NASA recently tested their “Deep Space Internet” protocol.  It sounds pretty slick, enabling more complex missions with multiple satellites or rovers all communicating to each other and back to earth.

Unfortunately, we won’t be pinging any satellites from our “Close Earth Internet” any time soon:

Unlike TCP/IP on Earth, the DTN does not assume a continuous end-to-end connection. In its design, if a destination path cannot be found, the data packets are not discarded. Instead, each network node keeps the information as long as necessary until it can communicate safely with another node.

This works great until some alien manages to send a bunch of data to a non-existent satellite, forcing your node to queue up all the information indefinitely, triggering an interplanetary equivalent SYN flood.

This begs the question: what is the security around communicating with interplanetary probes?

I assume there's some form of encryption, but these probes exist for a long time, what's the lifetime of their encryption schemes?

Does NASA do testing to accomadate rogue people with satellite dishes sending data to their probes? Or is the real barrier that the probe won't be aligned to your dish's location so it's impossible to send data?