Concept
The NASA COTS award was for and Orbital Sciences expected to invest an additional 130 million for the booster and 1.9 billion for eight flights was awarded in 2008. As of April 2012, development costs were estimated at $472 million. In June 2008, it was announced that the Mid-Atlantic Regional Spaceport, formerly part of the Wallops Flight Facility, in Virginia, would be the primary launch site for the rocket. Launch pad 0A (LP-0A), previously used for the failed Conestoga rocket, would be modified to handle Antares. Wallops allows launches which reach the International Space Station's orbit as effectively as those from Cape Canaveral, Florida, while being less crowded. The first Antares flight launched a Cygnus mass simulator. On December 10, 2009, Alliant Techsystems Inc. (ATK) test-fired their Castor 30 motor for use on the second stage of the Antares rocket. In March 2010, Orbital Sciences and Aerojet completed test firings of the AJ-26 engines. On February 22, 2013, a hot fire test was successfully performed, the entire first stage being erected on the pad and held down while the engines fired for 29 seconds. The first stage of Antares burns RP-1 (kerosene) and liquid oxygen (LOX). As Orbital had little experience with large liquid stages and LOX propellant, the first stage core was designed and is manufactured in Ukraine by Pivdenne Design Office and Pivdenmash and includes propellant tanks, pressurization tanks, valves, sensors, feed lines, tubing, wiring and other associated hardware. Like the Zenit—also manufactured by Pivdenmash—the Antares vehicle has a diameter of with a matching 3.9 m payload fairing. The Antares 100-series first stage was powered by two Aerojet AJ26 engines. These began as Kuznetsov NK-33 engines built in the Soviet Union in the late 1960s and early 1970s, 43 of which were purchased by Aerojet in the 1990s. Twenty of these were refurbished into AJ26 engines for Antares.
