TCP/IP has timeouts in it to allow it to detect dead connections. In fact the linus tcp code actually has the following comment in it highlighting the problems of talking to mars:
/* Increase the timeout each time we retransmit. Note that
* we do not increase the rtt estimate. rto is initialized
* from rtt, but increases here. Jacobson (SIGCOMM 88) suggests
* that doubling rto each time is the least we can get away with.
* In KA9Q, Karn uses this for the first few times, and then
* goes to quadratic. netBSD doubles, but only goes up to *64,
* and clamps at 1 to 64 sec afterwards. Note that 120 sec is
* defined in the protocol as the maximum possible RTT. I guess
* we'll have to use something other than TCP to talk to the
* University of Mars.
* PAWS allows us longer timeouts and large windows, so once
* implemented ftp to mars will work nicely. We will have to fix
* the 120 second clamps though!