Scenario
Why single-plane deployments have long outages
The same satellite count can mean a 15 hour outage or a 25 minute one. Deployment order and plane spread decide which.
The same satellites, in orbit at the same time, at the same altitude, can produce a 15.7 h outage or a 3.8 h one. The only difference is how many orbital planes they occupy. This is the least intuitive number on the site and the one most likely to matter in a commercial conversation, because early constellations are almost always single-plane constellations.
A rideshare or a dedicated launch puts every satellite from that launch into essentially one orbital plane. Spreading into separate planes needs either separate launches or a lot of time and propellant to drift the right ascension apart. So the first block of a fleet does not deliver its proportional share of the service. It delivers considerably less.
Loaded configuration: 5 satellites · 520 km · 53° inclination · min elevation 25° · latitude 40° · 1 plane
Why single-plane deployments have long outages
A against B
B is drawn dashed on the charts below, in the same colours.
Service timeline at your latitude
96 h · worst-case longitude at 40°Longest gap 15.7 h. Filled blocks mark at least one satellite above 25° elevation.
Outage vs constellation size
At 40° latitude, min elevation 25°, 520 km / 53.0°. Log scale. Labels mark the worst outage.
3 satellites do better here than 5: 6.6 h against 15.7 h. Coverage depends on how the planes interleave, not only on the count, and the automatic rule arranges each fleet size differently. Why this happens.
Worst outage vs latitude
5 sats · 520 km · 53.0° · min elevation 25°Latitude sweep is sampled at 60 s steps across 4 longitudes, so it is coarser than the headline figures.
Numbers
| Constellation | Planes | Worst outage | Avg wait | Windows/day | Service min/day | Coverage |
|---|---|---|---|---|---|---|
| 3 sats | 3 × 1 | 6.6 h | 2.7 h | 8.8 | 30 | 2.1% |
| 5 sats | 1 × 5 | 15.7 h | 86.9 min | 14.4 | 50 | 3.5% |
| 12 sats | 4 × 3 | 4.1 h | 37.3 min | 34.8 | 120 | 8.3% |
| 22 sats | 11 × 2 | 30.3 min | 19.2 min | 63.9 | 220 | 15.2% |
| 48 sats | 8 × 6 | 32.0 min | 6.9 min | 139.2 | 479 | 33.3% |
| 90 sats | 10 × 9 | 6.3 min | 3.9 min | 173.3 | 764 | 53.1% |
| 200 sats | 20 × 10 | 1.7 min | 71 s | 123.4 | 1294 | 89.9% |
Same sampling as the headline tiles: 8 longitudes, 20 s steps (40 s above 400 satellites). Every row except your own uses the automatic plane rule.
Model and assumptions
- Geometry: spherical Earth (R = 6371 km), circular orbits, Walker-delta constellation with evenly spaced planes and phasing F = 1, no J2 drift or drag. Service means at least one satellite above the minimum elevation angle.
- Sampling: headline numbers and the table simulate 48 h (96 h for fleets of 12 or fewer) at 20 s steps, worst-cased across 8 longitudes at your latitude. The latitude chart uses 60 s steps and 4 longitudes.
- Planes: "Auto" spreads satellites across the divisor of N nearest above the square root of N, a revisit-friendly default. Real constellations may choose otherwise: a single-plane test block clusters its passes.
- Fidelity: planning-grade, for sizing intuition and commercial conversations. Contractual coverage commitments need full-fidelity tooling (STK, GMAT) with real ephemerides, beam patterns and link budgets. This tool models geometry only, not capacity or link margin. Full method and validation anchors.
The same hardware, two arrangements
| Constellation | Planes | Worst outage | Avg wait | Windows/day | Service min/day | Coverage |
|---|---|---|---|---|---|---|
| 5 sats, 1 plane | 1 × 5 | 15.7 h | 86.9 min | 14.4 | 50 | 3.5% |
| 5 sats, 5 planes | 5 × 1 | 3.8 h | 1.6 h | 14.4 | 50 | 3.4% |
| 22 sats, 1 plane | 1 × 22 | 15.2 h | 17.8 min | 51.9 | 220 | 15.3% |
| 22 sats, 11 planes | 11 × 2 | 30.3 min | 19.2 min | 63.9 | 220 | 15.2% |
| 48 sats, 1 plane | 1 × 48 | 15.2 h | 60.6 min | 14.7 | 275 | 19.1% |
| 48 sats, 8 planes | 8 × 6 | 32.0 min | 6.9 min | 139.2 | 479 | 33.3% |
At 520 km, 53° inclination, minimum elevation 25°, latitude 40°. Each pair holds the satellite count fixed and changes only the plane count.
At 48 satellites the gap between the two arrangements is the difference between a product and a demonstration: 15.2 h of worst-case outage in one plane against 32.0 min across 8 planes. Daily service minutes tell the same story from the other side, 275 against 479.
Why one plane behaves so badly
Satellites in a single plane all trace the same ground track, just at different times along it. The Earth turns underneath that one track at roughly 15° of longitude per hour, so a site gets a burst of passes while the track sweeps over it, then nothing at all until the geometry comes back around. Adding satellites to that plane makes the burst denser. It does not make the wait between bursts shorter.
That is why average wait is such a misleading headline for a single-plane fleet. The average is dragged down by the tight cluster of passes, while the number a customer actually feels is the long silence between clusters. For 5 satellites in one plane the average wait is 86.9 min and the worst wait is 15.7 h. Quote the second one.
What to do with this
- When a deployment plan says "twenty satellites by the end of next year", ask how many launches and into how many planes. The answer changes the service estimate more than the satellite count does.
- When you model an interim milestone, set the plane count by hand rather than leaving it on automatic. The automatic rule assumes a mature, well spread shell, which is the end state and not the path to it.
- When a fleet looks underwhelming, check the plane arrangement before adding hardware. Redistributing an existing fleet is sometimes available and always cheaper than launching.
A caveat in the operator's favour: this model spreads planes perfectly evenly and phases satellites perfectly within them. Real fleets drift, and a real single-plane block will not be quite as pathological as the idealised one. The direction of the effect is solid even where the exact minute is not.
Other scenarios
- Why continuous coverage is not a thresholdContinuity depends on the elevation mask, altitude, latitude and plane arrangement, not on a satellite count. The explanation behind the sizing tool.
- Direct-to-phone coverage at 5, 25, 45 and 90 satellitesWhat a direct-to-device constellation can promise at each stage of a buildout, from a first block of five satellites to a 90-satellite shell.
- IoT store-and-forward with a polar constellationRevisit time for a sun-synchronous IoT constellation with a 10 degree mask, where the product is message latency rather than continuous service.
- Coverage vs latitude, and why 53 degrees stops at 61Inclination plus the coverage half-angle sets a hard latitude ceiling. Above it, no fleet size produces a single second of service.