Satgen138  Moon and Planets, Artificial Satellite Orbits  GM4IHJ 17 Nov 91

We will soon have satellites orbiting the Moon , and in a year or two,
Mars. Can we treat their orbits like earth orbits? Yes but only with care.
However getting approx data is easy using the following BASIC program:-
10 CLS:PRINT"CIRCULAR ORBIT HEIGHT+PERIOD - FOR SATS OF PLANETS OR MOON"
15 PRINT: LET G0=7.5369E13 : REM GM of Earth in (Orbs/day)^2/(kms)^3 
20 PRINT"Factor Moon .0123 : Mercury .0558 : Venus .815 : Mars .1074"
22 PRINT"Factor Jupiter 317.9 : Saturn 95.15 : Uranus 14.54 : Neptune
17.23" : PRINT : REM Earth = 1
24 Print "Radius Moon 1738 : Mercury 2439 : Venus 6052 : Mars 3398"
26 PRINT"Radius Jupiter 71398 : Saturn 60330 : Uranus 25400 : Neptune
24300" : PRINT : REM Earth = 6378
30 Input "Factor  = ";factor
40 Input "Moon or Planet Radius  = ";R
50 Input "Orbit Height kms = ";H : PRINT
60 let N0=((G0*FACTOR)/((R+H)^3))^(1/2) :LET PERIOD = 1440/N0 : PRINT
70 PRINT "Period  = "; PERIOD;"  mins   . Height  = ";H;"  kms"

Typical Answers      Height   Moonsat orbit period   Marsat orbit period
                      100 kms        117.8 mins          104.7 mins
                      250            132.6               111.5
                      500            158.3               123.2
                     1000            214.3               147.6
                     2500            412.6               229.2
                     5000            827.1               389.5
                    10000           1902.0               785.0

Please be careful . Some of the orbits you calculate may be occupied
already by Moons , or rings. Some may resonate with Moons and be unstable
. Some will be seriously perturbed. By the Earth or a planetary Moon.Some
as in the case of the Moon rotate around a body which does not spin on its
axis, so the orbit follows a surface track quite unlike Earth orbiter
tracks which shift markedly in Longitude every orbit because of Earth's
axial rotation.
In the case of our Moon and some of the smaller planetary moons , their
shape is irregular or unusual. Our Moon resembles a rugby ball ( what
Americans would call a football ) being longer on one axis than the other
axis. Indeed the Moon has no axial spin and points its long axis
permanently at the Earth. Worse still a satellite does not get far from
the Moon before the Earth begins to seriously perturb its orbit. Please
note how slow Lunar orbits are compared with Martian or Earth orbits
despite the Moon orbits much smaller circumference. This is a warning to
would be Moon Astronauts to keep their vehicle velocities low. A gentle
touch is required by a Moon jockey operating directly or remotely

Well I hope that answers a lot of your questions . Next week I must go
back to ordinary Earth sats, but I will discuss Lunar topics such as Moon
bounce doppler sometime in a month or so .73 de GM4IHJ @ GB7SAN