It is possible to log your data straight from the scope to a USB drive. To do this, you would use the Act on Event feature which will allow you to set the scope to save specified data on certain events, such as a Trigger. This feature is located in the Trigger menu under the Mode & Holdoff tab. Select Act on Trigger and the Act on Event menu will pop-up on the screen. There is a matrix of actions and events to choose from and a Save Configuration to define the location and file format of your data.
However, this solution will most likely give you lots of data and might fill up your USB before the collection is over. We have some software options available that might make capturing your data easier. I suggest that you look at TekScope Utility, a software with lots of configurability that will make saving data over a long period of time potentially easier. This software will allow you to save specified data formats at time intervals over the length of the test to a specific folder on your computer.
I would suggest taking a look at both of these options and maybe running some tests to see what works best for you.