The state of the art in interplanetary Internet

Developments in space technologies are enabling the realization of deep space scientific missions such as Mars exploration. Interplanetary (IPN) Internet is expected to be the next step in the design and development of deep space networks as the Internet in the space. However, there are significant challenges to be addressed for the realization of this objective. This article captures the current state of the art and open research challenges, and intends to motivate researchers around the world to tackle these challenging problems and help realize the IPN Internet.