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1. Space Environment
Lecture 8 – Effects on humans
Countermeasures: Zero ‘G’, radiation &
vacuum
Professor Hugh Lewis
SESA3038 Space Environment

2. Overview of lecture 8 Space Environment – Environmental effects
• In this lecture we will complete our study of countermeasures that can be
used to reduce or remove environmental effects. In particular, this lecture
focuses on:
– The Zero ‘G’ or microgravity environment (with a consideration of
countermeasures for long duration missions)
– The radiation environment
– The thermal and high vacuum environment, focusing exclusively on the
design of spacesuits

3. • Launch
• Zero ‘G’
• Radiation
• Thermal
• High vacuum
Countermeasures Space Environment – Environmental effects

4. Assessment of muscle wasting, loss of strength and function needs to be accurate and
reliable, e.g. objective decision-making related to extra-vehicular activity (EVA) or
surface planetary excursions, e.g. on Mars (‘Go” or “No-go” criteria)
Zero ‘G’ Space Environment – Environmental effects

5. Managing muscle wasting in zero ‘G’:
• Needs an understanding of the
mechanisms and risks
• Requires change monitoring
• Requires targeted interventions
• Needs to be managed in isolation
• No direct contact with ground
support
• Needs to be possible within limited
room on spacecraft
• Prevention: preconditioning
• Management: reconditioning
Zero ‘G’ Space Environment – Environmental effects

6. Long duration missions
Maintenance of astronaut condition during one long-duration mission cycle from Earth to Mars
and back
Zero ‘G’ Space Environment – Environmental effects
From Stokes et al., 2017

7. Long duration missions – synthetic gravity
Zero ‘G’ Space Environment – Environmental effects

8. For vestibular problems (e.g.
motion sickness):
• Drugs
• Head restraints
• Autonomic response control
(bio-feedback)
• Cuban boots
• Simulates Earth loads on
foot proprioceptors
Zero ‘G’ Space Environment – Environmental effects

9. Add shielding, e.g. Aluminium:
Radiation Space Environment – Environmental effects
Organ Exposure in 51.6 degree Orbit at 190 N.M. Altitude and Solar Minimum Activity
https://www.researchgate.net/publication/255039258_Estimate_of_Space_Radiation-Induced_Cancer_Risks_for_International_Space_Station_Orbits

10. Orbit selection:
Radiation Space Environment – Environmental effects
51.6 degree 400 km orbit avoids inner radiation belt
Proton belt
Electron belt

11. Astronaut radiation risks
Life-size plastic replica of a
human torso. The plastic closely
matches the density of organs
and tissues in the human body,
the torso is embedded with
hundreds of radiation sensors
and has real human blood cells.
Subjected to high-energy proton
beam at NASA's Space
Radiation Lab
Radiation Space Environment – Environmental effects

12. Spacesuits
Thermal & vacuum Space Environment – Environmental effects

13. Thermal & vacuum Space Environment – Environmental effects
Spacesuits
• X-ray of the spacesuit worn by
Alan Shepherd on the Moon
during the Apollo 14 mission
in 1971
https://www.nytimes.com/2010/12/21/science/21spacesuit.html?_r=1

14. Spacesuits
• Liquid Cooling and Ventilation Garment (LCVG)
• Made of spandex
• 91.5 metres of water-cooling tubes
• Water is pumped through the tubes near the
spacewalker's skin.
• The chilled water removes extra heat
• Vents in the garment draw sweat away from the
astronaut's body.
• Sweat is recycled in the water-cooling system.
• Oxygen is pulled in at the wrists and ankles to help
with circulation within the spacesuit.
Thermal & vacuum Space Environment – Environmental effects
https://www.nasa.gov/audience/foreducators/spacesuits/home/clickable_suit_nf.html

15. Spacesuits
• Primary Life Support Subsystem
• Oxygen, batteries, water-cooling
equipment, fan, radio
• Upper torso
• Hard upper torso, arm assembly
• EVA gloves
• Heaters in fingertips
• Displays and Control Module
• Lower Torso Assembly
• Helmet
• Bubble is covered by the
Extravehicular Visor Assembly
with a thin layer of gold film
• Communications Carrier Assembly
Thermal & vacuum Space Environment – Environmental effects

16. Spacesuit layers
• 14 layers of material
• LCVG garment makes up 1st
three layers
• Bladder layer creates correct
pressure and contains oxygen
• Bladder support layer
• Holds shape to astronauts
body
• Ripstop layer
• Next seven layers are Mylar
insulation for thermal control
and micro-debris impact
protection
• Outer layer is waterproof and
fire-resistant
Thermal & vacuum Space Environment – Environmental effects

17. Recap of lectures 7 and 8 Space Environment – Environmental effects
• In these lectures we studied the countermeasures that can be used to
reduce or remove environmental effects on humans. These effects were
associated with:
– The launch environment
– The Zero ‘G’ or microgravity environment, including long duration
missions
– The radiation environment
– The thermal and high vacuum environment, with a focus on the design of
spacesuits

18. Activity
• A reminder that you can find articles and
reports covering the contents of lectures 5 to 8
in the “Course Content” folder on the
Blackboard site:
• Reading these is not compulsory (especially because
some of the reports are long) but could provide
deeper insights into the topics we have covered
• Some of these articles are also linked to or cited in te
lecture slides
Space Environment – Environmental effects