Lifetime Analysis

Lifetime Analysis estimates long-term orbital decay until a configured re-entry altitude threshold is reached. The current ASTROLAB workflow is focused on DSST-style long-term propagation with atmospheric drag and configurable solar activity scenarios.

Engineering Questions

• How long until perigee or orbital altitude reaches the re-entry threshold?
• How does solar activity affect lifetime?
• How do mass, drag area, Cd, and atmosphere model change decay?
• What are the trends in altitude, perigee, apogee, SMA, eccentricity, inclination, density, and F10.7?

Inputs

Input	Description
Spacecraft	Provides initial state and optional physical/propagation defaults.
Maximum duration	Upper bound for propagation.
Output step	Sampling step for saved results.
Re-entry altitude	Stop threshold in km.
Propagation method	Current recommended workflow is DSST.
Gravity degree/order	Long-term gravity model settings.
Drag properties	Mass, drag area, Cd.
SRP settings	SRP area, Cr, include SRP.
Atmosphere model	NRLMSISE-00, DTM2000, Harris-Priester, Simple Exponential, JB2008 where available.
Space weather source	CSSI or Marshall forecast where supported.
Solar activity scenario	Low, Moderate, High, or comparison mode.

Processing Pipeline

flowchart TD
    A["Resolve spacecraft"] --> B["Get initial state"]
    B --> C["Build lifetime propagator"]
    C --> D["Build atmosphere and space weather providers"]
    D --> E["Propagate output samples"]
    E --> F["Extract orbital samples"]
    F --> G["Check re-entry altitude"]
    G --> H["Build time series and summary"]

Main Outputs

Output	Description
altitude	Instantaneous altitude time series.
perigee_altitude	Perigee altitude time series.
apogee_altitude	Apogee altitude time series.
semi_major_axis	Semi-major axis time series.
eccentricity	Eccentricity time series.
inclination	Inclination time series.
atmospheric_density	Density sampled along the propagated state.
spacecraft_mass	Spacecraft mass time series.
decay_rate	Derived decay-rate diagnostic.
f107_daily	Daily F10.7 flux where provider supports it.
f107_average	81-day average F10.7 where provider supports it.

Solar Activity Comparison

When configured to compare activity levels, ASTROLAB runs multiple scenarios and stores a scenario map:

payload["scenarios"]["Low"]
payload["scenarios"]["Moderate"]
payload["scenarios"]["High"]

This allows reports and plots to compare re-entry dates and lifetime days across solar activity assumptions.

Interpretation Notes

Lifetime analysis is sensitive to atmospheric density, ballistic coefficient, solar activity, orbit altitude, eccentricity, and integration settings. It should be used as an engineering estimate, not as a certified re-entry prediction.

For low altitudes near re-entry, numerical failures can occur because the orbit is no longer physically stable for the selected model. A robust lifetime workflow should treat near-threshold propagation failure as end-of-life rather than a user-facing crash.