BONNER BALL NEUTRON DETECTOR (BBND)
Research Area: Radiation Impacts on Humans
Expedition(s): 2-3
Principal Investigator(s): ● Haruhisa Matsumoto, Japan Aerospace Exploration Agency,
Tsukuba, Japan
● Kiyokazu Koga, Japan Aerospace Exploration Agency, Tsukuba,
Japan
● Hideki Koshiishi, Japan Aerospace Exploration Agency,
Tsukuba, Japan
RESEARCH OBJECTIVES
Bonner Ball Neutron Detector (BBND) measures neutron radiation (low-energy, uncharged
particles), which can deeply penetrate the body and damage blood forming organs. Neutron
radiation is estimated to be 20% of the total radiation on the International Space Station (ISS).
This study characterizes the neutron radiation environment to develop safety measures to
protect future ISS crews.
EARTH BENEFIT
The technology developed for BBND will also have application in
monitoring the environment of high-radiation facilities on Earth.
SPACE BENEFIT
A neutron is an elementary particle. Since a neutron has no electric
charge, it can penetrate most substances. Even low-energy
neutrons can reach the internal human organs, including bone
marrow. It is said that 5% to 30% of the whole radiation dose
astronauts receive is neutron energy. The obtained data is to be
used for the enhancement of space radiation exposure
management technology, needed for further human activity
aboard the ISS.
RESULTS
BBND characterized the neutron radiation aboard the ISS during
Expeditions 2 and 3 and determined that galactic cosmic rays were
the major cause of secondary neutrons measured inside the ISS
habitats. The neutron energy spectrum was measured from March
23, 2001, through November 14, 2001, in the U.S. Laboratory
Module. The timeframe enabled neutron measurements to be made
during a time of increased solar activity (solar maximum) as well as
observe the measurements from a solar flare on November 4, 2001.
BBND results show that the overall neutron environment at the ISS orbital altitude is influenced
by highly energetic galactic cosmic rays, except in the South Atlantic Anomaly (SAA) region
where protons trapped in the Earth's magnetic field cause a more severe neutron environment.
ISS002E5716 – Voss with
Bonner Ball Neutron Detector
Control Unit in Destiny
laboratory. This unit will
process and store neutron
information recorded by six
spherical detectors scattered
around the Station. JAXA
image.