EV Society™ · EV.ENGINEER™
CubeSat energy, mission and reliability analysis
14 September – 6 December 2026
Mission / team: __________________________
Educational R&D prototype · Simulated data · Not flight software.A small satellite. A finite battery. An extraordinary mission. Explore how sunlight, eclipse and the choices you make shape a spacecraft’s energy and reliability.
CubeTwin is an educational web simulator that helps students model the electrical-energy behaviour of a CubeSat. It calculates how orbit sunlight, eclipse, solar generation, subsystem loads and battery characteristics affect State of Charge, voltage, temperature, mission activities and safe-mode decisions. The project is an EV Society™ initiative hosted on EV.ENGINEER™, with commercial engineering handled separately by iTelematics Software Private Limited.
Begin with the reference mission. Change a parameter, run the model and follow the energy.
Estimated bus 8.22 V · 20.0 °C · DoD 20.0%
Whole-run metrics below. Energy is delivered after PMAD. Consumption is requested load; unmet demand is recorded separately. Reserve time uses the state at each interval’s start. Brownout counts are contiguous undervoltage or unmet-demand intervals.
| Activity | Mode | Outcome | Served / requested (s) |
|---|---|---|---|
| boot | boot | completed | 60 / 60 |
| detumble | detumble | completed | 240 / 240 |
| image-1 | payload | completed | 600 / 600 |
| downlink-1 | downlink | completed | 480 / 480 |
| Orbit | Modelled duration (min) | Generated − requested (Wh) |
|---|---|---|
| 1 | 94.47 | 5.195 |
| 2 | 94.47 | 5.245 |
| 3 | 94.47 | 3.578 |
| 4 | 94.47 | 4.445 |
| 5 | 94.47 | 5.291 |
| 6 | 94.47 | 5.204 |
| 7 | 94.47 | 5.245 |
| 8 | 94.47 | 5.245 |
| 9 | 94.47 | 5.278 |
| 10 | 94.47 | 5.254 |
| 11 | 94.47 | 5.204 |
| 12 | 94.47 | 5.245 |
| 13 | 94.47 | 5.245 |
| 14 | 94.47 | 5.245 |
| 15 | 94.47 | 5.245 |
| 16 | 22.96 | 3.827 |
11 nearby samples shown. CSV contains all 8,671 samples and units. Power is sampled at the timestamp; integration advances to the next timestamp.
| Time (s) | State | Truth SOC (%) | Observed SOC (%) | Solar (W) | Load (W) | Voltage (V) | Temperature (°C) |
|---|---|---|---|---|---|---|---|
| 0.0 | Sunlight | 80.00 | 80.00 | 18.00 | 3.00 | 8.22 | 20.00 |
| 10.0 | Sunlight | 80.10 | 80.10 | 18.00 | 3.00 | 8.23 | 20.01 |
| 20.0 | Sunlight | 80.20 | 80.20 | 18.00 | 3.00 | 8.23 | 20.02 |
| 30.0 | Sunlight | 80.30 | 80.30 | 18.00 | 3.00 | 8.23 | 20.04 |
| 40.0 | Sunlight | 80.40 | 80.40 | 18.00 | 3.00 | 8.23 | 20.05 |
| 50.0 | Sunlight | 80.49 | 80.49 | 18.00 | 3.00 | 8.23 | 20.06 |
| Time | Type | Trigger / outcome |
|---|---|---|
| 00:00:00 | mode | initial → boot · boot |
| 00:01:00 | mode | boot → detumble · detumble |
| 00:01:00 | activity | boot: completed (60 / 60 s served). |
| 00:05:00 | mode | detumble → nominal |
| 00:05:00 | activity | detumble: completed (240 / 240 s served). |
| 04:00:00 | mode | nominal → payload · image-1 |
| 04:10:00 | mode | payload → nominal |
| 04:10:00 | activity | image-1: completed (600 / 600 s served). |
| 05:00:00 | mode | nominal → downlink · downlink-1 |
| 05:08:00 | mode | downlink → nominal |
| 05:08:00 | activity | downlink-1: completed (480 / 480 s served). |
Build intuition first. Then connect each observation to a simple, inspectable equation.
A CubeSat is a small satellite built around standardized units and dispenser interfaces. Its payload performs the mission; its bus supplies power, computing, attitude control, communications and thermal support. A launch vehicle carries it to space.
3U ≈ three standard CubeSat unitsAltitude changes orbital period. With a mean Earth radius of 6,371 km, a circular orbit at 500 km takes about 94.5 minutes. Earth blocks direct sunlight during eclipse. This model starts each orbit in sunlight and uses a configurable eclipse at its end; real shadows depend on geometry and season.
T = 2π √((Rᴇ + h)³ / μ)Solar cells convert light to electricity. Panel area, efficiency and incidence angle determine generation; PMAD conditions and distributes that power. Beginner mode takes peak power directly. Engineering mode exposes the same assumptions. Delivered solar power is zero during the simplified eclipse.
Psolar = G × A × ηcell × derating × max(0, cos θ)Watts describe an instantaneous rate. Watt-hours describe energy accumulated over time. The nominal 8 W bus uses 4.67 Wh during a 35-minute eclipse before battery losses. Payload and downlink add 10 W and 6 W to the nominal bus. Essential-only operation uses 3 W.
Pnet = Psolar,delivered − PloadSOC is 100 × stored energy / usable capacity; DoD is 100 − SOC. Charging stores less energy than is supplied. Discharging removes more than the loads receive. The model clamps stored energy, records rejected charge at the upper limit and reports unmet demand when the battery is empty.
