Radioactivity in cissolar and cislunar space:
"...
the sun produces a fairly steady flux of light in optical wavelengths, it produces bursts of x-rays and other short wavelength photons that directly modify the ionosphere and high frequency radio communication; it emits
a continuous but unsteady flow of ionized material into the heliosphere (
the solar wind) that our magnetic field detects and must exclude;
it occasionally ejects high energy particles that can be deadly to electronic components and biological systems; it often ejects "tongues" or "ropes" or "clouds" of gas that move through the ambient interplanetary medium and impact the Earth and other planetary bodies; and it radiates noise in frequencies that can be received by working antennas and thus interferes with communication ..." -
intro
"...
The area between the Sun and the planets has been termed the interplanetary medium. Although sometimes considered a perfect vacuum, this is actually a turbulent area dominated by the solar wind, which flows at velocities of approximately 250-1000 km/s (about 600,000 to 2,000,000 miles per hour). Other characteristics of the solar wind (density, composition, and magnetic field strength, among others) vary with changing conditions on the Sun. The effect of the solar wind can be seen in the tails of comets (which always point away from the Sun). ...
...
Intense solar flares release very-high-energy particles that can be as injurious to humans as the low-energy radiation from nuclear blasts. Earth's atmosphere and magnetosphere allow adequate protection for us on the ground, but
astronauts in space are subject to potentially lethal dosages of radiation. The penetration of high-energy particles into living cells, measured as radiation dose, leads to chromosome damage and, potentially, cancer.
Large doses can be fatal immediately. Solar protons with energies greater than 30 MeV are particularly hazardous. In October 1989, the Sun produced enough energetic particles that an astronaut on the Moon, wearing only a space suit and caught out in the brunt of the storm, would probably have died. (Astronauts who had time to gain safety in a shelter beneath moon soil would have absorbed only slight amounts of radiation.) ..." -
http://web.archive.org/web/20050426205707/http://ess.geology.ufl.edu/ess/Notes/040-Sun/primer.html
As an instance of this:
"...
estimates of human exposure in interplanetary space, behind various thicknesses of aluminum shielding,
are made for the large solar proton events of August 1972 and October 1989. A comparison of risk assessment in terms of total absorbed dose for each event is made for the skin, ocular lens, and bone marrow. Overall,
the doses associated with the August 1972 event were higher than those with the October 1989 event and appear to be more limiting when compared with current guidelines for dose limits for missions in low Earth orbit and more hazardous with regard to potential acute effects on these organs.
Both events could be life-threatening if adequate shielding is not provided ..." -
Interplanetary crew exposure estimates for the August 1972 and October 1989 solar particle events - PubMed
Apollo 17 - December 7-19, 1972
"... The sun goes through a natural solar cycle approximately every 11 years. The cycle is marked by the increase and decrease of sunspots -- visible as dark blemishes on the sun's surface, or photosphere. The greatest number of sunspots in any given solar cycle is designated as "solar maximum." The lowest number is "solar minimum." ..." -
Solar Minimum; Solar Maximum
"... the epoch of AP8 model (1964 for solar minimum and
1970 for solar maximum) ...
...
Galactic cosmic ray particles originate outside the solar system. They include ions of all elements from atomic number 1 through 92. The flux levels of these particles are low but, because
they include highly energetic particles (10s of MeV/n ~ E ~ 100s of GeV/n) of heavy elements such as iron, they produce intense ionization as they pass through matter. As with the high energy trapped protons,
they are difficult to shield against. Therefore, in spite of their low levels,
they constitute a significant hazard to electronics in terms of SEEs. ...
...
The levels of galactic cosmic ray particles also vary with the ionization state of the particle.
Particles that have not passed through large amounts of interstellar matter are not fully stripped of their electrons. Therefore, when they reach the earth's magnetosphere, they are more penetrating than the ions that are fully ionized. The capacity of a particle to ionize material is measured in terms of LET and
is primarily dependent on the density of the target material and to a lesser degree the density and thickness of the shielding material." -
SEECA - Section 3
So the Apollo 16 & 17 'missings' were supposedly occurring during the timeframe of a peek solar maximum cycle.
"... We have rough estimates of what the moon travelers can expect, based on a few observations made during
the last solar maximum in 1957.
The most violent flares probably will produce exposures of 100 roentgens each hour and may hold this level for several hours ..." - The Sun Under Surveillance in the 1967 World Book Science Year; Edward P. Ney; page 89 -
https://www.google.com/search?tbm=b...s+made+during+the+last+solar+maximum+in+1957"
Apollo 12 (November 14-24, 1969)
Apollo 13 (April 11-17, 1970)
Apollo 14 (January 31, 1971 - February 9, 1971)
Apollo 15 (July 26 - August 7, 1971)
most of which is roughly 11 years later (1957 + 11, 1968) in the same solar maximum cycle (within about 3 years, 1969-71.
Again:
"... The main space weather hazard to human life is the ionizing radiation resulting from exposure to high energy particles. These energetic particles may come from distant stars and galaxies (galactic cosmic radiation); they may be found trapped in planetary radiation belts, such as the Earth's Van Allen radiation belts; or they may be ejected into space by the Sun in the solar wind or more rapidly by solar flare eruptions (figure 2).
To put the space weather radiation hazard to human life in perspective,
at geostationary orbit,
with only 0.1 gm/cm2 of aluminum shielding thickness, the predicted radiation dose (REM) for one year continuous exposure, with minimum-moderate solar activity, is estimated to be about 3,000,000; using 5.0 gm/cm2 of aluminum shielding, the REM for one year continuous exposure would be reduced to about 550. (Note: REM = dose (RAD) x Relative Biological Effectiveness (RBE) of particular ionizing radiation.) Although drastically reduced by shielding,
550 REM for a sample population would cause radiation sickness and about 50 percent deaths.
Astronauts protected with only a spacesuit during normal-length extra-vehicular activity at geostationary altitude could receive about 0.43 REM per day under minimum to moderate solar activity conditions, which is sufficient to damage the eyes and other vital organs. Under high solar activity, and most importantly during large solar flare occurrences, daily REM values could be a thousand-fold higher and probably lethal. In comparison, an earth-bound person would have an estimated total yearly radiation dosage in the range of 0.17 to 2.6 REM; the daily dosage would be approximately 4.7 x 10-4 to 7.1 x 10-3 REM (2 to 3 orders of magnitude less than the astronauts daily dosage in our example). ..." -
Spaced-Based Solar Monitoring and Alert Satellite System (SMASS)
