POWER OF ATTORNEY


	KNOW ALL BY THESE PRESENTS, that the undersigned
hereby constitutes and appoints each of Susan Herlick and Vanessa T. Hoang,
signing singly, the undersigned's true and lawful attorney-in-fact to:


	(1)	execute for and on behalf of the undersigned, in the undersigned's
capacity as an officer and/or director of Orbital Sciences Corporation (the
"Company"), Forms 3, 4 and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder;

	(2)	do and
perform any and all acts for and on behalf of the undersigned which may be
necessary or desirable to complete and execute any such Form 3, 4 or 5 and
timely file such form with the United States Securities and Exchange
Commission and any stock exchange or similar authority; and

	(3)	take
any other action of any type whatsoever in connection with the foregoing
which, in the opinion of such attorney-in-fact, may be of benefit to, in
the best interest of, or legally required by the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf
of the undersigned pursuant to this Power of Attorney shall be in such form
and shall contain such terms and conditions as such attorney-in-fact may
approve in such attorney-in-fact's discretion.

	The undersigned hereby
grants to each such attorney-in-fact full power and authority to do and
perform any and every act and thing whatsoever requisite, necessary or
proper to be done in the exercise of any of the rights and powers herein
granted, as fully to all intents and purposes as the undersigned might or
could do if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all that such attorney-in-fact,
or such attorney-in-fact's substitute or substitutes, shall lawfully do or
cause to be done by virtue of this power of attorney and the rights and
powers herein granted.  The undersigned acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company assuming, any of the
undersigned's responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934.

	This Power of Attorney shall remain in full
force and effect until the undersigned is no longer required to file Forms
3, 4 and 5 with respect to the undersigned's holdings of and transactions
in securities issued by the Company, unless earlier revoked by the
undersigned in a signed writing delivered to the foregoing
attorneys-in-fact.

	IN WITNESS WHEREOF, the undersigned has caused
this Power of Attorney to be executed as of this 28th day of October, 2004.


							DIRECTOR

							Frank L. Salizzoni