Quick search by citation:

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—
(A)
wholly by United States persons, or
(B)
in substantial part by United States persons, or
(C)
by the United States;
(2)
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
(3)
such articles were returned to the customs territory directly from space aboard such spacecraft or aboard another spacecraft which meets the requirements of paragraph (1)(A) through (C) of this section;
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.
(June 17, 1930, ch. 497, title IV, § 484a, as added Pub. L. 98–573, title II, § 209(a), Oct. 30, 1984, 98 Stat. 2976.)
Statutory Notes and Related Subsidiaries
Effective Date

Section applicable with respect to articles launched into space from the customs territory of the United States on or after Jan. 1, 1985, see section 214(c)(4) of Pub. L. 98–573, set out as an Effective Date of 1984 Amendment note under section 1304 of this title.