From: Larry Klaes (lklaes@bbn.com)
Date: Fri Nov 05 1999 - 14:59:47 MST
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From: "Cecchini, Ron" <Ron.Cecchini@GD-CS.COM>
Subject: Sagan: FW: Interplanetary Internet
A web that's out of this world NASA and network gurus are working together
to extend the Internet to other worlds in the next five years.
http://www.msnbc.com/modules/exports/ct_infobeat.asp?/news/325201.asp
By Alan Boyle MSNBC
Nov. 5 - NASA and network gurus are working together to extend the
Internet to other worlds in the next few years. But there are some limits
that not even the World Wide Web can route around, such as the speed of
light. So the builders of the Interplanetary Internet are going back to
the basics, retooling protocols for future communications with Mars and
beyond.
FOR THE PAST year or so, the vision of the Interplanetary Internet has
been championed by such visionaries as Vinton Cerf, one of the Internet's
founding fathers.
"By 2040, we hope a stable interplanetary backbone can be established
between the planets," Cerf said last month at a White House presentation.
Meanwhile, behind the scenes, engineers are adapting Internet architecture
to space communications, with funding from NASA as well as the Defense
Advanced Research Projects Agency's Next Generation Internet project.
Why do it? It's not just so Mars colonists can hear a cheery "you've got
mail" from their computers in 2040 - although space experts say a sense of
connectedness could be important in combating the isolation of
long-duration missions. At least in the short term, the biggest users of
the Interplanetary Net will not be humans, but robots.
In fact, Adrian Hooke of NASA's Jet Propulsion Laboratory argues that the
infant Interplanetary Internet is already in action, just as ARPANET
prefigured what we now know as the Internet. More than 100 space missions
have signed up to use protocols standardized by the international
Consultative Committee for Space Data Systems.
Internet pioneer Vinton Cerf discusses the global network's past and its
interplanetary future on CNBC.
The current studies are defining "how we need to grow and expand these
underpinnings over the next 20-odd years, i.e., what new protocols and
communications capabilities we will need," he said in an e-mail exchange.
THE ROAD AHEAD
Standardization is just one of the driving forces behind the
Interplanetary Net. NASA is moving toward "faster, cheaper, better" space
probes - and more of them. If off-the-shelf technologies can be adapted to
those robotic missions, so much the better.
"We steal what we can, bend when we need to, and as a last resort start
over and design something from scratch. But that's so expensive that it's
something we don't want to do," said Hooke, who is manager of NASA's space
mission operations standardization program. Lessons gained from the
growth of the Internet - and particularly wireless networking - can keep
NASA from having to reinvent the wheel as space missions proliferate,
Hooke explained.
PROBLEMS AND SOLUTIONS But there's a big difference between using the
Internet on Earth and connecting with Mars - a minimum of 34.6 million
miles of difference, to be specific. Even at the speed of light, it takes
radio signals three minutes to travel that far. And since the distance
between Mars and Earth is constantly changing, the travel time could be as
long as 20 minutes. Those kinds of time delays would wreak havoc on a
classical Internet, said Bob Durst, an engineer at Mitre Corp. who is
working on the architecture for the Interplanetary Net, also known as the
IPN.
"The Internet suite is pretty heavily based on the notion of
interactivity," he explained. Communicating computers trade signals back
and forth on a scale of milliseconds, checking to make sure packets are
received intact and re-sending them if necessary.
"That's real handy for us when you're in a terrestrial environment, but
when you get into round-trip times of 10 minutes, that just doesn't work,"
Durst said. "You can't take delays much past five minutes or so." To cope
with this cosmic speed limit, network architects envision a "network of
Internets," linked together with new protocols. They draw comparisons to
the Pony Express and United Parcel Service. "We need to distill out all
the interactivity and bundle up all the information into a single
transaction that has everything needed to process the information, either
interactively or noninteractively, on the other side," Durst said.
Each planet would have a gateway to manage data traffic over the
interplanetary backbone. For example, NASA's Deep Space Network, which
NASA uses now to communicate with distant probes like Galileo, could be
the gateway for Earth. "It's like dropping a package at UPS," Durst said.
"The notion is that you submit your data in the form of a bundle to a
gateway that says, 'I'm going to accept your data ... here's a claim
ticket, and I'll let you know when it's there ... if you want to be
notified.'"
