Two probes of NASA have been processed successfully to study the variation in gravity on the surfaces of moon. They will also study the mechanism lying in the core. The spacecrafts are referred to as Gravity Recovery and Interior Laboratory (GRAIL) i.e. Grail-A and Grail-B.
These spacecrafts will land on the destination on moon 24 hours apart. GRAIL mission is managed by NASA’s Jet Propulsion Laboratory, Pasadena, California.
The Massachusetts Institute of Technology, Cambridge, is home to the mission’s principal investigator, Maria Zuber. The GRAIL mission is part of the Discovery Program managed at NASA’s Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. Launch management for the mission is the responsibility of NASA’s Launch Services Program at the Kennedy Space Center in Florida. JPL is a division of the California Institute of Technology in Pasadena.
“Both spacecraft have performed essentially flawlessly since launch, but one can never take anything for granted in this business,” said mission chief scientist Maria Zuber of the Massachusetts Institute of Technology.
On New Year’s Eve, one of the Grail probes will work to be captured in the orbit by firing its engine. The same process will be repeated by the other the next day. Once in the orbit, the spacecraft will follow each other at a distance of 124 miles from each other and 35 miles above the surface. Data collection would start in March and upon the start of collection of samples the spacecrafts will transmit radio signals.
From NASA Grail News,
GRAIL-B’s rocket burn took place on Oct. 5 at 11 a.m. PDT (2 p.m. EDT). The spacecraft’s main engine burned for 234 seconds and imparted a velocity change of 56.1 mph (25.1 meters per second) while expending 8.2 pounds (3.7 kilograms) of propellant. GRAIL-A’s burn on Sept. 30 also took place at 11 a.m. PDT. It lasted 127 seconds and imparted a 31.3 mph (14 meters per second) velocity change on the spacecraft while expending 4 pounds (1.87 kilograms) of propellant.
Probes also contain cameras for educational purposes and middle school students from participating schools could choose the areas on moon to look at.