test_msisStepLag

Test that the MSIS temporal inputs are evaluated at the epoch of the extrapolated spacecraft state.

test_msisStepLag.test_temporal_inputs_are_unchanged_without_extrapolation()

Verify the temporal inputs stay at the update epoch when the extrapolation is disabled.

test_msisStepLag.test_temporal_inputs_follow_the_extrapolated_midpoint()

Verify the local solar time uses the same epoch as the extrapolated spacecraft state.

The state is written at 0 s and rewritten at 3600 s, so the update at 7200 s is extrapolated to 5400 s. Its density must be that of a plain update at the epoch advanced by 5400 s, and differ from the one at 7200 s.

test_msisStepLag.test_temporal_inputs_use_the_previous_update_while_the_period_is_unknown()

Verify the startup update, where the spacecraft is left at the previous update, uses that epoch as well.

The state is written at 0 s. The update at 3600 s has seen one write time only, so the geometry stays at 0 s and the temporal inputs must be those of 0 s.