Traveling beyond the protection of the Earth's geomagnetic field, astronauts
are constantly bombarded with radiation from outer space, which is different
in particle composition from radiation people are exposed to on Earth.
Prompted by concern that this space radiation may cause biological damage,
NASA is performing experiments to determine its effects, with the use of
BNL facilities and the expertise of Brookhaven's biologists.
At BNL's particle accelerator, the Alternating Gradient Synchrotron, Brookhaven
biologists aimed particles called heavy ions at cultured human cells to
determine the level at which this ionizing radiation would induce double-stranded
breaks in DNA, the most serious damage ionizing radiation could produce.
Using a new experimental technique developed at Brookhaven, the researchers
found that these breaks in DNA occurred at extremely low doses of heavy
ions - as small as one-hundredth of a Gray. (One Gray is a measure of 100
rads. Therefore, one-hundredth of a Gray is equal to one rad.) Previous
experiments had only measured damage at 100 times this dose, or one Gray
(100 rads). The Brookhaven researchers' next experiments will determine
how well the cells repair the DNA damage.
Recently, Brookhaven researchers have made important advances in understanding
the mechanisms of ozone depletion. Ozone can be a form of pollution, impairing
people's vision and breathing, but in the stratosphere, it protects life
on Earth from the harmful effects of ultraviolet radiation from the sun,
such as skin cancer. Scientists started taking measurements of stratospheric
ozone in the early 1950s and they have found that since 1978, the ozone
layer is thinning. Over the south pole, ozone completely disappears at
some altitudes by the end of every October, creating what is known as the
ozone hole. This ozone hole is a matter of concern because it has been
growing over the last two decades. Moreover, a similar hole can now also
be observed over the north pole.
Most scientists believe that an increase in chlorofluorocarbons, or CFCs,
which come from refrigerants, solvents and aerosol sprays, trigger chemical
reactions that cause ozone depletion. Once the CFCs rise some 7 to 30 miles
into the stratosphere, they are exposed to ultraviolet rays, which break
them apart chemically, resulting in the release of chlorine. When the chlorine
is activated by certain particles in the stratosphere, it can destroy ozone.
At Brookhaven, researchers have created particles containing sulfuric acid
and water that they believe duplicate the chlorine-activating particles
in the stratosphere. They then placed these particles in polar stratospheric
conditions that they mimicked in their laboratory and observed a new, unexpected
crystalline form that they predict will be extremely effective at chlorine
activation. These observations provide one of the missing links between
nature and theory.
Brookhaven researchers are making two different, but effective, coatings
that are resistant to corrosion and oxidation by recycling fly-ash waste
from blast furnaces used in the steel industry, and modifying cornstarch,
a very abundant, renewable natural resource in the U.S.
The recycled fly-ash is chemically treated, sprayed onto high-temperature
performance metal and baked at temperatures as high as 300ºC to make
the metal resistant to the deleterious effects of oxidation and abrasion.
A corrosion-resistant coating made from nonbiodegradable cornstarch has
also been developed through chemical modification. The performance of this
coating is comparable to that of conventional ones, but it is environmentally
friendlier and less expensive to make. Both coatings are being patented,
and Brookhaven soon will be seeking industrial partners to commercialize
them.