3-DOF attitude & pointing error budget: a scalar, pre-hardware AOCS/GNC
complement to high-fidelity tools (Basilisk, 42) — the environmental
gravity-gradient disturbance torque and a root-sum-square pointing-error budget
over the contributing error sources, producing a single pointing figure of
merit a systems engineer brackets before committing to a control design.
Torque-free rigid-body attitude dynamics: Euler’s rotational equations of
motion coupled to quaternion attitude kinematics, integrated with a
fixed-step RK4 propagator.
Cross-modality RAIM / protection level — receiver-autonomous integrity for a
heterogeneous pair of PNT solutions. Where crate::raim monitors many homogeneous
RF pseudoranges of one constellation, this module treats an RF PVT/time solution and
an optical PVT/time solution as two independent measurements of the same underlying
geometry, with disparate covariances (RF loose — metres, nanoseconds; optical tight —
centimetres, picoseconds), and monitors their consistency.
Clohessy–Wiltshire / Hill relative-motion dynamics: the linearised motion of a
chaser relative to a target on a circular reference orbit, expressed in the
target’s local-vertical/local-horizontal (LVLH) frame.
Numerically-robust sequential orbit determination — a hand-rolled Square-Root Information
Filter (SRIF; Bierman 1977) with reduced-dynamic empirical accelerations, the factored
complement to the batch differential corrector of crate::precise_od.
EGM2008 geopotential spherical-harmonic coefficients to degree/order 70 —
AUTO-GENERATED from tools/egm2008_to70.gfc by tools/gen_egm2008.py; do not
edit by hand. Fully normalized, tide-free. The EGM2008 model is an NGA
public-domain product (via ICGEM). EGM2008_COEFFS are (n, m, Cnm, Snm).
Earth-observation payload footprint & coverage geometry: the SMAD/Wertz
“space triangle” relations that turn an orbit altitude and a sensor field of
view into the angular radius of the Earth, the swath width, the nadir ground
sample distance, the maximum off-nadir access, and the equatorial ground-track
spacing that drives revisit.
Built-in low-precision analytical ephemerides for the third-body perturbing bodies, so
the numerical propagator’s third-body force (crate::forces::third_body_accel) needs no
external DE/SPK kernel for a low-fidelity run.
A pluggable ephemeris provider seam — the source of one body’s position relative to another
in the inertial frame — abstracted so the fidelity of those positions can be swapped without
touching the deep-space light-time correction (D0.7) or the interplanetary orbit determination
(D2/D3) that will consume it.
Fisher information, the Cramér–Rao lower bound, and observability/datum-defect
analysis — the information-geometry core for experiment design and rank diagnosis.
Passive emitter geolocation by TDOA (time-difference-of-arrival) and FDOA
(frequency-difference-of-arrival) across a network of receivers — the core of
locating a jammer/spoofer, or reverse-PNT off an opportunistic emitter, when GNSS
itself is the thing under attack.
Cold-atom gravimeter measurement model and a spherical-harmonic gravity-anomaly
reference field for gravity-map-matching navigation (GPS-denied alt-PNT).
Full tesseral spherical-harmonic geopotential — the EGM2008 field to degree/order 70,
the high-degree gravity model the numerical propagator’s crate::forces zonal-only field
was missing.
Ground-Support-Equipment signal-in-space / observable simulator and the end-to-end PNT
performance loop — the GSE half of the deep-space build (D4.2 + D4.3).
Optical ↔ RF measurement handoff — the receiver state-and-covariance transfer when
the active PNT measurement type switches between a tight optical modality (small
measurement noise R) and a loose RF modality (large R).
Joint availability / precision / integrity figure of merit for a heterogeneous
optical + RF PNT service (P5), plus the hybrid-optical-rf scenario that drives it
end-to-end.
Inter-satellite range / range-rate observables and their planar measurement
Jacobians — the per-link measurement model for cislunar observability analysis.
GNSS carrier-phase integer ambiguity resolution — the LAMBDA approach
(Teunissen 1995): integer least-squares with a decorrelating integer (Z) transform
and a closed-form bootstrapped success rate.
Launch-window & ascent geometry: the two-body relations a mission analyst uses
at the trade-study tier to turn a launch-site latitude and a target orbit into
launch azimuth(s), the minimum reachable inclination, the Earth-rotation
velocity bonus, plane-change (dogleg) Δv, and the number of daily launch
opportunities.
