Analysis of information sources in references of the Wikipedia article "Rentrée atmosphérique sur Mars" in French language version.
« the requirements for returning a first stage here on the Earth propulsively, and then ... the requirements for landing heavy payloads on Mars, there’s a region where the two overlap—are right on top of each other ... If you start with a launch vehicle, and you want to bring it down in a controlled manner, you’re going to end up operating that propulsion system in the supersonic regime at the right altitudes to give you Mars-relevant conditions. »