re: Should we be seeing rocket 'burns"

Philip Chien (kc4yer@amsat.org)
Sun, 7 Sep 1997 23:42:19 -0400

Catching up on my mail ...

Tony Beresford <starman@camtech.net.au> asked:

>With all the recently launched satellites that use their own
>low thrust rocket motors to get to final orbit, shouldnt we
>be seeing some evidence of such activity, like glowing
>patches of exhaust gases near such objects.

The visibility of propellants depends on the types of propellants and the
amount of thrust.  For a typical 100 lbf (440 newton) bi-propellant apogee
motor on a Hughes HS-601, Lockheed Martin A2100 I doubt it would be visible
due to its low thrust.

The space shuttle OMS are fairly powerful engines and have been observed
during major burns.

The Centaur (liquid hydrogen / oxygen) engines were observed during a
classified Titan launch from Europe.  The burn generated a large comet-like
tail and were almost certainly at an appropriate sun-angle which made them
visible from the ground.

Of course if you've got infrared eyes you've got more of a chance of seeing
the burns ...



>Perhaps somebody like Phil Chien can comment on when such
>activity takes place.

I could certainly make some inquiries ahead of time, but most of the time
it's dependent on many variables, most notably exactly what time the launch
occurs.


Philip Chien [M1959.05.31/31.145//KC4YER@amsat.org]