A connecting tunnel for the docking mechanism had not yet been developed, which prevented a simple internal transfer between the craft.

Turned out to be a docking mechanism we're not set up to receive!

Why isn't there flap covers like the iPad 2, that latch into the docking mechanism.

As a last resort, the Mir crew took a space walk and found that a plastic bag had blocked the docking mechanisms.

The docking mechanism had been withdrawn into deck and overhead, so the space immediately inside the cargo door was clear of obstruction.

Finally, after hours of preparations, the two docking mechanisms touched in a metallic kiss.

A gentle kick from the shuttle's engines at the last instant pushed the docking mechanisms tightly together, as planned.

One second the base of the Tower was still metres away; an instant later he felt and heard the impact of the docking mechanism.

Non-cooperative docking mechanisms were identified as critical mission elements to the success of such autonomous missions.

But Russian engineers were unable to resolve the problem with the docking mechanism and the undocking attempt was called off.