Direct Fusion Drive for Fast Mars Missions

Joseph Mueller of Princeton Satellite systems presented to the NASA Future in Space Operations (FISO) on Direct Fusion Drive for Fast Mars Missions

* Total mass of the mission is critical
* Cost is proportional to mass

Princeton Satellite Systems has licensed two fusion patents from Princeton University

NBF Note – John Slough is also working on direct drive fusion system which does not need Helium-3 and has different technical issues and potential performance I like the John Slough system more. This system has some interesting analysis but is shaped as a justification for the overpriced Space Launch System. This Princeton system looks like it will take a lot longer and cost more to get anywhere near ready.

Challenges to Direct Drive Fusion for this Princeton Satellite approach

* Need to demonstrate a burning plasma
Will be done in PFRC-4

* Fusion power demonstrated in Tokamaks – 10.7 MW in the Princeton Tokamak Fusion Test Reactor (TFTR) and – 16 MW in the Joint European Torus

* Need to get Helium-3
– Not that much needed for spaceflight, terrestrial sources have enough to support Mars exploration

* Must minimize engine mass

* Need high power per unit mass

* Need ways to startup the reactor in space

* Long duration cryogenic fuel storage in space

* Need all the supporting hardware to be low mass and have high reliability

* Ideally last for multiple missions

* Radiation shielding
– Neutrons (but not too many)
– Bremsstrahlung – x-rays

1. Low thrust trajectory takes 6 years one way and has a ∆V of 5.6 km/s

2. High thrust- Hohmann Transfer. Total mission 975 days
* 258 days in transfer orbit one way
* 459 days waiting to return

3A. Moderate Thrust – Direct Fusion Drive
Continuous Thrust Optimization
Total ΔV of 106.7 km/s
Total trip time of 277.5 days (Outbound transfer is 186.2 days)

3B. Moderate Thrust – Direct Fusion Drive
Impulsive Lambert solution (Ideal)
Total ΔV is 57.1 km/s
Total mission time is 244 days

3C. Modified Lambert Results
Total ΔV of 60.02 km/s
Total trip time of 307.8 days (Outbound transfer is 198.2 days)
Total mass of 120.7MT

This project funding and next steps

$58M to get to PFRC-4 via PFRC-3
Burning plasma in PFRC-4
$10M/5 years PFRC-3, $48M/8 years PFRC-4
Demonstrate magnetic nozzle
Demonstrate thrust augmentation
Demonstrate power generation
A lot of physics still needs to be done

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