Satellite Speed Calculator Formula
Understand the math behind the satellite speed calculator. Each variable explained with a worked example.
Formulas Used
Orbital Speed
speed = sqrt(3.986e14 / ((6371 + altitude) * 1000))Speed (km/s)
speed_kmps = sqrt(3.986e14 / ((6371 + altitude) * 1000)) / 1000Orbital Period
period_min = 2 * pi * sqrt(pow((6371 + altitude) * 1000, 3) / 3.986e14) / 60Variables
| Variable | Description | Default |
|---|---|---|
altitude | Altitude Above Surface(km) | 400 |
How It Works
Satellite Speed From Altitude
v = √(GM / r) where r = R_Earth + altitude
Using GM_Earth = 3.986e14 m³/s² and R_Earth = 6371 km.
The period follows: T = 2πr / v
Worked Example
Find the speed of the ISS at 400 km altitude.
altitude = 400
- 01r = 6371 + 400 = 6771 km = 6 771 000 m
- 02v = √(3.986e14 / 6 771 000) ≈ 7 673 m/s
- 03Period = 2π × 6 771 000 / 7 673 ≈ 5 542 s ≈ 92.4 min
Frequently Asked Questions
What altitude is the ISS?
About 400-420 km, orbiting every 92 minutes at about 7.67 km/s.
How fast is a GPS satellite?
GPS orbits at 20 200 km altitude at about 3.87 km/s with a 12-hour period.
Does satellite mass affect speed?
No. Orbital speed is independent of the satellite's mass.
Ready to run the numbers?
Open Satellite Speed Calculator