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What is DNA?
Deoxyribonucleic acid (DNA), the same “stuff”
that makes you uniquely you, also connects you to all living
things. Like a code, when deciphered, these pieces determine
whether you’re a human being or a banana.
Some call DNA a master blueprint. Others describe
it as a recipe. All realize that it is the essence of life.
DNA is a template for creating proteins. Proteins
form the different structures inside of cells. All living
things are made of cells.
Cells are filled with jelly-like cytoplasm.
Tiny structures called organelles are scattered throughout
this cytoplasm. The nucleus holds DNA and functions as a
command center for the cell. Inside the nucleus, long strands
of DNA are coiled into compact packages called chromosomes.
Unwound, DNA would stretch taller than most adults, but
it is so tiny, five million strands could fit through the
eye of a needle.
Hidden within DNA is the secret message that
defines you and all living things.
Change that code, and life is changed.
NASA researchers worry about changes as a
result of space radiation.
NASA astronauts have been in space, off and
on, for 45 years. Most of this time has been spent close
to the Earth. Only a few quick trips to the Moon took us
out away from the Earth’s protection. Deep space is
filled with protons from solar flares, gamma rays from newborn
black holes, and cosmic rays from exploding stars. A long
trip to Mars, with no big planet nearby to block that radiation,
is going to be a new adventure.
The main threat to astronauts on their way to Mars is galactic
cosmic rays (GCRs). These are particles that travel at speeds
close to the speed of light. They are launched into space
by distant supernova explosions. GCRs go right through the
skin of spaceships and people like tiny cannon balls. As
they go, they break strands of deoxyribonucleic acid (DNA)
molecules, damage genes, and kill cells.
Astronauts traveling to Mars will be “out
there” for a year or more. "We can't yet estimate
what cosmic rays will do to us when we're exposed for so
long," says Frank Cucinotta of NASA's Space Radiation
Health Project at the Johnson Space Center.
Finding out is the mission of NASA's Space
Radiation Laboratory (NSRL) team. This center is located
in New York. It opened in October 2003. "At the NSRL,
we have particle accelerators that can simulate cosmic rays,"
explains Cucinotta. Researchers will expose cells and tissues
to the particle beams. They will then study the damage.
They hope that by 2015 they can accurately estimate the
amount of damage an astronaut would receive on a trip to
Mars.
Once the risks are known, NASA can decide
what kind of spaceship to build. It's possible that ordinary
building materials like aluminum are good enough. If not,
other materials will be tested to see how well they can
block radiation.
Visit the links below for more resources from
NASA:
Cell
Structure Challenge - To learn about the structure
of an animal cell, and to create a model of the cell.
The
Brain in Space - This educator's guide explores
neuroscience, the study of the ways in which the body's
brain, spinal cord, and network of nerves control the activities
of animals and humans.
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