-- Revised Approach Will Maintain Required ISS Cargo Deliveries in 2015 and 2016 --

-- Accelerated Propulsion System Upgrade of Antares to be Implemented at Wallops --

DULLES, Va.Nov. 5, 2014-- Orbital Sciences Corporation (NYSE: ORB), one of the world s leading space technology companies, today announced comprehensive plans to fulfill its contract commitments under NASA s Commercial Resupply Services (CRS) program as well as to accelerate an upgrade of the Antares medium-class launcher s main propulsion system. Under the new approach and in line with Orbital s existing CRS contract, all remaining cargo will be delivered to the International Space Station (ISS) by the end of 2016. There will be no cost increase to NASA and only minor adjustments will be needed to the cargo manifest in the near term.

Orbital s Antares launch failure Accident Investigation Board (AIB) is making good progress in determining the primary cause of last week s failure. A preliminary review of telemetry and video data has been conducted and substantial debris from the Antares rocket and its Cygnus payload has been collected and examined. While the work of the AIB continues, preliminary evidence and analysis conducted to date points to a probable turbopump-related failure in one of the two Aerojet Rocketdyne AJ26 stage one main engines. As a result, the use of these engines for the Antares vehicle likely will be discontinued.

To maintain the CRS program s critical ISS supply line, Orbital plans an early introduction of its previously selected Antares propulsion system upgrade in 2016. This will be preceded by one or two non-Antares launches of the company s Cygnus cargo spacecraft to the ISS in 2015-2016, employing the spacecraft s compatibility with various launch vehicles and its flexibility to accommodate heavier cargo loads as launcher capacity permits. In addition, the company expects repairs to the Mid-Atlantic Regional Spaceport (MARS) launch complex at NASA s Wallops Flight Facility to be undertaken quickly, allowing launch operations to continue at Wallops Island with the upgraded Antares beginning in 2016.

Orbital is taking decisive action to fulfill our commitments to NASA in support of safe and productive operations of the Space Station. While last week s Antares failure was very disappointing to all of us, the company is already implementing a contingency plan to overcome this setback. We intend to move forward safely but also expeditiously to put our CRS cargo program back on track and to accelerate the introduction of our upgraded Antares rocket, said Mr. David W. Thompson, Orbital s Chairman and Chief Executive Officer.

Exact financial impacts to Orbital will depend on which of several specific options for near-term launches is selected, but they are not expected to be material on an annual basis in 2015. In all cases, no significant adverse effects are projected in 2016 or future years, in part because the cost of the Antares propulsion system upgrade was already part of our internal investment plan during that time, he added.

We very much appreciate the tremendous support Orbital has received from NASA and Virginia s MARS commercial spaceport team over the last seven years on our Antares rocket and CRS cargo programs. We look forward to working closely with them to quickly recover from last week s setback, Thompson concluded.

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. Follow the company on Twitter @OrbitalSciences.

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

Certain statements in this press release are "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995. These forward-looking statements include those related to the cause and impact of the Antares launch failure, our contingency plans and estimates of timing for an Antares propulsion upgrade, in addition to statements regarding our projected financial performance 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 "forecast," "expect," "will," "intend," "plan" and words of similar substance. Such forward-looking statements are subject to risks and uncertainties that could cause actual financial results or operating performance to be materially different from the forward-looking statement. Uncertainty includes factors such as the cause of the launch failure; the timing of any future launches; the outcome of any government agency review; the impact of the launch failure on our relationship with NASA or other government or commercial customers; the accounting, financial or commercial impact of the launch failure; the availability of insurance; changes in revenue and cost estimates and/or timing of programs; the potential termination of U.S. Government contracts and the potential inability to recover termination costs; unstable geopolitical conditions, including in Russia and Ukraine; supply and availability of components; and development of key technologies. Additional information concerning these and other factors can be found in Orbital's filings with the Securities and Exchange Commission. Orbital assumes no obligation to update or revise publicly the information in this press release except as otherwise required by law. Readers are cautioned not to place undue reliance on these forward-looking statements.

Source: Orbital Sciences Corporation

Orbital Sciences Corporation
Barron Beneski, 703-406-5000
Public and Investor Relations