  HH 900 is a peculiar protostellar outflow emerging from a small,
tadpole-shaped globule in the Carina nebula. Previous H{\alpha} imaging with
HST/ACS showed an ionized outflow with a wide opening angle that is distinct
from the highly collimated structures typically seen in protostellar jets. We
present new narrowband near-IR [Fe II] images taken with the Wide Field Camera
3 on the Hubble Space Telescope that reveal a remarkably different structure
than H{\alpha}. In contrast to the unusual broad H{\alpha} outflow, the [Fe II]
emission traces a symmetric, collimated bipolar jet with the morphology and
kinematics that are more typical of protostellar jets. In addition, new Gemini
adaptive optics images reveal near-IR H$_2$ emission coincident with the
H{\alpha} emission, but not the [Fe II]. Spectra of these three components
trace three separate and distinct velocity components: (1) H$_2$ from the slow,
entrained molecular gas, (2) H{\alpha} from the ionized skin of the
accelerating outflow sheath, and (3) [Fe II] from the fast, dense, and
collimated protostellar jet itself. Together, these data require a driving
source inside the dark globule that remains undetected behind a large column
density of material. In contrast, H{\alpha} and H$_2$ emission trace the broad
outflow of material entrained by the jet, which is irradiated outside the
globule. As it get dissociated and ionized, it remains visible for only a short
time after it is dragged into the H II region.
