-- Revenues Increase 46%, Net Income Rises 84%, EPS Climbs to $0.26 --
-- Company Raises Guidance for 2007, Provides Preliminary Outlook for 2008 --

(Dulles, VA 18 October 2007) - Orbital Sciences Corporation (NYSE: ORB) today announced its financial results for the third quarter and first nine months of 2007. Orbital's third quarter revenues increased 46% to $289.5 million in 2007, compared to $197.8 million in 2006. The company's third quarter operating income rose 54% to $23.2 million in 2007, compared to $15.1 million in 2006. Third quarter net income increased 84% to $15.7 million in 2007, compared to $8.5 million in 2006, and diluted earnings per share increased to $0.26, compared to $0.14 in the third quarter of 2006. Orbital reported third quarter 2007 free cash flow* of $22.4 million compared to free cash flow of $21.3 million in the third quarter of 2006.

Commenting on Orbital's third quarter 2007 results, Mr. David W. Thompson, Chairman and Chief Executive Officer, said, "The company reported strong revenue growth in all three of our business segments, boosted profit in most product lines, and generated solid free cash flow in the third quarter. Following the pattern established earlier in the year, communications satellites, human space systems and missile defense programs drove our revenue growth in the quarter."

For the first nine months of 2007, Orbital reported revenues of $791.0 million, up 35% compared to $587.0 million in the first nine months of 2006. The company's operating income for the first nine months of 2007 was $62.3 million, up 30% compared to $47.8 million during the same period in 2006. Net income for the first nine months of 2007 was $41.0 million, or $0.67 diluted earnings per share, compared to $27.3 million, or $0.44 diluted earnings per share, in the first nine months of 2006. Orbital generated $43.6 million of free cash flow in the first nine months of 2007, compared to $75.5 million during the same period in 2006.

^*"Free cash flow" is a non-GAAP financial measure discussed in this release. For additional details, please refer to the sections of this press release entitled "Cash Flow and Balance Sheet" and "Disclosure of Non-GAAP Financial Measure."

Financial Highlights

Summary financial results for the third quarter of 2007 compared to the third quarter of 2006 were as follows (in millions, except per share data):

Summary financial results for the first nine months of 2007 compared to the first nine months of 2006 were as follows (in millions, except per share data):

Revenues

Revenues by segment for the third quarter were as follows (in millions):

Orbital's third quarter 2007 revenues were $289.5 million, up 46% compared to third quarter 2006 revenues of $197.8 million, due to increased revenues in all business segments. Satellites and space systems segment revenues increased $58.0 million, or 49%, driven by contract activity on the Orion human spacecraft program for NASA which began in late 2006, and growth in the communications satellites product line that was mainly due to activity on recently awarded contracts. Launch vehicles segment revenues increased $29.0 million, or 41%, principally due to higher target and interceptor vehicle revenues driven by increased contract activity on several missile defense programs. Transportation management systems segment revenues increased $4.4 million, or 46%, largely due to an increase in product sales supporting follow-on and replacement demand for public transit fleet management systems.

Revenues by segment for the first nine months were as follows (in millions):

For the first nine months of 2007, Orbital reported $791.0 million in revenues, up 35% compared to the same period last year due to increased revenues in all business segments. Satellites and space systems segment revenues increased $133.1 million, or 40%, driven by contract activity on the Orion program which began in late 2006 and growth in the communications satellites product line mainly due to activity on recently awarded contracts. Launch vehicles segment revenues increased $60.4 million, or 26%, primarily due to the same factors that drove the increase in quarterly results, most notably higher target vehicle product line revenue. Transportation management systems segment revenues increased $9.4 million, or 35%, primarily due to an increase in product sales supporting follow-on and replacement demand for fleet management systems.

Operating Income

Operating income by segment for the third quarter was as follows (in millions):

Orbital reported operating income of $23.2 million in the third quarter of 2007, up 54% over the third quarter of 2006. This growth was due to a $4.3 million, or 61%, operating income increase in the satellites and space systems segment, a $3.1 million, or 38%, operating income increase in the launch vehicles segment and a $0.7 million, or 115%, operating income increase in the transportation management systems segment. The increase in operating income in the satellites and space systems segment was principally due to increased contract activity on the Orion program and new communications satellite programs. The increase in launch vehicles segment operating income was primarily due to increased activity levels on target and interceptor vehicle programs. The growth in the transportation management systems segment was largely attributable to the increase in product sales mentioned above.

Operating income by segment for the first nine months was as follows (in millions):

Orbital reported operating income of $62.3 million in the first nine months of 2007, up 30% over the first nine months of 2006. This increase was due to a $10.1 million, or 48%, increase in the satellites and space systems segment, a $3.6 million, or 14%, increase in the launch vehicles segment and a $0.7 million, or 49%, increase in the transportation management systems segment. The increases in operating income in all three segments were generally attributable to the same factors described above that drove the improvements in the third quarter results.

Net Income

Net income for the third quarter of 2007 was $15.7 million, or $0.26 diluted earnings per share, up from $8.5 million, or $0.14 diluted earnings per share, in the third quarter of 2006. Net income for the first nine months of 2007 was $41.0 million, or $0.67 diluted earnings per share, compared to $27.3 million, or $0.44 diluted earnings per share, in the same period of 2006.

