  Numerical simulations are at the center of predicting the space debris
environment of the upcoming decades. In light of debris generating events, such
as continued anti-satellite weapon tests and planned mega-constellations,
accurate predictions of the space debris environment are critical to ensure the
long-term sustainability of critical satellite orbits.
  Given the computational complexity of accurate long-term trajectory
propagation for a large number of particles, numerical models usually rely on
Monte-Carlo approaches for stochastic conjunction assessment. On the other
hand, deterministic methods bear the promise of higher accuracy and can serve
to validate stochastic approaches. However, they pose a substantial challenge
to computational feasibility.
  In this work, we present the architecture and proof of concept results for a
numerical simulation capable of modeling the long term debris evolution over
decades with a deterministic conjunction tracking model. For the simulation, we
developed an efficient propagator in modern C++ accounting for Earth's
gravitational anomalies, solar radiation pressure, and atmospheric drag. We
utilized AutoPAS, a sophisticated particle container, which automatically
selects the most efficient data structures and algorithms.
  We present results from a simulation of 16 024 particles in low-Earth orbit
over 20 years. Overall, conjunctions are tracked for predicted collisions and
close encounters to allow a detailed study of both. We analyze the runtime and
computational cost of the simulation in detail. In summary, the obtained
results show that modern computational tools finally enable deterministic
conjunction tracking and can serve to validate prior results and build
higher-fidelity numerical simulations of the long-term debris environment.
