Detecting radiation on lunar and Mars missions (Forwarded)

National Space Biomedical Research Institute
Houston, Texas

Contact:
Lauren Hammit, 713-798-7595

February 20, 2007

Detecting radiation on lunar and Mars missions

Astronauts on lunar and Mars missions will need to continually assess their
radiation risk and exposure. The faculty and midshipmen at the United States
Naval Academy (USNA) are developing a small device to do exactly that, as
well as alert crews during high-radiation events.

"Radiation on the moon and on a three-year mission to Mars is dangerous and
uncertain. Since the moon and Mars have no atmosphere and no global magnetic
field, astronauts will not have the protection from radiation that we have
on Earth and in low-Earth orbit," said Dr. Vince Pisacane, a researcher on
the National Space Biomedical Research Institute (NSBRI)'s Technology
Development Team. "Travel away from the Earth's surface makes it essential
to monitor the types and levels of radiation exposure."

Pisacane, along with other faculty and midshipmen of the USNA, is developing
a radiation detection and assessment system, called a microdosimeter, in
partnership with NSBRI. The instrument will measure radiation doses on the
cellular level and help determine regulatory dose limits for scientific and
medical purposes.

"In space, we can't predict when radiation events occur nor their severity,
so it's crucial to develop a rugged, light-weight, portable system that can
make real-time measurements of radiation environments," said Pisacane, R.A.
Heinlein Professor of Aerospace Engineering in USNA's Aerospace Engineering
Department. "Spacesuits and spacecrafts integrated with microdosimeter
sensors can help assess risk, provide warning at the onset of enhanced
radiation so astronauts can take protective action, and help crews determine
safe locations during these periods."

Radiation negatively affects missions in a number of ways. Radiation
exposure can lead to fatigue, hair loss, cataracts, vomiting, central
nervous system problems, changes in physiology and genetic make up, and
cancer, among other diseases. On the spacecraft, it could cause reduced
power generation, background noise in sensors and the failure of electronic
devices.

"Astronauts are exposed to radiations from different sources including
particles trapped in the Earth's magnetic field, cosmic rays and energetic
solar events," Pisacane said. "The instrument measures the integrated effect
of a radiation field since damage depends on the types of radiation and
their energy."

Pisacane and his colleagues have developed two systems; one for ground-based
lab testing and one for use in space. The microdosimeter flight instrument
will be tested aboard the USNA student-built MidSTAR-1, a satellite
developed by midshipmen expected to launch in early 2007 aboard a Lockheed
Martin Atlas V launch vehicle. The goal of the project is to reduce the size
of the sensors to the size of a deck of cards.

The flight instrument consists of three sensors and an electronic output
module that collects and stores data for transmission to the ground. One
sensor will be near the exterior of the spacecraft and the other two housed
at different locations inside. Of the interior sensors, one resides in a
block of polyethylene, which will simulate the effect of radiation on
tissue.

"The sensors measure the deposition of radiation energy in tiny microscopic
elements similar in size to a red blood cell," Pisacane said.

Each of the three sensors provide an energy spectrum from the various
locations within the spacecraft every three hours, but can provide more
frequent updates if an enhanced-radiation event occurs. The microdosimeter
will use the measurements to directly estimate the radiation risk. On the
MidSTAR-1 test flight, the group will focus on testing the device's
sensitivity, resolution and response to noise.

"The microdosimeter can also be used to evaluate the effectiveness of
shielding materials," Pisacane said.

On Earth, the microdosimeter's capabilities will be useful for nuclear
material clean up, in detecting radioactive devices, and to monitor patients
undergoing radiation treatment.

NSBRI, funded by NASA, is a consortium of institutions studying the health
risks related to long-duration space flight. The Institute's science,
technology and education projects take place at more than 70 institutions
across the United States.

Related photos are available at:
http://www.nsbri.org/NewsPublicOut/20070220.html