#include "stdlib.h"
#include <iostream>
#include "math.h"

#define NewtonG 6.67e-11
#define MassE 5.972e24
#define RadiusE 6.371e6
#define RadiusMoon 1.7374e6
#define InitialVel 1.67e3 //~2400/2+460

using namespace std;

int main () {
  
  double height[2], vel[2]={0.,0.}, accel, gLittle, time, timeStep, mass[2], dmOdt, dynamicMass[2];
  height[0] = 0.0;
  vel[0] = InitialVel;
  accel = 0.0; gLittle = 9.8;
  time = 0.0; timeStep = 0.1;
  mass[0] = 2.95e6;//3.58e6 + 1.32e6; //all #'s from https://en.wikipedia.org/wiki/SpaceX_Starship
  mass[1] = 1.31e5+41000;//180.e3 + 120.e3;
  dmOdt = -3.5e7 / (260. * gLittle); //p.11 of https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-07-dynamics-fall-2009/lecture-notes/MIT16_07F09_Lec14.pdf (6.5,380)
  dynamicMass[0] = mass[0];
  dynamicMass[1] = mass[0];
  
  while ( height[0] < 2e6 ) { //(384.4e6-(RadiusE+RadiusMoon)) ) {
    
    gLittle = NewtonG * MassE / ( (RadiusE+height[0]) * (RadiusE+height[0]) );
    accel = -dmOdt*(vel[1]/dynamicMass[0]) - gLittle;
    vel[1] = vel[0] + timeStep * accel;
    height[1] = height[0] + timeStep * vel[1];
    time += timeStep;
    if ( dynamicMass[1] > mass[1] ) {
      dynamicMass[1] = dynamicMass[0] + dmOdt * timeStep; //dmOdt /= 1.;
    }
    else dmOdt = 0.0;
    
    cout << time << "\t" << height[1] << "\t" << vel[1] << "\t" << (vel[1]-vel[0])/timeStep << "\t" << dynamicMass[1] << "\t";
    if ( vel[1] > 11186. ) cout << "ESCAPE!" << endl; else cout << endl;
    
    height[0] = height[1];
    vel[0] = vel[1];
    dynamicMass[0] = dynamicMass[1];
    
  }
  
  return 1;
  
}