Andrew Yee[_1_]
May 14th 08, 09:54 PM
Fraunhofer-Gesellschaft
Munchen, Germany
Contact:
Dipl.-Ing., Dipl.-Wirtsch.-Ing. Martin Traub
Phone: +49 241 8906-342
Fax: 0241/8906-121
Fraunhofer Institute for Laser Technology
ILT
Steinbachstr. 15
52074 Aachen
www.ilt.fraunhofer.de
13 May 2008
Satellite communications by laser
Satellites currently use radio waves to exchange data. Now the data rate has
been increased a hundredfold by using lasers instead of radio signals. Two
test satellites each carried a diode laser pump module developed with the
help of Fraunhofer researchers.
The data whizzed back and forth at the speed of light between German
satellite TerraSAR-X and US satellite NFIRE, covering more than 5000
kilometers in space without any errors. What was special about this space
test recently performed by Tesat-Spacecom was that the data was transmitted
by laser. The bandwidth achieved in the test was a hundred times greater
than during conventional communication by radio waves, enabling a data rate
equivalent to roughly 400 DVDs per hour. This could make it possible to
transmit large data packets between several satellites in the future, for
instance to send image data from Earth observation satellites to a ground
station. That has not been possible until now, as the bandwidth of radio
waves is not large enough. Another advantage of this new form of
communication is that lasers are easier to focus than radio waves, which
means that data transmissions can be directed more accurately.
The communication lasers on board the satellite are actuated by pump
modules, which were developed to a large extent by researchers at the
Fraunhofer Institute for Laser Technology ILT in Aachen on behalf of Tesat
GmbH & Co. KG as part of a program financed by the German Aerospace Center
(DLR).
"The modules have to withstand the vibrations and forces of acceleration on
board the satellites during the launch and must then survive the
inhospitable conditions in space -- such as extreme radiation and strong
temperature differences," says Martin Traub, who led the developments at the
ILT. "We therefore tested the pump modules under extreme conditions in
advance, subjecting them to temperatures of -35 C to 60 C, acceleration
forces 1300 times as strong as those of the Earth, and gamma rays."
The modules mustn't be too big or too heavy for use in space: Measuring 5 x
5 x 2 centimeters, they are barely larger than a matchbox, and weigh little
more than a bar of chocolate at 130 grams. "We achieved this minimal weight
by selecting the right materials and a sophisticated housing: Any material
that wasn't absolutely essential was milled away," says Traub. The major
challenge is that, despite the reduced weight, the heat generated by the
laser's several-watt output still has to be dissipated.
Munchen, Germany
Contact:
Dipl.-Ing., Dipl.-Wirtsch.-Ing. Martin Traub
Phone: +49 241 8906-342
Fax: 0241/8906-121
Fraunhofer Institute for Laser Technology
ILT
Steinbachstr. 15
52074 Aachen
www.ilt.fraunhofer.de
13 May 2008
Satellite communications by laser
Satellites currently use radio waves to exchange data. Now the data rate has
been increased a hundredfold by using lasers instead of radio signals. Two
test satellites each carried a diode laser pump module developed with the
help of Fraunhofer researchers.
The data whizzed back and forth at the speed of light between German
satellite TerraSAR-X and US satellite NFIRE, covering more than 5000
kilometers in space without any errors. What was special about this space
test recently performed by Tesat-Spacecom was that the data was transmitted
by laser. The bandwidth achieved in the test was a hundred times greater
than during conventional communication by radio waves, enabling a data rate
equivalent to roughly 400 DVDs per hour. This could make it possible to
transmit large data packets between several satellites in the future, for
instance to send image data from Earth observation satellites to a ground
station. That has not been possible until now, as the bandwidth of radio
waves is not large enough. Another advantage of this new form of
communication is that lasers are easier to focus than radio waves, which
means that data transmissions can be directed more accurately.
The communication lasers on board the satellite are actuated by pump
modules, which were developed to a large extent by researchers at the
Fraunhofer Institute for Laser Technology ILT in Aachen on behalf of Tesat
GmbH & Co. KG as part of a program financed by the German Aerospace Center
(DLR).
"The modules have to withstand the vibrations and forces of acceleration on
board the satellites during the launch and must then survive the
inhospitable conditions in space -- such as extreme radiation and strong
temperature differences," says Martin Traub, who led the developments at the
ILT. "We therefore tested the pump modules under extreme conditions in
advance, subjecting them to temperatures of -35 C to 60 C, acceleration
forces 1300 times as strong as those of the Earth, and gamma rays."
The modules mustn't be too big or too heavy for use in space: Measuring 5 x
5 x 2 centimeters, they are barely larger than a matchbox, and weigh little
more than a bar of chocolate at 130 grams. "We achieved this minimal weight
by selecting the right materials and a sophisticated housing: Any material
that wasn't absolutely essential was milled away," says Traub. The major
challenge is that, despite the reduced weight, the heat generated by the
laser's several-watt output still has to be dissipated.