Building Launch Assist System Technology using Electricity and Magnetism
I. Background and Motivations
For the last half-century, the fundamental design of mission launch technology has changed very little. The most significant disadvantage of the current launch system is weight and cost of the propellant. Propellant typically comprises 90% of the weight of the total launch system. Much of the energy stored in the propellant is expended in raising the altitude of the propellant itself. It quickly becomes obvious that vast improvements to any new launch delivery technology would depend upon the reduction of the amount of propellant necessary to reach orbital velocity.
In this proposal we shall focus upon the application of an Electromagnetic Launch-Assist System (ELAS) which will vastly reduce the amount of propellant necessary to reach lunar orbital speeds. While an earth based ELAS needs to overcome significant drag penalties, a lunar ELAS would be very attractive as there is no atmosphere on the Moon. An ELAS would provide the necessary thrust to escape lunar gravity by using stored electric energy instead of chemical propulsion. This would eliminate the need to either bring propellant to the moon or generate propellant on the surface of the moon.
This project will support NASA’s vision for space exploration by easing the economic requirements of maintaining a lunar base. By eliminating the need for propellant to get off the lunar surface, we hypothesize the ELAS will lower the cost to travel to and from the moon. This will enable larger payloads to return to earth from the lunar surface than what otherwise be possible, and has the potential to be safer than chemical propellants.
The operating principles of the ELAS (a.k.a. “railgun”) are relatively simple in concept. The system consists of two parallel conductive “rails” which are fixed to the ground. Between the rails lies a conductor (in electrical contact with each rail) which is freely movable parallel to the rails. When current is applied to one rail, the charge flows across the bridging conductor and into the second rail. The current of each rail contributes to inducing a magnetic field between the two rails. The existence of moving charges (in the bridging conductor) in the presence of a magnetic field produces a Lorentz force which propels the conductor forward. A spacecraft is attached to this conductor, and is accelerated with the conductor. The concept is be similar to launching fighter jets from an aircraft carrier’s catapult, except with magnetic propulsion rather than a steam piston.
II. Investigative Questions
- What is the feasibility of building and maintaining a lunar launch-assist system?
- What are the economic tradeoffs between an ELAS and traditional chemical propellant?
- What scale would we need to build to achieve desired velocity for a wide range of mission potentials?
- What stress could the railgun survive?
- What application to business would this project have?
- What are the other functions the ELAS could perform other than launch?
- Engineering study; draft up plans and for the ELAS
- To develop a small scale demo of the concept and put through several tests
- Understand the economic tradeoffs of the ELAS system versus traditional systems.
- Effects on the design of future spacecraft
There will be four mail groups of the project, two people per group, with the culmination resulting in the final experiment of the idea:
- Group 1: Design and construct the railroad function of the railgun
- Group 2: Design and construct the shuttle part of the railgun
- Group 3: Design and construct the energy storage for the railgun
- Group 4: Develop the business aspects of the project
V. Preliminary Timeline
- Week 2, June 8 – 12: Determine final group project topic and make initial presentation, assign project roles, discuss funding with Space Grants.
- Week 3, June 15 – 19: Conduct a cost and feasibility study, develop a list of people to contact or visit on Academy trips, contact them, begin trade analysis, develop requirements
- Week 4, June 22 – 26: Acquire facilities necessary for conducting the experiments and make sure all state and federal laws are being followed in the implementation.
- Week 5, June 29 – July 2: Gather individual parts for experiments.
- Week 6, July 6 – 10: Build individual parts for experiments.
- Week 7, July 13 – 15: Run preliminary experiments and gather materials for secondary experiment.
- Week 8, July 20 – 24: Run secondary experiments and fix any problems with initial experiments.
- Week 9, July 27 – 31: Finalize conceptual design and explore possible furthered research efforts.
- Week 10, August 1 – 7: Prepare and give final presentation.
In essence, the goal of this project is to conduct a feasibility study of the ELAS technology as well as build a small-scale demonstration model of this surface-to-orbit technology. This system would greatly reduce fuel needed to propel the spacecraft form surface to orbit, because the mass of modern launch systems is dominated by the fuels needed to propel it. We feel this “railgun” project would be an important contribution to NASA’s vision for space exploration of the moon and beyond.