More LEO satellites for less total launch cost
gudi
satellites having 1 hour visibility each ( adequate beam-width ) by
using a smaller rockets, rather than one large geosynchronous
satellite launcher?
Regards,
Narasimham
Jeff Findley
In article <08b758e8-80b8-45bc-a265-9b82d3c29092
@l14g2000pre.googlegroups.com>, math...@hotmail.com says...
>
> satellite launcher?
The devil is in the details. That's what the Iridium network was
supposed to be, but it's not been financially successful.
Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011
cra...@gmail.com
My following response assumes you're referring to communication
satellites based on the "adequate beam width" statement:
That depends on several factors regarding each system. If you can
launch the 24 satellites with just a few launches then, yes, you can
probably beat the cost of a large geosynchronous satellite.
However, the 24 low-orbit satellites have a problem: narrow coverage.
A single satellite at geosynchronous orbit can provide coverage to
most of
a hemisphere. A satellite in a true "low orbit" (under 1000km) will
only
have a small broadcast footprint.
Also, if you actually put the satellites in a single chain, then
they'll
only broadcast over a narrow belt of land. A good example of a
low-orbit communication satellite constellation is Iridium, which
requires
66 satellites at 780km altitude to provide global coverage.
Further, single large satellites are often not "single." For example,
Boeing has produced many geosynchronous satellites on the
common "Boeing 601" chassis. With such standard-model
satellites, you get significant cost reductions.
Mike Miller
Alain Fournier
It might be cheaper to launch but the satellites will be more expensive
to build (24 satellites should cost more than 1). More importantly, you
will need tracking antennas to follow the LEO satellites, which will be
expensive. The antenna on my roof top points to one direction and catches
the signal of a single satellite in GSO, it does not move to do so.
Also, a 500 km high satellite will be below the horizon if you are more
than 2375 km from it. So if you have your 24 satellites over the equator
they will always be out of sight anywhere north of 22 degrees north or
south of 22 degrees south. Between about 6 and 22 degrees south or north
you have coverage sometimes when a satellite is close to your longitude. Only
for a narrow band do you have permanent coverage.
Alain Fournier