8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT
PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): June 30, 2006

ORBITAL SCIENCES CORPORATION

(Exact name of registrant as specified in its charter)

Delaware	1-14279	06-1209561
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)

21839 Atlantic Boulevard, Dulles, Virginia 20166

(Address of principal executive offices)

Registrant’s telephone number, including area code: (703) 406-5000

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 5.04 Temporary Suspension of Trading Under Registrant’s Employee Benefit Plans

     On June 19, 2006, the plan administrator for the Deferred Salary and Profit Sharing Plan for Employees of Orbital Sciences Corporation (the “401(k) Plan”) sent a notice to the participants in the 401(k) Plan stating that the custodian of the 401(k) Plan has determined to change the 401(k) Plan’s provider of self-directed account services. The notice stated that, as a result of this change, participants in the 401(k) Plan will not be able to buy or sell shares of common stock of Orbital Sciences Corporation (the “Company”) under the 401(k) Plan during a period that will begin on July 24, 2006 and will end late in the week of August 7, 2006. This period is referred to as the “Blackout Period.”

     On June 30, 2006, the Company sent a notice to its directors and executive officers (the “BTR Notice”) informing them that, pursuant to Section 306(a) of the Sarbanes-Oxley Act of 2002 and the rules and regulations of the Securities and Exchange Commission promulgated thereunder, they would be prohibited from purchasing, selling or otherwise acquiring or transferring certain equity securities of the Company (including the Company’s common stock, options, restricted stock units and derivative securities pertaining to any of the Company’s equity securities) on the open market or otherwise during the Blackout Period. A copy of the BTR Notice is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

     A participant in the 401(k) Plan, a security holder, or any other interested person may obtain, without charge, information regarding the Blackout Period by contacting Emily Bender, Vice President, Human Resources at 21839 Atlantic Boulevard, Dulles, Virginia 20166 (703) 406-5026.

Item 9.01 Financial Statements and Exhibits

     (c) The Company hereby files the following exhibit:

99.1 Notice to Directors and Executive Officers of Orbital Sciences Corporation Regarding 401(k) Plan Blackout Period and Restrictions on Ability to Trade in Company Securities

SIGNATURE

     Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	ORBITAL SCIENCES CORPORATION (Registrant)
Date: June 30, 2006	By:	/s/ David W. Thompson
		David W. Thompson
		Chairman and Chief Executive Officer

EXHIBIT INDEX

Exhibit Number	Description of Exhibit
99.1	Notice to Directors and Executive Officers of Orbital Sciences Corporation Regarding 401(k) Plan Blackout Period and Restrictions on Ability to Trade in Company Securities

EX-99.1

Exhibit 99.1

M E M O R A N D U M

To:	Directors and Executive Officers of Orbital Sciences Corporation
From:	Susan Herlick
	Senior Vice President and General Counsel
Date:	June 30, 2006
Subject:	Important Notice Regarding 401(k) Plan Blackout Period and
	Restrictions on Ability to Trade in Company Securities

This notice is to inform you of significant restrictions on your ability to trade in securities of Orbital Sciences Corporation (the “Company”) during an upcoming “blackout period” that will apply to the Deferred Salary and Profit Sharing Plan for Employees of Orbital Sciences Corporation (the “401(k) Plan”). The blackout period, which is imposed to facilitate a change in the 401(k) Plan’s provider of self-directed account services, will begin on July 24, 2006, and will end late in the week of August 7, 2006. During the blackout period, participants will not have any ability to buy or sell the Company’s common stock held in the 401(k) Plan.

In accordance with Section 306(a) of the Sarbanes-Oxley Act of 2002 and the SEC’s rules and regulations promulgated thereunder, the Company’s directors and executive officers are prohibited from July 24, 2006 through late in the week of August 7, 2006 from purchasing, selling, or otherwise acquiring or transferring, directly or indirectly, any equity security of the Company acquired in connection with his services as a director or executive officer. ^*

Please note the following:

• The term “equity securities” is defined broadly to include the Company’s common stock, options, restricted stock units and derivative securities pertaining to any of the Company’s equity securities.

• Covered transactions are not limited to those involving your direct ownership, but include any transaction in which you have a pecuniary interest (for example, transactions by your immediate family members living in your household).

• Although you are permitted to engage in transactions involving equity securities that were not acquired in connection with your services as a director or executive officer, there is a presumption that any such transactions are prohibited unless you can identify the source of the shares and show that you used the same identification for all related purposes, such as tax reporting and disclosure requirements.

^* Exemptions from these rules generally apply for purchases or sales under Rule 10b5-1 plans, dividend reinvestment plans, sales required by law, and certain other “automatic” transactions.

• Among other things, these rules prohibit exercising options granted to you in connection with your services as a director or executive officer, selling Company stock acquired pursuant to such options, and selling Company stock originally received as a restricted stock grant or pursuant to a restricted stock unit grant.

These rules apply in addition to the trading restrictions under the Company’s insider trading policy. If you engage in a transaction that violates these rules, you may be required to disgorge your profits from the transaction, and you may be subject to civil and criminal penalties and appropriate action under the Company’s insider trading policy. Because of the complexity of these rules and the severity of the penalties and other remedies, please contact me before engaging in any transaction involving the Company’s equity securities during the blackout period.

You may obtain, information regarding whether the blackout period has begun or ended by contacting Emily Bender, Vice President, Human Resources at 21839 Atlantic Boulevard, Dulles, Virginia 20166 (703) 406-5026.

If you have any questions, please feel free to contact me at (703) 406-5002.

Thank you.