  Protoplanetary disk surveys by the Atacama Large Millimeter/sub-millimeter
Array (ALMA) are now probing a range of environmental conditions, from low-mass
star-forming regions like Lupus to massive OB clusters like $\sigma$ Orionis.
Here we conduct an ALMA survey of protoplanetary disks in $\lambda$ Orionis, a
~5 Myr old OB cluster in Orion, with dust mass sensitivities comparable to the
surveys of nearby regions (~0.4 $M_\oplus$). We assess how massive OB stars
impact planet formation, in particular from the supernova that may have
occurred ~1 Myr ago in the core of $\lambda$ Orionis; studying these effects is
important as most planetary systems, including our Solar System, are likely
born in cluster environments. We find that the effects of massive stars, in the
form of pre-supernova feedback and/or a supernova itself, do not appear to
significantly reduce the available planet-forming material otherwise expected
at the evolved age of $\lambda$ Orionis. We also compare a lingering massive
"outlier" disk in $\lambda$ Orionis to similar systems in other evolved
regions, hypothesizing that these outliers host companions in their inner disks
that suppress disk dispersal to extend the lifetimes of their outer primordial
disks. We conclude with numerous avenues for future work, highlighting how
$\lambda$ Orionis still has much to teach us about perhaps one of the most
common types of planet-forming environments in the Galaxy.
