[Mep-dev] Something to take a look at for a possible adaptation for Mep...?

[James French]

http://www.nasa.gov/home/hqnews/2008/nov/HQ_08-298_Deep_space_internet.txt
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RELEASE: 08-298

NASA SUCCESSFULLY TESTS FIRST DEEP SPACE INTERNET

PASADENA, Calif. -- NASA has successfully tested the first deep space 
communications network modeled on the Internet. 
Working as part of a NASA-wide team, engineers from NASA's Jet 
Propulsion Laboratory in Pasadena, Calif., used software called 
Disruption-Tolerant Networking, or DTN, to transmit dozens of space 
images to and from a NASA science spacecraft located about 20 million 
miles from Earth. 

"This is the first step in creating a totally new space communications 
capability, an interplanetary Internet," said Adrian Hooke, team lead 
and manager of space-networking architecture, technology and 
standards at NASA Headquarters in Washington. 

NASA and Vint Cerf, a vice president at Google Inc., in Mountain View, 
Calif., partnered 10 years ago to develop this software protocol. The 
DTN sends information using a method that differs from the normal 
Internet's Transmission-Control Protocol/Internet Protocol, or 
TCP/IP, communication suite, which Cerf co-designed. 

The Interplanetary Internet must be robust to withstand delays, 
disruptions and disconnections in space. Glitches can happen when a 
spacecraft moves behind a planet, or when solar storms and long 
communication delays occur. The delay in sending or receiving data 
from Mars takes between three-and-a-half to 20 minutes at the speed 
of light. 

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 store-and-forward method, similar to 
basketball players safely passing the ball to the player nearest the 
basket means information does not get lost when no immediate path to 
the destination exists. Eventually, the information is delivered to 
the end user. 

"In space today, an operations team must manually schedule each link 
and generate all the commands to specify which data to send, when to 
send it, and where to send it," said Leigh Torgerson, manager of the 
DTN Experiment Operations Center at JPL. "With standardized DTN, this 
can all be done automatically." 

Engineers began a month-long series of DTN demonstrations in October. 
Data were transmitted using NASA's Deep Space Network in 
demonstrations occurring twice a week. Engineers use NASA's Epoxi 
spacecraft as a Mars data-relay orbiter. Epoxi is on a mission to 
encounter Comet Hartley 2 in two years. There are 10 nodes on this 
early interplanetary network. One is the Epoxi spacecraft itself and 
the other nine, which are on the ground at JPL, simulate Mars 
landers, orbiters and ground mission-operations centers. 

This month-long experiment is the first in a series of planned 
demonstrations to qualify the technology for use on a variety of 
upcoming space missions. In the next round of testing, a NASA-wide 
demonstration using new DTN software loaded on board the 
International Space Station is scheduled to begin next summer. 

In the next few years, the Interplanetary Internet could enable many 
new types of space missions. Complex missions involving multiple 
landed, mobile and orbiting spacecraft will be far easier to support 
through the use of the Interplanetary Internet. It also could ensure 
reliable communications for astronauts on the surface of the moon. 

The Deep Impact Networking Experiment is sponsored by the Space 
Communications and Navigation Office in NASA's Space Operations 
Mission Directorate in Washington. NASA's Science Mission Directorate 
and Discovery Program in Washington provided experimental access to 
the Epoxi spacecraft. The Epoxi mission team provided critical 
support throughout development and operations.