Mars Rover Redesign

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Context

To conduct human exploration missions to a variety of destinations, NASA has developed the MMSEV, Multi-Mission Space Exploration Vehicle, a modular spacecraft system that is primarily comprised of a pressurized core cabin that can be configured with a variety of mission-specific augments, including a suit-port, windowed nosecone, and a chassis with wheels to serve as a rover with expedited Extravehicular activity (EVA), and life support systems, for in-space and surface exploration of planetary bodies, including near-Earth asteroids and Mars.
However, during the 2009 Desert Research and Technology Studies (DRATS), it was found that the latest prototype of the MMSEV had ergonomic issues.
During his time at the design school in Harvard, Maharshi, with his architecture and computational design background, and his colleague, Francisco Jung, with his knowledge of the subject was acquired while working at NASA. Under the advisory of Professor Sawako Kaijima, students carried out an independent, true to science, yet speculative intervention to improve upon the existing MMSEV Nosecone design and address the issues of ergonomics brought to the fore during DRATS.
SUMMARY

Redesigning crewed exploration rovers to make them more human centered

PLACE

Harvard GSD

DATE

2019

Challenge

Improving NASA’s existing Space Exploration Vehicle (MMSEV) design with a focus on Human Factors such as visibility and ergonomics, to address fatigue build-up and situational awareness.
SUMMARY

Redesigning crewed exploration rovers to make them more human centered

PLACE

Harvard GSD

DATE

2019

Nosecone issue reported in 2B (Top, Bottom Left); Form-factor for proposal 3A (Bottom Right)

Research

The MMSEV is a conceptual platform derived from the Apollo missions as well as the unmanned rovers on Mars that, in the near future, may be used to house and transport astronauts (Bobskill, et al., 2015; Drake, 2009; NASA, 1971; NASA 1972; NASA 1973).
The 2009 Desert Research and Technology Studies (DRATS) found that the prototyped 2B glass nosecone for the MMSEV pressurized rover had issues with visibility and foot clearance due to its dome-like geometry (Abercromby, Gernhardt, & Litaker, 2010)

The structural configuration of the MMSEV has morphed since the 2009 DRATS To accommodate various mission requirements. In-space configurations require significant structural attention to the cabin's positive pressure, which entails an affinity for symmetric and curvilinear form. This led to a redesign of the windowed nosecone to meet the structural requirements for an asteroid free-flyer and address the issues of visibility reported in the DRATS 2009 experiment (Image 2).

A human factors assessment at the National Buoyancy Lab revealed that although visibility was not an issue for the crewmembers in simulated microgravity when tested in a rover configuration under 1G conditions, there were issues with foot collision and difficulties with peripheral vision.

SUMMARY

Redesigning crewed exploration rovers to make them more human centered

PLACE

Harvard GSD

DATE

2019

NASA's Multi Mission Space Exploration Vehicle, Generation 2B

Requirements and Goals

Developing a workflow that would enable us to find a balance between maximum visibility, and minimum mass increment, without compromising structural integrity.
The specific architecture element of the MMSEV that was investigated is the glass nosecone augment. Primary design considerations investigated in this research included Minimal mass, which refers to the bias of the rocket equation toward structures with the lowest weight in materials, maximum visibility is the overall percentage of fenestrations in areas that crewmembers focus most on, and structural integrity, which was measured by the standard displacement, Von Mises, stiffness factor, and stress lines. From a top-down perspective, crewmembers require maximum visibility for surface operations. The least amount of replaceable window panels would decrease maintenance and preempt additional weight for spares.

Based on this information, both bottom-up and top-down strategies for design considerations were incorporated to design a novel MMSEV rover nosecone. For the bottom-up approach, a CAD model of the nosecone was examined through several finite element analyses (FEA) to deduce structural design elements. Proposals for improvement on human factors such as visibility were approached in a top-down fashion wherein decisions about aperture placement relative to stress concentration regions were deduced from the FEA.

Structural analysis of the existing 2B glass nosecone was done as a benchmark case for potential design iterations, SEV 3, to meet or exceed.

The experimental setup consisted of 4 analyses:

1. Analysis I, of the benchmark 2B

2. Analysis II, of the SEV 3A shell with dead and live load

3. Analysis III, of the SEV 3A shell with dead and live load and various iterations of window openings.

4. Analysis IV of the iteration with windows with the minor maximum deflection was further reinforced with corrugations.

SUMMARY

Redesigning crewed exploration rovers to make them more human centered

PLACE

Harvard GSD

DATE

2019

Analysis I, 2B as Benchmark showing Von Mises Stresses and Stiffness Factor

Analysis

With 2B as a benchmark and using computational tools typically used in the architecture, engineering, and construction (AEC) industry to carry out Finite Element Analysis (FEA), comparisons were made to inform design changes.
We used numerical and visual data such as weight and stress distribution. In turn, this design development exercise brought together different approaches held by human-factors designers and structural engineers.
The exercise was intended- to gather information and develop an intuitive understanding of how the stresses act on the nosecone shells with various form factors, based on visual cues provided by the analysis.- as an example of how the workflow introduced in this experiment can be incorporated to make progress towards a more resolved design.

Historically, there has been a consistent divide between design and engineering cultures. From a designer’s perspective, this experiment has also been an exercise in unpacking the nuances of engineering that play an essential role in guiding design decision

SUMMARY

Redesigning crewed exploration rovers to make them more human centered

PLACE

Harvard GSD

DATE

2019