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02/28/2002
Twisted Minds and Mirrors
This morning I made a special effort to be on the beach shortly
after 6 AM and was beautifully rewarded. Those who have read
my earlier years'' columns from Marco Island may guess
correctly that this was one of those mornings when the full moon
sets as the first rays of dawn appear in the opposite direction.
The moon was behind some clouds when I started walking but
emerged fully as a bright orange orb just before setting. Turning
around a bank of mackerel clouds was painted a brilliant pink by
the about-to-emerge sun - spectacular! I also walked a mile or
two beyond where I had walked in previous years. It was a
different world, with no hotels and only a couple of intrepid shell
seekers to be seen.
A distressing aspect of my walk was the huge number of dead
fish, casualties of the red tide. I hadn''t planned to mention any
more about the tide, but I have made some observations that
intrigued me over the past weeks. When the red tide first
appeared, the dead fish were all the same type and virtually the
same size, foot-long mullets. A day or two later, it seemed as
though a school of much smaller fish were affected. The newly
deceased were uniformly 2-3 inches long and reminded me of
sardines. In another day or so, a raft of intermediate size fish,
about 6 inches long, appeared. It was as though the Gulf was
running them through sieves of different size openings.
Then we had a daylong rainstorm with very high winds and the
next day, all bets were off. The beach was littered with all
shapes and sizes of marine life. There were flat fish, big fish (3
feet long), foot-wide skates, hermit crabs and other crab
varieties, starfish, sand dollars and all kinds of shells and
shellfish. I had never seen what I assume was a recently living
shrimp on Marco Island''s beach before. I had a golden
opportunity to collect a very large shell that would have been $20
in the shell store. Unfortunately, the shell was still inhabited by
its owner, a creature that looked to me like a bright red pound of
liver. Not only would I have been ignorant of the procedure for
cleaning out the shell but also taking live shells off the beach is
illegal. According to one of the local Marco publications that I
read just a few minutes ago, the reason for the law again
harvesting "live" shells is that these live shells provide food for
the shore birds. The law is very effective - I''ve walked through
groups of hundreds of gulls and other birds on the beach.
Perhaps it''s the full moon and/or the red tide that causes some
people''s minds to get a bit twisted or warped down here in
Florida. Take an item in Sunday''s Naples Daily News. There
was this guy hitting a fellow on the head with a beer bottle.
Nothing unusual about that - happens all the time, doesn''t it?
But you''ll have to admit it isn''t every day that a fellow responds
by stabbing the guy with a swordfish!
If both of those fellows'' minds were a bit twisted, mine was also
out of sync on Sunday. Not only did I forget to take the key to
our condo when I left on my predawn walk, but after making my
customary orange juice-banana drink in the blender and cleaning
the blender, I realized I forgot to add the banana. The banana-
orange juice blend not only supplies extra potassium to counter
the diuretic blood pressure pill but also helps the morning
vitamins and pills go down smoothly. After drinking the glass of
blend and taking my pills, I notice a green thing on the floor. For
the first time in my life, my blood pressure pill had not
completed its journey from container to my mouth! Hopefully,
all these things were due to the moon or red tide and not to some
serious mental problem.
In addition to twisted minds, there are twisted mirrors, which
serve the noble objective of exploring our universe. What
brought this to mind was an article by Marcia Dunn, also in
Sunday''s Naples Daily News, concerning the launch this week of
the space shuttle Columbia. Columbia''s mission is a major
servicing of the Hubble Space Telescope that includes
replacement of the power control unit and damaged solar panels,
repair of one camera and installation of a new one, etc. It''s an
awesome job that NASA has assigned these astronauts, one of
them a veterinarian skilled in performing surgery on elephants,
whales, rhinoceroses and other animals. Who would have
thought that such a background qualifies one to do surgery on an
orbiting space telescope?
With the new and rejuvenated equipment, it is hoped that Hubble
will bring back photos and data on wider areas of the sky and
maybe gather information on when the first galaxies formed and
uncover more planets orbiting nearby stars. The Hubble has cost
many billions of dollars over the years to maintain and operate
but it has amply repaid us with over 400,000 exposures of
thousands of different areas of the universe. To date, over 3,200
papers have been published utilizing data from the Hubble.
The Hubble has been so successful primarily due to the fact that
out in space it can operate free from the atmospheric distortions
that limit the performance of earthbound telescopes. These
distortions are what cause stars to twinkle and that twinkling
causes fuzzy pictures of distant objects taken by telescopes on
earth. Without the distortions, Hubble gives much sharper
images.
What does all this have to do with twisted mirrors? "Adaptive
optics" is the answer. I''ve touched on this briefly over a year
ago, though not by this name as I recall. An article by Bob
Berman in the March 2002 issue of Discover is titled "Twisted
Mirrors Sharpen the View" and is one of several articles I''ve
read on the subject of adaptive optics. First, what is the twinkle
of a star due to? As light from a star travels through the
atmosphere it bends as it passes through different layers of the
atmosphere with different temperatures and, I would guess,
compositions. As temperatures change, the bending is different
so, over a period of time required for the telescope to gather
enough light for an image, the light comes from different
directions and the image is fuzzy.
Let''s take one example of adaptive optics cited by Berman. It
involves a "synthetic star". The "star" is a patch of sodium
atoms out in the upper atmosphere somewhere. (I''m assuming
these sodium atoms were placed there by some rocket shot of
some sort.) Now let''s shoot a laser beam up at the sodium "star".
Sodium when excited gives off a yellow light. By measuring the
twinkle of this synthetic star, if we''re clever we can then
translate the twinkle into a correction to apply to our telescope,
which is looking at a real star or galaxy.
How do we do this? Let''s take the image we get from our
telescope and send it to a flexible mirror. Now connect the
mirror to a few hundred tiny pistons controlled by our computer.
By activating these little pistons, or actuators, we can push and
pull and twist the various sections of the mirror to compensate
for the twinkle. We can do this hundreds of times a second. The
results are astounding. The Discover article shows pictures of
the planet Neptune taken by the Keck telescope on Mauna Kea in
Hawaii. The normal picture shows a blurry blob with a
suggestion of a dark area and a pronounced round bright spot.
With adaptive optics, Neptune emerges with clearly defined
bands of cloud formations and the bright spot is resolved onto
two bright areas, neither of which is remotely round. (I should
note that I''m not sure that the synthetic star method was used
with the Keck photos; there are other techniques.)
As a result of adaptive optics, ground based telescopes will
compete with the Hubble to see which will be the first to deliver
an actual image of a planet outside our solar system. Some feel
that day may come within the next year or so. There are some
limitations, however. For the larger telescopes, adaptive optics
so far is only feasible for infrared light, which isn''t as affected by
atmospheric distortions. It seems those pistons can''t twist those
flexible mirrors fast enough to keep up with the twinkling of
visible light in telescopes bigger than 15 feet. I guess you never
can have everything.
Lest you think adaptive optics is only useful for astronomical
purposes, spy satellites use it to resolve smaller features -
possibly less than a foot in size. There are camcorders and
binoculars on the market that use different adaptive optics
methods to provide jitter-free images.
Returning to twisted minds, in case you''re wondering, both the
guy with the beer bottle and the fellow with the swordfish were
charged with aggravated battery. The swordfish stabber
required stitches for his head injuries while the beer bottle basher
was in fair condition, with wounds to his lower abdomen. As for
me, since last Sunday I''ve remembered my key, added the
bananas and swallowed my pills on the first try!
Allen F. Bortrum
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