the agency's best-known programs from the robotic hunts for past life on Mars to exploring distant galaxies with the James Webb Space Telescope.

She will also oversee a NASA study group formed in 2022 to help the U.S. military detect and characterize UFOs, or so-called Unidentified Aerial Phenomena - mysterious objects that the White House and Pentagon officials see as threats to U.S. airspace.

Fox will succeed Thomas Zurbuchen, a Swiss-American astrophysicist who had led the directorate since 2016 before his retirement in December. Sandra Connelly, formerly Zurbuchen's deputy, has been leading the directorate in an acting capacity.

NASA did not immediately respond to a request for comment.