# How to know when to exit Slipspace?

We know that UNSC ships use particle accelerators to punch a hole through normal Space/Time to enter into Slipspace.

However, how do the ships know when to exit Slipspace when approaching the destination, especially taking into account the fact that special relativity becomes an incomplete concept while in Slipspace so it'd be hard to calculate the location of the ship using normal equations.

Is this ever explained?

A few things.

1. [A Shaw-Fujikawa Translight Engine] remains active for the entire period that a spacecraft is in the slipstream. - Halo Wiki

2. Human Slipspace velocities are ... approximately 2.625 light years per day - Halo Wiki

3. In addition to temporal anomalies, UNSC ships aren't able to jump with exact precision. A ship may transition back to normal space millions of kilometers from its intended destination. - Halo Wiki

So, let's say you want to travel 13.125 light years to a star. You turn on your drive, enter the Slipstream Space, and proceed in the direction of the star for 5 days. Then you turn off the drive and you exit Slipstream Space. You know when to exit because you know the distance you want to travel and the average time it takes to cover that distance while in Slipstream Space.

Because of the time distortion that results in Slipstream Space, you don't usually emerge exactly where you want to go. So you expected to have traveled 13.125 light years, but maybe it is more like 13.12497.

• Missed that they had an approximate velocity, was thinking they were unable to calculate a value for that. Makes sense. Thanks! Nov 3, 2015 at 13:13