This was very probable for so brave new program. - Energia, unlike most other Soviet rockets, only launch to suborbital trajectory (perigee under sea level), s

This was very probable for so brave new program. - Energia, unlike most other Soviet rockets, only launch to suborbital trajectory (perigee under sea level), so payload have to add few hundreds m/s speed by its own engines to stay on more or less stable circular orbit, and have only few minutes to do this. Development of Polyus was not careful enough, to make this operation reliable, because on all previous Soviet rockets top stage launched to payload target orbit.