What is the average time it takes for a planet to lose its atmosphere after losing its moon(s)?

 The time it takes for a planet to lose its atmosphere after losing its moon(s) can vary widely depending on a number of factors. These include the size and mass of the planet, its distance from its star, the type of atmosphere, and whether other factors such as solar wind, magnetic field, and radiation are in play. 

However, there is no standard or universally agreed-upon "average" time for this process, as it depends on the specifics of the planet's system. For example:

1. **Without a moon, tidal forces are reduced**: Moons create tidal forces that can help maintain the planet's rotation and sometimes contribute to maintaining a magnetic field. If a planet loses its moon(s), it could potentially experience changes in its climate, rotation, and magnetic protection. Without the moon's tidal forces, a planet's rotation could slow down, and its magnetic field could weaken, which might make it more vulnerable to atmospheric stripping by solar wind.

2. **Solar wind stripping**: If a planet lacks a strong magnetic field (which a moon's tidal forces could help support), it becomes more susceptible to solar wind erosion, especially if it's close to its star. This could result in atmospheric loss over millions to billions of years.

3. **Atmospheric composition**: Planets with thick atmospheres or those that are further from their star are less likely to lose their atmosphere quickly, even without moons.

Given all of these variables, it's difficult to pinpoint an average time, but the process could take anywhere from millions to billions of years for a significant atmosphere loss to occur after the loss of moons.

In short, the time varies greatly based on a range of environmental and planetary factors.