A team from TRW and NASA's Jet Propulsion Laboratory has produced video pictures from the world's first infrared imaging system to employ superconducting digital electronics.
The digital data were displayed on a standard TV monitor, where
engineers observed moving images of a human hand and simulated
spacecraft.
"This demonstration marks an important step toward better and
cheaper satellite-based infrared imaging for commercial, space
science and military missions," said Larry Eaton, TRW's
superconducting electronics program manager.
"The improved imaging capability will help sensors track and
image very faint or very cool objects in space, such as distant
stars or incoming ballistic missiles in their midcourse phase.
"Superconducting circuits greatly boost the speed of imaging
systems, which operate at temperatures near absolute zero (10
degrees Kelvin or -273 degrees Celsius), while dramatically cutting
overall size, complexity, power consumption and cost — all key
advantages for any satellite."
At the heart of the breakthrough is a tiny, TRW-developed
superconducting chip that performs high-speed digital signal
processing like a conventional silicon integrated circuit, but
consumes 1,000 times less electrical power. The superconductor chip
is also hundreds of times smaller and lighter.
Superconductivity is a phenomenon exhibited by certain materials
in which all resistance to electrical current disappears when the
material is cooled to a very low temperature. In theory, a current
introduced under superconducting conditions will flow forever without
experiencing any electrical losses.
Funded jointly by the Ballistic Missile Defense Organization
and NASA, the imaging system was integrated by TRW and NASA at
JPL's facilities in Pasadena, Calif. It includes the TRW-built
superconducting analog-to-digital converter (ADC) chip coupled to
the sensor, a Boeing-supplied focal plane array cooled to about 10
degrees above absolute zero.
No-Heat Chip Allows Integration With Focal Plane Array
The project represents the first time that a superconducting chip
has been integrated with a focal plane array. "TRW's ADC circuit
itself uses less than 40 microwatts, while the full chip consumes
barely one-third of a milliwatt — about 1,000 times less power than
a comparable silicon circuit — hence, it generates almost no heat,"
Eaton said.
"As a result, we were able to put the chip in the same compartment
as the infrared sensors, which must be kept at about 10 degrees above
absolute zero." The test bed illustrates graphically how the
insertion of small, low-power superconducting electronics can
simplify the design and construction of focal plane array systems,
Eaton added.
Placing the ADC chip next to the focal plane sensor leads to major
improvements in the performance of space-based imaging systems. "By
converting the incoming signals to digital form at the focal plane,
we eliminated the noise-susceptible analog transmission lines
previously needed to carry the signals away from the focal plane,"
Eaton said.
"The removal of this potential noise source helps preserve the
quality of the original signal, which will allow us to produce images
of fainter objects at greater distances."
TRW's ADC chip, whose key electronic elements are made from
niobium nitride, was designed, fabricated and tested at the company's
superconducting electronics foundry in Redondo Beach, the only
facility of its kind in the world. In production quantities, the
chip is expected to operate 10 times faster and consume about 1,000
times less power than a comparable silicon-based ADC chip.
