----

----

| þ | QUARTERLY      REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF      1934 |
|--------|---------------------------------------------------------------------------------------------------|
|   | For      the quarterly period ended September 30,2009                                             |

| o      | TRANSITION      REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIESEXCHANGE      ACT OF 1934 |
|--------|---------------------------------------------------------------------------------------------------|
|   | For      the transition period from ______ to______                                               |

| Delaware                                    | 06-1209561                                |
|---------------------------------------------|-------------------------------------------|
| (State      of Incorporation of Registrant) | (I.R.S.      Employer Identification No.) |

----

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TABLE 

|     |                  |                                                                                                             | Page   |
|----------|-----------------------|------------------------------------------------------------------------------------------------------------------|--------|
|     |                  |                                                                                                             |   |
| PART I.  | FINANCIAL INFORMATION |                                                                                                             |
|     |                  |                                                                                                             |   |
|     | Item 1.               | Financial Statements                                                                                             |   |
|     |                  |                                                                                                             |   |
|     |                  | Condensed Consolidated Balance Sheets as of      September 30, 2009 and December 31, 2008                        | 1      |
|     |                  |                                                                                                             |   |
|     |                  | Condensed Consolidated Income Statements for the Quarters and      Nine Months Ended September 30, 2009 and 2008 | 2      |
|     |                  |                                                                                                             |   |
|     |                  | Condensed Consolidated Statements of Cash Flows for the      Nine Months Ended September 30, 2009 and 2008       | 3      |
|     |                  |                                                                                                             |   |
|     |                  | Notes to Condensed Consolidated Financial      Statements                                                        | 4      |
|     |                  |                                                                                                             |   |
|     | Item 2.               | Management’s Discussion and Analysis of Financial Condition      and Results of Operations                 | 18     |
|     |                  |                                                                                                             |   |
|     | Item 3.               | Quantitative and Qualitative Disclosures About Market      Risk                                                  | 29     |
|     |                  |                                                                                                             |   |
|     | Item 4.               | Controls and Procedures                                                                                          | 30     |
|     |                  |                                                                                                             |   |
| PART II. | OTHER INFORMATION     |                                                                                                             |
|     |                  |                                                                                                             |   |
|     | Item 1.               | Legal Proceedings                                                                                                | 31     |
|     |                  |                                                                                                             |   |
|     | Item 1A.              | Risk Factors                                                                                                     | 31     |
|     |                  |                                                                                                             |   |
|     | Item 2.               | Unregistered Sales of Equity Securities and Use of      Proceeds                                                 | 31     |
|     |                  |                                                                                                             |   |
|     | Item 3.               | Defaults Upon Senior Securities                                                                                  | 31     |
|     |                  |                                                                                                             |   |
|     | Item 4.               | Submission of Matters to a Vote of Security      Holders                                                         | 31     |
|     |                  |                                                                                                             |   |
|     | Item 5.               | Other Information                                                                                                | 31     |
|     |                  |                                                                                                             |   |
|     | Item 6.               | Exhibits                                                                                                         | 31     |
|     |                  |                                                                                                             |   |
|     |                  |                                                                                                             |

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Table of Contents

PART I

FINANCIA

|   | ORBITAL SCIENCES  CORPORATION |
|--------|-------------------------------|

|                                                                                                  |   | September      30, |    |   | December      31,  |   |
|-------------------------------------------------------------------------------------------------------|--------|--------------------|---------|--------|--------------------|--------|
|                                                                                                  |   | 2009               |    |   | 2008               |   |
|                                                                                                  |   |               |    |   | (As      Adjusted) |   |
| ASSETS                                                                                                |   |               |    |   |               |   |
| Current      assets:                                                                                  |   |               |    |   |               |   |
|   Cash      and cash equivalents                                                            |   | $                  | 364,184 |   |               | $      | 328,307 |   |
|   Receivables,      net                                                                     |   |               | 204,890 |   |               |   | 203,111 |   |
|   Inventories,      net                                                                     |   |               | 39,636  |   |               |   | 33,434 |   |
|   Deferred      income taxes, net                                                           |   |               | 33,279  |   |               |   | 35,368 |   |
|   Other      current assets                                                                 |   |               | 17,186  |   |               |   | 8,951 |   |
| Total      current assets                                                                             |   |               | 659,175 |   |               |   | 609,171 |   |
| Investments                                                                                           |   |               | 12,700  |   |               |   | 16,700 |   |
| Property, plant and      equipment, net                                                               |   |               | 121,734 |   |               |   | 104,880 |   |
| Goodwill                                                                                              |   |               | 55,551  |   |               |   | 55,551 |   |
| Deferred income taxes,net                                                                             |   |               | 57,028  |   |               |   | 63,206 |   |
| Other      non-current assets                                                                         |   |               | 13,930  |   |               |   | 4,387 |   |
| Total      assets                                                                                     |   | $                  | 920,118 |   |               | $      | 853,895 |   |
|                                                                                                  |   |               |    |   |               |   |   |   |
| LIABILITIES      AND STOCKHOLDERS’ EQUITY                                                       |   |               |    |   |               |   |   |   |
| Current      liabilities:                                                                             |   |               |    |   |               |   |   |   |
|   Accounts      payable and accrued expenses                                                |   | $                  | 184,640 |   |               | $      | 179,658 |   |
|   Deferred      revenues and customer advances                                              |   |               | 118,103 |   |               |   | 80,059 |   |
| Total      current liabilities                                                                        |   |               | 302,743 |   |               |   | 259,717 |   |
| Long-term      obligations                                                                            |   |               | 119,027 |   |               |   | 115,372 |   |
| Other      non-current liabilities                                                                    |   |               | 7,851   |   |               |   | 5,700 |   |
| Total      liabilities                                                                                |   |               | 429,621 |   |               |   | 380,789 |   |
| Commitments      and contingencies                                                                    |   |               |    |   |               |   |   |   |
| Stockholders’      equity:                                                                      |   |               |    |   |               |   |   |   |
|   Preferred      Stock, par value $.01; 10,000,000 shares authorized, none      outstanding |   |               | — |   |               |   | — |   |
|   Common      Stock, par value $.01; 200,000,000 shares authorized, 56,832,783      and     |   |               |    |   |               |   |   |   |
|     57,499,260      shares outstanding, respectively                              |   |               | 568     |   |               |   | 575 |   |
|   Additional      paid-in capital                                                           |   |               | 536,972 |   |               |   | 547,389 |   |
|   Accumulated      other comprehensive loss                                                 |   |               | (2,321  | )      |               |   | (2,813 | ) |
|   Accumulated      deficit                                                                  |   |               | (44,722 | )      |               |   | (72,045 | ) |
| Total      stockholders’ equity                                                                 |   |               | 490,497 |   |               |   | 473,106 |   |
| Total      liabilities and stockholders’ equity                                                 |   | $                  | 920,118 |   |               | $      | 853,895 |   |

