Second of two NASA probes in lunar orbit to explore Moon

WASHINGTON - Agence France-Presse

This image shows how the twin GRAIL spacecraft will map the Moon’s gravity field. AP photo

The second of two NASA lunar probes on a mission to study the Moon’s inner core so scientists can better understand the origins of planets went into orbit on Jan. 1 as planned, the US space agency said.

The second Gravity Recovery and Interior Laboratory (GRAIL-B) began orbiting the Moon at about 2243 GMT, according to officials at NASA’s Jet Propulsion Laboratory in Pasadena, California. GRAIL-A reached its lunar orbit on Dec. 31.

“The twin GRAIL spacecraft will vastly expand our knowledge of our moon and the evolution of our own planet,” NASA Administrator Charles Bolden said in a statement.

The $500-million pair of washing machine-sized satellites were launched on Sep. 10 on a mission to map the Moon’s inner core for the first time.

The spacecraft are in a near-polar elliptical orbit, traveling around the Moon in about 11.5 hours, NASA said. In the coming weeks, that orbit time will be reduced to just under two hours, it added. Beginning in March, the two unmanned spacecraft will send radio signals that allow earth-based scientists to create a high-resolution map of the Moon’s gravitational field, helping them to better understand its sub-surface features and the origins of other bodies in the solar system. The mission should shed light on the unexplored far side of the Moon.