Scenario kind pagesEdit on GitHubSource: docs/kinds/by-kind/reentry.md

reentry (scenario kind)

Scenario kind of the engine v0.38.0, family Mission analysis, links and space operations. Advisory: analysis output from a research and engineering tool, not type-approved navigation equipment and not a safety-of-life service. Every label here is the engine's or the verification matrix's; a kind is MODELLED unless the matrix says otherwise (how a label is earned: the README's Evidence section).

What it does#

Allen-Eggers ballistic re-entry corridor: peak deceleration (ballistic-coefficient-independent, V_e^2 sin|γ|/(2eH)), the velocity and altitude at peak-g, and the peak-heating velocity, for an entry velocity/flight-path-angle/ballistic-coefficient through an exponential atmosphere, plus a planar point-mass integration of the same ballistic entry with gravity, Earth curvature and the US Standard Atmosphere 1976 (peak deceleration, speed, altitude and time at the peak). MODELLED ballistic (no-lift) entry; heating output is the peak-heating VELOCITY, not a heat-flux (no aerothermal/TPS model).

One run of scenarios/reentry.toml summarises as: reentry (Allen–Eggers): V_e 7800 m/s, γ 6.0° -> peak 16.6 g at 49 km, 4731 m/s; heating peaks at 6603 m/s; point mass (gravity, curvature, US76) peak 16.4 g (MODELLED ballistic, no aerothermal)

Inputs#

From the schema (kshana kinds --json):

  • Required fields: none
  • Optional fields: entry_velocity_m_s, flight_path_angle_deg, ballistic_coeff_kg_m2, scale_height_m, rho0_kg_m3, entry_interface_altitude_m

The example scenarios/reentry.toml sets, among others:

Field Value Unit
ballistic_coeff_kg_m2 100 kg/m^2
entry_velocity_m_s 7800 m/s
flight_path_angle_deg 6 deg
kind reentry text

Run it#

kshana scenarios/reentry.toml

What it gives#

The scalar results of that run, with the units the engine states:

Result Value Unit
altitude_at_peak_g_m 48512.90039 m
ballistic_coeff_kg_m2 100 kg/m^2
entry_interface_altitude_m 122000 m
entry_velocity_m_s 7800 m/s
flight_path_angle_deg 6 deg
peak_deceleration_g 16.567086 1
peak_deceleration_m_s2 162.467612 m/s^2
point_mass.altitude_at_peak_m 46111.729788 m
point_mass.flight_path_angle_at_peak_deg 7.06172 deg
point_mass.peak_deceleration_g 16.366138 1

Result label (the engine's): MODELLED — Allen–Eggers ballistic (no-lift) entry, exponential isothermal atmosphere, constant flight-path angle; peak-g is ballistic-coefficient-independent; heating is the peak-heating VELOCITY, NOT a heat-flux (no aerothermal/TPS model)

The chart the engine writes for scenarios/reentry.toml, kind reentry

Evidence#

MODELLED: the verification matrix rows that name this kind.

  • MODELLED Peak deceleration (ballistic-coefficient-independent), velocity + altitude at peak-g, and peak-heating velocity for an exponential-atmosphere ballistic entry. Tests: reentry_point_mass_accelerometer_oracle.rs.
  • MODELLED Planar gravity-turn ascent of a multi-stage vehicle over a non-rotating spherical Earth through the US Standard Atmosphere 1976 (density and pressure), with a pitch kick, thrust reduced by the nozzle back-pressure, stage burnouts at exact s

The rows the run itself exercised, with the oracle the matrix gives each (the public sources are named there):

  • MODELLED Deterministic, scenario-hashed, SBOM + cross-platform golden gates. Oracle (ExternalDataset): SBOM conformance to the official CycloneDX 1.5 JSON Schema (+ valid SPDX identifiers) — an external published standard, zero validation errors over the full dependency graph; the FoM-determinism / byte-reproducibility part remains a pinned self-consistency check, so the row stays MODELLED
  • MODELLED Peak deceleration (ballistic-coefficient-independent), velocity + altitude at peak-g, and peak-heating velocity for an exponential-atmosphere ballistic entry. R. Oracle (InternalConsistency): Closed-form Allen–Eggers analytic entry, additionally cross-checked vs a scipy 1.18 solve_ivp (DOP853) numerical integration of the SAME drag-only entry ODE (tests/ballistic_re_entry_corridor_reference.rs, 36 cases, worst a_max rel 2.9e-9) — a numeric-integral-vs-own-analytic-form check, so still InternalConsistency, NOT an external validation. MODELLED ballistic (no lift), no aerothermal/TPS — heating output is a ve

Limitations#

What the run's own report says is not modelled or not validated:

  • MODELLED — Allen–Eggers ballistic (no-lift) entry, exponential isothermal atmosphere, constant flight-path angle; peak-g is ballistic-coefficient-independent; heating is the peak-heating VELOCITY, NOT a heat-flux (no aerothermal/TPS model) (result label)
  • MODELLED ballistic (no-lift) entry; heating output is the peak-heating VELOCITY, not a heat-flux (no aerothermal/TPS model). (kind catalogue (kshana kinds --json))
  • HONEST SCOPE: MODELLED ballistic (no-lift), exponential isothermal atmosphere, constant flight-path angle. No aerothermal/TPS model -- the heating output is the peak-heating VELOCITY, not a heat-flux. Not a 3-/6-DoF trajectory. Run: kshana scenarios/reentry.toml (scenario file comment, lines 8 to 11)
  • Reproducibility & software assurance is MODELLED, not validated: a sub-claim is externally checked, but the whole capability composes modelled pieces, so the capability stays Modelled. (verification matrix (docs/MODELLED-RATIONALE.md))
  • Ballistic re-entry corridor (Allen–Eggers) is MODELLED, not validated: checked against its own closed-form / analytic identity — catches transcription and coefficient errors, but is not an external oracle. (verification matrix (docs/MODELLED-RATIONALE.md))

See also#