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Table of Contents

ORBITAL 

|                                                       |   | Quarters      Ended September 30, |    |   | Nine      Months Ended September 30, |   |
|------------------------------------------------------------|--------|-----------------------------------|---------|--------|--------------------------------------|--------|
|                                                       |   | 2009                              |    |   | 2008                                 |   |   | 2009 |   |   | 2008 |   |
|                                                       |   |                              |    |   | (As      Adjusted)                   |   |   |   |   |   | (As      Adjusted) |   |
| Revenues                                                   |   | $                                 | 277,092 |   |                                 | $      | 278,628 |   |   | $ | 842,962 |   |   | $ | 863,396 |   |
| Cost      of revenues                                      |   |                              | 214,574 |   |                                 |   | 227,253 |   |   |   | 669,737 |   |   |   | 704,724 |   |
| Research      and development expenses                     |   |                              | 31,440  |   |                                 |   | 11,676 |   |   |   | 81,145 |   |   |   | 30,082 |   |
| Selling,      general and administrative expenses          |   |                              | 17,496  |   |                                 |   | 18,699 |   |   |   | 54,513 |   |   |   | 61,112 |   |
| Income      from operations                                |   |                              | 13,582  |   |                                 |   | 21,000 |   |   |   | 37,567 |   |   |   | 67,478 |   |
| Investment      impairment charge                          |   |                              | (2,000  | )      |                                 |   | (1,000 | ) |   |   | (3,300 | ) |   |   | (11,600 | ) |
| Interest      income and other                             |   |                              | 577     |   |                                 |   | 1,763 |   |   |   | 7,990 |   |   |   | 5,601 |   |
| Interest      expense                                      |   |                              | (2,327  | )      |                                 |   | (2,236 | ) |   |   | (6,741 | ) |   |   | (6,557 | ) |
| Income      from continuing operations before income taxes |   |                              | 9,832   |   |                                 |   | 19,527 |   |   |   | 35,516 |   |   |   | 54,922 |   |
| Income      tax provision                                  |   |                              | (450    | )      |                                 |   | (8,080 | ) |   |   | (8,193 | ) |   |   | (21,302 | ) |
| Income      from continuing operations                     |   |                              | 9,382   |   |                                 |   | 11,447 |   |   |   | 27,323 |   |   |   | 33,620 |   |
| Income      from discontinued operations, net of taxes     |   |                              | — |   |                                 |   | — |   |   |   | — |   |   |   | 15,918 |   |
| Net      income                                            |   | $                                 | 9,382   |   |                                 | $      | 11,447 |   |   | $ | 27,323 |   |   | $ | 49,538 |   |
|                                                       |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
| Basic      income per share:                               |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|    Income      from continuing operations   |   | $                                 | 0.16    |   |                                 | $      | 0.19 |   |   | $ | 0.47 |   |   | $ | 0.56 |   |
|    Income      from discontinued operations |   |                              | — |   |                                 |   | — |   |   |   | — |   |   |   | 0.27 |   |
|    Net      income                          |   |                              | 0.16    |   |                                 |   | 0.19 |   |   |   | 0.47 |   |   |   | 0.83 |   |
|                                                       |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
| Diluted      income per share:                             |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|    Income      from continuing operations   |   | $                                 | 0.16    |   |                                 | $      | 0.19 |   |   | $ | 0.47 |   |   | $ | 0.55 |   |
|    Income      from discontinued operations |   |                              | — |   |                                 |   | — |   |   |   | — |   |   |   | 0.26 |   |
|    Net      income                          |   |                              | 0.16    |   |                                 |   | 0.19 |   |   |   | 0.47 |   |   |   | 0.81 |   |

