NASA successfully tests first deep space Internet
19/11/2008 16:45
NASA has successfully tested the first deep space communications network
modeled on the Internet, the US space agency reported yesterday.
NASA
engineers used Disruption-Tolerant Networking software, or DTN, to transmit
dozens of images to and from a NASA science spacecraft located about 20 million
miles (32 million km) from Earth.
"This is the first step in creating a
totally new space communications capability, an interplanetary Internet," said
Adrian Hooke, team leader and manager of space-networking architecture,
technology and standards at NASA headquarters in Washington.
NASA and Vint
Cerf, a vice president at Google Inc., partnered 10 years ago to develop the
software protocol. The DTN sends information using a method that differs from
the Internet's Transmission-Control Protocol/Internet Protocol, or TCP/IP,
communications suite, which Cerf co-designed.
The Interplanetary Internet
must be robust to withstand delays, disruptions and disconnections in space.
Glitches can occur when a spacecraft moves behind a planet, or when solar storms
and long communications delays happen.
Unlike TCP/IP on Earth, 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 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 NASA's
DTN Experiment Operations Center. "With standardized DTN, this can all be done
automatically."
NASA began a month-long series of DTN demonstrations in
October. Data was transmitted using NASA's Deep Space Network in demonstrations
occurring twice a week. Engineers used 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, simulate Mars
landers, orbiters and ground mission-operations centers.
This is the first in
a series of planned demonstrations to qualify the technology for use on a
variety of upcoming space missions. A NASA-wide demonstration using new DTN
software loaded aboard the International Space Station is scheduled to begin
next summer in the next round of testing. NASA expects that in the next few
years, the Interplanetary Internet could enable many new types of space
missions.
Xinhua
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