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ZL2VAL > TECHNO 13.02.04 12:25l 101 Lines 3991 Bytes #999 (0) @ WW
BID : A30520ZL2VAL
Read: GUEST OE7FMI
Subj: Interplanetary Internet
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Sent: 040213/1050Z @:ZL2AB.#46.NZL.OC #:35745 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : TECHNO@WW
Interplanetary International Internet Launched
By Robert Roy Britt
Senior Science Writer
posted: 01:25 pm ET
12 February 2002
In a sign of cosmic communications to come, last week mission
controllers sent signals to a Mars-orbiting European spacecraft, which
relayed the instructions to NASA's Spirit rover on the surface, and a
signal was returned to Earth back along the same path.
It was the initial transmission across what could be called the
first-generation Interplanetary International Internet.
"We have an international interplanetary communications network
established at Mars," said Jennifer Trosper, Spirit mission manager at
NASA's Jet Propulsion Laboratory (JPL).
Pioneering demonstration
NASA has used its own orbiters to communicate with surface probes at
Mars before, but the Feb. 6 "pioneering demonstration," as officials
called it, was the first to involve multiple nations.
The Mars Express orbiter, which relayed the signals, is a project of the
15-nation European Space Agency (ESA). It reached Mars late last month
and has been returning photographs of the planet from above and recently
added to the case for ancient rivers on Mars.
"This is the first time we have had an in-orbit communication between
ESA and NASA spacecraft, and also the first working international
communications network around another planet," said Rudolf Schmidt,
ESA's project manager for Mars Express.
The planned demonstration is part of an ongoing effort between the two
agencies to cooperate, including using joint communication assets,
according to a NASA statement released today.
Someday, e-mail
Today's solar system network is crude and limited to what some envision.
Other plans are underway for eventually creating a true Interplanetary
Internet that is more like the one you're using to read this story.
The IPN, as it's been dubbed, might one day serve as a backbone
connecting hubs at various planets to spaceships. If built -- NASA is
among the institutions researching the idea -- it could overcome a
drawback to the current system: Spacecraft can only communicate with
Earth via line-of-sight. That means a craft on the far side of Mars
can't send signals to Earth.
The IPN would behave more like e-mail. Data could be stored at any of
various hubs around the solar system and transmitted to their
destination via the best path at the moment.
The capability will be more important in the future when more
spacecraft, with more complex tasks, reach the red planet, perhaps
including human missions.
Great news
The terrestrial portion of the test communication last week was routed
from JPL in Pasadena, Calif, to ESA's European Space Operations Center
in Darmstadt, Germany. Spirit returned basic telemetry data in the trial
effort.
"This is excellent news," said JPL's Richard Horttor, project manager
for NASA's role in Mars Express. "The communication sessions between
Mars Express and Spirit were pristine. Not a single bit of data was
missing or added, and there were no duplications."
Spirit and its twin rover, Opportunity, normally get communications
support from NASA's Mars Odyssey and Mars Global Surveyor orbiters. Each
rover can also communicate directly with Earth. All these signals
originating on or near Mars are received by NASA's Deep Space Network of
three radio receivers, in California, Spain and Australia.
Radio signals take several minutes, travelling at the speed of light, to
traverse the void between the two planets. Most of the communications
are made in what engineers call the X-band, high-frequency waves that
are much higher than those received by an FM radio.
=========================
73 de Alan, (Sysop ZL2AB).
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Points to ponder
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