[amsat-bb] NASA's DTN & SDR
Alan Sieg WB5RMG
wb5rmg at somenet.net
Mon Mar 16 16:02:49 PDT 2009
Someone sent me a copy of this article last week, and I didn't get around
to posting it here for the AMSAT-BB readers. This concept started out
with a name "Delay Tolerant Networking" and was being designed to accomodate
the need for command queuing under long delay situations like Mars orbit.
Even Lunar presents more delay than a traditional tcp/ip architecture is
optimized for... Factors other than delay contribute to overal "Disruption"
so it made sense for the name to be more inclusive. Some of the folks
working on this concept are in my building, and I hope to be doing some
tinkering with this in my lab before too long.
At least they didn't have to change the acronym.
I'm sure Lowell won't mind if I repost this without the funky
web-formatting that tries to tag along sometimes...
Here is the link to the original article :
COMMUNICATIONS / NETWORKS
NASA plans improved Internet in space
* By Sean Gallagher
* Mar 09, 2009
NASAs Deep Space Network is on the way toward becoming a true Internet in
space, thanks to the agencys research and investment in software-defined
radios (SDRs). Also, the agency is preparing an SDR test module for the
International Space Station that will be capable of connecting the station
with an uplink of 100 megabits per second.
Pat Elben, the chairman of NASAs software defined radio architecture and
technology team (SAT) at NASAs Space Communications and Navigation
directorate, told attendees at the IDGAs Software Radio Summit that the
agency is setting up a new test platform. The platform, named the
Communication Navigation and Networking Reconfigurable Testbed (CoNNeCT) will
help NASA test waveforms based on the agency's Space Telecommunications Radio
System (STRS), NASA's own standard for space-rated software-defined radio
CoNNeCT will be added to the International Space Station in 2011, and
demonstrate communications between the space station and the Tracking and Data
Relay Satellite constellation that makes up the backbone of NASAs network
with three radio systems -- the Electra radio that flew aboard MRO, the
General Dynamics Starlight radio, and the Orion radio -- the system being
designed for NASA's follow-on to the space shuttle.
NASA developed its own standard because of the demanding requirements of
space, where reprogramming a radio often has to be done remotely while the
radio is on a spacecraft traveling through the solar system.
That was the case, Elben said, when the Mars Reconnaissance Orbiter (MRO) was
launched. Technicians discovered the Electra radio aboard MRO, a
software-defined radio that was to act as the communications link to the two
Mars rovers on the surface, was getting interfered with by something else on
the spacecraft just before launch. NASA was able to launch the MRO and create
a software patch and upload it to the Electra radios aboard it while the
spacecraft was en route to Mars, he said.
Some observers have expressed concerns that suppliers might be reluctant to
write software to yet another SDR architecture the Defense Departments
Joint Tactical Radio System uses the Software Communications Architecture,
which has been adopted by the Software Defined Radio Forum along with its own
SW Radio standard. Elben said NASA plans on buying more than 1,000 STRS-based
radios between now and 2025, but the price of these radios between $1
million and $5 million makes STRS radios a potentially $1 billion market for
Although NASA has deployed software-defined radios for years, starting with
the Blackjack global positioning system receiver on spacecraft in 2000, STRS
will be part of the basis of an ambitious revamp of the agencys Deep Space
Network. The re-engineering will be based on SDRs and on high-bandwidth
optical links, Elben said. It will also entail the use of software-defined
systems and a move to less-expensive arrays of dish antennas instead of the
old larger dishes. The new approaches are expected to make the network more
automated and less expensive.
In the 1960s when NASA first created what became its Deep Space Network,
there was no grand vision, Elben said. NASAs goal for 2024 is a highly
integrated, IP-based disruption resistant network.
Last November, NASA successfully tested Disruption Tolerant Networking (DTN),
an Internet Protocol-based network using store-and-forward technology to
ensure that packets of data would not be lost when being passed through the
Deep Space Network. The agency will begin testing DTN aboard the International
Space Station this summer.
<- Licensed in 1976, WB5RMG = Alan Sieg * AMSAT#20554 ->
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