-- First of Two STAR(TM) Spacecraft Launched for Australian Satellite Operator -- -- Optus D1 Spacecraft Is 10th Company-Built GEO Satellite Delivered in Last Five Years; Its Launch Marks the Beginning of Busy Deployment Schedule Through 2008 --

DULLES, Va., Oct 16, 2006 (BUSINESS WIRE) -- Orbital Sciences Corporation (NYSE:ORB) announced today that the Optus D1 commercial communications satellite, built by Orbital for Optus Networks Pty Limited (Optus) of Australia, was successfully launched into its targeted orbit aboard an Ariane 5 rocket on Friday, October 13. The mission originated from the spaceport at Kourou, French Guiana at approximately 4:56 p.m. (Eastern). The Optus D1 satellite was deployed into a geosynchronous (GEO) transfer orbit about 32 minutes after lift-off. Initial communications with the satellite have been established and it is performing as expected in the early stages of the mission.

The Optus D1 satellite is the first of two satellites that Orbital is building for Optus. The second satellite, Optus D2, is scheduled for completion and launch in 2007. Both of the Optus satellites are based on Orbital's STAR 2.4 platform, which can generate nearly five kilowatts of payload power and can weigh over 5,000 pounds (2,500 kilograms) at launch, making them the largest and most powerful commercial communications spacecraft in Orbital's satellite product line. The Optus program's design, manufacturing and testing activities are being carried out at Orbital's state-of-the-art satellite production facility in Dulles, Virginia.

The Optus D1 satellite will operate in the Ku-band frequencies from its orbital location at 160 degrees East longitude. The satellite is designed to provide fixed satellite services and direct-to-home television broadcasting services to Australia and New Zealand.

During the next several days, the Optus D1 spacecraft will perform a series of orbit-raising burns of its onboard rocket engine to achieve a circular orbit 22,300 miles (35,800 kilometers) above the Earth. For several weeks afterwards, the mission's engineering team will conduct comprehensive tests to ensure the spacecraft is ready for final hand-over to Optus.

Orbital is one of the leading suppliers of GEO communications satellites, which are based on the STAR family of smaller GEO satellite platforms and are capable of accommodating most types of commercial communications payloads. For many applications, the STAR design is an attractive alternative to the larger, more costly GEO satellites offered by other industry suppliers. STAR satellites are smaller and significantly less expensive to manufacture and launch, making them a perfect fit for customers in the early stages of building their business or for established companies that wish to replace or add capacity to their network.

Customer demand for Orbital's STAR GEO satellites has been robust over the past several years. Since the beginning of 2005, Orbital received orders for STAR satellites from U.S.-based PanAmSat (now Intelsat), the Horizons joint venture between JSAT of Japan and PanAmSat/Intelsat, Telenor of Norway, Measat of Malaysia and Alcatel Alenia Space for SES Americom of the U.S. Including the Optus D1 spacecraft, Orbital is now in varying stages of design, manufacturing and testing of eight commercial GEO satellites that will be launched over the next two years.

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; 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.

More information about Orbital can be found at http://www.orbital.com

Note to Editors: A high-resolution image of the Optus satellite is available on Orbital's web site at: http://www.orbital.com/NewsInfo/Images/GEO

SOURCE: Orbital Sciences Corporation

Orbital Sciences Corporation
Public and Investor Relations
Barron Beneski, 703-406-5528