I heard a talk from a fairly well informed guy about the exomars mission. He was saying that the orbiter will, initially have a very elliptical orbit and that it would be using aerobraking to make it circular (saving a lot of fuel). I have a problem understanding that because aerobraking can only remove energy and the resulting orbital height would (I reckon) bring the orbiter below the fringe of the Martian atmosphere. That would mean it would 'fall down' fairly soon. I have to conclude that the aerobraking would only reduce the highest orbital distance to what was required and that some fuel would be used to raise the minimum distance out of the atmosphere. (Perigee and apogee terms only apply on Earth???). Someone here must have definitive answer to this. Am I right?