Orbital lifetime calculator

Decay of a circular orbit under atmospheric drag with the density model of the PocketQube review. Change the spacecraft, the altitude or the solar activity, or add a drag sail, and check the five- and 25-year limits.

Spacecraft
Start from a form factor

Sets the mass limit and the mean tumbling area A_tot/4.

kg
cm²

Average area facing the flow; A_tot/4 for a randomly tumbling convex body.

m²

Flat sail tumbling with the spacecraft: adds half its area to the mean cross-section.

Ballistic parameter C_D·A/m = 0.0330 m²/kg

Orbit
km
Space weather
Solar activity

F10.7 = 140 sfu, Ap = 12, held constant

Estimated lifetime20.4 months
Five-year ruleMeetsLimit for this spacecraft: 559 km
25-year guidelineMeetsLimit for this spacecraft: 656 km
High to low activity9 months – 5.8 yearsLifetime range at constant activity
  • Low: 5.8 years
  • Moderate: 20.4 months
  • High: 9 months
Altitude against time from 500 km1502002503003504004505000123456Time (years)Altitude (km)180 kmLowModerateHigh
Show the data as a table
Time (years)Low: 5.8 yearsModerate: 20.4 monthsHigh: 9 months
0500500500
1492454—
2482——
3469——
4450——
5418——
6———
Decay under low, moderate and high solar activity (and the custom setting, dashed). Re-entry is assumed at 180 km.
Drag force at the start
0.136 µN
Δv per year to hold altitude
17.2 m/s
Initial decay rate
2.65 km/month

First-order model: constant solar activity, single scale height, no lift or attitude changes. Real decay follows the solar cycle, so quote lifetimes as ranges; compliance analyses need empirical models such as NRLMSISE-00 and solar-cycle forecasts.