The Effect of Microgravity on
the Oxidation of Iron Exposed
to a Saltwater Solution
Griffin Eslinger and Alexander Puckhaber
Co-Principal Investigators
Palmetto Scholars Academy
North Charleston, SC
Description of Experiment
Our experiment compared the structural integrity
of an iron bar oxidized in the presence of saltwater
in microgravity to an iron bar oxidized in the
presence of saltwater on Earth.
Hypothesis
We predicted that the iron bar oxidized in
microgravity would be weaker than the iron bar
oxidized on Earth. Without gravity, the surface
tension of the salt water will be relatively
stronger. Stronger surface
tension in microgravity might
make the oxidation process
happen at a faster pace.
Why this is Important
If we find that the iron bar oxidized in microgravity
is significantly weaker than the iron bar oxidized
on Earth, our findings could impact how engineers
design space missions.
Many pressurized spacecraft are built with iron
alloys. There would most likely be oxygen and
water on the inside. If rust in microgravity causes
iron to become weaker than expected, there might
be a high potential for catastrophic failures.
Materials
Experiment Materials
1. Type Two FME (Fluid Mixture Enclosure)
2. 3.5% salt water solution
3. Iron tensile testing bar (9.5mm by 75mm by 2mm)
Testing Materials
1. Tensile testing machine
2. Scanning electron microscope
Methods
1.
2.
3.
4.
5.
5 identical FMEs prepared
and numbered (+2 old
FMEs)
One (Sample #2) randomly
selected to go to ISS
Sent up for 9 weeks in space
as part of SSEP Mission 4
Upon return, tested at
University of South Carolina
Mechanical Engineering
Department on a Tensile
Testing Machine.
After tensile testing, surface
examined under scanning
electron microscope at
NOAA lab.
Tensile Testing
•
Five properties measured
o
o
o
o
o
Modulus of Elasticity (Young’s Modulus)
Yielding Strength
Maximum Strength
Elongation
Ductility
Tensile Results
Scanning Electron Microscope
Space sample had small circular rust spots.
Controls had larger plate-like rust patches.
Space
Earth Control
Scanning Electron Microscope
The controls had a rougher surface (more rusting)
and a thicker breaking cross section
Space
Earth Control
Summary
• The Iron bar that went to space:
o
o
o
o
o
Yielding Strength: Average
Elongation: Average
Maximum Strength: 2nd highest
Modulus of Elasticity: Average
Ductility: Highest
 But none statistically significant
• SEM showed less rust and in a
•
different pattern.
Hypothesis: false, bar not weaker
Acknowledgments
Thank you to the Partners and Sponsors who
made this experiment possible:
Partners
•
•
•
•
•
•
Space and Naval Warfare
Systems Command
(SPAWAR)
Center for the Advancement of
Science in Space (CASIS)
National Center for Earth and
Space Science Education
College of Charleston
Medical University of South
Carolina (MUSC)
National Oceanic and
Atmospheric Administration
(NOAA)
Sponsors
•
•
•
•
•
ISHPI
Google
CASIS
Palmetto Scholars
Academy Board
Members
Palmetto Scholars
Academy Families
Questions?
Closeup of Stress vs Strain Curves