Trans-earth networking protocols
Will your credit card work on Mars?

Assuming you read scifi novels — have you ever stopped, really stopped and thought about how the technology in those stories work? Let’s skip the obvious things that you just have to suspend your belief over like ray guns, faster-than-light travel, space lifts and sentient artificial intelligences.

What I’m talking about is the small stuff. Everyday stuff. Like the Internet and paying for a late-night space-age kebab meal.

Pub Crawl at Valles Marineris

So you take the trans-planet express line from Earth to Mars and after a long and thorough pub crawl with your local green-skinned friends you feel peckish, and order the space-age Buck Lightyear premium kebab. You whip out your earthen debit card, chuck it to the reader, enter your pin and

    wait

    wait

    wait

    wait some more,

    and a lot more

    for a total of 40 stomach-grumbling long minutes.

At least this would happen if current EMV protocols are used in the space-age future.

Why? The speed of light is finite. Your chip debit card will talk with the card issuer’s backend systems over the network (actually, it’s the terminal that does the talking, and that doesn’t talk directly to the issuer but to a … well, that’s just details) so that the kebab vendor will get a confirmation they’ve been reserved the cost of the meal by the issuer, and the customer’s bank balance (or credit) is valid.

This information needs to travel back and forth between your Earthen card issuer and the Martian card terminal. Distance between Earth and Mars varies between 3 and 20 minutes depending on their relative orbital positions so just one round-trip — request and response — will take 6 minutes in the best case and over 40 minutes in the worst case.

In case you’re thinking BitCoins … they won’t work either. Transactions are asynchronous, yes, but you’d still need to send one over the high-latency link, wait for the transaction to complete, and of course wait for the new transaction block to be sent to you. «grumble grumble» says your stomach.

This pretty much means that any kind of online protocol is not going to work in space, except if both endpoints are really close (Earth to Moon, Mars to Phobos and Deimos).

Even if you are patient and willing to wait for hours for a transaction to clear, most today’s network services have timeouts (connection timeouts, nonce validity timeouts etc.) that will prevent whatever you are trying to do from completing if endpoints are separated by distances of light minutes.

Is it going to be IPv6? For what I know there are no limitations in the IPv6 itself that prevent Earth-Mars Internet from working. TCP has a fixed maximum segment lifetime of 2 minutes, but this is easily circumvented with packet reassembly at trans-planet gateways. More critical are applications and protocols that set limits within themselves. Of course many IP-based protocols are very chatty and synchronous, neither being good for very long latency links.

This would also mean you can’t post those boozing pictures on Twitter, either.

The card should clear immediately!

And so it will. But the clearing protocol will not be based on the current model. Your card issuer has probably pre-reserved a portion of your balance or credit and “transferred” it over to a local Martian operator, and this local balance would be balanced between Earth and Mars “behind the scenes”, asynchronously.

Twitter, Google? Probably twitter.com and google.com map to geo-located planet-located IP addresses and these services are set up to do long-haul asynchronous synchronization on their (relevant) data sets between Earth and Mars.

There are other ways, of course. These are just examples to show that it is possible to at least generate an illusion of network service ubiquity even over planetary distances.

So, doable.

But not directly.

But it’s the far future, why worry now?

When eventually we’ve transitioned from IPv4 to IPv6 do you really think it will be EVER UPGRADED AGAIN?

Absolutely no. No, no no and no.

This is one prediction I’ll put down.

IPv6 will not be replaced within my lifetime.

It will be extended and expanded with new options and potentially other minor backwards-compatible (as with IPv4) changes, but fundamentally, current-day IPv6 will be the internet protocol even when we’re building outposts and colonies on the Moon and on Mars.

My point is that some portion of internet protocol choices made today are going to be around much, much later. IPv4 is 35 years old now, and not going anywhere in a hurry. IPv6 in 2100? Highly probable.

Challenge of the future

Internet use has gone through several phases, each with different assumptions, starting from early constantly connected and centrally operated (wired networks only, most users had only one or few “connection points”) to current intermittently connected model (assumptions of multiple location-fluid devices with variable connectivity).

All previous and current models have an implicit assumption of a small latency of less than a few seconds. There may be sometimes congestion leading to temporary latency increases, but more or less we’ve lived under the knowledge that a network packet can traverse to the farthest end of our planet within a fraction of a second. It will — it’s a fact of physics.

In a potential future with spread of human populations to different moons and planets this latency assumption will work only locally. That’s a world where service designers have to tackle yet another problem: how to provide good service when network latencies are minutes or hours.

Though, this is not a problem that should keep anyone awake at night.

Back to the kebab

I referred to scifi books and our hidden assumptions of the world. A good scifi writer will not get bogged down by thinking how today’s technology would not work in the future. Good story it makes not.

Technology and its improvement doesn’t work like that way. We can’t ignore laws of physics for the sake of a good story. Similarly there is a human imperative (scientific, commercial or out of curiosity) to make these things work.

I’ll be waiting for the first Twitter post from Mars base.