China’s Tiandu-1 satellite has entered a critical fuel-efficient orbit that synchronises with the motion of the Earth and moon, but claims that it is the first spacecraft to achieve the feat have been challenged by US and Canadian experts.
The 3:1 resonant orbit – in which Tiandu-1 completes three loops of the Earth for every circuit made by the moon – is seen as a breakthrough for lunar infrastructure, including a BeiDou-like guidance system that will be needed for interplanetary…
