GRAIL mission: NASA twin probes to measure moon's gravity field

The GRAIL mission involves twin spacecraft in a polar orbit around the moon to map its gravitational field by measuring changes in distance between them. These changes are due to regional variations in the moon's gravity. The probes will arrive by New Year's Day and take two months to position themselves before starting measurements in March. The data collected will provide detailed insights into the moon's structure, enhancing our understanding of its formation and evolution.

When are the GRAIL probes expected to begin taking measurements?

What will the GRAIL mission help scientists understand about the moon?