Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar to the right or below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.
In the heat of competition: Even as it has accepted delivery of two new Russian engines to power its Antares rocket, Orbital ATK has ordered a second Atlas 5 rocket to launch its Cygnus cargo capsule to ISS.
I suspect they want to give themselves some cushion time to test and install these new Russian engines prior to an actual launch. In order to fulfill their contract with NASA, however, they have to launch several times next year, thus requiring more replacements for Antares.