dim GravParam = Length^3 / Time^2;

type TransferResult {
    TransferResult(dv1: Velocity, dv2: Velocity, total_dv: Velocity, tof: Time),
}

const node r_earth: Length = 6371.0 km;
const node gm_earth: GravParam = 3.986004418e5 km^3/s^2;

param parking_alt: Length = 200.0 km;
param target_alt: Length = 35786.0 km;

node r1: Length = @r_earth + @parking_alt;
node r2: Length = @r_earth + @target_alt;
node a: Length = (@r1 + @r2) / 2.0;

node v1: Velocity = sqrt(@gm_earth / @r1);
node v2: Velocity = sqrt(@gm_earth / @r2);
node dv1: Velocity = sqrt(2.0 * @gm_earth * @r2 / (@r1 * (@r1 + @r2))) - @v1;
node dv2: Velocity = @v2 - sqrt(2.0 * @gm_earth * @r1 / (@r2 * (@r1 + @r2)));

node transfer: TransferResult = TransferResult(
    dv1: @dv1,
    dv2: @dv2,
    total_dv: @dv1 + @dv2,
    tof: PI * sqrt(@a ^ 3 / @gm_earth),
);

node total_dv: Velocity = @transfer.total_dv;
node tof_hours: Time = @transfer.tof -> h;