[extropy-chat] FWD (UFO UpDate) A Better Transmission System For Deep-Space

[Terry W. Colvin]

Source: Eureka Alert.Org - Washington, DC, USA

        The American Science Serving Society

http://tinyurl.com/7t26l

Public release date: 24-Oct-2005

Contact: Harvey Leifert
hleifert at agu.org
202-777-7507

American Geophysical Union

Creating A Better Transmission System For Deep-Space Applications

Recent advances in wireless computing technology could improve 
deep-space missions like asteroid research and remote spacecraft 
operations by changing the way signals are sent from Earth. A 
new method designed to effectively deliver commands and 
instructions using hundreds of millions of tiny transmitters 
linked together could also free the giant satellite dishes 
currently used to send and receive the long-range information 
for other applications. A research paper describing the scheme 
for relatively simple high-power transmitters will be published 
in the October issue of Radio Science, a journal of the American 
Geophysical Union.

The technique is based on a principle known as a phased array, a 
method to align a number of mini-transmitters alongside one 
another and direct their combined beam into the sky. Such a 
system has previously been used for military radar technology, 
but has only recently become cost effective for civilian use 
because of improvements in consumer computing technology, 
according to the paper authored by Louis Scheffer at Cadence 
Design Systems. He indicates that the advantages from so many 
individual transmitters, using designs similar to cell phone 
technology, could include improved reliability and efficiency 
over currently used systems while reducing the transmission 
costs associated with the mammoth satellite dishes. Overall, he 
suggests that the net result could be significantly lowered 
costs for space communications, more data from science 
spacecraft, and an increase in planetary and deep-space research 
that requires remote signals.

Currently, planetary radars and distant spacecraft 
communications need transmitters with extremely high power, 
which has been accomplished by combining a strong microwave 
source with a large reflective antenna. This is now done with 
giant satellite dishes mechanically steered to a point in the 
sky. NASA's Goldstone radar, for example, the agency's 
sensitive, deep-space analysis radar, uses a 500 kilowatt 
transmitter and a 70-meter [230-foot] reflector for tracking 
asteroids that may collide with Earth. The large antenna is 
focused on only a small point in space at a time, and must be 
adjusted--and occasionally shut down--due to changing weather 
conditions. In addition, Scheffer points out that while almost 
all of the world's largest antennas are used to both send and 
receive, the powerful transmissions severely hinder their 
ability to detect faint signals from space.

"Imagine trying to listen for a whisper while you are shouting," 
Scheffer said. "Also, these antennas are incredibly busy, so 
only a small fraction of the possible science gets done."

He proposes a large, flat array of low-power transmitters 
printed on a number of circuit boards and attached to an 
unmoving infrastructure on the ground, controlled by computers, 
which can deliver an enormously powerful beam in any direction, 
or even multiple directions at once. The paper outlines the 
requirements of a new system that would offer enhanced 
reliability, since a single failure would not affect the overall 
signal, and improved maintenance costs because of its lack of 
moving parts and weather resistance. The system Scheffer 
proposes is designed solely to transmit, as is needed for 
planetary radar and spacecraft control. The transmitters would 
also allow existing antennas to operate in a more efficient 
receive-only mode.

If available mass-production manufacturing techniques used for 
electronics can be assumed for the centimeter-sized chips, a 
transmitter similar to the Goldstone radar could be constructed 
for nearly one-quarter the cost, Scheffer reports. He notes that 
the significant amount of research and work done in the field of 
phased array radars renders the development of such a system 
plausible, though no previous applications to earth and space 
sciences have been studied. He further suggests that as computer 
chip technology continues to improve, additional wavelength and 
smaller antennas are possible to further improve the systems.

The first possible application would likely be for spacecraft 
command and asteroid research to observe objects that may pose a 
threat to Earth. A more speculative application, according to 
Scheffer, is that sending powerful signals to distant stars is 
easier and cheaper than previously thought. This dramatically 
reduces the cost of potential interstellar transmissions, such 
as searched for by SETI.


[Thanks to Stuart Miller of http://www.uforeview.net for the lead]



-- 
"Only a zit on the wart on the heinie of progress." Copyright 1992, Frank Rice


Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1 at mindspring.com >
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