The Soyuz 4 and 5 spacecraft docked on 16 January 1969, the first time two crewed spacecraft had docked (Apollo 9 would do the same in March of the same year). The two craft possessed only a primitive probe (Soyuz 4) and drogue (Soyuz 5) docking assembly. A connecting tunnel for the docking mechanism had not yet been developed, which prevented a simple internal transfer between the craft. This required the two transferring cosmonauts to spacewalk from one vehicle to the other. Aboard Soyuz 5, Yevgeny Khrunov and Aleksei Yeliseyev immediately began preparing for their extravehicular activity (EVA). Boris Volynov, who would remain aboard Soyuz 5, filmed them donning their Yastreb space suits.