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Location: UFOUpDatesList.Com > 2003 > Dec > Dec 13

Radiation Mars Mission's Invisible Enemy

From: Terry W. Colvin <fortean1@mindspring.com>
Date: Sat, 13 Dec 2003 09:57:58 -0700
Fwd Date: Sat, 13 Dec 2003 13:42:17 -0500
Subject: Radiation Mars Mission's Invisible Enemy

Source: The New York Times


December 9, 2003

Mars Mission's Invisible Enemy: Radiation

By Matthew L. Wald

UPTON, N.Y. - As the United States considers new goals for NASA
after the loss of the Columbia, some space enthusiasts have
renewed calls for a mission to Mars.

But a team of physicists and biologists here at a laboratory on
Long Island is demonstrating that even if the nation wanted to
commit to such a goal, it would be far more complex than the
Moon mission that gripped the country in the 60's.

One reason is radiation, in the form of heavy ions from distant
stars, zipping through everything in their path. Others include
price, estimated at $30 billion to $60 billion, and launching
enough food, supplies and fuel for a round trip. Any one of
these could make the project impractical.

In a new $34 million NASA laboratory here, part of Brookhaven
National Laboratory, scientists are using subatomic particles
accelerated to nearly the speed of light to slam into materials
that could be used in a spaceship, and tissue samples and small
animals. Using tools like PET and M.R.I. scans and DNA
sequencing, they hope to shed light on ways that radiation
damages biological tissue, and what can be done about it.

On a trip to Mars and back, probably every cell in the body
would be hit by an ionized particle or a proton, researchers
say, and they have very little idea what that would do. "If
every neuron in your brain gets hit, do you come back being a
blithering idiot, or not?" asked Dr. Derek I. Lowenstein, the
chairman of Brookhaven's collider accelerator department.

A trip to Mars means "trying to live in an environment that
human beings were not built to live in," Dr. Lowenstein said.
"Space is not `Star Trek,' but the public certainly doesn't
understand that."

On earth, radiation shielding is easy; just add concrete or
lead. That is not so easy on a spaceship, where weight is of the
essence. Nor is there much prospect of significantly reducing
the amount of time the astronauts would be exposed, unless NASA
develops a much more effective propulsion system.

The NASA administrator, Sean O'Keefe, has identified radiation
as one of three problems that will have to be solved before a
Mars mission. The others are better propulsion and on-board
power generation.

Brookhaven is studying the radiation in a a sprinkling of
undistinguished-looking corrugated metal buildings, connected by
low earthen berms. "That's where the action is," said Mona Rowe,
a spokeswoman. The berms are shields for tracks underneath that
carry the accelerated particles that slammed into targets or one
another. Above the berms, wild turkeys amble through the woods.

The radiation environment that the accelerator is mimicking is
vastly different from the terrestrial one.

The average American receives about 350 millirem of radiation a
year: the fraction of solar and cosmic radiation that makes it
through Earth's magnetic field and atmosphere; radiation from
naturally radioactive rocks and minerals, some incorporated into
building materials; higher doses from flying in airplanes; and
sources like medical X-rays.

In contrast, the astronauts who went to the Moon on Apollo 14
accumulated about 1,140 millirem, equivalent of about three
years on Earth in their nine-day mission. The astronauts on the
Skylab 4, who spent 87 days in low Earth orbit, received a dose
of about 17,800 millirem (equivalent to a 50-year background
dose on Earth).

That dose was near the threshold of radiation exposure that
produces clinically measurable symptoms. Longer-term effects
like increases in cancer rates have not been observed in adults
exposed to doses at that level, but experts presume the effects
exist. By comparison, nuclear power plant workers are limited by
law to exposures no greater than 5,000 millirem a year; in this
country they are generally held below 2,000.

A round trip to Mars would be of a different order of magnitude.
Brookhaven puts the exposure at 130,000 millirem over two and a
half years. That is equivalent to almost 400 years of natural

But radiation in space is not like radiation on Earth.

On Earth the dose is mostly made up of gamma rays, which have
far less energy than the heavy charged particles of space. But
beyond Earth's protective atmosphere and magnetic field, the
radiation is mostly ions of every element on the periodic table
up to iron (No. 26), moving at a substantial fraction of the
speed of light, and approaching from distant stars in all
directions. Astronauts in low Earth orbit get some protection
from the magnetic field.

