Mars Cargo Transportation Systems Enabled By The Dual-Stage 4-Grid Ion Thruster Concept
- Paper number
IAC-07-D3.2.05
- Author
Dr. Cristina Bramanti, European Space Agency (ESA), The Netherlands
- Coauthor
Dr. Dario Izzo, European Space Agency (ESA)/ESTEC, The Netherlands
- Coauthor
Dr. Roger Walker, European Space Agency (ESA)/ESTEC, The Netherlands
- Coauthor
Dr. David G. Fearn, EP Solutions, United Kingdom
- Year
2007
- Abstract
The long-term, sustained human exploration of planet Mars will need a significant number of large modules and consumable supplies to be transported between the surfaces of Earth and Mars in an economic manner. Past exploration approaches such as Apollo to the surface of the Moon had extremely high associated programmatic costs due to the fact that all flight hardware was expended and never reused. Apart from reducing the Mars cargo transportation cost significantly by developing reuseable Earth-to-orbit launchers, another substantial cost saving may be found in developing highly reuseable Earth-to-Mars orbit transportation spacecraft. Such spacecraft should be capable of transporting multi-ton Mars surface infrastructure (pressurised habitation modules, in-situ resource utilisation modules, power modules etc) from Low Earth Orbit (LEO) to a Low Mars Orbit (LMO) and return back to LEO several times, preferably without any in-orbit refuelling. This places a very high delta-V capability on the spacecraft, dictating the use of advanced propulsion systems with a very high specific impulse in order to reduce propellant mass. Solar Electric Propulsion (SEP) technology could offer an attractive solution for this role, but it is clear that the SEP system would need to operate at very high power and specific impulse, combined with lightweight technology for the solar generator and power processing electronics.
A new concept for an innovative Dual-Stage 4-Grid (DS4G) ion thruster has been studied and experimentally proven in the laboratory. The concept offers substantial improvements in specific impulse over the current state-of-the-art, at the expense of a higher power-to-thrust ratio and hence thrust. Operating at a beam potential of 30kV with Xenon propellant, the predicted performance of this advanced thruster is a specific impulse of 19,300 s, with specific power of 100 W/mN and efficiency of over 60
In the paper, we present the basic concept, design and measured performance of the advanced dual-stage gridded ion thruster and assess the potential benefits and exploitation of this technology for multiple round-trip Mars cargo transportation systems requiring very high delta-V propulsive capabilities. Such benefits could include a reduction in the total mass to Low Earth Orbit for a given amount of cargo mass delivered to Low Mars Orbit per year, leading to the use of lower cost launchers or a reduction in the number of launches of a given launcher compared to present systems. However, this needs to be assessed. An Electric Propulsion Mission and System Optimisation tool, developed by the Advanced Concepts Team, is applied to a reference cargo transportation scenario and architecture in order to find optimum system design solutions in the 100-500 kW power range in terms of minimum transfer time and maximum cargo mass within launcher constraints for a number of round trips to Mars with a fixed cargo and no in-orbit refuelling. (launch, spacecraft system design, EP system performance and low-thrust trajectory combined). SEP and NEP options will be assessed for the design of the high power cargo tug vehicle. The key design parameters, sizing and configuration of such a vehicle concept are then presented, along with the enabling power/propulsion system technologies for its realisation.
- Abstract document