  Motivated by the representation of the super Virasoro constraints as
generalized Dirac-K{\"a}hler constraints $(d \pm d^\dagger)|\psi> = 0$ on loop
space, examples of the most general continuous deformations $d \to e^{-W} d
e^W$ are considered which preserve the superconformal algebra at the level of
Poisson brackets. The deformations which induce the massless NS and NS-NS
backgrounds are exhibited. Hints for a manifest realization of S-duality in
terms of an algebra isomorphism are discussed. It is shown how the first order
theory of 'canonical deformations' is reproduced and how the deformation
operator $W$ encodes vertex operators and gauge transformations.
