Instrumented Cylindrical Punch Indentation of Solid Nitrogen at 30-40 K.

Area of Science:

• Materials Science
• Cryogenics
• Planetary Science

Background:

• Mechanical response data for solid nitrogen is essential for NASA's Triton Hopper project concept validation.
• Existing mechanical properties data for solid nitrogen is limited, with only three known indentation measurements between 30 and 40 K.

Purpose of the Study:

• To generate new mechanical response data for solid nitrogen under Triton-relevant thermodynamic conditions.
• To validate and support the development of NASA's Triton Hopper project.

Main Methods:

• Development of a custom instrumented hardness tester designed to interface with a cryostat.
• Cylindrical punch indentation testing conducted at temperatures between 30 and 40 K.
• Acquisition of pressure versus displacement curves and hardness values.

Main Results:

• Solid nitrogen exhibited a hardness ranging from approximately 2 kg/mm² to 0.5 kg/mm² within the tested temperature range.
• Observations suggest potential brittle fracture behavior at the lower end of the tested temperature range.

Conclusions:

• The study successfully generated novel mechanical data for solid nitrogen under relevant cryogenic conditions.
• The findings provide critical data for the mechanical validation of the Triton Hopper mission.
• Further investigation into the brittle fracture behavior of solid nitrogen at low temperatures is warranted.