Orbital Sciences Corp.

Screenshot of the Orbital Sciences footage of the Antares rocket separating from the Cygnus mass simulator during the Antares test launch on April 21, 2013.Orbital Sciences Corp.

On April 21, Orbital Sciences Corp. saw its Antares rocket take to the skies in a flawless test flight, delivering a test payload to orbit as planned. Today, the private spaceflight company released a striking screen capture from the Antares' onboard camera just as the upper stage rocket separated from the "mass simulator."

NASA has contracted the company to deliver cargo to the International Space Station (ISS) as part of its ongoing commitment to use private launch companies to resupply the orbiting outpost. Orbital Sciences is currently developing the unmanned Cygnus spacecraft that will ultimately be launched atop the Antares.

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Sunday's test launch used the mass simulator -- a 4-ton dummy payload -- to replicate the mass of a fully-laden Cygnus capsule. In late June or early July, the company will carry out a full dress rehearsal, launching a Cygnus capsule into orbit where it will navigate its own way to the space station.

The mass simulator and rocket upper stage will remain in orbit for several months until their orbits decay and burn up in the Earth's atmosphere.

Orbital Sciences joins Space Exploration Technologies (SpaceX) as part of a joint private effort to resupply the space station. SpaceX has already begun cargo runs with its unmanned Dragon capsule.