scholarly journals Radiation Risks in Cis-Lunar Space for a Solar Particle Event Similar to the February 1956 Event

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 107
Author(s):  
Fahad A. Zaman ◽  
Lawrence W. Townsend

Solar particle events (SPEs) can pose serious threats for future crewed missions to the Moon. Historically, there have been several extreme SPEs that could have been dangerous for astronauts, and thus analyzing their potential risk on humans is an important step towards space exploration. In this work, we study the effects of a well-known SPE that occurred on 23 February 1956 on a mission in cis-Lunar space. Estimates of the proton fluence spectra of the February 1956 event were obtained from three different parameterized models published within the past 12 years. The studied geometry consists of a female phantom in the center of spherical spacecraft shielded by aluminum area densities ranging from 0.4 to 40 g cm−2. The effective dose, along with lens, skin, blood forming organs, heart, and central nervous system doses, were tallied using the On Line Tool for the Assessment of Radiation In Space (OLTARIS), which utilizes the High Z and Energy TRansport code (HZETRN), a deterministic radiation transport code. Based on the parameterized models, the results herein show that thicknesses comparable to a spacesuit might not protect against severe health consequences from a February 1956 category event. They also show that a minimum aluminum shielding of around 20 g cm−2 is sufficient to keep the effective dose and critical organ doses below NASA’s permissible limits for such event. In addition, except for very thin shielding, the input models produced results that were within good agreement, where the doses obtained from the three proton fluence spectra tended to converge with slight differences as the shielding thickness increases.

Author(s):  
Ram Tripathi ◽  
Lawrence Townsend ◽  
Tony Gabriel ◽  
Lawrence PIinsky ◽  
Tony Slaba

Author(s):  
Ram Tripathi ◽  
Lawrence Townsend ◽  
Tony Gabriel ◽  
Larry Pinsky ◽  
Tony Slaba ◽  
...  

Aerospace ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 143
Author(s):  
Fahad A. Zaman ◽  
Lawrence W. Townsend ◽  
Naser T. Burahmah

Within the past decade, evidence of excess atmospheric 14C production in tree rings, coupled with an increase in annually resolved measurements of 10Be in Arctic and Antarctic ice cores, have indicated that an extremely large solar particle event (SPE) occurred in AD 993/4. The production of cosmogenic nuclei, such as 36Cl in consonance with 10Be, indicate that the event had a very energetic “hard” particle spectrum, comparable to the event of February 1956. Herein, we estimate the potential radiation risk to male and female crew members on a mission to Mars that would occur from such an SPE. Critical organ doses and effective doses are calculated and compared with NASA space radiation limits for an SPE comparable to the AD 993/4 event, occurring during the transit phase to Mars, or while the crew members are operating on the surface of Mars. Aluminum shielding, similar in thickness to a surface lander, a spacecraft, and a storm shelter area within the spacecraft, are assumed for the transit phase. For surface operations, including the shielding provided by the atmosphere of Mars, shielding comparable to a spacesuit, enclosed rover, and a surface habitat are assumed. The results of our simulations indicate that such an event might have severe consequences for astronauts in transit to Mars. However, on the surface of Mars, the atmosphere provides some protection against an event similar to the 993/4 SPE. In general, the results show that additional shielding may be required for some of the assumed shielding scenarios.


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