Why can't we compete for the commercial comsat launch market? I thought about this, and I think it just boils down to not launching from the equator. I think that's the energy/cost issue. Does that sound right?
It depends on what type of orbit you're trying to achieve. For high inclination orbits, such as polar or sun-synchronous, there is no advantage to being near the equator. However, launch sites near the equator gain a big advantage for geostationary orbits. First, just to get into a LEO parking orbit, Cape Canaveral suffers a 54 m/s penalty versus Kourou due to the speed of Earth's rotation. The big difference, though, comes from the fact a satellite launched from Canaveral has to make a 28.5 degree plane change to get into GEO, versus only about 7 degrees for Kourou. The numbers vary a bit depending on the exact parameters, but I calculate Kourou has a delta-v advantage of about 313 m/s for GEO delivery.
I've tried to estimate how much more payload could be delivered to GEO by moving the launch from Cape Canaveral to Kourou. For my example I used an Atlas V, version 401. I had to make several assumptions, but in summary, I used a Centaur upper stage to insert the payload into GTO and a hypergolic or solid propellant apogee motor (specific impulse 300 s) to insert into the final GEO.
Based on my calculations, I estimate that the final payload mass could be increased about 16%. This means that Cape Canaveral suffers about a 16% penalty in cost per unit mass for delivering payloads to GEO. Of course this is for just one example and will probably vary from one launch vehicle to another.
