Interplanetor Internet, How it Works?

[SreeKanth]

We have been successful in conducting a first test of a deep space communications network modeled on the internet with the help of Interplanetary Internet.

"This is the first step in creating a totally new space communications capability, an interplanetary internet," Adrian Hooke, NASA's manager of space-networking architecture, technology and standards, said in a statement.

The key to the "Interplanetary Internet" is technology that doesn't lose the content of a transmission if something cuts off a signal.

Traveling at the speed of light, a signal can take anywhere from 3 1/2 to 20 minutes to reach Mars, depending on how close Mars and Earth are.

All kinds of interference can crop up over that time and distance - solar flares, the harsh radiation in space, or the obstacle created when a spacecraft swings behind a planet.

"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."

After 10 years as partners, NASA and a Google vice-president named Vint Cerf have got around this with something called disruption-tolerant networking (DTN). If a signal is blocked, the server can sense this, can save the content and send it on when the way is clear.

This goes beyond sending signals. Let suppose If a Mars rover finds something interesting, "it could communicate to Odyssey (a NASA probe in orbit): 'Gee, I found this rock and I don't know what it is; I need MRO (another NASA orbiter) with its very powerful cameras to take a picture of this.' That's more advanced than what we have done to date."

[SreeKanth]

Disruption-Tolerant Networking (DTN) software to transmit dozens of space images from earth station to spacecraft some 32.4 million km from Earth. DTN sends information using a method that differs from the normal Internet's Transmission-Control Protocol/Internet Protocol, or TCP/IP, communication suite.

Unlike TCP/IP, DTN does not assume a continuous end-to-end connection, noting that glitches can happen when a spacecraft moves behind a planet, or when solar storms and long communication delays occur. It said the delay, for example, in sending or receiving data from Mars takes between three-and-a-half minutes and 20 minutes at the speed of light.

If a destination path cannot be found, data packets are not discarded but kept by each network node until it can communicate safely with another node.

"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 the Jet Propulsion Laboratory in Pasadena, California.

It is said that an "Interplanetary Internet" could enable many new types of space missions including complex flights involving multiple spacecraft and ensure reliable communications for astronauts on the moon.