NASA GRAIL

Nasa has placed the second of two Gravity Recovery and Interior Laboratory (GRAIL) spacecraft, GRAIL-B, into orbit to study the moon’s inner core.

GRAIL-B joined GRAIL-A in orbit and both spacecraft have been placed into elliptical paths around the moon after performing braking manoeuvres following their journey from Earth.

Nasa administrator Charles Bolden said: "The twin GRAIL spacecraft will vastly expand our knowledge of our moon and the evolution of our own planet. We begin this year reminding people around the world that Nasa does big, bold things in order to reach for new heights and reveal the unknown."

The spacecraft will be in orbit at an altitude of about 34 miles ready to start the science phase of the mission in March 2012.

GRAIL will send radio signals that define the distance between them and allow scientists to create a high-resolution map of the Moon’s gravitational field.

The twin spacecrafts will also help the scientists to understand the Moon’s sub-surface features and the origins of other solar system bodies, and will enhance the knowledge of how the Earth and its rocky neighbors in the inner solar system developed.

The spacecraft, built by Lockheed Martin Space Systems, are equipped with a small camera called GRAIL MoonKAM that will be used for education and public outreach.

GRAIL MoonKAM will engage middle schools across the US in the GRAIL mission and lunar exploration.

The $500m twin satellites were launched on 10 September 2011 to map the Moon’s inner core for the first time.

The GRAIL mission is conducted under the Discovery Programme managed at Nasa’s Marshall Space Flight Centre in Huntsville, Alabama, US, and is managed by Nasa’s Jet Propulsion Laboratory in Pasadena, California.

Image Caption:The $500m washing machine-sized twin satellites will map the Moon’s inner core for the first time. Image Courtesy: Nasa