ISS position and a spoofed radio signal on four maps
Hypothesis. Radio signals received from the International Space Station are spoofed: ground transmitters along its track imitate a source moving at the measured speed, 7.36 km/s.
Test. The station is placed at its position in the published orbit, where it is seen and received; its speed across each map follows from that map's distances. The spoofed signal starts level with the station at each northbound equator crossing and moves along the same track at 7.36 km/s. A city turns red when the station is above its horizon and the signal is not, or the reverse.
——
Station, published-orbit position
Spoofed signal, 7.36 km/s
Gap along the track
Above the horizon
City: station and signal in view
City: one without the other
Globe
Sphere, radius 6,371 km
Map speed
—
Acceleration
—
Signal
—
Cities out of sync
—
Map speed this orbit, km/s · dashed: measured
North-pole AE
Centred on the North Pole
Map speed
—
Acceleration
—
Signal
—
Cities out of sync
—
Map speed this orbit, km/s · dashed: measured
Dual-pole AE
Centred on 0°N 0°E
Map speed
—
Acceleration
—
Signal
—
Cities out of sync
—
Map speed this orbit, km/s · dashed: measured
Mercator
True on the equator, edges joined
Map speed
—
Acceleration
—
Signal
—
Cities out of sync
—
Map speed this orbit, km/s · dashed: measured
Result
On the globe the signal stays level with the station, within 0.06 km over 16 orbits. On the flat maps it falls behind by 25 min per orbit on the North-pole map, 15 min on Mercator and 12–68 min on the dual-pole map; on each orbit 50 to 400 cities of a million or more see the station without its signal, or receive the signal with no station in view. A signal kept level with the station instead would carry the map speed in its Doppler shift, up to 3.7 times the recorded shift on the North-pole map. The SatNOGS recordings from Europe, South America and Australia in The Shape of Distance match the published orbit.
Over 16 orbits
Globe
North-pole AE
Dual-pole AE
Mercator
Map speed, km/s
6.86–6.94
7.40–27.43
6.86–690
6.92–11.10
Doppler shift kept level, largest
×1.00
×3.73
×94
×1.51
Largest acceleration, g
0.01
2.65
1,563
0.53
Signal lag at end of orbit
0.01 s
24 min 40 s
11 min 57 s – 67 min 34 s
15 min 26 s
Largest gap, map km
0.06
24,411
53,633
7,283
Cities out of sync per orbit, mean
0
235
232
232
Method
Orbit
ISS (NORAD 25544) orbital elements from CelesTrak, epoch 2026-10-28 14:18 UTC; positions every second by SGP4 for 16 orbits from 2026-10-28 15:51 UTC. Period 92.9 min, mean altitude 426 km.
Measured speed
The station's speed relative to the ground, 7.34–7.37 km/s. On the globe the point beneath it moves at that speed × 6,371 / (6,371 + altitude), 6.86–6.94 km/s. Over a plane, in level flight, the point beneath moves at the station's own speed.
Map speed
Speed of the point beneath the station across the map, from positions 1 s apart, subdivided where a step exceeds 20 km on the map. Acceleration: change in that speed over 10 s.
Signal
Restarted level with the station at each northbound equator crossing. Lag: time since the station was at the signal's position. Gap: distance between them along the track, on the map.
In view
Within 20.4° of arc (2,267 km) of the point beneath the station or the signal: above the horizon at 426 km. Cities: GeoNames, population one million or more (573).
Maps
As in the Cable Latency Survey, except that Mercator's east and west edges are joined so that the track continues across 180°.