As of version 0.11 of the AstroBox software image, SSH access has been disabled by default. This was done following the security recommendations of the Raspberry Pi Foundation and in accordance with their own Raspbian builds.
If you need to (hopefully temporarily) enable SSH access to your unit, you can do this in two ways:
1) Access your Raspberry pi by connecting it to an HDMI monitor and USB cable. You can then log into the command line with the following credentials:
username: pi password: raspberry
Once inside, you can run the following commands:
sudo touch /boot/ssh sudo reboot
2) Open the SD card in a computer and place a file called 'ssh' into the root directory of the card. The file can be anything. You can even copy and rename one of the files already there.
Once SSH is enabled, it will stay enabled. To disable it again run:
sudo update-rc.d ssh disable