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@Ryder said:
Drasnor I read a tweet regarding Dragon being attached to the space station. Do you know why it takes so long to open the hatch?
The comment was "hatch opening will occur over the next day"

Thanks.

It's a somewhat involved process. It takes a couple of hours for controllers operating Canadarm2 to swing ~6 metric tons of spacecraft from the capture point over to line up on the ISS active common berthing mechanism with the passive common berthing mechanism on Dragon. Engaging the CBM is a manual process for the crew and has a fairly large number of individual checklist steps and verification steps due to the critical nature of the task. Once there's confidence that the mechanism is engaged properly, the hatch vestibule is slowly pressurized from hard vacuum to one atmosphere and monitored for leaks and signs that the mechanism isn't quite right. Once pressurized, everything is left alone for a few hours to check the leak rate and make sure it's acceptably low. Opening both hatches is another manual process with air quality checks, surface contaminant checks, and visual inspection of all the important bits followed by a series of cable hookups between ISS and Dragon. Only after all of that is complete is the crew allowed to move into unloading cargo.

It's worth noting that the capture occurred at 10:55 AM from the crew's point of view, that the CBM mechanism wasn't engaged until ~1:30 PM, and that the crew work day is pretty much over at 6:15 PM. For the previous Dragon flight, orbital mechanics were such that Dragon was captured a couple of hours earlier which permitted a same-day hatch opening. The nominal operation is to open it in the morning on the following day.