The paper presents an integrated communications and localization (ICAL) scheme for massive MIMO low earth orbit (LEO) satellite systems, aiming to support both global communications and seamless localization. The authors characterize the signal propagation properties and derive a localization performance bound. They focus on hybrid analog/digital precoding design to achieve high communication capability and localization precision. Numerical results demonstrate that the proposed ICAL scheme supports both wireless communication and localization operations for typical system setups. The main contributions include investigating the ergodic spectral efficiency (SE) upper bound and the Cramér-Rao lower bound (CRLB) for channel parameters, multi-objective optimization for trade-offs between communication and localization, and developing a hybrid precoding strategy to jointly design the signal waveform based on statistical channel state information (sCSI).The paper presents an integrated communications and localization (ICAL) scheme for massive MIMO low earth orbit (LEO) satellite systems, aiming to support both global communications and seamless localization. The authors characterize the signal propagation properties and derive a localization performance bound. They focus on hybrid analog/digital precoding design to achieve high communication capability and localization precision. Numerical results demonstrate that the proposed ICAL scheme supports both wireless communication and localization operations for typical system setups. The main contributions include investigating the ergodic spectral efficiency (SE) upper bound and the Cramér-Rao lower bound (CRLB) for channel parameters, multi-objective optimization for trade-offs between communication and localization, and developing a hybrid precoding strategy to jointly design the signal waveform based on statistical channel state information (sCSI).