exv99w1

EX-99.1 3 w83766exv99w1.htm CERTIFICATION OF DAVID THOMPSON exv99w1

Exhibit 99.1

CERTIFICATION
OF
CHIEF EXECUTIVE OFFICER
PURSUANT TO 18 U.S.C. SECTION 1350 AS ADOPTED PURSUANT TO
SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

The undersigned, David W. Thompson, Chairman and Chief Executive Officer of Orbital Sciences Corporation (the “Company”), hereby certify, to his knowledge on the date hereof, that:

(a) the Form 10-Q/A of the Company for the quarter ended September 30, 2002 filed on the date hereof with the Securities and Exchange Commission (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(b) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ David W. Thompson

David W. Thompson
Chairman and Chief Executive Officer
February 21, 2003

(a)		the Form 10-Q/A of the Company for the quarter ended September 30, 2002 filed on the date hereof with the Securities and Exchange Commission (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(b)		the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.