# Ionospheric Models
**URL:** https://learn.safran-navigation-timing.com/t/ionospheric-models/525
**Category:** Skydel Discussion
**Created:** [March 3, 2022, 2:34pm UTC](https://learn.safran-navigation-timing.com/t/ionospheric-models/525 "2022-03-03T14:34:18Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@mventresca](https://learn.safran-navigation-timing.com/u/mventresca)
#### Post date: [March 3, 2022, 2:34pm UTC](https://learn.safran-navigation-timing.com/t/ionospheric-models/525/1 "2022-03-03T14:34:18Z")
How is the “Spacecraft” ionospheric model defined?
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### Author:  [@Grace](https://learn.safran-navigation-timing.com/u/Grace)
#### Post date: [March 4, 2022, 2:49pm UTC](https://learn.safran-navigation-timing.com/t/ionospheric-models/525/2 "2022-03-04T14:49:22Z")
Hi @mventresca,
The Spacecraft ionospheric model is intended for use only for a vehicle in space, above the ionosphere. For the most part, the spacecraft will have a direct line of sight through empty space. However, when GNSS satellites pass behind the Earth, the line of sight will pass through the ionosphere for a short time. During this time, the effect on the GNSS signal is not negligible.
We will also make available the Nequick model which is more efficient for simulations in space, but we must finalize some tests before confirming that this model will work for space.
Regards,
Grace
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### Author:  [@Joshua.Prentice](https://learn.safran-navigation-timing.com/u/Joshua.Prentice)
#### Post date: [June 24, 2024, 3:57pm UTC](https://learn.safran-navigation-timing.com/t/ionospheric-models/525/3 "2024-06-24T15:57:59Z")
Hi Grace, can you provide any further information on how the ionospheric effects on the signal are taken into account within the spacecraft model? For example when the signal does pass through the ionosphere is the effect determined based on an existing model (e.g. NeQuick)?