  We construct several BV master actions for open superstring field theory in
the large Hilbert space. First, we show that a naive use of the conventional BV
approach breaks down at the third order of the antifield number expansion,
although it enables us to define a simple "string antibracket" taking the
Darboux form as space-time antibrackets. This fact implies that in the large
Hilbert space, "string fields-antifields" should be reassembled to obtain
master actions in a simple manner. We determine the assembly of the string
antifields on the basis of Berkovits' constrained BV approach, and give
solutions to the master equation defined by Dirac antibrackets on the
constrained string field-antifield space. It is expected that partially
gauge-fixing enables us to relate superstring field theories based on the large
and small Hilbert spaces directly: Reassembling string fields-antifields is
rather natural from this point of view. Finally, inspired by these results, we
revisit the conventional BV approach and construct a BV master action based on
the minimal set of string fields-antifields.
