Is there a way to reduce the number of Credential Challenges when accessing the protal at top level from outside the network?

In this scenario there are 3 Web Apps involved (Portal/MySite/Apps). Inside the network when users go to the portal top level page no logon in is required (all sites added to local intranet).

When accessimg the portal top level page from outside the network they are challenged three times (the page has an app and that app accesses thier my site for profile picture).

Is there anyway I can prevent users from having to login 3 times? One is tolerable (to the user) but 3 is generating hate mail. 🙂

Thanks, Bill