Tools
Spacecraft engineering calculators
First-order in-browser sizing tools for the mission-design questions we keep being asked. Pure physics, cited constants, no backend.
// a growing suite of calculators live, more on the way. constants and assumptions documented inline on every tool.
The design studio
ENKI — AI Design Assistant
Describe a mission and ENKI designs it with you conversationally, running the calculators below as tools and tracking a live mission design state.
Debris compliance & reentry
Satellite debris-compliance calculators for the checks every LEO filing now has to pass: post-mission orbital lifetime against the FCC 5-year rule, ESA Zero Debris, and the legacy 25-year limit, reentry casualty risk, and the printable report that ties them together. New to the rules themselves? Start with our FCC 5-year rule vs ESA Zero Debris vs 25-year guideline comparison.
Compliance Report Generator
One disposal plan, checked against the FCC 5-year rule, ESA Zero Debris, the legacy 25-year rule, and reentry casualty risk — as a clean, printable ODAR-style report.
Deorbit & Lifetime Compliance
Checks a disposal orbit against the FCC 5-year rule, ESA Zero Debris, or the legacy 25-year limit — and sizes the drag area or disposal delta-v needed to comply.
Reentry Casualty Risk
Screens what survives reentry against the 1-in-10,000 ground-casualty limit (ODMSP / NASA-STD-8719.14) — per-material demise, debris casualty area, design-for-demise vs. controlled-reentry remediation.
LEO Drag & Decay Timeline
Days-to-reentry from atmospheric drag at LEO altitudes. Three solar-activity tiers, ballistic-coefficient scaling, altitude-vs-time chart.
Radiation environment
Space-radiation calculators for parts selection: total ionizing dose behind aluminum shielding for your orbit, and the single-event-upset rate a COTS device will actually see.
Radiation Dose vs. Shielding
Total-ionizing-dose dose-depth curve for any LEO/MEO/GEO orbit — trapped-electron, bremsstrahlung, and proton contributions, and the aluminum needed to keep a COTS part under 10 krad(Si).
Single-Event-Effect Rate
Single-event-upset rate from a device Weibull cross-section and the orbit cosmic-ray environment (CREME96 IRPP) — upsets per day, mean time between upsets, and where they come from by ion LET.
RF & links
Satellite RF calculators — a full comms link budget with ITU-R P.618 rain fade, ITU Article 22 EPFD screening for NGSO constellations, and the power-transmission link and tether-power trades.
Comms Link Budget (rain fade)
Satellite comms link budget with ITU-R P.618 rain attenuation — EIRP, path loss, C/N0, Eb/N0, and the link margin, with a per-term gains/losses table. S/X/Ku/Ka/Q/V band.
EPFD Screening (NGSO vs. GSO)
Single-entry EPFD screen for an NGSO constellation downlink against representative ITU Article 22 limits — spreading loss + GSO antenna discrimination. A design screen, not an S.1503-2 validation.
Microwave Power Link Budget (35 GHz)
Antenna sizing, beam density, free-space path loss, and end-to-end efficiency for a Ka-band microwave power transmission link.
Electrodynamic Tether Power
Motional EMF, circuit current, generated power, and the J×B drag back-reaction for a conductive tether in LEO.
Orbits & propulsion
Orbital-mechanics and propulsion calculators: delta-v and propellant budgets, SGP4 pass prediction and ground tracks, eclipse seasons, and how fast drag brings an orbit down.
Delta-V Maneuver Budget
Delta-v and propellant for a Hohmann transfer, plane change, combined maneuver, circularization, or deorbit — with a per-burn breakdown.
Propulsion System Sizing
Propellant mass, tank volume, and burn time from a delta-v requirement and propellant choice — Tsiolkovsky rocket equation.
Ground Track & Pass Predictor
TLE-driven ground track and pass windows for a ground station — AOS/LOS times, max elevation, azimuths — with elevation-mask filtering and a world-grid track plot. SGP4.
Eclipse & Beta-Angle Timeline
Beta angle and eclipse fraction across a year, accounting for J2 nodal regression and the Sun moving along the ecliptic.
Bus sizing budgets
The everyday spacecraft budget calculators CubeSat teams run first: power, mass, data, thermal, and ADCS sizing — each with cited constants and stated assumptions.
Spacecraft Power Budget
Solar array, battery, and power-system mass sizing for typical LEO missions, with a side-by-side beamed-power trade.
Power Budget by Operating Mode
Per-operating-mode power draw and the orbit energy balance, with eclipse depth-of-discharge against the battery limit.
Spacecraft Mass Budget
Subsystem mass roll-up with maturity-based contingency margins, checked against a launch-mass cap.
Onboard Data Budget
Data generation versus ground-station downlink capacity versus onboard storage — daily balance, fill time, break-even analysis.
Steady-State Thermal Balance
Hot- and cold-case equilibrium temperature from absorbed solar, albedo, Earth-IR and internal heat versus radiated heat, plus radiator sizing.
ADCS Sizing
LEO disturbance torques — gravity-gradient, aerodynamic, solar-pressure, magnetic — and reaction-wheel and magnetorquer sizing.
// Lost in the acronyms? Every term the tools use is defined in the spacecraft engineering glossary.
// Need a tool that's not here yet? Drop a note via the contact form.
// Building on top of these? We're scoping API access to the calculator + compliance engines.