首先是发射难题。鉴于在火星上制造氧气和火箭燃料尚无直接经验,载人飞船必须携带往返飞行和滞留火星期间所需的全部物资,因而其总重必然大于阿波罗登月飞船。这样一来,如果是从地面直接发射,需要研制比目前火箭推力还要大的运载火箭;如果是近地轨道发射,目前的最大载重的航天? The first is the launch of the problem. In view of the lack of direct experience with the manufacturing of oxygen and rocket fuel on Mars, a manned spacecraft must carry all the material needed for both round-trip flights and stranded Mars, so its total weight must be greater than the Apollo spacecraft. In this way, if it is launched directly from the ground, it needs to develop a launch vehicle larger than the current thrust of the rocket; if it is launched in near-Earth orbit, the current maximum load of space flight?