CubeSTEM Digital Twin — V3.6A
Mission Realism Lab
A real mission depends on whether the satellite is visible from the ground station, how long the contact window lasts, how much data can be transmitted, whether the link margin is enough, whether packets arrive or are lost, and whether the spacecraft is pointing well enough to make contact.
Change parameters and see why communication windows, link margin, packet errors, and pointing affect mission success. Teaching-grade approximations — not certified STK / GMAT / RF analysis.
Complexity mode
Grade-level mode
Controls which parameters and explanations are visible. All modes use the same teaching-grade models underneath.
Quick scenarios
Mission Scenario Presets
Select a scenario to load a pre-configured set of parameters. All panels update together.
Step 1 — Orbit & coverage
Ground Track & Coverage
The ground track is the path the satellite traces over Earth. The coverage band shows which latitudes the satellite can pass over.
Coverage summary
Ground station latitude (-34°) is within the orbit's coverage band (inclination 97°). Regular passes expected at low LEO altitude (500 km).
Estimated passes in mission window: 3
Pass windows (first 3)
| Pass | Start (min) | Duration | Max elev. | Quality |
|---|---|---|---|---|
| 1 | T+66 | 5.5 min | 34.6° | MEDIUM |
| 2 | T+601 | 7.5 min | 64.2° | HIGH |
| 3 | T+1132 | 4.2 min | 13.8° | LOW |
Teaching approximation — not certified orbital propagation.
Step 2 — Contact window
Contact Window
The contact window is the time when the satellite is above the horizon and can communicate with the ground station. AOS = Acquisition of Signal · TCA = Time of Closest Approach · LOS = Loss of Signal.
Usable time
510 s
Raw capacity
4.90 Mbit
Effective data
4.75 Mbit
Teaching model — not certified ground-station tracking software.
Step 3 — Link budget
Link Budget
The link budget tells you whether the signal is strong enough to reach the ground station. Link margin = received power − required power. More margin = more reliable link.
Frequency band
Atmospheric / fade preset
Nominal clear-sky conditions. Minimal attenuation.
EIRP
34.5 dBm
FSPL
140.8 dB
Rx power
-100.8 dBm
Packet success
97%
FSPL = 32.44 + 20·log₁₀(d_km) + 20·log₁₀(f_MHz) — teaching formula, not certified RF analysis.
Step 4 — Packet protocol
Telemetry Packet Protocol
Telemetry is sent as packets — blocks of data with headers, payload, and an integrity check. Choose the protocol to see how checksums, CRC, and ACK/NACK retries affect delivery.
Success
11
91.7%
Corrupted
1
checksum fail
Dropped
0
unrecoverable
Retries
0
attempts
Teaching CRC-16: 91.7% success. 1 CRC failures. 0 dropped. Stronger detection than checksum.
Packet log
| Seq | Type | Asset | Timestamp | Status |
|---|---|---|---|---|
| 1 | health telemetry | SAT-01 | T+10s | valid |
| 2 | battery status | ROVER-A | T+20s | valid |
| 3 | thermal status | GND-01 | T+30s | valid |
| 4 | attitude data | SAT-01 | T+40s | valid |
| 5 | mission data | ROVER-A | T+50s | valid |
| 6 | command ack | GND-01 | T+60s | valid |
| 7 | fault event | SAT-01 | T+70s | valid |
| 8 | health telemetry | ROVER-A | T+80s | checksum failed |
| 9 | battery status | GND-01 | T+90s | valid |
| 10 | thermal status | SAT-01 | T+100s | valid |
| 11 | attitude data | ROVER-A | T+110s | valid |
| 12 | mission data | GND-01 | T+120s | valid |
Teaching CRC/checksum — not a real protocol implementation. Deterministic, dependency-free.
Step 5 — ADCS coupling
ADCS Pointing → Link Margin
If the spacecraft antenna is not pointing accurately toward the ground station, the signal weakens. This directly reduces link margin and increases packet errors.
Connects: Track 5 ADCS → Track 4 Communication → Track 6 Telemetry
ADCS control mode
Pointing loss
0.2 dB
Margin reduction
−0.2 dB
Packet impact
−1%
Wheel warning
No
Good pointing: 3° error is well within the 70° beamwidth. Pointing loss: 0.2 dB — negligible link margin impact.
One-axis teaching coupling only — not full 3-axis flight ADCS. Not a certified ADCS simulator.
Evidence output
Mission Realism Evidence Report
Copy this evidence report for your portfolio, mission review, or teacher submission. Includes scenario, orbit, contact window, link budget, packet summary, and ADCS coupling.
