Transcript In-situ Propellant Production and ERV Propulsion System

In-situ Propellant
Production and
ERV Propulsion System
Preliminary Design Review
2/6/01
Adam Butt
In-situ Propellant
Production
Propellants selected to be produced
Reasons for the selection
Method of production to be used
Risk Analysis
Selections and Criteria
Methane
Advantages
CH4/LOX reaction
capable of Isp~365s
Relatively efficient and
cost effective to make
Disadvantages
Must be cryogenically
stored
Requires 3.5 times as
much O2 for optimal
reaction
Methanol
Advantages
Does not require
cryogenic storage
Higher density 
smaller tanks
Requires only 1.5 times
as much O2
Disadvantages
CH3OH/LOX reaction
Isp~340
Method of Production
Methane
Sabatier Reactor
LOX
Water Electrolysis
Zirconia Cell process
Methanol
2C0+3H2CH3OH+2H2O
Methane derived methanol
More in-depth study
needed
ERV Propulsion System
Consists of two stages
Lower stage of Methanol/LOX
Utilizes methanol’s higher density and lower
mixture ratio to achieve an overall smaller and
lighter system than just methane/LOX (Zubrin)
Upper stage of Methane/LOX
Utilizing this reaction’s increased performance to
provide final impulsive DV to the smaller upper
stage
Staging Comparison
Assumptions: DV=5.7km/s, mpayload=33tonnes, neglect drag/gravity loss
Two stages – both
Methane/LOX
Total
mass=190tonnes
Vol of CH4=65m3
Vol of LOX=96m3
Two stages – 1st
Methanol/LOX, 2nd
Methane/LOX
Total
mass=185tonnes
Vol of CH3OH=70m3
Vol of LOX=74m3
Power Requirements
Based on the following equation,
Pe = [0.145(MT)1.238] kW
And on the ~115kW power production of the
nuclear reactor
It will take around 800 days to produce all the
necessary propellant. Therefore as the HAB departs
Earth 2 years after the ERV, around 90% of the
propellant will have been produced.
Basic Risk Assesment
The main back up will be the 2nd ERV/in-situ
plant arriving around the same time as the
astronauts
In-situ plant
Zirconia cell process involves the use of large brittle
cells – Cannot withstand high g-loading, additional
replacement cells need to be brought.
Sabatier reactor comprised of simple, rugged steel
pipes
ERV Launch System – The more stages the
more complexity, the greater the risk
Future Work
Research Methanol production in greater
depth
Size in-situ production plant
Further asses possible failure modes, and
determine necessary redundancy plans