If you have already tried downloading once, and it won't let you download again, try this alternate link.
To get past this, go to Settings, then select General .. Profiles (or Device Management) .. Su-Kam Intelligent Education Systems ... Trust
Register a user account by opening SKIES and tapping "New to SKIES? Sign up now." An e-mail will be sent to you. Find this e-mail and click on the verification link inside.
Log in to SKIES and explore our universe!
If you own a Skybox, convert your iDevice into a mobile scientific instrument by downloading the Tricorder app here.
For more information about SKIES, visit our website. You can also run SKIES through this website.