migrating a tablespace between postgres instances in shared disk environment

Is there a way to allow migration of a single table/database/tablespace
from one postgres instance to another (in a system with multiple
tables/databases/tablespaces) ?
The postgres instances would all share their storage using a clustered file
system.
Ideally, one postgres instance would "close" a table/database/tablespace
and another postgres instance would then "open" it, to support the
migration.
But I didn't find a way to "close" anything without destroying it.
Is there a way to do this using Postgres ?

thanks
Paula