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ORBITAL 

|                                                                                                    |   | Nine      Months Ended September 30, |    |
|---------------------------------------------------------------------------------------------------------|--------|--------------------------------------|---------|
|                                                                                                    |   | 2009                                 |    |   | 2008 |   |
|                                                                                                    |   |                                 |    |   | (As      Adjusted) |   |
| Operating      Activities:                                                                              |   |                                 |    |   |   |   |
|   Net      income                                                                             |   | $                                    | 27,323  |   |   | $ | 49,538 |   |
|   Adjustments      to reconcile net income to net cash provided by operating      activities: |   |                                 |    |   |   |   |   |   |
|       Gain      on sale of business, net of tax                           |   |                                 | — |   |   |   | (14,800 | ) |
|       Investment      impairment charge                                   |   |                                 | 3,300   |   |   |   | 11,600 |   |
|       Depreciation      expense                                           |   |                                 | 14,071  |   |   |   | 13,877 |   |
|       Deferred      income taxes                                          |   |                                 | 7,462   |   |   |   | 15,569 |   |
|       Stock-based      compensation and other                             |   |                                 | 8,278   |   |   |   | 7,155 |   |
|   Changes      in assets and liabilities                                                      |   |                                 | 18,779  |   |   |   | 4,099 |   |
|      Net cash provided by      operating activities                            |   |                                 | 79,213  |   |   |   | 87,038 |   |
|                                                                                                    |   |                                 |    |   |   |   |   |   |
| Investing      Activities:                                                                              |   |                                 |    |   |   |   |   |   |
|   Capital      expenditures                                                                   |   |                                 | (28,827 | ) |   |   | (18,865 | ) |
|   Net      proceeds from sale of business                                                     |   |                                 | — |   |   |   | 41,612 |   |
|   Net      proceeds from sale of property                                                     |   |                                 | 100     |   |   |   | 2,193 |   |
|   Sale      of investment                                                                     |   |                                 | 1,138   |   |   |   | — |   |
|      Net cash (used in) provided by investing      activities                  |   |                                 | (27,589 | ) |   |   | 24,940 |   |
|                                                                                                    |   |                                 |    |   |   |   |   |   |
| Financing      Activities:                                                                              |   |                                 |    |   |   |   |   |   |
|   Repurchase      of common stock                                                             |   |                                 | (16,681 | ) |   |   | (21,521 | ) |
|   Net      proceeds from issuances of common stock                                            |   |                                 | 2,030   |   |   |   | 10,495 |   |
|   Tax      effect of stock-based compensation                                                 |   |                                 | (1,096  | ) |   |   | 3,888 |   |
|      Net cash used in financing      activities                                |   |                                 | (15,747 | ) |   |   | (7,138 | ) |
|                                                                                                    |   |                                 |    |   |   |   |   |   |
| Net      increase in cash and cash equivalents                                                          |   |                                 | 35,877  |   |   |   | 104,840 |   |
| Cash      and cash equivalents, beginning of period                                                     |   |                                 | 328,307 |   |   |   | 235,822 |   |
| Cash      and cash equivalents, end of period                                                           |   | $                                    | 364,184 |   |   | $ | 340,662 |   |

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NOTES

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|                                                | Quarter      Ended September 30, 2008     |    |
|-----------------------------------------------------|-------------------------------------------|---------|
|                                                | Previously Reported                       |    | Adjustment |   | As Adjusted |
| Interest      expense                               |  $(1,107                             | )       |   |   | $(1,129 | ) |   |  $(2,236 | )  |
| Income      from continuing operations before taxes |  20,656                              |    |   |   |  (1,129 | ) |   |  19,527 |   |
| Income      tax provision                           |  (8,513                              | )       |   |   |  433 |   |   |  (8,080 | )  |
| Net      income                                     |  12,143                              |    |   |   |  (696 | )  |   |  11,447 |   |
|                                                |                                      |    |   |   |   |   |   |   |   |
| Basic      net income per share                     |  $          0.21 |    |   |   |        $  (0.02 | )  |   |  $     0.19 |   |
| Diluted      net income per share                   |  0.20                                |    |   |   |  (0.01 | )(1) |   |  0.19 | (1) |
|                                                |                                      |    |   |   |   |   |   |   |   |
|                                                | Nine      Months Ended September 30, 2008 |    |
|                                                | Previously Reported                       |    | Adjustment |   | As Adjusted |
| Interest      expense                               |  $(3,250                             | )  |   |   | $(3,307 | ) |   |  $(6,557 | ) |
| Income      from continuing operations before taxes |  58,229                              |    |   |   |  (3,307 | )  |   |  54,922 |   |
| Income      tax provision                           |  (22,571                             | )  |   |   |  1,269 |   |   |  (21,302 | )  |
| Net      income                                     |  51,576                              |    |   |   |  (2,038 | )  |   |  49,538 |   |
|                                                |                                      |    |   |   |   |   |   |   |   |
| Basic      net income per share                     |  $          0.88      |    |   |   | $       (0.05) |   |   |  $          0.83 |   |
| Diluted      net income per share                   |  0.85                                |    |   |   |  (0.04) | (1) |   |  0.81 | (1) |

|                                        | Previously Reported |          | Adjustment |   | As Adjusted |
|---------------------------------------------|---------------------|---------------|------------|--------|-------------|
| Non-current      deferred income taxes, net |                | $      73,851 |       |   |        |  $(10,645 | ) |   |   |  $      63,206 |   |
| Other      non-current assets               |                | 5,033         |       |   |        |  (646 | ) |   |   |  4,387 |   |
| Total      assets                           |                | 865,186       |       |   |        |  (11,291 | ) |   |   |  853,895 |   |
| Long-term      obligations                  |                | 143,750       |       |   |        |  (28,378 | )  |   |   |  115,372 |   |
| Total      liabilities                      |                | 409,167       |       |   |        |  (28,378 | ) |   |   |  380,789 |   |
| Additional      paid-in capital             |                | 525,027       |       |   |        |  22,362 |   |   |   |  547,389 |   |
| Accumulated      deficit                    |                | (66,770       | )          |   |        |  (5,275 | )  |   |   |  (72,045 | )  |
| Total      stockholders' equity             |                | 456,019       |       |   |        |  17,087 |   |   |   |  473,106 |   |

