Think about a busy day at an airport, says Moriba Jah, an astrodynamicist at the University of Texas at Austin: planes line up in the sky, landing and taking off close to one another in a carefully choreographed routine.

德克萨斯大学奥斯汀分校的天体动力学家莫里巴·贾 (Moriba Jah) 说，想象一下在机场忙碌的一天：飞机在天空中排成一排，按照精心设计的程序降落和起飞，彼此靠近。