19 U.S. Code § 1484a. Articles returned from space not to be construed as importation
The return of articles from space shall not be considered an importation, and an entry of such articles shall not be required, if:
(1) such articles were previously launched into space from the customs territory of the United States aboard a spacecraft operated by, or under the control of, United States persons and owned—
wholly by United States persons, or
in substantial part by United States persons, or
by the United States;
such articles were maintained or utilized while in space solely on board such spacecraft or aboard another spacecraft which meets the requirements of paragraph (1)(A) through (C) of this section; and
without regard to whether such articles have been advanced in value or improved in condition by any process of manufacture or other means while in space.