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|   | • | Launch      Vehicles.  Rockets that are used as interceptor and      target vehicles for missile defense systems, small- and medium-class space      launch vehicles that place satellites into Earth orbit, and suborbital      launch vehicles that place payloads into a variety of high-altitude      trajectories. |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | Satellites and Space      Systems.  Small- and medium-class spacecraft that are      used to enable global and regional communications and broadcasting, to      conduct space-related scientific research, to carry out interplanetary and      other deep-space exploration missions, to enable national security      applications, to collect imagery and other remotely-sensed data about the      Earth and to demonstrate new space  technologies. |
|--------|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | Advanced Space      Programs.  Human-rated space systems for Earth-orbit and      lunar exploration, advanced launch systems for medium-class satellites,      and small satellites and satellite subsystems primarily used for national      security space programs and to demonstrate new space      technologies. |
|--------|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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|                                  |   | Quarters      Ended September 30, |    |   | Nine      Months Ended September 30, |   |
|---------------------------------------|--------|-----------------------------------|---------|--------|--------------------------------------|--------|
|                                  |   | 2009                              |    |   | 2008                                 |   |   | 2009 |   |   | 2008 |   |
| Launch      Vehicles:                 |   |                              |    |   |                                 |   |   |   |   |   |   |   |
|   Revenues(1)               |   | $                                 | 109,978 |   |                                 | $      | 111,815 |   |   | $ | 346,290 |   |   | $ | 332,096 |   |
|   Operating      income     |   |                              | 3,227   |   |                                 |   | 8,416 |   |   |   | 11,595 |   |   |   | 29,430 |   |
|   Identifiable      assets  |   |                              | 146,962 |   |                                 |   | 127,609 | (2) |   |   | 146,962 |   |   |   | 127,609 | (2) |
|   Capital      expenditures |   |                              | 2,014   |   |                                 |   | 2,792 |   |   |   | 4,741 |   |   |   | 7,749 |   |
|   Depreciation              |   |                              | 1,076   |   |                                 |   | 1,464 |   |   |   | 4,157 |   |   |   | 4,091 |   |
| Satellites and Space      Systems:    |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|   Revenues(1)               |   | $                                 | 75,650  |   |                                 | $      | 100,006 |   |   | $ | 279,928 |   |   | $ | 314,486 |   |
|   Operating      income     |   |                              | 5,709   |   |                                 |   | 8,060 |   |   |   | 21,243 |   |   |   | 23,507 |   |
|   Identifiable      assets  |   |                              | 167,459 |   |                                 |   | 164,119 | (2) |   |   | 167,459 |   |   |   | 164,119 | (2) |
|   Capital      expenditures |   |                              | 3,735   |   |                                 |   | 1,912 |   |   |   | 12,199 |   |   |   | 6,981 |   |
|   Depreciation              |   |                              | 2,219   |   |                                 |   | 2,241 |   |   |   | 6,564 |   |   |   | 6,604 |   |
| Advanced      Space Programs:         |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|   Revenues                  |   | $                                 | 94,448  |   |                                 | $      | 68,608 |   |   | $ | 224,847 |   |   | $ | 220,936 |   |
|   Operating      income     |   |                              | 4,646   |   |                                 |   | 4,524 |   |   |   | 4,729 |   |   |   | 15,096 |   |
|   Identifiable      assets  |   |                              | 104,765 |   |                                 |   | 85,185 | (2) |   |   | 104,765 |   |   |   | 85,185 | (2) |
|   Capital      expenditures |   |                              | 3,915   |   |                                 |   | 698 |   |   |   | 9,664 |   |   |   | 698 |   |
|   Depreciation              |   |                              | 3       |   |                                 |   | 3 |   |   |   | 9 |   |   |   | 9 |   |
| Corporate      and Other:             |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|   Revenues(1)               |   | $                                 | (2,984  | )      |                                 | $      | (1,801 | )  |   | $ | (8,103 | ) |   | $ | (4,122 | )  |
|   Operating      income     |   |                              | — |   |                                 |   | — |   |   |   | — |   |   |   | (555 | )(3) |
|   Identifiable      assets  |   |                              | 500,932 |   |                                 |   | 476,982 | (2)(4) |   |   | 500,932 |   |   |   | 476,982 | (2)(4) |
|   Capital      expenditures |   |                              | 806     |   |                                 |   | 1,608 | (3) |   |   | 2,223 |   |   |   | 3,437 | (3) |
|   Depreciation              |   |                              | 1,141   |   |                                 |   | 1,013 | (3) |   |   | 3,341 |   |   |   | 3,173 | (3) |
| Consolidated:                         |   |                              |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|   Revenues                  |   | $                                 | 277,092 |   |                                 | $      | 278,628 |   |   | $ | 842,962 |   |   | $ | 863,396 |   |
|   Operating      income     |   |                              | 13,582  |   |                                 |   | 21,000 |   |   |   | 37,567 |   |   |   | 67,478 |   |
|   Identifiable      assets  |   |                              | 920,118 |   |                                 |   | 853,895 | (2)(4) |   |   | 920,118 |   |   |   | 853,895 | (2)(4) |
|   Capital      expenditures |   |                              | 10,470  |   |                                 |   | 7,010 |   |   |   | 28,827 |   |   |   | 18,865 |   |
|   Depreciation              |   |                              | 4,439   |   |                                 |   | 4,721 |   |   |   | 14,071 |   |   |   | 13,877 |   |

