[Tutor] Problems using odeint

[Grace Roberts]

Hi,
I'm a python beginner, currently using scipy's 'odeint' to compute to a set of ODEs (obtained by splitting Newton's law of gravity ma=-Gm1m2r/r^3 in two ordinary differentials). The idea is that I'm modelling the orbit of a satellite as it approaches Mars.
I have two problems:-For certain initial conditions the programme displays impossible orbits, showing the satellite making immediate sharp turns or jumping up and down in velocity. The exact same code can also end up displaying different graphs when run multiple times. For example when initial conditions are set at:  xx0=[1000.,10000.,1000.,10000.].-Often when run an error message appears saying: "Excess work done on this call (perhaps wrong Dfun type). Run with full_output = 1 to get quantitative information." You can see that as part of the odeint function I tried to stop the excess work by increasing the maxstep and I also tried to run with full_output =1. It's quite possible I haven't done this right. If I have, what else can I do to stop this message from appearing?
I've attached a quick print-screen of the code.
Any help is much appreciated. 		 	   		  
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