═══════════════════════════════════════════════════════ MISSION REALISM LAB — EVIDENCE REPORT CubeSTEM / CubeTwin — V3.6A Teaching-Grade ═══════════════════════════════════════════════════════ Grade Mode: High School Scenario: Good LEO pass — strong link ─── ORBIT / GROUND TRACK ──────────────────────────── Altitude: 500 km Inclination: 97° Orbit period: 94.43 min (teaching approx.) Max latitude: ±97° Passes in window: 3 Coverage note: Ground station latitude (-34°) is within the orbit's coverage band (inclination 97°). Regular passes expected at low LEO altitude (500 km). ─── CONTACT WINDOW ───────────────────────────────── Pass duration: 10 min Elevation quality: high Data rate: 9.6 kbps Usable time: 510 s Raw capacity: 4896 kbit Effective data: 4749 kbit (after packet loss) Downlink status: EXCELLENT Backlog warning: No AOS / TCA / LOS: T+0s / T+300s / T+600s ─── LINK BUDGET (TEACHING-GRADE) ──────────────────── Frequency band: UHF (437 MHz) Tx power: 33 dBm Tx antenna gain: 2 dBi Slant range: 600 km Preset: clear sky EIRP: 34.5 dBm FSPL: 140.8 dB Rx power: -100.8 dBm Link margin: 9.2 dB Link quality: STRONG Packet success: 97.0% ─── PACKET PROTOCOL ───────────────────────────────── Protocol: crc16 teaching Total packets: 12 Max retries: 3 Success: 11 packets (91.7%) Corrupted: 1 packets Dropped: 0 packets Retried: 0 attempts Outcome: Teaching CRC-16: 91.7% success. 1 CRC failures. 0 dropped. Stronger detection than checksum. ─── ADCS POINTING COUPLING ────────────────────────── Pointing error: 3° Antenna beamwidth: 70° Control mode: balanced Wheel effort: 30% Battery impact: 8% Pointing loss: 0.2 dB Margin reduction: 0.2 dB Packet impact: −1% Control warning: No Battery warning: No Coupling note: Good pointing: 3° error is well within the 70° beamwidth. Pointing loss: 0.2 dB — negligible link margin impact. ─── STUDENT CONCLUSION ────────────────────────────── Link quality was STRONG with 9.2 dB margin. 91.7% of telemetry packets were successfully delivered. Teaching CRC-16: 91.7% success. 1 CRC failures. 0 dropped. Stronger detection than checksum. Pointing error of 3° was within acceptable limits. Data volume was manageable within the contact window. ─── LIMITATION NOTE ───────────────────────────────── This report uses teaching-grade approximations only. Orbit period: simplified Kepler formula (±5% vs real). FSPL: standard teaching formula (32.44 + 20log₁₀ terms). Link margin: no noise figure, no system temperature model. ADCS: one-axis teaching coupling only, not 3-axis flight ADCS. Packet model: deterministic teaching CRC, not real protocol. NOT certified for mission planning, operations, or real RF design. ═══════════════════════════════════════════════════════
Teaching-grade evidence only. Not certified mission report. Not for real satellite operations.
Teacher guide
Using Mission Realism Lab in the Classroom
Recommended flow (45 min)
- Select grade mode (middle school for younger, university for engineering students).
- Load "Good LEO pass" scenario — show what a successful mission looks like.
- Switch to "Low elevation pass" — discuss how geometry affects link margin.
- Try "Heavy rain — high-frequency band" — compare UHF vs Ku-band rain sensitivity.
- Load "ADCS pointing error" — show why Track 5 pointing connects to Track 4 comms.
- Copy the evidence report — use as a student deliverable or portfolio artifact.
Key teaching moments
- • Ground track / coverage: why inclination limits which ground stations can be used.
- • Contact window: why mission data volume is constrained by orbit geometry.
- • Link margin: why +6 dB matters and what happens below 0 dB.
- • Rain / fade: why frequency choice matters for different mission environments.
- • Packet protocol: the real cost of a noisy link — errors, retries, and data loss.
- • ADCS coupling: why pointing error is not just an attitude problem — it is a comms problem.
Grade-level guidance
- • Middle school: focus on qualitative outcomes — strong / marginal / broken link labels, backlog warning, pointing status.
- • High school: introduce dB margin, data volume calculations, packet success rates.
- • University intro: show FSPL formula, EIRP, Rx power chain, CRC, full ADCS coupling parameters.
Classroom safety and boundaries
All calculations are browser-local and deterministic. No network requests, no student data stored, no real satellite commands. Evidence reports are for educational portfolio use only, not certified mission documents.
Boundary & limitations
What this lab does — and does not — do
What it does
- ✓ Teaching-grade ground track and coverage model
- ✓ Contact window with AOS / TCA / LOS and data volume estimate
- ✓ Simplified link budget using FSPL teaching formula
- ✓ Rain and fade attenuation presets by frequency band
- ✓ Packet protocol with checksum / CRC / ACK-NACK / retry
- ✓ One-axis ADCS pointing error coupled to link margin
- ✓ Grade-level modes (middle school → university intro)
- ✓ Copyable evidence report for portfolios
What it does NOT do
- ✗ Certified orbital propagation (not SGP4 / Orekit / STK)
- ✗ Certified RF link budget (no noise figure / system temp)
- ✗ Full 3-axis ADCS (one-axis teaching model only)
- ✗ Real packet protocol (teaching CRC, not standard CRC-16)
- ✗ Real SDR, live ground station, or real satellite commanding
- ✗ Backend storage, accounts, or official grades
- ✗ Flight operations, official mission analysis, certified outputs
Apply this lab in context
CubeSat–Rover Relay·Lunar Rover Rescue·Local mission report·Packet protocol spec (hardware-ready)