|   |  (1)  Corporate      and other revenues are comprised solely of the elimination of intersegment      sales.  Launch vehicles segment revenues include $1.9 million      and $0.3 million of intersegment sales in the quarters ended September 30,      2009 and 2008, respectively, and $5.2 million and $0.7 million of      intersegment sales in the nine months ended September 30, 2009 and 2008,      respectively.  Satellites and space systems segment revenues      include $1.0 million and $1.3 million of intersegment sales in the      quarters ended September 30, 2009 and 2008, respectively, and $2.7 million      and $3.0 million in the nine months ended September 30, 2009 and 2008,      respectively. |
|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (2)  As      of December 31, 2008. |
|--------|----------------------------------------------|

|   | (3)  Includes      amounts attributable to a former business unit that was sold in the second      quarter of 2008. |
|--------|-------------------------------------------------------------------------------------------------------------------------------|

|   | (4)  As      adjusted (see Note 3). |
|--------|-----------------------------------------------|

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|                                             |                                                                    | Quarters      Ended September 30, |   | Nine      Months Ended September 30, |
|--------------------------------------------------|-------------------------------------------------------------------------|-----------------------------------|--------|--------------------------------------|
| Numerator                                        | 2009                                                                    |                              |   | 2008                                 |   |   |   | 2009 |   | 2008 |
|                                             | Income      from continuing operations                                  |  $      9,382                |   |                                 | $11,447 |   |   |   | $27,323 |   |  $33,620 |
|                                             | Percentage      allocated to shareholders (1)                           | 98.9%                             |   |                                 | 98.2% |   |   |   | 98.6% |   | 98.2% |
|                                             | Numerator      for basic and diluted earnings per share                 |  $      9,279                |   | $                                    | $11,241 |   |   |   | $26,940 |   |  $33,015 |
|                                             |                                                                    |                              |   |                                 |   |   |   |   |   |   |   |
| Denominator                                      |                                                                    |                              |   |                                 |   |   |   |   |   |   |
|                                             | Denominator      for basic earnings per share -                         |                              |   |                                 |   |   |   |   |   |   |   |
|                                             |   weighted-average      shares outstanding                    |  56,674                      |   |                                 |  58,776 |   |   |   |  56,769 |   |  58,643 |
|                                             | Dilutive      effect of stock options                                   |  693                         |   |                                 |  1,165 |   |   |   |  728 |   |  1,239 |
|                                             | Dilutive      effect of convertible notes                               | —                           |   |                                 |  163 |   |   |   | — |   |  55 |
|                                             | Denominator      for diluted earnings per share                         |  57,367                      |   |                                 |  60,104 |   |   |   |  57,497 |   |  59,937 |
|                                             |                                                                    |                              |   |                                 |   |   |   |   |   |   |   |
| Per      share income from continuing operations |                                                                    |                              |   |                                 |   |   |   |   |   |   |
|                                             | Basic                                                                   |  $   0.16     |   |                                 | $         0.19 |   |   |   |          $    0.47 |   |         $    0.56 |
|                                             | Diluted                                                                 |  0.16                        |   |                                 |  0.19 |   |   |   |  0.47 |   |  0.55 |
|                                             |                                                                    |                              |   |                                 |   |   |   |   |   |   |   |
| _________________________                        |                                                                    |                              |   |                                 |   |   |   |   |   |   |
|  (1)                                        | Basic      weighted-average shares outstanding                          |  56,674                      |   |                                 |  58,776 |   |   |   |  56,769 |   |  58,643 |
|                                             | Basic      weighted-average shares outstanding and                      |                              |   |                                 |   |   |   |   |   |   |   |
|                                             |    unvested      restricted stock units expected to vest |  57,290                      |   |                                 |  59,859 |   |   |   |  57,555 |   |  59,722 |
|                                             | Percentage      allocated to shareholders                               | 98.9%                             |   |                                 | 98.2% |   |   |   | 98.6% |   | 98.2% |

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|                                |   | September      30, |    |   | December      31, |   |
|-------------------------------------|--------|--------------------|---------|--------|-------------------|--------|
|                                |   | 2009               |    |   | 2008              |   |
| Billed                              |   | $                  | 64,236  |   |              | $      | 51,156 |   |
| Unbilled                            |   |               | 140,654 |   |              |   | 151,955 |   |
|      Total |   | $                  | 204,890 |   |              | $      | 203,111 |   |

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|   |   | September      30, 2009     |    |   | December      31, 2008   |   |
|--------|--------|-----------------------------|---------|--------|--------------------------|--------|
|   |   | Cost      or Amortized Cost |    |   | Net      Unrealized Loss |   |   | Fair      Value |   |   | Cost      or Amortized Cost |   |   | Net      Unrealized Loss |   |   | Fair      Value |   |
| Debt   |   |                        | $11,400 |   |                     |   | $(700 | ) |   |   | $10,700 |   |   |   | $12,900 |   |   |   | $       — |   |   |   | $12,900 |   |
| Equity |   |                        | 2,000   |   |                     |   | — |   |   |   | 2,000 |   |   |   | 3,800 |   |   |   | — |   |   |   | 3,800 |   |
| Total  |   |                        | $13,400 |   |                     |   | $(700 | ) |   |   | $12,700 |   |   |   | $16,700 |   |   |   | $       — |   |   |   | $16,700 |   |
|   |   |                        |    |   |                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |

