ORBITAL ANNOUNCES SECOND QUARTER 2011 FINANCIAL RESULTS

For Immediate Release		For More Information Contact: Barron Beneski (703) 406-5528 Public and Investor Relations beneski.barron@orbital.com

ORBITAL ANNOUNCES SECOND QUARTER 2011 FINANCIAL RESULTS

--Quarterly Revenues Set New Record, Operating Profit Margins Increase in All Segments--
--Company Increases 2011 Financial Guidance--

(Dulles, VA 21 July 2011) - Orbital Sciences Corporation (NYSE: ORB) today reported its financial results for the second quarter of 2011. Second quarter 2011 revenues were $354.3 million, up 5% compared to $337.7 million in the second quarter of 2010. Second quarter 2011 operating income was $22.7 million, compared to $12.2 million in the second quarter of 2010.

Net income was $21.2 million, or $0.36 diluted earnings per share, in the second quarter of 2011, compared to net income of $6.3 million, or $0.11 diluted earnings per share, in the second quarter of 2010. The second quarter 2011 results included a favorable non-recurring income tax adjustment of $7.7 million, or $0.13 diluted earnings per share. Excluding this favorable income tax adjustment, net income was $13.5 million,* or $0.23 diluted earnings per share.* Orbital's free cash flow* in the second quarter of 2011 was positive $24.4 million compared to negative $76.5 million in the second quarter of 2010.

Mr. David W. Thompson, Orbital's Chairman, President and Chief Executive Officer, said, "Our second quarter 2011 revenues set a new quarterly record on strong growth in the company's launch vehicles segment, while operating profit margins increased in all business segments. Operational activity continued at a good pace, with six major rocket launches and space system deployments in addition to eight additional system deliveries in the second quarter."

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* These adjusted amounts and "free cash flow" are non-GAAP financial measures. For additional details concerning free cash flow, please refer to the sections of this press release entitled "Cash Flow" and "Disclosure of Non-GAAP Financial Measure."

Financial Highlights

Summary financial results were as follows:

SEE TABLE A

Revenues increased $16.6 million, or 5%, in the second quarter of 2011 compared to the second quarter of 2010, primarily due to increased activity on national security satellite, space and target launch vehicle and space technical services contracts. These factors were partially offset by decreased activity on the Orion human spacecraft Launch Abort System (LAS) contract that was terminated for convenience by the customer in the second quarter of 2010, decreased revenues on the International Space Station Commercial Resupply Services (CRS) contract, resulting from a particularly high level of subcontract activity in the second quarter of 2010, and decreased activity on science and remote sensing satellite contracts.

Operating income increased $10.5 million, or 86%, in the second quarter of 2011 compared to the second quarter of 2010 due to improved operating results in all of the company's business segments. This improvement was largely attributable to the absence of three factors that lowered operating income in the second quarter of 2010: (i) research and development (R&D) expenses that were not recovered under U.S. Government contracts, (ii) costs pertaining to the successful resolution of the Galaxy 15 satellite anomaly that occurred in early 2010 and (iii) transaction expenses pertaining to the company's 2010 spacecraft business acquisition.

The company recorded an income tax benefit of $0.5 million in the second quarter of 2011 compared to an income tax provision of $4.0 million in the second quarter of 2010. The reduction in income taxes was largely due to a favorable non-recurring income tax adjustment of $7.7 million, or $0.13 diluted earnings per share, recorded in the second quarter of 2011 pertaining to the company's election to claim extraterritorial income (ETI) exclusions related to prior-year export activity.

Net income in the second quarter of 2011 increased to $21.2 million, or $0.36 diluted earnings per share, compared to $6.3 million, or $0.11 diluted earnings per share, in the second quarter of 2010. Excluding the favorable ETI income tax adjustment noted above, net income was $13.5 million, or $0.23 diluted earnings per share.

Segment Results

Second quarter operating results by business segment were as follows:

Launch Vehicles

SEE TABLE B

Launch vehicles segment revenues increased $35.7 million in the second quarter of 2011 compared to the second quarter of 2010 primarily due to increased activity on space launch vehicle contracts, driven by the company's new Taurus II rockets, and increased activity on target launch vehicle contracts.

Segment operating income increased $3.3 million in the second quarter of 2011 compared to the second quarter of 2010 primarily due to the absence of unrecovered R&D expenses that were recognized in the second quarter of 2010, in addition to favorable profit adjustments on missile defense interceptor contracts and increased activity on target launch vehicle contracts. Segment operating margin increased primarily due to the absence of unrecovered R&D expenses and the favorable profit adjustments on missile defense interceptors.

Satellites and Space Systems

SEE TABLE C

Satellites and space systems segment revenues declined $1.2 million in the second quarter of 2011 compared to the second quarter of 2010 primarily due to decreased activity on science and remote sensing satellite contracts, partially offset by increased activity on space technical services contracts.

Segment operating income increased $1.0 million in the second quarter of 2011 compared to the second quarter of 2010 primarily due to improved results from communications satellite contracts, partially offset by the reduction in activity on science and remote sensing satellite contracts. Communications satellite operating results improved primarily due to the absence of costs incurred in the second quarter of 2010 pertaining to the successful resolution of the

Galaxy 15 satellite anomaly that occurred in early 2010. Segment operating margin increased primarily due to the absence of the Galaxy 15 anomaly resolution costs.

