Direct Fusion Drive for Fast Mars Missions

August 14, 2013

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