Interest expense for the third quarter and first nine months of 2007 decreased to $1.3 million and $3.6 million, respectively, compared to $3.1 million and $9.3 million, respectively, in the same periods in 2006. The reduction in interest expense is due to lower interest rates on long-term debt as a result of Orbital's December 2006 refinancing transaction.

Diluted weighted-average shares outstanding decreased to 60.9 million in the third quarter of 2007 compared to 62.9 million in the third quarter of 2006 due to share repurchases made by the company. Diluted weighted-average shares outstanding in the first nine months of 2007 decreased to 61.0 million compared to 62.6 million in the first nine months of 2006, also driven by company share repurchases.

Cash Flow and Balance Sheet

Orbital reported free cash flow of $22.4 million for the third quarter of 2007. The company repurchased approximately 700,000 shares of its common stock for $15.0 million in the third quarter of 2007. This stock repurchase is part of a 12-month, $50 million securities repurchase program authorized by the company's Board of Directors in April 2007. Orbital's unrestricted cash and marketable securities balances were $197.8 million and $34.5 million, respectively, as of September 30, 2007.

The company's cash flow was as follows (in millions):

Summary balance sheet data as of September 30, 2007 was as follows (in millions):

New Business Highlights

During the third quarter of 2007, Orbital received approximately $420 million in new firm and option contract bookings. In addition, the company received approximately $35 million of option exercises under existing contracts. Year-to-date, Orbital received approximately $1.51 billion in new firm and option contract bookings, and approximately $240 million of option exercises under existing contracts. As of September 30, 2007, the company's firm contract backlog was approximately $1.96 billion and its total backlog (including options, indefinite-quantity contracts and undefinitized orders) was approximately $4.06 billion.

Operational Highlights

The company conducted four spacecraft and launch vehicle missions in the third quarter. These operational events included the launch and preliminary check-out of Dawn, Orbital's first interplanetary spacecraft, developed for NASA's Jet Propulsion Laboratory. In addition, the company's long-range missile interceptor, the Orbital Boost Vehicle, achieved its sixth successful flight test as part of a Missile Defense Agency (MDA) national missile defense exercise. Orbital also carried out two MDA target vehicle launches in the third quarter.

During the third quarter, the company also delivered two satellites, two space payloads and five launch vehicles for future missions, including two OBV interceptors for operational deployments in California and Alaska.

In early October, two Orbital-built communications satellites, Intelsat-11 for Intelsat, Ltd. and Optus D2 for Optus Networks, Pty., were launched and are now undergoing in-orbit commissioning. During the remainder of 2007, the company expects to carry out one or two additional satellite launches and three to five additional rocket launches, and to complete and deliver four space payloads and several more launch vehicles for future missions.

2007 Financial Guidance

Orbital updated its financial guidance for full-year 2007, increasing its forecast for revenues, earnings per share and free cash flow as follows:

2008 Preliminary Outlook

The company provided its preliminary financial guidance for 2008, as summarized in the table below:

Orbital is considering the merits of a major new product development program to increase the payload capacity of its space launch vehicle platforms to include a medium-capacity rocket called Taurus II. Orbital believes that this new rocket could substantially expand the company's space launch market, yielding significant potential revenue growth in 2009 and beyond. However, the Taurus II program would entail a substantial development effort, the financial impact of which is not reflected in the 2008 guidance above. Orbital anticipates that this effort would require a net $40 million to $45 million use of cash in 2008. In addition, proceeding with the Taurus II program is expected to result in a revenue increase of up to $25 million and a $0.12 to $0.16 reduction in diluted earnings per share next year. The company plans to update its 2008 guidance, including its intentions with respect to the Taurus II program, when it reports fourth quarter and full-year 2007 results early in 2008.

Disclosure of Non-GAAP Financial Measure

Free cash flow is defined as GAAP (Generally Accepted Accounting Principles) net cash provided by operating activities (the most directly comparable GAAP financial measure) less capital expenditures for property, plant and equipment. A quantitative reconciliation of free cash flow to net cash provided by operating activities is included above in the section entitled "Cash Flow and Balance Sheet." 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 this 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 rockets and space systems for commercial, military and civil government customers. The company's primary products are satellites and launch vehicles, including low-orbit, geosynchronous-orbit and planetary 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 offers space-related technical services to government agencies and develops and builds satellite-based transportation management systems for public transit agencies and private vehicle fleet operators.

"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. 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, product performance and market acceptance of products and technologies, the outcome of the government investigation, 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

^*The company's 2006 financial statements have been restated as required by a new accounting standard pertaining to the company's L-1011 airplane which is used in the Pegasus launch vehicle program. The effect of the new accounting standard is not material to 2006 or 2007 financial statements.

^*The company's 2006 financial statements have been restated as required by a new accounting standard pertaining to the company's L-1011 airplane which is used in the Pegasus launch vehicle program. The effect of the new accounting standard is not material to 2006 or 2007 financial statements.

^*The company's 2006 financial statements have been restated as required by a new accounting standard pertaining to the company's L-1011 airplane which is used in the Pegasus launch vehicle program. The effect of the new accounting standard is not material to 2006 or 2007 financial statements.