DP-BHIA: A Decoupled-Periapsis Bifurcated Hyperbolic Intercept Architecture for Planetary Atmospheric Sample Return

Direct physical sample return from extraterrestrial atmospheres remains an unexecuted frontier in deep-space exploration, in part because conventional planetary orbit insertion (POI) and dedicated multi-stage rocket ascent from deep gravity wells can impose substantial propellant mass penalties. To explore a possible means of decoupling this mass-closure problem, this Technical Note introduces the Decoupled-Periapsis Bifurcated Hyperbolic Intercept Architecture (DP-BHIA) — a generalized architecture for planetary atmospheric sample return in which the primary carrier is never captured. The architecture decouples the primary carrier from the atmospheric sampling excursion: the carrier preserves positive specific mechanical energy (Ec > 0) on an uncaptured planetary flyby, while a separated daughter lifting-body probe executes a transient aerodynamic pass through the target atmospheric corridor. The atmospheric excursion is controlled through the lifting body's aerodynamic force authority and bank-angle modulation before the probe exits onto a high-energy outbound arc to target an intercept with the carrier at Node B. Formulated as a general planetary architecture adaptable to different atmospheric planetary bodies, the concept is evaluated using Venus as a first-order reference case because its dense atmosphere provides a demanding environment for assessing atmospheric flight, aerothermal constraints, and post-atmospheric targeting. For an illustrative tangential post-atmospheric state with v_exit = 10.185 km/s at 100 km altitude, treating the exit point as the periapsis of the post-egress two-body arc gives a semi-major axis of a ≈ 172,800 km and a corresponding apoapsis radius of r_a ≈ 339,400 km. At the illustrative Node-B condition, an assumed 1.8° velocity-vector divergence gives an instantaneous velocity-matching value (Δv_match) of approximately 765 m/s. A preliminary subsystem mass ledger gives a 2,440 kg baseline against an adopted 4,100 kg study reference injection envelope; the resulting 1,660 kg difference is treated as an unallocated mass allowance rather than a demonstrated launch or engineering margin. These first-order results support further investigation of DP-BHIA as a candidate architecture for planetary atmospheric sample return, while atmospheric trajectory closure, carrier-daughter reachable-set closure, and complete system-level mass closure remain unresolved.