|                                                  |   | Quarters      Ended September 30, |   |   | Nine      Months Ended September 30, |   |
|-------------------------------------------------------|--------|-----------------------------------|--------|--------|--------------------------------------|--------|
|                                                  |   | 2009                              |   |   | 2008                                 |   |   | 2009 |   |   | 2008 |   |
| Debt      Securities                                  |   |                              |   |   |                                 |   |   |   |   |   |   |   |
| Fair      value at beginning of period                |   | $                                 | 13,100 |   |                                 | $      | 17,300 |   |   | $ | 12,900 |   |   | $ | 17,700 |   |
| Temporary      impairment (charges) credits, net      |   |                              | (900   | )      |                                 |   | (1,800 | ) |   |   | (700 | ) |   |   | (800 | ) |
| Other-than-temporary      impairment charges          |   |                              | (1,500 | )      |                                 |   | (100 | ) |   |   | (1,500 | ) |   |   | (1,500 | ) |
|     Net      change in fair value |   |                              | (2,400 | )      |                                 |   | (1,900 | ) |   |   | (2,200 | ) |   |   | (2,300 | ) |
|          Fair value at end of period   |   | $                                 | 10,700 |   |                                 | $      | 15,400 |   |   | $ | 10,700 |   |   | $ | 15,400 |   |
|                                                  |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|                                                  |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
| Equity      Securities                                |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
| Fair      value at beginning of period                |   | $                                 | 1,600  |   |                                 | $      | 5,300 |   |   | $ | 3,800 |   |   | $ | 10,300 |   |
| Temporary      impairment (charges) credits, net      |   |                              | 900    |   |                                 |   | 100 |   |   |   | - |   |   |   | 4,300 |   |
| Other-than-temporary      impairment charges          |   |                              | (500   | )      |                                 |   | (900 | ) |   |   | (1,800 | ) |   |   | (10,100 | ) |
|     Net      change in fair value |   |                              | 400    |   |                                 |   | (800 | ) |   |   | (1,800 | ) |   |   | (5,800 | ) |
|          Fair value at end of period   |   | $                                 | 2,000  |   |                                 | $      | 4,500 |   |   | $ | 2,000 |   |   | $ | 4,500 |   |
|                                                  |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|                                                  |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
| Total                                                 |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
| Fair      value at beginning of period                |   | $                                 | 14,700 |   |                                 | $      | 22,600 |   |   | $ | 16,700 |   |   | $ | 28,000 |   |
| Temporary      impairment (charges) credits, net      |   |                              | -      |   |                                 |   | (1,700 | ) |   |   | (700 | ) |   |   | 3,500 |   |
| Other-than-temporary      impairment charges          |   |                              | (2,000 | )      |                                 |   | (1,000 | ) |   |   | (3,300 | ) |   |   | (11,600 | ) |
|     Net      change in fair value |   |                              | (2,000 | )      |                                 |   | (2,700 | ) |   |   | (4,000 | ) |   |   | (8,100 | ) |
|          Fair value at end of period   |   | $                                 | 12,700 |   |                                 | $      | 19,900 |   |   | $ | 12,700 |   |   | $ | 19,900 |   |
|                                                  |   |                              |   |   |                                 |   |   |   |   |   |   |   |   |   |   |   |

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|                                                          |   | Quarter      Ended September 30, |    |   | Nine      Months Ended September 30, |   |
|---------------------------------------------------------------|--------|----------------------------------|---------|--------|--------------------------------------|--------|
|                                                          |   | 2009                             |    |   | 2008                                 |   |   | 2009 |   |   | 2008 |   |
|                                                          |   |                             |    |   | (As      Adjusted)                   |   |   |   |   |   | (As      Adjusted) |   |
| Net      income                                               |   | $                                | 9,382   |   |                                 | $      | 11,447 |   |   | $ | 27,323 |   |   | $ | 49,538 |   |
| Temporary      investment impairment                          |   |                             |    |   |                                 |   |   |   |   |   |   |   |   |   |   |   |
|     (charges)      credits, net           |   |                             | — |   |                                 |   | (539 | ) |   |   | (700 | ) |   |   | 4,661 |   |
| Defined      benefit plans, net of tax                        |   |                             | 766     |   |                                 |   | (827 | ) |   |   | 1,191 |   |   |   | (1,814 | ) |
|      Total      comprehensive income |   | $                                | 10,148  |   |                                 | $      | 10,081 |   |   | $ | 27,814 |   |   | $ | 52,385 |   |

|                                   | Restricted      Stock Units |                                              | Stock      Options |
|----------------------------------------|-----------------------------|---------------------------------------------------|--------------------|
|                                   | Number      of Units        | Weighted      Average Measurement Date Fair Value |               | Number      of Options |   | Weighted      Average Exercise Price |
| Outstanding      at December 31, 2008  |  877,794               |                                              |  $23.01       |   |   |  2,500,233 |   |   |  $9.01 |   |
|   Granted(1)                 |  86,010                |                                              |  15.16        |   |   | — |   |   | — |   |
|   Exercised                  | —                     |                                              | —            |   |   |  (87,305 | ) |   |  10.33 |   |
|   Vested                     |  (460,638              | )                                                 |  21.70        |   |   | — |   |   | — |   |
|   Forfeited                  |  (19,303               | )                                            |  22.73        |   |   |  (7,500 | )  |   |  12.15 |   |
|   Expired                    | —                     |                                              | —            |   |   |  (81,300 | )  |   |  27.97 |   |
| Outstanding      at September 30, 2009 |  483,863               |                                              |  $22.87       |   |   |  2,324,128 |  (2) |   |  $8.29 |   |

|     (1)    | The      fair value of restricted stock unit grants is determined based on the      closing market price of Orbital’s common stock on the date of      grant.  Such value is recognized as expense over the service      period, net of estimatedforfeitures. |
|-----------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|          (2)  | The      weighted average remaining contractual term is 2.81  years. |
|-----------------------------------|----------------------------------------------------------------------|

