X0306 4 2012-12-20 0 0000820736 ORBITAL SCIENCES CORP /DE/ ORB 0001045847 ELIAS ANTONIO L C/O ORBITAL SCIENCES CORPORATION 45101 WARP DRIVE DULLES VA 20166 0 1 0 0 Executive Vice President Common Stock 2012-12-20 4 M 0 33333 5.65 A 182675 D Common Stock 2012-12-20 4 M 0 16667 5.65 A 199342 D Common Stock 2012-12-20 4 S 0 50000 13.5958 D 144342 D Employee Stock Option (right to buy) 5.65 2012-12-20 4 M 0 33333 0 D 2006-12-14 2013-02-18 Common Stock 33333 0 D Employee Stock Option (right to buy) 5.65 2012-12-20 4 M 0 16667 0 D 2007-02-28 2013-02-18 Common Stock 16667 0 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 6, 2012. This transaction was executed at prices ranging from $13.50 to $13.76. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer, full information regarding the number of shares and prices at which the transaction was effected. /s/ James S. Black, II, Attorney-in-Fact 2012-12-21