Atmospheric Models¶
Atmospheric density is a major driver of low Earth orbit lifetime.
ASTROLAB uses Orekit atmosphere models where available. The selected model, space weather source, and solar activity assumptions can significantly affect drag and lifetime results.
Supported Model Families¶
| Model | Notes |
|---|---|
| NRLMSISE-00 | General-purpose atmosphere model using solar and geomagnetic activity inputs. |
| DTM2000 | Density model that also depends on solar and geomagnetic activity. |
| Harris-Priester | Simpler model, useful for lower-fidelity studies. |
| Simple Exponential | Idealized model for simplified behaviour. |
| JB2008 | Requires specific data availability and should be validated before use. |
Space Weather Sources¶
ASTROLAB can use available Orekit space weather providers such as:
- CSSI Space Weather.
- Marshall Solar Activity Forecast.
These providers can supply activity parameters such as F10.7 where supported.
F10.7¶
F10.7 is a solar radio flux index commonly used by atmosphere models. It acts as a proxy for solar activity, which affects thermospheric density.
In ASTROLAB, F10.7 is most relevant for:
- NRLMSISE-00.
- DTM2000.
For simpler atmosphere models, F10.7 may not be physically used even if it is present in reports.
Solar Activity Scenarios¶
Lifetime Analysis can compare solar activity assumptions:
- Low.
- Moderate.
- High.
Higher solar activity generally increases atmospheric density and reduces orbital lifetime for low Earth orbit spacecraft.
Practical Interpretation¶
Atmospheric models are a source of uncertainty. Lifetime estimates should not be treated as exact dates unless validated with a specific operational model and updated space weather data.
For engineering studies:
- Use Compare All to understand sensitivity.
- Report the selected model and activity assumption.
- Avoid over-interpreting exact re-entry dates.
- Use conservative margins when making mission decisions.