To use another comparison, the Interplanetary Internet would be like
e-mail: Mission controllers would entrust their transmissions to the Net
gateway, with a "soft expectation" that the bundle of data will eventually
get to the right destination.
Some other twists will be required: Bandwidth and memory are extremely
limited when you go beyond Earth, so engineers want to avoid having to
keep an updated Internet address book on every spacecraft. Instead, data
traffic would be routed to the proper gateway (say, "earth.sol" or
"mars.sol"). The gateway would then figure out how to get it to the exact
address specified by the sender.
Also, since celestial objects are constantly moving in relation to each
other, the communication paths between gateways will have to stretch and
turn like a cat's cradle between a child's moving fingers. That's where
the experience of wireless telecom providers like Iridium and Teledesic
will come in handy, Hooke said. Security is another big concern: What's
to stop someone from hacking into Mars' interplanetary gateway?
"We're making assumptions that because the bandwidth is still going to be
precious ... access to the Interplanetary Internet is something that
needsto be mediated," replied Howard Weiss, an engineer at Sparta Corp.
That means not everyone will be allowed to send messages to
rover@pathfinder.mars.sol, at least in the short term.
NASA's Deep Space Network will still be limited, although one company is
working on a secure Web-based system for controlling spacecraft from
laptop computers. Weiss said the lack of interactivity over so-called
"bundle space" means that the latest crypto protocols, based on public-key
exchange, can't be used. "We're going to have to go back to the good old
golden days ... and use things like pre-shared keys," he said. Other
time-honored protocols such as BitNet and UUCP - which provided the
foundation for newsgroups - also may be adapted, said Eric Travis, an
engineer at Global Science and Technology.
WHAT THE NET WILL DO
When it comes to putting these networking theories in practice, all eyes
turn to Mars. "Think of it as the first stop on the Interplanetary
Internet," said Chad Edwards, manager of the Mars Network Project Office
at the Jet Propulsion Laboratory.
NASA's Hooke said the Mars lander and orbiter, both due to be launched in
2001, would communicate with each other using their own style of "Internet
service," but Edwards' project would build a real telecom constellation
around the Red Planet. The telecom satellites could hitch rides on Mars
missions every two years, beginning in 2003.
"As his Mars Network constellation builds up, we will progressively add
more IPN-derived standard protocols to his communications suite," Hooke
said. "We will also try to start infusing regular terrestrial Internet
capabilities into the Mars rover and lander missions as we get the chance,
probably starting about 2005."
The Mars Network could greatly increase the data flow back to Earth,
Edwards said. Back in 1997, Mars Pathfinder could only send 30 megabits of
data per day back to Earth, which averages out to 300 bits per second, he
said. In contrast, typical modems on personal computers transmit data at
rates up to 56,000 bits per second.
The Mars Network could relay data at more than 30 times Pathfinder's rate,
or an average of 11,000 bits per second. That is enough to send back a
full-resolution, 360-degree panorama of the Red Planet every day. By
2007, Edwards said, there could be a "permanent robotic presence" on Mars,
pumping data back and forth using Internet protocols, and communicating
with Earth via a central gateway. He even envisions a relay satellite
flying 10,625 miles (17,000kilometers) above Mars, in an orbit stationary
with respect to the Red Planet. Such a satellite could transmit 1 megabit
of data per second, enoughfor a continuous video feed via the Mars
Channel. That kind of bandwidth also could be used to send back a
detailedvirtual-reality representation of the Martian surface - in a
sense, allowing scientists and sightseers to study Mars without leaving
Earth.
"The public may just want to go for a walk on Mars. ... And with a gigabit
of data, I can bring a rock from Mars to here, plop it in front of a field
geologist and let him look at it," Edwards said. Although this may sound
like blue-sky thinking, it's not too early to lay the technical foundation
for the reality yet to be, Hooke said. And he's hoping that the next
generation will help out with what he views as one of this world's most
intriguing research projects.
"There are some great Ph.D.s to be mined here," he said. "This is cool
technology." Hooke already has written the International Organization for
Standardization in Geneva to ask what would be required to set up
"earth.sol" and "moon.sol" superdomains. "It provoked an interesting
exchange with those guys," he said. "They said I essentially had to get
the sovereign representatives of the moon and the earth to write them a
letter."
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