Solar Storms
Solar storms are not new phenomena and have existed as long as there has been a star in the sky and on Jan. 20, 2005, a giant sunspot named "NOAA 720" exploded sparking an X-class solar flare.
This is the most powerful kind, and this one hurled a billion-ton cloud of electrified gas (a coronal mass ejection, or CME) into space. Solar protons accelerated to nearly light speed by the explosion reached the Earth-moon system minutes after the flare and it was the beginning of a days-long "proton storm."
Proton storms can cause all kinds of problems from interfere with ham radio communications, zapping satellites and causing short circuits and computer reboots and also cause sickness. This same sunspot exploded 5 times between Jab 15th to 20th.
An astronaut caught outside in this storm would have at first, felt fine. A few days later, symptoms of radiation sickness would appear which include vomiting, fatigue and low blood counts. These symptoms might persist for days.
This January storm came with proton energies exceeding 100 million electron volts. These are the kind of high-energy particles that can do damage to human cells and tissue. Here on Earth, our planet's thick atmosphere and magnetic field protects us from protons and other forms of solar radiation. The actual CME arrived 36 hours after the initial blast where it hit Earth's magnetic field.
Such protons can burrow through 11 centimetres of water. A thin-skinned spacesuit would have offered little resistance.
Using this storm as a reference:
|
Situation |
REM dosage |
|
ISS crew |
Probably absorbed no more than 1 rem |
|
Typical diagnostic CAT scan |
About 1 rem |
|
A Lunar astronaut walking on the surface during this storm |
About 50 rem of ionizing radiation (non-fatal) |
|
Fatal Dosage |
About 300 rem in a very short period. |
|
Non Fatal Dose |
300 rem absorbed over a period of days or weeks |
|
The solar storm of August 1972 |
An astronaut might have absorbed 400 rem and only a quick trip back to Earth for medical care could have saved the astronaut's life. |
|
Inside an Apollo command module |
Attenuation from 400 rem to less than 35 rem That's the difference between needing a bone marrow transplant, or having a headache. |
|
Modern spaceships |
Shielding measurements of space ships is done in units of areal density - or grams per centimetre-squared," |
|
|
The hull of an Apollo command module rated 7 to 8 g/cm2 |
|
|
The space shuttle has 10 to 11 g/cm2 |
|
|
The hull of the ISS, in its most heavily shielded areas, has 15 g/cm2 |
|
Future moon bases will have storm shelters made of polyethelene and aluminum |
... possibly exceeding 20 g/cm2 |
|
A typical space suit |
only 0.25 g/cm2, offering little protection |
This table of information would indicate that with advanced warning, an astronaut could survive a solar storms radiation if:
a. It was a small storm
b. The shelter was constructed with a high enough areal density
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