Much less is known about the biological effects of this
radiation, because very few places can simulate the
interplanetary radiation. Brookhaven can do it, but its method,
sequentially firing ions of different elements, resembles
playing a symphony by mimicking one instrument at a time.

One recent afternoon, scientists were adjusting the flow of iron
ions being delivered to the 400-square-foot "target room" of the
laboratory here, using a control a bit like a shower head, which
could vary the dimensions and density of the spray. The target
would eventually be a flask filled with human tissue, but for
now was a monitoring instrument that captured an image the way
an X-ray film would.

Dr. Adam Rusek, a physicist, shuttled between a control panel
and the main room of the Space Radiation Laboratory, where Dr.
Betsy Sutherland, a staff biologist and some assistants, were
watching instruments that analyzed the beam.

Intermittently, an assistant went into the heavily shielded
target room to adjust the target, a procedure that requires a
retina scan by a security device and the insertion of special
keys to assure that no one unauthorized enters.

Inside the room, the lighting dimmed before each initiation of
the beam, so that anyone trapped inside could hit a panic switch
to stop it.

At last, the beam assumed the desired size, density and
uniformity. "Is that better?" Dr. Rusek asked. "Yes, don't
breathe on it," Dr. Sutherland replied.

One persistent question about radiation exposure is the
importance of the delivery rate, but Dr. Sutherland is simply
trying to hit each cell once. "If a cell is hit once, there is
no rate," she said. "Once is once."

After irradiation, the cells are moved to a nutrient medium that
is known to support cancer cells but not normal cells.

The experiment is repeated with ions of several elements. Dr.
Sutherland also uses protons, which come from the Sun and stars
and far outnumber the ions.

One theory holds that cells busy repairing damage from protons
will not be able to cope with damage from heavy ions; another
says that proton irradiation will prime the cell's repair system
to be ready for particle damage.

"It's a reasonable thing to ask, what are these first protons
going to do to the later response to iron," said Dr. Sutherland,
noting that the theory had not been tested.

Another Brookhaven scientist, Dr. Marcelo Vazquez, a physician,
plans to irradiate mice to look for brain damage. Damage from
heavy ions, he said, will include a column of cells formed by
the track of the ion, and a surrounding halo of cells damaged by

Dr. Vazquez, who also has a doctorate in neurobiology and
radiobiology, said that neither the column nor the penumbra was
visible on post-mortem examination. But changes in motor skills
are tested by stimulating animals with cocaine and measuring
movement with infrared beams, Dr. Vazquez said. Memory can be
observed. Mice are put in water and trained to escape to a
platform; then they are irradiated and the drill is run again.

NASA's chief scientist, John M. Grunsfeld, who as an astronaut
made several spacewalks to maintain the Hubble telescope, said
the research would take years. "The current plan is about five
years but I suspect we'll extend that," he said in an interview
in Washington. He hopes that the research reveals the biological
mechanism of radiation damage to cells, he added.

Also, some targets are structural materials. The incoming
protons and ions have so much energy that they make neutrons
peel off the aluminum or other materials; those neutrons are a
potent form of radiation. In addition, irradiating some
materials can cause changes that make them radioactive. Such
"activation products," commonly produced in nuclear reactors on
Earth, give off yet more radiation. Researchers hope they can
pick materials that will resist such activation or neutron

A third area of research is shielding. On Earth, radiation
shielding is commonly provided by concrete or lead, but the
costs of launching spacecraft are so high that this is not
practical. One possible solution is a water tank, with the
astronauts' living in a chamber in the middle. "It's just so
expensive to put material into orbit that you'd like to use
materials you have to bring anyway," Dr. Lowenstein said.

And beyond the spaceship itself, making space safe for extended
trips beyond the magnetosphere will probably require a new
system to monitor the Sun.

Physicists predict solar storms now by watching the Sun from
Earth or from satellites in Earth orbit, but protecting a Mars
mission will probably require watching the side of the Sun that
faces away from Earth. The job could be done with a small number
of satellites launched into orbit around the Sun, somewhere
outside the orbit of Mercury, Dr. Lowenstein.

Copyright 2003 The New York Times Company


“Only a zit on the wart on the heinie of progress.” Copyright
1992, Frank Rice

Terry W. Colvin
Sierra Vista, Arizona (USA)