Two robotic probes on a synchronized gravity-mapping mission to the Moon began orbiting the Earth’s natural satellite over the weekend, NASA said on its website.
The twin Gravity Recovery And Interior Laboratory (GRAIL) spacecraft were launched on a 2.6-million-mile roundabout trip to the Moon on September 10 last year.
Over the next two months, the orbit of the solar-powered probes will be adjusted so that at the start of the science phase in March they will be in a near-polar, near-circular orbit with an altitude of about 55 kilometers (34 miles).
During the 82-day science phase of the mission, the probes will fly in formation low over lunar poles and transmit data on changes in the distance between the two craft back to Earth. Scientists will translate this information into a high-resolution map of the moon's gravitational field.
“The data will allow scientists to understand what goes on below the lunar surface,” NASA said on Sunday. “This information will increase knowledge of how Earth and its rocky neighbors in the inner solar system developed into the diverse worlds we see today.”
If the spacecraft remain operational after the partial lunar eclipse in June, the scientists plan to extend the $496-million mission to take an even closer look at the Moon’s gravitational field by lowering the probes’ orbit to 25 km (15.5 miles).
