computerwriter.com

Surfing the Interplanetary Internet

Toronto Star Fast Forward column for June 7, 2001

Copyright ©, Myles White, 2001 All rights reserved.

What will they think of next? Or, just how will you get your e-mail while on Mars or in a spacecraft somewhere between here and the moons of Jupiter? 

This may not be one of your dire concerns this month, but you can take comfort in knowing that when it does become a question, there is a group of industrious folk who are already at work on the answer. 

That's what I discovered last week when one of my more industrious contacts sent me the address of the "Interplanetary Internet (IPN): Architectural Definition." 

It's a 58-page document written by several authors from MCI Worldcom, NASA's Jet Propulsion Laboratory, the MITRE Corporation, Global Science and Technology, and SPARTA Inc.. The effort is led by Dr. Vinton G. Cerf, MCI Worldcom's senior vice president, data architecture, under the auspices of the Internet Engineering Task Force (IETF - www.ietf.org). The IETF is open to anyone and describes itself as "a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet."

Are they kidding? If you want to read the full document (and I hope you will at http://www.ietf.org/internet-drafts/draft-irtf-ipnrg-arch-00.txt), you may be struck as I was at the quality of the work and the writing. In fact, the document is laced with so much gentle humour that at first I wondered if it wasn't simply an elaborately creative hoax committed by someone with a great imagination and too much time on his or her hands. 

So, I checked. 

All of the authors are real people who really do work for the organizations listed at the end of the paper. I contacted several of them - not only to get permission to quote from the document, but also to ask straight out whether this was serious or someone just having a lot of fun. 

Either way, I figured it was well worth sharing with you - and the fact that these people are serious makes it that much better. 

Their purpose? Nothing less than an attempt to describe the Interplanetary Internet: "a communication system to provide Internet-like services across interplanetary distances in support of deep space exploration."

Some highlights... 

Okay, I know you have a busy life and may not get the time to visit the site, so here are some highlights, beginning with what one of the authors, Scott C. Burleigh of the Pasadena, CA-based Jet Propulsion Laboratory, calls the Desiderata of Interplanetary Internetworking (quoted with permission).

Go thoughtfully in the knowledge that all interplanetary communication derives from the modulation of radiated energy, and sometimes a planet will be between the source and the destination.

Therefore rely not on end-to-end connectivity at any time, for the universe does not work that way.

Neither rely on ample bandwidth, for power is scarce out there and the bit error rates are high. Know too that signal strength drops off by the square of the distance, and there is a lot of distance.

Consider the preciousness of interplanetary communication links, and restrict access to them with all your heart. Protect also the confidentiality of application data or risk losing your customers.

Remember always that launch mass costs money. Think not, then, that you may require all the universe to adopt at once the newest technologies. Be backward compatible.

Never confuse patience with inaction. By waiting for acknowledgment to one message before sending the next, you squander tracking pass time that will never come to you again in this life. Send as much as you can, as early as you can, and meanwhile confidently await responses for as long as they may take to find their way to you.

Therefore be at peace with physics, and expect not to manage the network in closed control loops -- neither in the limiting of congestion nor in the negotiation of connection parameters nor even in on-demand access to transmission bands. Each node must make its own operating choices in its own understanding, for all the others are too far away to ask. Truly the solar system is a large place and each one of us is on his or her own. Deal with it.

More Points to Ponder... 

The authors make at least one major presumption: "...that the exploration of space will eventually lead to the need for communication among planets, satellites, asteroids, robotic spacecraft and crewed vehicles." Their goal is, "advocating the development of a stable interplanetary backbone network." 

In essence, they see the formation of a "network of internets" with multiple gateways that may be located on orbiting bodies (planets, moons, asteroids, satellites), and/or free-flying spacecraft. The main problems are routing, standardizing addressing conventions, very long distances with speeds limited by the speed of light, security, and what happens when things (like the planet of that moon, or the sun), get in the way of a transmitted signal. 

