Categories of ARS impacts and recommendations for flight notes
The severity of various ARS symptoms can be calculated with
biomathematical models developed for neurovascular system and
hematopoietic system, which are highly dose dependent according to
previous investigations (Hu et al., 2009; 2011; 2012; 2015). Therefore,
they can be categorized solely from the total BFO doses as estimated
from the organ dose projection algorithm and can be roughly scored
similar to the Response Category system (Fliedner et al., 2001). The
scores for NV (nausea/vomiting), FW (fatigue/weakness), and HG
(HemoGrade) in the following categories are estimated by assuming acute
exposure at different levels, while the textual descriptions are giving
based on Tables 1 and 2, as well as SRAG space weather console practice.
For protracted exposure like during typical ESPEs, the neurovascular
effects may be less severe than predicted this way.
Because the current NASA short-term (30 days) permissible exposure limit
(PEL) for acute radiation effects is 250 mGy-Eq to the blood forming
organs (BFO) (NASA, 2014), focus of this
categorization for near future deep space exploration should be those in
the low dose range. As discussed in the introduction section, generally
SPEs can be effectively shielded, and current vehicle designs
incorporate smart shielding concepts such as the redistribution of
vehicle mass in MPCV. In addition, an effective warning system for a
large SPE could also help to reduce the event exposure. Therefore, it is
unlikely that astronauts inside an interplanetary spacecraft will
experience the full spectrum of following health impacts. Nevertheless,
significant exposure on lunar or planetary surfaces is possible if the
crew is not well protected, and the various acute risks depicted below
should be of concerns.
Short term crew impacts:
- 0-100 mGy-eq: (NV1-FW1-HG0) The accumulative dose will not induce any
effects of acute radiation syndrome over the next 48 hours.
- 100-250 mGy-eq: (NV1-FW1-HG0) Prodromal effects are not expected
during the next two days; however, crew is encouraged to report
symptoms of fatigue or nausea to Surgeon.
- 250-500 mGy-eq: (NV1-FW1-HG1) Prodromal effects are not expected
during the next two days; however, crew is encouraged to report
symptoms of fatigue or nausea to Surgeon. Bloodwork may indicate an
asymptomatic low-to-normal lymphocyte concentration.
- 500-1000 mGy-eq: (NV2-FW2-HG2) Symptoms such as nausea and anorexia
may appear within 24 hours of exposure, manifested as an upset stomach
with clammy/sweaty skin and watering mouth. Complete disappearance of
these symptoms is certain within 48 hours of exposure. Fatigue and
mild weakness may appear during this time period. Bloodwork will
indicate a mostly asymptomatic decrease in lymphocyte concentration.
- 1000-1500 mGy-eq: (NV3-FW2-HG2) Within the first hours after exposure,
crew may experience mild nausea and anorexia accompanied by
considerable sweating and frequent swallowing to avoid vomiting.
Symptoms are expected to persist for two days. Fatigue and mild
weakness are possible. Bloodwork may indicate a rapid decrease in
lymphocyte concentration.
- 1500-2000 mGy-eq: (NV3-FW3-HG2) Within the first hours after exposure,
crew may experience moderate nausea and anorexia accompanied by a few
episodes of vomiting. Symptoms are expected to persist for two days.
Fatigue and moderate weakness are possible. Bloodwork may indicate a
rapid decrease in lymphocyte concentration.
- 2000-3000 mGy-eq: (NV3-FW3-HG3) The crew will vomit several times,
experiencing dry heaves and severe nausea. Fatigue and moderate
weakness will appear. Bloodwork may indicate a rapid decrease in
lymphocyte count.
- > 3000 mGy-eq: (NV4-FW3-HG3) The crew will vomit several
times, experiencing dry heaves and severe nausea. Fatigue and weakness
will appear. Bloodwork may indicate a rapid decrease in lymphocyte
count and increase in granulocyte count.
Continuing crew impacts:
- 0-100 mGy-eq: (NV1-FW1-HG0) No symptoms of acute radiation syndrome
are expected over the next six weeks. The crew should make a best
effort to keep the exposure as low as reasonably achievable, per the
As Low As Reasonably Achievable (ALARA) principle to minimize
potential late health impacts such as cancer, cataracts, heart
disease, and damage to the central nervous system.
- 100-250 mGy-eq: (NV1-FW1-HG0) No acute radiation syndrome symptoms are
expected during the next six weeks. Bloodwork may indicate an
asymptomatic low-to-normal concentration of lymphocytes, platelets and
granulocytes. The crew should make a best effort to keep the exposure
as low as reasonably achievable (i.e., the ALARA principle) to
minimize potential late health impacts such as cancer, cataracts,
heart disease, and damage to central nervous system.
- 250-500 mGy-eq: (NV1-FW1-HG1) No acute radiation syndrome symptoms are
expected during the next six weeks. Bloodwork may indicate an
asymptomatic decrease in the concentration of lymphocytes, platelets,
and granulocytes to the lower end of the normal range. The crew should
make a best effort to keep the exposure as low as reasonably
achievable (i.e., the ALARA principle) to minimize potential late
health impacts such as cancer, cataracts, heart disease, and damage to
central nervous system.
- 500-1000 mGy-eq: (NV2-FW2-HG2) Fatigue and weakness may persist for
several weeks. The crew are at low risk of developing infectious
diseases or bleeding due to a decrease in concentrations of
lymphocytes, platelets, and granulocytes below the lower end of the
normal range. Autologous recovery is certain.
- 1000-1500 mGy-eq: (NV3-FW2-HG2) Fatigue and weakness may persist for
several weeks. The crew are at risk of developing infectious diseases
or bleeding due to a decrease in concentrations of lymphocytes,
platelets, and granulocytes below the lower end of the normal range.
Autologous recovery is certain.
- 1500-2000 mGy-eq: (NV3-FW3-HG2) Fatigue and weakness may persist for
several weeks. The crew are at a high risk of developing infectious
diseases or bleeding due to a decrease in concentrations of
lymphocytes, platelets, and granulocytes far below the lower end of
the normal range. Autologous recovery is certain.
- 2000-3000 mGy-eq: (NV3-FW3-HG3) Severe nausea and vomiting may recur
after two days, with fatigue and weakness persisting for several
weeks. The crew are at a high risk of developing infectious diseases
or bleeding due to a decrease in concentrations of lymphocytes,
platelets, and granulocytes far below the lower end of the normal
range. Autologous recovery is still certain.
- > 3000 mGy-eq: (NV4-FW3-HG3) Severe nausea and vomiting
may recur after two days, with fatigue and weakness persisting for
several weeks. The crew are at a very high risk of developing
infectious diseases or bleeding due to a decrease in concentrations of
lymphocytes, platelets, and granulocytes far below the lower end of
the normal range. Autologous recovery is possible.