Thank you Tom for your response. I asked because I try to imagine what an early return to the Moon might look like and worried that a duration much longer than the original Apollo missions would cause serious heat rejection issues for any lander. Then I thought that total stay time could be held down if two 2 man crews could be sent, so that they could work two shifts in effect. And I was hoping that the Apollo descent engine and tanks could be the model for this first effort. This might be the case only until the time that Lunar oxygen could be used, but that will take time to develop the infrastructure.