Things to do for completing this app

- satellite
  - implement update for TLE files
  - adjust stored trajectory data if TLE file is updated

- registration
  - add location.altitude
  - complete class Location
  - make class LocationList

- user
  - change profile data (password)
  - add new location
  - modify existing location (?)

- submission
  - make a form
  - store the data

- data display
  - make a page
  - create ranking view