PASADENA, Calif. (AP) — A day after a NASA spacecraft safely entered orbit around the moon, its twin was poised to do the same.
The duo are on a mission to study what's inside the moon by mapping its uneven gravity field.
On New Year's Eve, a probe named Grail-A fired its engine and was captured into lunar orbit. NASA hopes for a similar flawless performance from Grail-B on New Year's Day.
Once in orbit, the near-identical probes will spend two months tweaking their positions until they are circling 34 miles above the surface. They will begin collecting data in March.
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