; (ii) improve spectral efficiency, such as by improving compression technologies; or (iii) otherwise do not substantially modify the space station authorized by the license. (C) Exclusion This paragraph shall not apply to a request to modify a license for— (i) the addition of an ancillary terrestrial component; or (ii) modifying the service offered under the initial license granted under subsection (c) between fixed satellite service and mobile satellite service. (3) Expedited treatment for certain modifications (A) In general Not later than 30 days after the Commission receives a request to modify a license granted under subsection (c), a grant of market access granted under subsection (d), an authorization granted under subsection (e), or a covered authorization, in order to conduct a replacement described in subparagraph (B), the Commission shall grant or deny the request. (B) Replacement A replacement described in this subparagraph is a replacement of— (i) 1 space station, or component of a space station, with a technically similar space station, or component of a space station, previously approved by the Commission; or (ii) 1 earth station, or component of an earth station, with a technically similar earth station, or component of an earth station, previously approved by the Commission. (4) Exceptions The Commission may extend the deadlines under paragraphs (1) and (2) for a request subject to review under subsection (n). (h) Emergency grant, renewal, or modification If the Commission finds that there are extraordinary circumstances involving a danger to life or property or an action that is necessary for the national defense or security of the United States, the Commission— (1) may grant, for a period not to exceed 180 days in a manner and upon the terms the Commission shall by rule prescribe— (A) a license described in subsection (c), a grant of market access described in subsection (d), or an authorization described in subsection (e)