I have done some more work on my Mars flyby trajectory Maple worksheet.  

Thank you again for your help on the piecewise function problem I was having.

@SUN ZHUOYU You can adjust the fonts on the axes using, for example, axesfont=[Helvetica,bold,18].  Also, again for example,the label's font using, for example, labelfont=[Helvetica,bold,24] inside your display command.

q1_(1).mw

Take a look at this and see if it is what you expect.  Perhaps you can "eye-ball" the maximum value for a particular q and p.

plot(rhs(solution), t = 0 .. 600, view = [default, -600000 .. 0], size = [1200, 1200], gridlines = true, color = red, thickness = 5, background = "Azure", axesfont = [Helvetica, bold, 24])