Donna Drelick							April  3, 1996
Goddard Space Flight Center, Greenbelt, Md. 
(Phone:  301/286-7995)

RELEASE: 96- 016


GODDARD DEVELOPMENT NAMED INVENTION OF THE YEAR


	NASA has selected a technique for encoding and compressing digital data as the winner 
of the Government Invention of the Year Award for 1995.  The "Method For Coding Low 
Entropy Data" a creation of Dr. Pen-Shu Yeh of the NASA Goddard Space Flight Center in 
Greenbelt, Md.,  has been selected by the NASA Office of General Counsel for the honor. 

	As scientific instruments grow increasingly more precise and sophisticated, the amount 
of data generated by them also increases. The data compression technology reduces redundancy in 
the data representation while guaranteeing its full and accurate reconstruction. Using data 
compression technology on a spacecraft reduces the requirements for onboard memory and 
ground station contact time, which often translates into saving millions of dollars for a single 
space mission.
	
	The new coding method also will benefit industry, particularly the medical community. 
Studies at Goddard indicate the new coding method offers superior performance for medical 
imaging data systems such as magnetic resonance, ultrasound and nuclear medicine. "The needs 
of space imaging systems and medical imaging systems are similar in many ways," said Yeh.  
"Doctors, like scientists, always demand full fidelity of their data."  

	"This encoding method for improving digital data is just one part of the advanced data 
compression technology developed at Goddard.  Several years ago, we realized the need to initiate 
this technology development because our science community has demanded more and more data 
from their instruments," said Dr. Yeh.  "The Method for Coding Low Entropy Data extends 
performance beyond the bounds set by traditionals codes, making this technology more adaptive 
to various kinds of instruments and applications."
	
	 Implementing data compression on spacecraft requires a technique that adapts easily to 
changes in data while using little power and memory.  Yeh and her colleagues at Goddard found 
that the Rice algorithm, developed at the Jet Propulsion Laboratory in the early 1970s, adapted to 
their needs for lossless data compression.   Yeh  showed that the Rice algorithm was actually a 

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derivative of a widely accepted code, and extended it to increase the efficiency of her method. The 
extended Rice algorithm has since been designed in silicon circuits suitable for space flights.  
These circuits have been integrated in several space missions, including the Small Satellite 
Technology Initiative Lewis spacecraft, and for software onboard the Mars Observer and the 
Submillimeter Wave Astronomy Satellite. 

	Yeh's data compression technology is under consideration to become an international 
standard for space data systems.  "Dr. Yeh has extended a method for data compression which will 
benefit NASA and industry as well," said Warner Miller, Panel Chairman of the Consultative 
Committee for Space Data Systems. "The data compression method already has been endorsed by 
industry and universities."

	Dr. Yeh will be honored for her advancements in encoding digital data at a NASA 
Headquarters ceremony in Washington, DC.
	
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