EXECUTIVE RELOCATION AGREEMENT

August 7, 2003
Mr. Ronald J. Grabe
13302 East Country Shadows 
Chandler, Arizona 85249

Dear Ron:

This letter agreement (the "Agreement’) sets forth certain compensation terms described below that Orbital Sciences Corporation (the "Company") agrees to provide to you in connection with your temporary relocation to Chandler, Arizona. This Agreement is not an employment contract nor does it alter your status as an at-will employee of the Company who may resign or be terminated at any time, with or without cause.

1. Relocation. At the Company’s request, you have agreed to extend your relocation assignment in Chandler, Arizona for a minimum period of two (2) years commencing June 1, 2003. The monthly relocation benefits provided to you pursuant to the relocation memorandum dated April 23, 2002 from J. R. Thompson to you (the "Relocation Memorandum") shall cease upon the effective date set forth herein and be super ceded by the terms and conditions of this Agreement. The Relocation Memorandum shall expire in its entirety upon the sale of your Chandler home and reimbursement to the Company of the initial down payment pursuant to the terms of the memorandum.

2. Term. This Agreement is effective as of the date written above and shall remain in effect until the earlier of (i) the date on which your relocation assignment to Chandler, Arizona is terminated by the Company, in its sole discretion, or (ii) you are no longer employed as an executive officer of the Company.

3. Special Cash Bonuses. In connection with your extended relocation, you shall receive the special cash bonuses outlined below, subject to the approval of the Company’s Human Resources and Nominating Committee. This Section 3 shall not become effective unless and until such consent has been received.

(a) You shall receive a special cash bonus in the amount of$103,000.00 promptly following the effective date of this Section 3.

(b) On June 1, 2005, you shall be entitled to receive a special cash bonus in the amount of$65,000.00, provided, however, that you must be relocated and employed by the Company in Chandler, Arizona on the date that the special cash bonus is due under this Section 3 in order to receive it, unless your employment was previously terminated under any of the following circumstances:

(i) by reason of death or Disability (as defined in your Executive Employment Agreement),

(ii) by the Company for any reason other than for Cause, as defined in your Executive Employment Agreement,

(iii) by you for Good Reason, as defined in your Executive Employment Agreement, or

详细内容见附件