Impact of Solar Cycle Duration on Astronaut Radiation Exposure during a Human Mars Mission

Date

7/10/2022

Journal Title

Journal ISSN

Volume Title

Publisher

51st International Conference on Environmental Systems

Abstract

The mitigation of health risks from GCR presents a significant challenge for human missions to Mars. Mission dose varies significantly with solar cycle. The flux of galactic cosmic rays varies over an approximate 11-year cycle with an intensity that is inversely correlated with solar activity. During higher solar activity, the GCR intensity is at a minimum, whereas at solar minimum, the GCR intensity is maximal. At solar maximum exposure estimates behind typical spacecraft shielding are reduced by roughly a factor of two. Significant shielding would be required to provide an equivalent reduction in dose. Major SPEs during solar active periods could reduce the variability by increasing mission dose during solar active periods, but since SPE exposure is significantly reduced by nominal spacecraft shielding, and further reduced by internal storm shelters, the largest exposure would still likely occur on missions occurring over Solar Minimum. Efforts to improve the ability to forecast solar cycle length would be beneficial to long range Mars Mission planning. Under conditions modeled here, it was found that reducing the uncertainty in solar cycle duration by half (from 2.8 years to 1.4 years) increases the length of the launch window to meet a 600 mSv exposure limit, from six months to two years. However, the dates of favorable launch depend on the average forecast duration. Research is focused on predicting solar cycle intensity: peak at Solar Maximum and depth at Solar Minimum. However, solar cycle duration is going to have a significant impact on forecasts of solar activity if the projection is for twenty years out: Two short cycles (9.6 years) will be at solar minimum in 2039; two nominal solar cycles (11 years) will be at solar minimum in 2042; two long cycles (12.4 years) will be at minimum in 2045.

Description

Ronald Turner, Analytic Services Incorporated, US
ICES503: Radiation Issues for Space Flight
The 51st International Conference on Environmental Systems was held in Saint Paul, Minnesota, US, on 10 July 2022 through 14 July 2022.

Keywords

Radiation Exposure, Mars Missions, Solar Cycle

Citation