Project Moon1: A Profitable Minimum Viable Tether

By Vince Cate

For decades, space tethers have been discussed as "future technology." Project Moon1 is a design to change that status to "current technology." This is a proposal for a Minimum Viable Product (MVP) tether system that can launch on a rideshare mission, fly itself to the Moon using electric propulsion, and immediately begin generating revenue by delivering payloads to the lunar surface—and eventually, lifting them off.

Concept: A rotating momentum-exchange tether in elliptical lunar orbit dropping payloads at zero relative velocity.

The Core Concept

Instead of a massive infrastructure project requiring billions of dollars, Moon1 is a self-transporting tether. It uses a cluster of high-efficiency ion thrusters to spiral from Low Earth Orbit (LEO) to Lunar Orbit over 6 months. Once there, it spins up to function as a "skyhook," cancelling its orbital velocity at the lowest point (perigee) to gently drop payloads onto the Moon or catch payloads tossed up from the surface.

1. The Mission Profile

The mission is designed in phases to minimize risk while allowing for early revenue generation.

Phase 1: Transit (Months 0-6): The stacked system launches to LEO. Using solar power and a cluster of 12 Turion ion thrusters, it raises its orbit, traverses to the Moon, and captures into a high-eccentricity polar orbit.
Phase 2: Deployment & Spin-up: We use "Gravity Gradient Pumping" to initiate rotation. The heavy "Ballast Bus" (engines + solar) retracts and extends the tether at resonant frequencies to build up rotation without fuel.
Phase 3: Downhill Logistics: The tether drops 50-100 small payloads (10kg each) to the surface. The tether tip velocity (~1.6 km/s) cancels the orbital velocity, allowing payloads to "hover" momentarily before dropping 100m to the surface.
Phase 4: Uphill Logistics (The "Catch"): Surface robots (delivered in Phase 3) build a simple catapult. They toss regolith bags upward. The tether, now empty, catches them to recharge its momentum.

2. System Architecture & Specs

To keep costs low, we use COTS (Commercial Off-The-Shelf) components where possible. The critical enabler is the new generation of high-thrust, high-ISP electric propulsion.

The Thruster Array

We have selected the Turion TIE-20 GEN2. A single unit is too small for a quick transit, so we use a cluster. This provides redundancy and the necessary thrust to reach the Moon in under 8 months.

Specification	Value per Unit	System Total (12 Units)
Thrust	79 mN	~0.95 Newtons
ISP (Specific Impulse)	4,500 sec	4,500 sec
Power Consumption	2,000 W	24 kW (Peak)
Propellant	Krypton	~350 kg total mass

Mass Budget & Cost Estimates

The "Ballast Bus" contains the solar arrays, thrusters, and winches. It acts as the counterweight. The "Tip Assembly" is kept as light as possible (approx 20-30kg) to minimize the required tether mass.

Component	Est. Mass (kg)	Notes
Payloads	500 kg	50 customers @ 10kg each
Tether	350 kg	~30km Zylon/Spectra (tapered)
Tip Assembly	30 kg	Net, comms, grapple, sensors
Ballast Bus (Dry)	750 kg	12x Thrusters, 26kW Solar, Structure, Winch
Propellant (Krypton)	350 kg	Sufficient for LEO->Moon + station keeping
TOTAL LAUNCH MASS	~1,980 kg	Fits easily on Falcon 9 Rideshare

3. The "Killer App": The Catch

Dropping payloads is useful, but lifting them is revolutionary. Once the payloads land, they reconfigure into small robotic backhoes and a mechanical catapult.

Backhoe robots fill bags with lunar regolith to create standard mass payloads.

The Net: The tether tip features a 10m diameter net with 5cm holes.
The Hook: Payloads have grappling hooks designed to slip through the net mesh and catch.
The Toss: A simple spring or electromagnetic catapult on the Moon tosses the payload 100m up.
Practice Perfect: We can perform hundreds of "dry runs"—tossing dummy payloads and sweeping the net past them—without attempting a catch, until the timing is perfected to the millisecond.

If we catch a payload, we gain momentum. If we drop a payload, we lose momentum. By balancing drops (Earth to Moon) and catches (Moon to Orbit), the system can theoretically run indefinitely without using propellant for orbital maneuvering.

4. Economics & Crowdfunding

This mission is small enough to be funded by a mix of anchor investors and crowdfunding.

Cost Item	Estimate
Launch (SpaceX Rideshare @ $1k-2k/kg)	$2.0M - $4.0M
Thrusters (12 x Turion TIE-20)	$1.8M
Bus, Solar & Tether Hardware	$3.0M
TOTAL DIRECT MISSION COST	~$7M - $9M

Revenue Potential:
We can sell payload slots to universities, space agencies, and private collectors.
Pricing: $50,000 for 1kg, or $400,000 for 10kg.
If we sell just 20 slots at the 10kg rate, we raise $8 Million, essentially covering the hardware and launch costs.

5. Future Roadmap: The L5 Gateway

Once the "Catch" is proven, we can scale up. By adjusting the tether length and rotation speed (using the mobile ballast module), we can release payloads at a higher velocity, tossing them directly from Lunar Orbit to the Earth-Moon L5 Lagrange point. This creates a "Propellant-Free Pipeline" from the Lunar surface to deep space.

Calculations based on standard orbital mechanics for a polar frozen lunar orbit (Perilune ~100km). Delta-V budget from LEO to Moon estimated at ~7.5 km/s for low-thrust spiral trajectories.

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