The Fobos-Grunt includes a Fregat-SB based propulsion module, which provides also the trans-Mars injection from low earth orbit. This Fregat-stage is part of the payload. The Zenit-2FG features the payload fairing of the three stage Zenit-3F, which features the Fregat as upper stage.
|Version||Stage 1||Stage 2|
|Zenit-2FG||Zenit-2SB41 (St. 1) / RD-171||Zenit-2SB41 (St. 2) / RD-120 + RD-8|