On Saturday, a spacecraft built in Colorado will enter orbit around the moon, followed by its twin on New Year’s Day.
The Grail mission aims to answer questions about the moon’s quirky magnetic field and evolution, and how Earth and its solar system siblings came to be.
From an altitude of 34 miles, the spacecraft will be an average of about 125 miles apart as they send radio signals to each other to map the moon from crust to core.
“This mission will rewrite the textbooks on the evolution of the moon,” said Maria Zuber, Grail’s principal science investigator, of the Massachusetts Institute of Technology.
With 100 missions to the moon, a dozen people who have walked on the surface and rock and soil samples brought back to Earth, “you might think that given all of these observations, that we would know what we need to know about the moon,” Zuber said.
“But that is not so,” Zuber said . “We actually know more about Mars than we do about our own moon.”
The two washing machine-size spacecraft were designed and built by Lockheed Martin at its Waterton Canyon facility in Jefferson County. They were launched Sept. 10 aboard a Delta II rocket provided by United Launch Alliance in Centennial.
It has taken 3 1/2 months to reach the moon by a 2.5-million-mile leisurely path designed to reduce fuel, give time to check out electronics and dissipate gases from instruments.
Commands for the orbit insertions — Grail A at 2:21 p.m. MST Saturday and Grail B at 3:05 p.m. MST Sunday — already have been uplinked to the two spacecraft.
Stuart Spath, Lockheed’s chief Grail engineer, said about two dozen Lockheed engineers will be in the company’s mission support area monitoring the spacecraft, ready to handle contingencies.
The orbits will be fine-tuned before the three-month science mission begins in March.
Ann Schrader: 303-954-1967 or aschrader@denverpost.com
