Orbital-2 launch on Antares. Credits: NASA/B. Ingalls

Orbital-2 launch on Antares. Credits: NASA/B. Ingalls

After some delays due to bad weather Cygnus’ Orbital-2 supply spacecraft was launched last Sunday from Virginia, USA. The spacecraft was put into the same orbit as the International Space Station but at a lower altitude.

Since then Orbital-2 has been gaining height as it approaches the Station. When the time comes tomorrow for the unmanned supply ship to dock with the Space Station, NASA astronaut-commander Steve Swanson will work with Alexander Gerst to grapple the spacecraft with the 17-meter Canadarm and bring it safely into contact with a berthing port.

Canadarm practice session. Credits: ESA/NASA

Canadarm practice session on Space Station. Credits: ESA/NASA

Steve will be ‘M1’, operating the robotic arm while Alexander will be ‘M2’, monitoring the approach, communicating with ground control and commanding the vehicle.

The crew had a few refresher session last week to practice with the robotic arm, setting up a workstation in Europe’s Cupola observatory.

The crew spent 100s of hours before leaving Earth practicing these operations in simulations as the operation requires manoeuvring the arm in six dimension at the same time, while floating in microgravity.

Read ESA astronaut Luca Parmitano recount how he helped grapple the Cygnus test-flight during his Volare mission last year on his blog.

Watch the operation tomorrow. 16 July, live via NASA TV from 9:15 GMT.

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Practice session in Houston, USA, before Alexander’s mission.