Enew = E + ηc Pnet Δt/3600 (charging); E + Pnet Δt/(3600ηd) (discharging)Open-circuit voltage comes from an editable illustrative pack lookup. Positive current means discharge. The current estimate uses requested battery power divided by OCV. Greater resistance produces more voltage sag. This diagnostic approximation does not determine SOC from voltage or solve a coupled circuit.
Vterminal = OCV(SOC) − I × RinternalThe optional lumped model balances resistive heating, an assumed external heat input and heat exchange with a fixed bus temperature. Its parameters are educational assumptions. It excludes radiative geometry, cell chemistry and thermal runaway, and cannot assess battery safety.
ΔT = Δt/Cth × (I²R + Qexternal − (T − Tbus)/Rth)The deterministic controller defers noncritical payload/downlink below reserve and enters safe mode below its entry threshold. It exits only after the higher recovery threshold holds for the specified dwell time. This hysteresis prevents rapid switching. Completion, brownout intervals and per-orbit margins describe the simulated outcome.
safe entry < reserve ≤ recovery ≤ maximum SOCEPS background: NASA Small Spacecraft Power Systems. Unit and interface guidance: Cal Poly CubeSat Design Specification. Model values are illustrative assumptions.
Twelve guided weeks of learning, calculation, development and evidence. Every checkbox is a small step forward.
14 September – 6 December 2026 · Learn → Calculate → Build → Verify → Deliver
The guide plans a concept submission milestone for 30 September. Confirm eligibility, deadline and submission requirements with the organizer; the full learning project continues to December.
A good model teaches you about the unexpected. Introduce a fault and compare it against the same mission without faults.
The array produces less power throughout the fault window.
Compare charging slopes and daily energy margin.
This experiment replaces existing faults. Import a scenario JSON to combine fault windows.
The baseline uses the current mission configuration with all faults removed. Both runs use identical models and schedules.
| Whole-run metric | Baseline | Experiment |
|---|---|---|
| Minimum SOC | 80.00 % | 80.00 % |
| Final SOC | 91.81 % | 91.81 % |
| Energy margin | 79.99 Wh | 79.99 Wh |
| Below reserve | 0.00 min | 0.00 min |
| Minimum voltage | 7.92 V | 7.92 V |
| Safe-mode entries | 0 | 0 |
| Unmet energy | 0.00 Wh | 0.00 Wh |
Fault injection is not proof of detection. The SOC discrepancy detector uses simulated truth; real detection requires independent measurements.
Sample battery capacity, solar output, total subsystem load and resistance independently from uniform ± ranges. Seeded trials run in a worker. Bounds are clipped to the scenario limits; temperature and faults stay fixed.
A trial succeeds when all activities complete with no unmet load or undervoltage. This is a simulated probability under stated assumptions.
The portal and workbook share the same content. Print the lessons, checklist and experiments, or save them as a PDF.
A printable companion to the same lessons, equations and 12-week project. Capture your predictions before you run, then explain what changed.
Notes stay in this browser. No account or upload is needed.
A searchable field guide to spacecraft, energy and simulation.
97 of 97 terms
Verification checks the implementation against the equations. Validation requires evidence that a model represents its intended physical system.
No physical test article or measured mission data calibrates this prototype. These results do not demonstrate flight readiness, qualification, battery safety or real mission reliability.
Start with what you know. The laboratory is here to help with the rest.
CubeTwin is an educational CubeSat electrical-energy simulator and 12-week learning portal. It uses transparent models and simulated data to connect orbit, sunlight, battery behaviour, mission activities and power faults.
During sunlight, the solar array supplies spacecraft loads and charges the battery. In eclipse, the battery supplies those loads. Teams size the energy store, account for conversion losses, protect a reserve and schedule demanding activities around available energy.
The Electrical Power System (EPS) generates, stores, manages and distributes electrical power. It includes solar generation, batteries and power management and distribution (PMAD) electronics.
No. Start with the bundled 3U LEO Beginner Mission, run the simulation and follow the plain-language lessons. The 12-week guide introduces the science, hand calculations, software and verification in stages.
No. All data is simulated in your browser. CubeTwin is not flight software, live telemetry, certified analysis or a validated operational digital twin. Calibration against a specific physical test article is future work.
It is the fraction of seeded simulated trials completing all activities without unmet load or undervoltage under the selected uniform input uncertainty. The confidence interval describes sampling uncertainty. Neither value is a prediction of real spacecraft reliability.
Export the complete scenario or run as JSON, export telemetry as CSV, or use Print the Workbook and choose Save as PDF. Workbook notes and weekly progress are stored only in this browser when local storage is available. Downloads can be used offline; the portal is not an offline application.
CubeTwin is an EV Society™ education and research initiative hosted on EV.ENGINEER™. Commercial engineering is handled separately by iTelematics Software Private Limited under explicit agreements. UFlight™ is referenced for the broader aerospace HUMS ecosystem.
Education, commercial engineering and the broader monitoring ecosystem have distinct roles.
CubeTwin is an EV Society™ education and research initiative hosted on EV.ENGINEER™.
Explore EV SocietyCommercial engineering products, implementation services and customer engagements, where applicable, are handled separately by iTelematics Software Private Limited under explicit agreements.
Explore iTelematicsUFlight™ is referenced within the broader ecosystem for Health and Usage Monitoring Systems related to aerospace and autonomous platforms.
Explore UFlightThese references do not imply a partnership, endorsement, certification or government affiliation.
Authoritative starting points for your reading and future model comparisons. Record the document revision used in your report.
Content last reviewed: · Model and scenario schema v1.0. Applicable launch-provider requirements supersede preliminary interface guidance.