Re: Sea Launch Second Stage

Phillip Clark (
Thu, 1 Apr 1999 07:04:06 +0100 (BST)

There are two primary launch proifiles for the Zenit-3SL, both of which 
have the first two stages of the vehicle (essentially the Zenit-2 
launcher) sub-orbital.

First profile is for the Block DM-SL to perform low, parking orbit 
injection and then re-start to enter geosynch transfer orbit where the 
payload is deployed: since all of the propellant is used for these two 
burns it maximises the payload mass, although the payload has to pergorm 
its own injection to geosynch orbit.

Second profile is for the DM-SL stage to perform three burns: at the 
apogee of the GTO the stage ignites for a third time to circularise the 
orbit at GEO.   This reduces the mass of the payload which can be 
launched, but means that the payload has to perform only a small 
manoeuvre to enter its operational orbit (like the Russian domestic GEO 

There are variations on these themes, with delayed second burns and 
delayed third burns to optimise the GEO injection longitude.   Plus one 
assumes that the third stage can be used to deploy the satellite in a 
super-GTO but lower than GEO, as has happened on the commercial Proton-K 
missions (with the exception of INMARSAT-3 2 which was very light for a 
Proton launch).

Phillip Clark

Phillip S Clark                                       25 Redfern Avenue
Molniya Space Consultancy                             Whitton
Compiler/Publisher, Worldwide Satellite Launches      Middx   TW4 5NA

Specialist in "space archeology" - the older and more obscure the more 
interesting it is !