The goal was to measure the AU; then, knowing the orbital speeds of all the other planets around the Sun, the scale of the Solar System would fall into place.

目标是测量 AU；随后，当我们知道了所有围绕太阳的其他行星的轨道速度，对太阳系的规模就有充分的认识了。

youdao

In such a scheme, a payload vehicle (holding, say, a satellite) would piggyback to high altitude aboard the scramjet, which in theory could reach near-orbital speeds.

在这个方案中，一个载物飞行器(比如说搭载着卫星)将(首先)搭载超燃冲压发动机进入相当高度，理论上能够达到近似轨道速度。

youdao

This is because orbital debris travels at speeds of thirty-two thousand kilometers an hour or more.

VOA: special.2009.04.01