With so many flowers and so little time, life as a bee is not always as
sweet as honey.
Fortunately, many flowers help these hard-working insects by showing them
patterns that direct them to food sources. These patterns, however, are only
visible in the ultraviolet range, something that many insects can detect.
Humans, on the other hand, cannot see these signatures with the naked eye,
but instead must use special equipment.
To the delight of scientists, technological progress at JPL has produced a
high-performance chip that is capable of detecting very weak ultraviolet
signals. The new chip has increased sensitivity and robustness to the point
that it could be used to explore distant planets.
Yet searching for life on distant planets was not the original goal of the
scientists who developed this new technology. A simple demonstration of a
camera containing the new chip showed that the technology intended for
ultraviolet astronomy could also detect ultraviolet signatures of Black-eyed
Susan flowers, and gave researchers a glimpse of its potential for future
applications in astrobiology.
“We had this sophisticated ultraviolet chip technology that we had used, for
example, to image galaxies, and we wanted to set up a simple, indoor
demonstration. This simple demonstration of a new technology may lead to
exciting new applications in the search for life in the universe,” said Dr.
Shouleh Nikzad, researcher and head of the Nanoscience and Advanced Detector
Arrays Group at JPL. “What may appear as a lifeless environment in visible
light could come alive when seen in ultraviolet. This is an example of the
vital part that technology plays in all sciences.”
Using ultraviolet signatures to study the chemical composition and processes
in celestial objects is nothing new. Ever since humans figured out a way to
send spacecraft beyond Earth’s atmosphere, ultraviolet astronomy has given
scientists a new view.
But the key to flying this technology on a future spacecraft, in addition to
its high performance, is its exceptional durability. The reason for its
superior capacity to withstand the rigors of space flight is built into the
tough silicon lattice of the chip. The camera uses the same charge-coupled
device, or CCD chip, found in a regular camcorder, only modified to be
sensitive to ultraviolet light. The chip response to light changes
dramatically when a few layers of crystal silicon are added to the chip
surface with a procedure called delta doping. The key to seeing the
ultraviolet light is to control what happens to the electrons that are very
near the surface of the chip. By building this control into the silicon
crystal, JPL scientists created an extremely durable device.
“The camera is sturdy, just like a camcorder, and the chip technology is
very durable. I keep the chip in my desk drawer; take it on the field, store
it in the lab. It’s extremely robust,” Nikzad says as she handles the
lightweight camera.
Stability is what some other devices that see in the ultraviolet lack. Those
devices must work under tightly controlled conditions such as low
temperatures, or must be in a vacuum, or they lose their sensitivity to
ultraviolet photons almost immediately.
The chip’s ability to see in ultraviolet is stunning. Compared to a similar
imaging array on the Hubble Space Telescope, this chip is three to 10 times
more efficient in detecting ultraviolet light, depending on the region of
the spectrum.
Eventually, astronomers might make a beeline for this technology to help
them study the cosmos.
