As much as I'd love to poke fun and suggest they could get it open in a minute or two with a grinder, with the amount of time taken for the overall mission it's reasonable enough to really take their time and make sure they're not going to contaminate the material.
Preventing contamination is the main issue. If the samples are exposed in any way to an earth environment, their scientific value will plummet and the samples will be next to useless.
