Mission planners at NASA and ESA’s Operations Centre (ESOC) have spent months debating the pros and cons of different orbits, and have now decided on the path of the lunar Gateway – a ‘near-rectilinear halo orbit’, or NRHO.
Instead of orbiting around the Moon in a low lunar orbit like Apollo, the Gateway will follow a highly ‘eccentric’ path. At is closest, it will pass 3000 thousand km from the lunar surface and at its furthest, at 70 000 km. The orbit will actually rotate together with the moon, and as seen from the Earth will appear a little like a lunar halo.
A permanent base in this orbit around the Moon will act as a staging post, from where parts can be left behind, picked up and assembled. After liftoff, only a moderate manoeuvre will be needed to slow a visiting spacecraft to rendezvous with the Gateway.
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