Week 1 HW: Final Project Ideas

HTBAA Homework #1: Self-Healing Biopolymer for Mars Habitat Repair

Ansh Jaiswal

(1) What would you like to biomanufacture, and why?

Target: An engineered bacterial cellulose-based biopolymer patch/sealant that can be produced on-demand to repair micro-meteorite punctures, seal cracks, or reinforce weak points in a Mars habitat’s structural skin.

Why it matters: Habitat hull integrity is a life-or-death constraint on Mars — a single unpatched puncture causes catastrophic pressure loss. Earth-supplied repair kits are finite and can’t be resupplied quickly (a Mars resupply mission takes roughly 6–9 months). Bacterial cellulose is an especially strong candidate because it is mechanically robust (high tensile strength, comparable to some plastics), can be grown into custom shapes/sheets, and — because it is produced by a living culture — can theoretically be regenerated indefinitely from simple feedstock rather than shipped as a fixed, exhaustible supply. This is both a utilitarian safety project and a genuinely interesting materials-science problem: making a renewable, self-produced structural material in an environment where nothing is renewable by default.

(2) What living system would you use?

Chassis: Komagataeibacter xylinus (formerly Acetobacter xylinum) — the standard bacterial cellulose producer, well-studied and already used commercially (e.g., in wound dressings and some sustainable textiles).

Process, high level:

• In: a simple carbon/nitrogen feedstock (glucose or sucrose, plus a nitrogen source), water, mild aeration, near-neutral pH, roughly 28–30°C.
• Biological process: K. xylinus secretes cellulose nanofibrils extracellularly, self-assembling into a dense, continuous pellicle (mat) at the air-liquid interface of the culture.
• Out: a wet cellulose pellicle, harvested and shaped (e.g., into a flat patch or a mold matching a specific repair geometry), then dried/treated for mechanical strength and possibly infused with a sealant resin for airtightness.

Assumptions: feedstock (glucose) is either pre-supplied or derived from recycled biomass/food waste onboard; the pellicle’s growth geometry can be controlled well enough with a mold to match irregular repair sites; drying/curing can happen in a low-power onboard unit.

(3) How would you use automation?

Technology: A combination of an automated bioreactor/culture module for growth, plus a robotic liquid-handling and molding system (Opentrons-style) for feedstock preparation and shaping — paired with an ML-based monitoring layer to track culture health.

What’s automated, and why:

• Feedstock/media prep: automated liquid handling mixes glucose/nitrogen media in the right ratios without a human technician.
• Culture monitoring: sensors plus an ML anomaly-detection layer (an ensemble / Isolation Forest–LOF style approach) flag contamination, unexpected pH drift, or stalled pellicle growth — critical since there is no onboard microbiologist to visually check culture health daily.
• Molding/shaping automation: once damage is detected (e.g., via a habitat pressure-sensor alert), the system can automatically start a batch sized to the specific repair geometry, minimizing wasted material and crew intervention.

(4) How much would you need to make, and how long would it take?

(a) How much?

Define scale: enough patch material to repair a meaningful puncture/crack event during a 3-year Mars mission for a habitat with roughly 500 m² of surface area (a reasonable multi-module habitat estimate).

• Assume micro-meteorite/micrometeoroid strikes serious enough to require patching occur at a rate of about 1 event per 6 months (a conservative placeholder — flagged as an unknown below), i.e. ~6 patch events over 3 years.
• Assume each patch is 0.5 m × 0.5 m × 3 mm thick:

$$0.25 \text{ m}^2 \times 0.003 \text{ m} = 0.00075 \text{ m}^3 \text{ per patch}$$

• Bacterial cellulose density ≈ 1.0 g/cm³ (near water density when wet-processed):

$$750 \text{ cm}^3 \times 1 \text{ g/cm}^3 = \textbf{750 g per patch}$$

• Total:

$$6 \text{ patches} \times 750 \text{ g} \approx \textbf{4.5 kg}$$

of biopolymer over the mission, plus a ~30% buffer for failed batches/trimming waste → ~5.9 kg.

(b) How long?

• Typical bacterial cellulose pellicle growth time: ~7–14 days for a usable mat thickness (static culture); using 10 days as a working estimate.
• Assume a single culture tray produces one ~0.25 m² patch per growth cycle.
• Per-patch timeline: 10 days growth + ~2 days drying/curing = 12 days per patch.
• Sequential (single culture module):

$$6 \text{ patches} \times 12 \text{ days} \approx \textbf{72 days}$$

total active production time across the mission — very manageable spread over 3 years.

• If multiple patches are needed urgently (e.g., after a larger impact event requiring 2–3 patches at once), parallelizing with 3 culture trays cuts a multi-patch emergency response to ~12 days instead of 36. The real value of automation here is fast turnaround during an actual emergency, not raw throughput.

(5) What don’t you know yet?

• Actual micro-meteorite impact rate and damage severity distribution — the “1 event per 6 months” assumption is a placeholder; the real number depends on orbital/atmospheric data (Mars’ thin atmosphere offers some protection versus the Moon) and would need mission-specific risk modeling to size production capacity correctly.
• Mechanical performance of bacterial cellulose in a Mars environment — whether the material’s strength, flexibility, and airtightness hold up under Mars’ temperature swings, low pressure, and dust exposure, or whether it needs a composite/resin treatment to be viable as a real structural patch.
• Growth reliability in a fully automated, unsupervised closed-loop system — static pellicle culture is usually manually tended on Earth; whether an automated system can reliably detect and correct problems (contamination, uneven pellicle formation) without human visual inspection is untested at this scale.

AI Usage Disclosure

I used Claude (Anthropic) to brainstorm and help structure this project idea, including generating candidate project directions, drafting explanations for the living system and automation sections, and working through the back-of-the-envelope scale/time calculations. I reviewed and understand all content presented here. Representative prompts used included:

• “Can you suggest me a project looking at my background” (with resume attached)
• “I like the idea of Self-healing biopolymer for habitat repair”
• “Tell me 5 ideas that might be useful”
• “Can you make a pdf for this also reference used Claude for brainstorming as asked in the main document generate a document”

Final Project