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|                                                                                               | Quarters      Ended |        | Nine      Months Ended |
|----------------------------------------------------------------------------------------------------|---------------------|-------------|------------------------|
|                                                                                               | September      30,  |        | September      30,     |
| (in      millions)                                                                                 | 2009                |        | 2008                   |   | 2009 |   | 2008 |
| Stock-based      compensation expense                                                              |                |  $2.4  |                   |   |   |  $2.6 |   |   |   |  $7.5 |   |   |   |  $6.6 |   |
| Income      tax benefit related to stock-based compensation expense                                |                |  0.7   |                   |   |   |  0.8 |   |   |   |  2.2 |   |   |   |  2.2 |   |
| Intrinsic      value of stock options exercised computed as the market    price                    |                |        |                   |   |   |   |   |   |   |   |   |   |   |   |   |
|    on      the exercise date less the price paid to exercise the stock      options |                |  0.1   |                   |   |   |  3.3 |   |   |   |  0.4 |   |   |   |  10.4 |   |
| Cash      received from exercise of stock options                                                  |                |  0.5   |                   |   |   |  4.0 |   |   |   |  0.9 |   |   |   |  9.3 |   |
| Tax      effect of stock-based compensation transactions recordedas                                |                |        |                   |   |   |   |   |   |   |   |   |   |   |   |   |
|   credits      (charges) to additional paid-in capital                                   |                |  (1.2) |                   |   |   |  1.5 |   |   |   |  (1.1) |   |   |   |  3.9 |   |

|                                                                                                  | As      of              |
|-------------------------------------------------------------------------------------------------------|-------------------------|
| (in      millions)                                                                                    | September      30, 2009 |
| Shares      of common stock available for grant under stock-based incentive      plans                |                    |  1.6 |   |
| Aggregate      intrinsic value of restricted stock units that are expected to      vest               |                    |  $7.2 |   |
| Unrecognized      compensation expense related to non-vested restricted stock units,      expected to |                    |   |   |
|    be      recognized over a weighted-average period of 1.61 years                     |                    |  8.8 |   |
| Aggregate      intrinsic value of stock options outstanding, all fully    vested                      |                    |  15.6 |   |

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ITEM 2. 

| ·   | Launch      Vehicles.  Rockets that are used as interceptor and      target vehicles for missile defense systems, small- and medium-class space      launch vehicles that place satellites into Earth orbit, and suborbital      launch vehicles that place payloads into a variety of high-altitude      trajectories. |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Satellites and Space      Systems.  Small- and medium-class spacecraft that are      used to enable global and regional communications and broadcasting, to      conduct space-related scientific research, to carry out interplanetary and      other deep-space exploration missions, to enable national security      applications, to collect imagery and other remotely-sensed data about the      Earth and demonstrate new spacetechnologies. |
|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Advanced Space      Programs.  Human-rated space systems for Earth-orbit and      lunar exploration, advanced launch systems for medium-class satellites,      and small satellites and satellite subsystems primarily used for national      security space programs and to demonstrate new space      technologies. |
|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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|                                    |   | Third      Quarter |    |   |   |   |    | First      Nine Months |   |   |   |   |
|-----------------------------------------|--------|--------------------|---------|--------|--------|--------|---------|------------------------|--------|--------|--------|--------|
| (in      thousands, except percentages) |   | 2009               |    |   | 2008   |   |    | %      Change          |   |   | 2009   |   |   | 2008 |   |   | %      Change |   |
| Revenues                                |   | $                  | 109,978 |   |   | $      | 111,815 |                   |   |   | (2%)   |   |   | $ | 346,290 |   |   | $ | 332,096 |   |   |   | 4% |   |
| Operating      income                   |   |               | 3,227   |   |   |   | 8,416   |                   |   |   | (62%)  |   |   |   | 11,595 |   |   |   | 29,430 |   |   |   | (61% | ) |
| Operating      margin                   |   |               | 2.9     | %      |   |   | 7.5     | %                      |   |   |   |   |   |   | 3.3 | % |   |   | 8.9 | % |   |   |   |   |

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|                                    |   | Third      Quarter |   |   |   |   |    | First      Nine Months |   |   |   |   |
|-----------------------------------------|--------|--------------------|--------|--------|--------|--------|---------|------------------------|--------|--------|--------|--------|
| (in      thousands, except percentages) |   | 2009               |   |   | 2008   |   |    | %      Change          |   |   | 2009   |   |   | 2008 |   |   | %      Change |   |
| Revenues                                |   | $                  | 75,650 |   |   | $      | 100,006 |                   |   |   | (24%   | )      |   | $ | 279,928 |   |   | $ | 314,486 |   |   |   | (11% | )  |
| Operating      income                   |   |               | 5,709  |   |   |   | 8,060   |                   |   |   | (29%   | )      |   |   | 21,243 |   |   |   | 23,507 |   |   |   | (10% | )  |
| Operating      margin                   |   |               | 7.5    | %      |   |   | 8.1     | %                      |   |   |   |   |   |   | 7.6 | % |   |   | 7.5 | % |   |   |   |   |

