Ok this is really only relevant to US residents, but hey this is the world wide web, so it's worth a look......
Entries become the property of Sponsor and will not be returned or acknowledged. By entering the Contest, all entrants (and their respective parents and legal guardians) grant a royalty-free, irrevocable, perpetual, non-exclusive license to Sponsor, its designees, licensees and affiliates ("Authorized Parties"), to reproduce, distribute, display and create derivative works of the entries (along with a name credit) in connection with the Contest and promotion of the Contest, in any media now or hereafter known, including, but not limited to: Display at a potential exhibition of winners; publication of a book featuring select entries in the Contest; publication in National Geographic Kids Magazine or online highlighting entries or winners of the Contest. Entrants consent to the Sponsor doing or omitting to do any act that would otherwise infringe the entrant's "moral rights" in their entries. Display or publication of any entry on an Authorized Party's website does not indicate the entrant will be selected as a winner. Authorized Parties will not be required to pay any additional consideration or seek any additional approval in connection with such use.
LIMITATION OF LIABILITY
By participating, entrants (and their parents or legal guardians) agree to release, discharge and hold harmless National Geographic Society, Airbus, and their partners, affiliates, subsidiaries, agents and their employees, officers, directors, and representatives from any claims, losses, and damages arising out of their participation in this Contest or any Contest-related activities and the acceptance and use, misuse, or possession of any prize awarded hereunder.
The line in bold is a good one!