Spiral-Transfer from LEO to LLO

Using GMAT for specific types of missions.

Spiral-Transfer from LEO to LLO

Postby Ultron » Tue Aug 05, 2014 9:11 pm

Hello everyone,

first of all I would like to introduce myself:

My name is Marcel, I'm a student of aerospace engineering at the University of Stuttgart, Germany where I'm currently working on a project concerning an comparison and assessment of various transportation scenarios for use between LEO and LLO. I chose GMAT as a tool for a (preliminary) mission analysis and I'm currently getting used to it.

Some of the scenarios I'm investigating employ means of electric / low-thrust-propulsion. Therefore only finite-burn-maneuvres are possible resulting in a spiral-like shaped trajectory. I'm currently exploring ways of implementing this continuous low-thrust finite-burn maneuvre in GMAT and experience some difficulties in doing so.

I would appreciate it if you could help me with my starting difficulties:

1. I want to define an initial orbit around earth where the spacecraft's thruster starts burning (low-thrust, around 1 - 10 N)

2. The final orbit should be around the Moon - approximately in the equatorial plane.

3. Anything between these two orbits should be accomplished with the low-thrust thruster(s): the inclination-change and the approach to the moon.


At the moment I'm considering the employment of two propagators (like in the impulsive lunar-transfer tutorial), one for the SOI of the Earth and one for the SOI of the Moon - the change would be at around RMAG 325000 between the spacecraft and the Earth's center. From there on it would be a downward spiral in the lunar-centric coordinate system.


At the moment I see no possibility of varying the amount of thrust or the attitude during the whole low-thrust finite-burn maneuvre. Is there any possibility or another workaround?


Is there any existing example for this scenario that I could use (by scaling). E. g. a model of the SMART-1 Mission (which worked in a rather comparable way).



The trajectory doesn't need to be optimized, for the moment I'm just trying to simulate it properly.


It would be great if anyone of you had an idea on how to achieve this or could provide me with some (maybe already existing) examples.

I kindly appreciate your help.

Thank you very much.


Regards

Marcel
Ultron
 
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