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|                                    |   | Third      Quarter |   |   |   |   |   | First      Nine Months |   |   |   |   |
|-----------------------------------------|--------|--------------------|--------|--------|--------|--------|--------|------------------------|--------|--------|--------|--------|
| (in      thousands, except percentages) |   | 2009               |   |   | 2008   |   |   | %      Change          |   |   | 2009   |   |   | 2008 |   |   | %      Change |   |
| Revenues                                |   | $                  | 94,448 |   |   | $      | 68,608 |                   |   |   | 38%    |   |   | $ | 224,847 |   |   | $ | 220,936 |   |   |   | 2% |   |
| Operating      income                   |   |               | 4,646  |   |   |   | 4,524  |                   |   |   | 3%     |   |   |   | 4,729 |   |   |   | 15,096 |   |   |   | (69% | ) |
| Operating      margin                   |   |               | 4.9    | %      |   |   | 6.6    | %                      |   |   |   |   |   |   | 2.1 | % |   |   | 6.8 | % |   |   |   |   |

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ITEM 3.

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ITEM 4. 

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PART II

ITEM1.  

ITEM1A.

| ITEM      2.                  UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF  PROCEEDS |
|--------------------------------------------------------------------------------------------------------------------------------------------------------|

| (a) |        None. |
|-----|-------------------|
| (b) |        None. |
| (c) |        None. |

| ITEM      3.                  DEFAULTS UPON SENIOR SECURITIES |
|---------------------------------------------------------------------------------------------------------------------------|

| ITEM      4.                  SUBMISSION OF MATTERS TO A VOTE OF SECURITY  HOLDERS |
|------------------------------------------------------------------------------------------------------------------------------------------------|

| ITEM      5.                  OTHER INFORMATION |
|-------------------------------------------------------------------------------------------------------------|

| ITEM      6.                  EXHIBITS |
|----------------------------------------------------------------------------------------------------|

| (a) |   Exhibits – A complete listing of      exhibits required is given in the ExhibitIndex. |
|-----|----------------------------------------------------------------------------------------------------|

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|                                    | ORBITAL      SCIENCES CORPORATION |
|-----------------------------------------|-----------------------------------|
|                                    |                              |   |
|                                    |                              |   |
| DATED:  October      29, 2009 | By:                               | /s/      David W. Thompson |
|                                    |                              | David      W. Thompson |
|                                    |                              | Chairman      and Chief Executive Officer |
|                                    |                              |   |
|                                    |                              |   |
| DATED:  October      29, 2009 | By:                               | /s/      Garrett E. Pierce |
|                                    |                              | Garrett      E. Pierce |
|                                    |                              | Vice      Chairman and Chief FinancialOfficer |

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| Exhibit No. | Description                                                                                                                                                                                                                                                             |
|-------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 3.1         | Restated      Certificate of Incorporation (incorporated by reference to Exhibit 4.1 to      the company’s Registration Statement on Form S-3 (File Number 333-08769)      filed and effective on July 25, 1996).                                                 |
| 3.2         | Amended      and Restated Bylaws (incorporated by reference to Exhibit 3.2 to the      company’s Quarterly Report on Form 10-Q for the quarter ended June 30,      2005).                                                                                         |
| 3.3         | Certificate      of Amendment to Restated Certificate of Incorporation, dated April 29,      1997 (incorporated by reference to Exhibit 3.3 to the company’s Annual      Report on Form 10-K for the fiscal year ended December 31,      1998).                   |
| 3.4         | Certificate      of Amendment to Restated Certificate of Incorporation, dated April 30,      2003 (incorporated by reference to Exhibit 3.4 to the company’s Quarterly      Report on Form 10-Q for the quarter ended June 30,  2003).                                 |
|        |                                                                                                                                                                                                                                                                         |
| 4.1         | Form      of Certificate of Common Stock (incorporated by reference to Exhibit 4.1      to the company’s Registration Statement on Form S-1 (File Number 33-33453)      filed on February 9, 1990 and effective on April 24, 1990).                               |
| 4.2         | Indenture      dated as of December 13, 2006, by and between Orbital Sciences Corporation      and The Bank of New York, as Trustee (incorporated by reference to Exhibit      4.1 to the company’s Current Report on Form 8-K filed on December 13,      2006).  |
| 4.3         | Form      of 2.4375% Convertible Senior Subordinated Note due 2027 (incorporated by      reference to Exhibit 4.2 to the company’s Current Report on Form 8-K filed      on December 13, 2006).                                                                        |
|        |                                                                                                                                                                                                                                                                         |
| 31.1        | Certification      of Chairman and Chief Executive Officer pursuant to Section 302 of the      Sarbanes-Oxley Act of 2002 (18 U.S.C. Section 1350) (transmitted      herewith).                                                                                         |
| 31.2        | Certification      of Vice Chairman and Chief Financial Officer pursuant to Section 302 of      the Sarbanes-Oxley Act of 2002 (18 U.S.C. Section 1350) (transmitted      herewith).                                                                                    |
| 32.1        | Written      Statement of Chairman and Chief Executive Officerpursuant      to Section 906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C. Section 1350)      (transmitted herewith).                                                                                      |
| 32.2        | Written      Statement of Vice Chairman and Chief Financial Officerpursuant      to Section 906 of the Sarbanes-Oxley Act of 2002 (18 U.S.C. Section 1350)      (transmitted herewith).                                                                                 |