The researchers have already pretty much figured out that interactive, two-way communication isn't going to be a successful model because of the distances involved. Instead, they're recommending the electronic mail model, for several reasons: "First, there is no expectation of continuous or instantaneous connectivity. Second, electronic mail embodies the concept of indirection as a means of providing store-and-forward traversal of different, sometimes-disconnected networks. Finally, the electronic mail concept is generally considered to be a non- interactive communications mechanism, potentially well suited to long delay environments." 

This method has drawbacks, such as being unsuitable for communicating with robotic spacecraft and carrying process information, but the authors have some ideas along those lines, too.

You've got mail... 

If you ever do come to a point in your life where you're planning to vacation on Mars or somewhere even more remote, your e-mail address would end in mars.sol or ganymede.sol (for example, buck.rogers@saturn.sol). The actual example of the address of one of the gateways given in the study is ipngw1.jpl.nasa.gov, earth.sol. 

Far fetched? Perhaps, but according to the paper, by 2010 there could be as many as seven communications and navigation satellites in LMO (low Mars orbit) to support NASA's Mars exploration program set to begin after 2003. That may as well be tomorrow. 

And that's not all. Have a gander at this: "We expect that space will eventually be commercialized - not only for communication services, but also for mining the asteroids, for the operation of space-based hotels, for manufacturing and medical treatments, and for general tourism. While such developments may still lie decades in the future, the potential investment and benefits can be appreciated as we contemplate the explosion of new markets associated with the commercialization of the Internet that began only ten years ago, in 1990. We will therefore architect the Interplanetary Internet in anticipation of possibly rapid commercialization."

But, no Internet Relay Chat... 

If you're expecting to use the Interplanetary Internet to shmooze with your friends after school, you may be disappointed as the authors point out, "The distances between the planets are, well, astronomical. For example, the round-trip propagation delays - at the speed of light - between Earth and Mars range from about 8 minutes to over 40 minutes. This makes 'chatty' protocols like TCP relatively unattractive because of their heavy dependence on near real-time exchanges between the communicating parties." 

Darn, eh? 

There may also be unusual interruptions to interplanetary Internet communications not encountered in our Earth-bound Internet. Receivers for ground-based installations located on planetary surfaces, for example, may not be available at all times. You see, planets and other astronomical bodies rotate. Sometimes they tumble. Smaller bodies, such as asteroids, may not be in the immediate neighbourhood if, for example, they're at their orbit's furthest point out from the sun. 

There is also, of course, the small matter of how you're going to get repeater stations in place. Mass costs money to lift out of gravity wells, so they need to be small. And reliable. You think the amount of time you spend on hold on Earth while waiting for tech support isn't fun? Exactly how were you planning to get one of those repeaters repaired? Have you ever seen the cartoon of the chubby guys in various poses of extreme mirth, asking the rhetorical question, "You want it when???" 

And how were you planning to power those stations? Think about it. 

Oh, and how were we planning to pay for all this service? See the musings in section 3.4, beginning on page 20, titled, "Bandwidth Allocation via Market Mechanisms: 'Starbucks'" (I did say there was some gentle humour in this thing). I have this vision of an independent asteroid mining craft, or interplanetary trader (shades of Han Solo), making part of its living by carrying an IPN gateway/repeater and charging for message traffic.

Security 

There is much more to the document, but I'm going to draw the curtain on it with one more quote, and a little musing, about security of the Interplanetary Internet (IPN): "We do not have a detailed list of security requirements for the Interplanetary Internet, primarily because there currently aren't any "users" of the IPN and few, if any, of the potential users have given enough thought to security to commit to a set of security "requirements". However, we know that the Interplanetary Internet's bandwidth resources will be precious. We can also safely assume that the IPN will be a prized hacker's target (at least from Earth). We can also envision that there will be precious, private data flowing across the IPN. As a result, we assume that various security mechanisms and services will be required to provide protection for the bundles traversing the IPN and for the IPN infrastructure itself." 

Interplanetary hackers? Yoiks! No, not once do the authors speculate on using the IPN to communicate with aliens (they left that sort of nonsense for "Independence Day"). 

I don't often quote from my own books, but I suspect that the following bit of silliness is apt here, taken from the section on modems: 

Ahh, don't you just love being alive in the here and now?

Back to top