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E-STEP: Extraterrestrial Surface Terrain EVA CramPon

Eric Miller - ASTE 527

December 13th 2022

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Current Physiological & EVA Issues with Partial Gravity

  • Biological maladaptation

  • Slow & physically taxing
  • Historically prone to imbalance - slipping and falling

Astronaut Harrison Schmitt - Apollo 17

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The Problem with Partial Gravity

  • Humans evolved to walk in Earth-like conditions
  • Toe-toe step
  • Soleus deactivation, gastrocnemius activation

Muscles of the lower leg

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Next Generation: Artemis xEMU EVA Suit

  • Major improvements over Apollo EVA suits

  • Lower pressure, increased mobility, increased range
  • Facilitates new technologies to address some partial gravity issues
  • Expected to remove bunny-hopping and allow for some form of lunar walking

Apollo and Artemis EVA suits

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Context

  • Extraterrestrial Exploration - Moon as a case study

  • Most permanently shadowed regions are inaccessible to EVA
  • Current EVA requirement is a 20° slope
  • Limited Exploration – Walk back range – 1.38 km
  • EVA following lander touchdown

Artemis Pressurized Rover Concept Art

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Operations Rationale

  • Geological exploration needs unplanned EVA

  • Landing location determined by landing terrain and accessible nearby features for EVA

Red = 100m landing circle (slope <5°. Yellow = max walking range 1.38 km radius

Potential Artemis III Landing and First EVA Location (de Gerlache-Shackleton ridge)

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E-STEP Concept

  • External crampon system

  • Attaches around Artemis xEMU EVA Boot
  • Interfaces with each step to “grab” on to the Moon
  • Removable in case of issue

STEP: Side View

STEP: Bottom View

  • Sealed bearings and orifices to keep lunar dust out
  • Ratcheting mechanism to lock foot in place similar to snowboarding shoe

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Goals

  • Create external downwards force during EVA

  • Potentially allow for EVA over more difficult terrain
  • Increase stability over uneven terrain
  • Facilitate a more Earth-like gait

Apollo 17 - Lunar Crater near Station 1

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Operation

  • Retractable needles are a relatively passive component

  • Actuated by pressure sensor under the ball of the foot
  • Microspines are sole active component

Microspines

Needles

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Traction Mechanism

  • Needles angled to aid in walking and provide more traction

  • Needles retract when stepping on rocks

Toe

Heel

  • Microspines available to catch on any rock under step
  • Needles catch on irregular topography of regolith or sink into lunar dust

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Some Hard to Access Extraterrestrial / Lunar Features

  • Tops of boulder and between them – to emplace payload

Lunar Lava Tube

  • Areas inaccessible to rovers
  • Lips of lunar lava tube skylight
  • Cliff faces
  • Steep slopes
  • Crevices

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Increasing Scientific Capabilities

  • Allows access to more permanently shadowed regions - key scientific points of interest
  • Facilitate sampling of lunar boulders and steep rocky surfaces

Harrison Schmitt - Apollo 17

  • Allow for determination if sufficient cold traps exist in PSRs to retain volatiles

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Extending EVA

  • Rappel into ravines and allow for vertical EVA
  • Can be paired with other mountaineering tools
  • Facilitate safer exploration of lunar caves

Rappel Concept Art

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Merits

  • More Earth-like gait - more natural/intuitive

  • Decrease consumable usage
  • Lessen fatigue and improve balance
  • EVA becomes more ergonomic
  • Make EVA faster and more productive
  • Allow for EVA over a wider range of terrain

Limitations

  • May be difficult to design around current xEMU Artemis Suits
  • Difficult to test and optimize on Earth
  • Will require study & test before being used
  • TPS unfinished for xEMU boot for lunar south pole

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Further Potential Merits

  • May improve or compensate for some biological maladaptation

  • May reduce body’s tendency to switch from using gastrocnemius muscle over soleus muscle
  • May facilitate heel-toe walking

Lips of Lava Tube Skylights

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Future Studies

  • Simulated terrain testing with a partial lifting harness

  • Parabolic flights
  • Neutral and partial buoyancy testing
  • Partial gravity treadmill
  • Develop alternate prototypes - specialized based off terrain
  • Decide on best microspine and needle design

Methods

Data

  • Space qualification - electrostatic lunar dust
  • Ease of stowage - minimize footprint
  • Minimize mass, risk to EVA suit, and increase durability
  • Materials testing

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Questions?

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Sources

Miller, Matthew & Claybrook, Austin & Greenlund, Suraj & Marquez, Jessica & Feigh, Karen. (2017). Operational Assessment of Apollo Lunar Surface Extravehicular Activity. 10.13140/RG.2.2.28009.80487. Link

Mackin, M., Gonia, P. and Lombay-Gonzalez, J. (2010) Effective presentation of metabolic rate information for lunar extravehicular activity (EVA) - NASA technical reports server (NTRS), NASA. NASA. Available at: https://ntrs.nasa.gov/citations/20100039148 (Accessed: November 22, 2022).

Yoshinobu, O. (2022). 6th Global Moon Village Workshop; Symposium. In Plenary Session 1. Los Angeles, CA.

Scoville, Z. (n.d.). Artemis III Eva Mission Capability for de Gerlache-Shackleton Ridge - NASA Technical Reports Server (NTRS). NASA. Retrieved December 6, 2022, from https://ntrs.nasa.gov/citations/20210026296

XEVA System Requirement Document Attachment J-02 80JSC021R0006, (2021), NASA

Sustained Phase Human Landing System (HLS) Program System Requirements Document, (2021), NASA, HLS-RQMT-006

Merriam, E. G., Berg, A. B., Willig, A., Parness, A., Frey, T., &amp; Howell, L. L. (2016). Microspine Gripping Mechanism for Asteroid Capture. BYU ScholarsArchive. Retrieved November 9, 2022, from https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=1187&amp;context=studentpub