Here is a little program:

clg
Vearthpos=150
Hearthpos=150
hdist=0
vdist=62
vspeed=2
hspeed=8
radius=55
fastgraphics

Loop:
distance= (hdist^2 + vdist^2)^(1/2)
gravity= (radius/distance)^2
haceleration=(hdist/distance)*gravity
vaceleration=(vdist/distance)*gravity
hspeed= hspeed-haceleration
vspeed= vspeed-vaceleration
hdist= hdist+hspeed
vdist= vdist+vspeed
clg
circle Hearthpos,Vearthpos,radius
circle Hearthpos+hdist, Vearthpos+vdist, 2
refresh
if distance<radius then print "crash"
if distance<radius then end
goto Loop

end