  Atmospheric characterisation of temperate, rocky planets is the holy grail of
exoplanet studies. These worlds are at the limits of our capabilities with
current instrumentation in transmission spectroscopy and challenge our
state-of-the-art statistical techniques. Here we present the transmission
spectrum of the temperate Super-Earth LHS 1140b using the Hubble Space
Telescope (HST). The Wide Field Camera 3 (WFC3) G141 grism data of this
habitable zone (T$_{\rm{eq}}$ = 235 K) Super-Earth (R = 1.7 $R_\oplus$), shows
tentative evidence of water. However, the signal-to-noise ratio, and thus the
significance of the detection, is low and stellar contamination models can
cause modulation over the spectral band probed. We attempt to correct for
contamination using these models and find that, while many still lead to
evidence for water, some could provide reasonable fits to the data without the
need for molecular absorption although most of these cause also features in the
visible ground-based data which are nonphysical. Future observations with the
James Webb Space Telescope (JWST) would be capable of confirming, or refuting,
this atmospheric detection.

Earth and Planetary Astrophysics