Assessment of Radiation Exposure of Astronauts in Space

Draft document: Assessment of Radiation Exposure of Astronauts in Space
Submitted by Nick Sion, Intercan Technologies
Commenting on behalf of the organisation

Overall:       A timely and informative document. The reader will have to be well versed in space radiation technology to appreciate it fully. The document could include more explanatory notes to be useful to the less knowledgeable.




147, 728      Explain the significance of 100 mSv. Who imposed this limit and why.

182,183       Explain how an increasing LET results in a stronger decrease in Q. for higher LET from heavier particles and high energies a higher Q is needed to offset the detriment to the tissue.

264, 304      Acronym ICRU International Commission on Radiation Units should be added to Glossary.

371             Explain why the fluence rate of the GCR in the heliosphere is inversely correlated with the solar activity. Consider an SPE when they are directly proportional.

413             Show the letter “y” as the symbol of Lineal Energy.

632             Define Muons and Pions:

                  Muons: an elementary particle with a negative charge similar to an electron. They are unstable and decay to three particles, an electron and 2 neutrinos.

                  Pions:  short for pi-meson, and play a major role in explaining the low energy properties of the strong nuclear force, i.e. the force between two or more nucleons. They decay into an electron and its corresponding electron anti-neutrino.

751             ISO, Omni Directional Exposure should also be shown in the Glossary section.



                  Is loaded with information that may not be suitable for a document whose purpose is oriented towards radiation Protection. It just states the status of radiation out in space that we cannot do anything about. Wait till he next chapters if this info can be of use later.


779             Units should also be explained in the Glossary: G=giga=109 ; eV = electron Volt; u = nucleon.

784             Add to Glossary UTC = Coordinated universal Time = GMT but does not observe Daylight Savings Time.

996             When there is an equation, the symbols/units should clearly be identified. Best if all symbols including Greek, appear in the Glossary as a subsection.



1391           Table 3.1; first box; quantify: “remainder”

1393           Different weighting factors should be given to each of the testes and to the ovaries, if numbers are available. Ovaries are far more sensitive to radiation than testes.

1408,1409   This statement negates what is stated in line 1393 and affirms my comment above.

1432           Could not find “expanded” nor “aligned “  radiation fields in Glossary.

1467-69       It would be helpful to state who proposed the stated depths as appropriate.

1536 Parag (88)   Suggest a clearer re-write of this paragraph explaining L, L∆, δ-electrons and δ-rays, since they are used to relate track structure LET and RBE in paragraph (93), lines 1604-1613.

Parag 94;95 Are we to understand that a new paradigm is proposed based on Katz etal 1972, of deriving RBE from Z* effective charge multiplied by β2 ? has it been applied to human cells, rather than to hamsters Fig. 3.9?



                  A thorough rendition of the detectors currently in use, or in contemplated use, for radiation detection and/or measurement. I fear that the chapter will gradually obsolesce as new technologies come to the fore. I would recommend that a statement of requirements be stated for each type of sensor and whether these requirements are met, and where they fall short. This will encourage instrument manufacturers and their researchers, to focus and to improve their product



Parag.212   As stated before, Greek symbols in Formulae could all be gathered in the Glossary together within their Superscripts and Subscripts.

Parag.213-218   Even more helpful is to give the numbers of the constants in the equations, or at least state where they are available. Those using these equations would likely spend a lot of time finding these numbers.   

2955           Table5.1, second box under SECONDARY. State what (d,t,h,α) are, else place them in the  Glossary.

3081           Transport symbols forl high energy protons, neutrons etc appear as boxes. Sometimes computers cannot find the Greek symbol and show it as a box. Also in line 3089. I checked your PDF file and it is shown there too, hence it is not my computer.

Section 5.3  A great compendium of transport codes. Just try to get my company to acquire any of them !!!!!!

3245           Identify what STS-48 is. It is a shuttle mission launched on 12 September 1991 whose payload was the Upper Atmosphere Research Satellite.

3303 Fig.5.9      Typo in the graphs. Spelling of Polyethylene.   

3331 Fig.5.10    Radiation dose is time dependent. How long time-wise do these represent to arrive at fose equivalent?

NOTE          There is no mention of a newly invented shielding material (by Dr. Raj Kaul and Dr. Barghouty, both of NASA, Brookhaven National Labs) named RXF1, patent pending, and probably classified. It is predominantly made of polyethylene, and has 3 times the strength of Aluminum, and is 2.6 times lighter. And has considerable shielding properties.   


CHAPT. 6      

3420           Delete “the” in the “… dosimetry on the Earth…” it would read better.

Parag. 270  Where do we get the conversion coefficients from?

3545           No such data was found in the Annex. I have 145 pages in the document I am reviewing. Are there any more?

Figs 6.4, 6.10    Tough to scale numbers from a graph. For accuracy we need tables, and these are not found in the Annex.

4159-4160   A very profound statement to have no dose limits set for a given mission. It cannot be open ended. How much dose would be allowed?