Advanced Space Programs

SEE TABLE D

Advanced space programs segment revenues decreased $14.1 million in the second quarter of 2011 compared to the second quarter of 2010 primarily due to decreased revenues on the CRS contract, resulting from a particularly high level of subcontract activity in the second quarter of 2010, and decreased activity on the Orion LAS contract. These factors were partially offset by increased activity on national security satellite contracts in the second quarter of 2011.

Segment operating income increased $4.6 million in the second quarter of 2011 compared to the second quarter of 2010 primarily due to increased activity on national security satellite contracts and the absence of unrecovered R&D expenses that were recognized in the second quarter of 2010. Segment operating margin increased primarily due to the absence of unrecovered R&D expenses.

Cash Flow

Cash flows for the second quarter and first six months of 2011 were as follows:

SEE TABLE E

New Business Highlights

During the second quarter of 2011, Orbital received approximately $235 million in new firm and option contract bookings. In addition, the company received approximately $20 million of option exercises under existing contracts. As of June 30, 2011, the company's firm contract backlog was approximately $2.1 billion and its total backlog (including options, indefinite-quantity contracts and undefinitized orders) was approximately $5.3 billion.

Operational Highlights

In the second quarter of 2011, the company carried out six launch vehicle and space systems missions. The company also completed and shipped another eight rockets and satellite systems to customers for missions to be carried out in the future. Among the missions conducted in the second quarter was the recent launch of a Minotaur I space launch vehicle carrying a U.S. military satellite. It was the 21st consecutive success for the Minotaur family of launchers developed by Orbital for the U.S Air Force. In addition, Orbital successfully launched three Coyote target missiles for the U.S. Navy in the quarter. The company also deployed the New Dawn communications spacecraft for Intelsat during the second quarter.

Orbital's Dawn interplanetary spacecraft, which was launched in 2007 on an eight-year mission to explore the main asteroid belt located between Mars and Jupiter, recently completed its approach and orbital injection around Vesta, the second largest asteroid in the solar system. Dawn is now returning first-ever images of this near planet-size asteroid, which it is expected to orbit for the next year prior to embarking on a multi-year transfer to Ceres, the largest asteroid.

The company also achieved numerous milestones on its Taurus II and Cygnus development programs in the last three months. These included the delivery of virtually all the hardware for the Taurus II test flight vehicle and the initial power-on testing of the first Cygnus spacecraft for NASA's Commercial Orbital Transportation Services (COTS) demonstration mission. However, delays in completing the launch complex construction and certification have resulted in a two-month schedule delay for the first Taurus II test flight, moving it from October to December of this year.

For the remainder of 2011, Orbital is scheduled to complete up to 30 additional space missions, product deliveries and major R&D milestones. These operational events will be in addition to 32 space missions, product deliveries and R&D milestones completed in the first six months of this year.

2011 Financial Guidance

The company updated its previous financial guidance for the full year 2011 as follows:

SEE TABLE F

The updated guidance for 2011 reflects increases in revenues and earnings per share in addition to an improvement in free cash flow. The increase in diluted earnings per share is primarily due to the impact of the non-recurring favorable income tax adjustment of $7.7 million, or $0.13 diluted earnings per share, recognized in the second quarter of 2011.

Disclosure of Non-GAAP Financial Measure

Free cash flow is defined as GAAP (Generally Accepted Accounting Principles) net cash provided by operating activities less capital expenditures for property, plant and equipment. A reconciliation of free cash flow to net cash provided by operating activities is included above in the section entitled "Cash Flow." Management believes that the company's presentation of free cash flow is useful because it provides investors with an important perspective on the company's liquidity, financial flexibility and ability to fund operations and service debt.

Orbital does not intend for the above non-GAAP financial measure to be considered in isolation or as a substitute for the related GAAP measure. Other companies may define this measure differently.

About Orbital

Orbital develops and manufactures small- and medium-class rockets and space systems for commercial, military and civil government customers. The company's primary products are satellites and launch vehicles, including low-Earth orbit, geosynchronous-Earth orbit and planetary exploration spacecraft for communications, remote sensing, scientific and defense missions; human-rated space systems for Earth-orbit, lunar and other missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense systems that are used as interceptor and target vehicles. Orbital also provides satellite subsystems and space-related technical services to U.S. Government agencies and laboratories. More information about Orbital can be found at http://www.orbital.com.

"Safe Harbor" Statement Under the Private Securities Litigation Reform Act of 1995

Certain statements in this press release may be forward-looking in nature or "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, those related to our financial outlook, liquidity, goals, business strategy, projected plans and objectives of management for future operating results and forecasts of future events. These statements can be identified by the fact that they do not relate strictly to historical or current facts. Forward-looking statements often include the words "anticipate," "forecast," "expect," "believe," "should," "intend," "plan" and words of similar substance. Such forward-looking statements are subject to risks, trends and uncertainties that could cause the actual results or performance of the company to be materially different from the forward-looking statement. Uncertainty surrounding factors such as continued government support and funding for key space and defense programs, new product development programs, achievement of important performance milestones on significant contracts, product performance and market acceptance of products and technologies, government contract procurement and termination risks, income tax rates, as well as other risk factors and business considerations described in the company's SEC filings, including its annual report on Form 10-K, could impact Orbital's actual financial and operational results. Orbital assumes no obligation for updating the information contained in this press release.

A transcript of the earnings teleconference call will be available on Orbital's website at http://www.orbital.com/Investor.

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ORBITAL SCIENCES CORPORATION
Condensed Consolidated Income Statements
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ORBITAL SCIENCES CORPORATION
Segment Information
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ORBITAL SCIENCES CORPORATION
Condensed Consolidated Balance Sheets
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ORBITAL SCIENCES CORPORATION
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