Neutron measurements onboard the space shuttle

Area of Science:

• Space radiation physics
• Astrobiology and space medicine

Background:

• Spacecraft radiation environments comprise charged and neutral particles, with charged particles historically receiving more research attention.
• Secondary neutrons are significantly produced within spacecraft, especially from aluminum structures, due to galactic cosmic rays and solar energetic particles.
• Neutrons possess a higher radiation quality factor than charged particles, making them a critical concern for astronaut health.

Purpose of the Study:

• To review Shuttle flight experiment results on neutron contributions to dose equivalent.
• To analyze neutron energy spectra contributing to dose equivalent.
• To assess the significance of neutron radiation in habitable modules.

Main Methods:

• Review of data from Shuttle flight experiments conducted during solar maximum and minimum.
• Analysis of theoretical calculations for estimating neutron energy contributions.
• Measurement of neutron and charged particle contributions to dose equivalent.

Main Results:

• Neutron production is significant in low Earth orbit spacecraft, particularly from aluminum structures.
• Albedo neutrons exhibit a non-isotropic distribution due to GCR and SPE interactions with the atmosphere.
• The average radiation quality factor for neutrons inside habitable modules is 4-5 times higher than for charged particles.

Conclusions:

• Neutrons represent a critical component of the space radiation environment, with a higher biological impact than charged particles.
• Accurate measurement and understanding of neutron energy spectra are essential for effective radiation shielding and astronaut safety.
• Further research and experimental validation are needed to fully characterize and mitigate neutron radiation risks in space.