X0202 4 2006-12-18 0 0000820736 ORBITAL SCIENCES CORP /DE/ ORB 0001231084 PIERCE GARRETT E 21839 ATLANTIC BOULEVARD DULLES VA 20166 1 1 0 0 VC and CFO Common Stock 2006-12-18 4 M 0 73000 5.50 A 220747 D Common Stock 2006-12-18 4 S 0 73000 19.1596 D 147747 D Common Stock 2006-12-19 4 M 0 144800 5.50 A 292547 D Common Stock 2006-12-19 4 S 0 144800 18.5926 D 147747 D Stock Option (right to buy) 5.50 2006-12-18 4 M 0 73000 0.00 D 2012-04-25 Common Stock 73000 237000 D Stock Option (right to buy) 5.50 2006-12-19 4 M 0 144800 0.00 D 2012-04-25 Common Stock 144800 92200 D The option vested in three installments on June 30, 2002, June 30, 2003 and June 30, 2004. /s/ Garrett E. Pierce by Vanessa T. Hoang, Attorney-In-Fact 2006-12-20