Deep-space communications link budget — the Friis transmission account that turns transmit
power, antenna gains, range and noise temperature into the carrier-to-noise-density C/N₀, the
energy-per-bit-to-noise-density Eb/N₀, and the link margin over a required Eb/N₀. This is
the telecom-design half of a deep-space mission, the companion to the navigation observable model
in crate::radiometric: the navigation kernel says where the spacecraft is from the signal’s
timing; the link budget says whether the signal closes at all across the same Earth–Mars range.
Lunar differential PNT (a lunar DGNSS / SBAS analogue): a fixed reference
station at a known lunar-surface location computes per-satellite differential
corrections from a Moonlight / LCNS-class constellation, and a roving user applies
them so the common-mode orbit + clock errors cancel — leaving only a residual
that grows with the user↔reference baseline (spatial decorrelation) — plus user
protection levels that reuse the crate’s DO-229E SBAS machinery.
Lunar interoperability export — the lunar reference frame, lunar time scale and
lunar ephemeris emitted in LunaNet/IOAG-aligned, CCSDS-based interchange forms
with round-trip / field conformance.
Impulsive / finite-burn maneuvers, a Lambert two-body transfer solver, and a
porkchop (departure × arrival C3 / arrival-V∞) sweep — the maneuver-modeling and
trajectory-design beachhead.
Mars PNT — a simulated MARCONI-style relay constellation at Mars plus reference user
scenarios, run through the D3.1 joint one-way + two-way radiometric fusion estimator (D3.2/D3.3).
Sparse-monitor-network detection sizing: how many surveyed, known-location
monitor receivers does it take to catch a wide-area / orbital-scale spoof or jam?
Navigation-message-authentication (TESLA/OSNMA) budget sizing: turns the
assertion “an OSNMA-style authentication scheme fits an AFS
(autonomous-formation-flying / augmented-navigation-service) message and
timing budget” into a sized result — the authentication overhead as a
fraction of the nav-data rate, a bounded authentication latency, and the
forgery-resistance figures.
Optical ground-network availability — the clear-sky / pointing availability of a
free-space optical PNT link, and the diversity gain of an N-station network. An optical
link is weather-limited: a single site is available only when its sky is clear and the
terminal can point and acquire. Distributing several sites across uncorrelated weather
systems raises the network availability toward unity — the P5 Table 2 / Fig 1b argument.
Optical (1550 nm) two-way link budget — the photonic companion to the RF
crate::linkbudget module. Where the RF budget turns EIRP / G/T / range into a
carrier-to-noise density, the optical budget turns transmit power, aperture, range and
detection efficiency into a detected-photon rate, and from that photon count into a
photon-limited ranging precision and a diffraction-limited beam footprint. This
is the optical column of the P5 heterogeneous-PNT table.
Ground-station pass prediction: the time-domain rise/set scheduler that turns
an orbit + a ground station + an elevation mask into the list of visibility
passes (AOS, TCA, LOS, maximum elevation, duration) over a window — the
ground-segment planning query the static look-angle primitives in
crate::frames (look_angles/elevation/is_visible) do not provide on
their own.
Full-force precise orbit determination from position observations — the precise
estimator that fits Kshana’s complete force model (EGM2008 tesseral gravity + solid/ocean/
atmospheric tides + Sun/Moon third body + SRP + drag + Schwarzschild/Lense–Thirring GR) to a
track of inertial position fixes and reports the post-fit residuals in the radial/transverse/
normal (RTN) frame.
Numerical orbit propagator: a configurable force model integrated by the adaptive
Runge–Kutta driver, the first non-analytic propagator in Kshana (the rest of the
orbit stack is the analytic SGP4/SDP4 of crate::sgp4).
Radiometric observable corrections for deep-space tracking — the light-time solution and the
Shapiro relativistic delay that turn a geometric range into the time a signal actually takes
to travel between two bodies.
Ballistic re-entry corridor (Allen–Eggers): the closed-form analytic entry of a
non-lifting body through an exponential atmosphere at a constant flight-path
angle. It turns an entry velocity + flight-path angle into peak deceleration,
the velocity and altitude where that peak occurs, and the peak-heating velocity
— the pre-Phase-A corridor numbers an EDL analyst brackets before any
high-fidelity trajectory or aerothermal run.
CCSDS Space Packet Protocol (CCSDS 133.0-B) primary-header framing: the
standards-compliant TM/TC packet structure ground systems and on-board
software exchange. This is the simulation/test-level bridge that lets any
Kshana scenario output be wrapped as a conformant packet stream (or a captured
stream be parsed back), the “speak the agency packet format” interop layer.
Space-weather environment model: solar (F10.7) and geomagnetic (Kp/ap) activity
indices and their first-order effect on thermospheric neutral density — the
activity dependence the static US-Standard-Atmosphere-1976
(crate::forces::atmospheric_density) deliberately omits.