NASA launches GRAIL lunar probes

The launch of NASA's GRAIL(Gravity Recovery and Interior Laboratory) spacecraft from Cape Canaveral, Fla., Saturday, Sept. 10, 2011.

KENNEDY SPACE CENTER, Fla., - A United Launch Alliance Delta 2 rocket blasted off and boosted two NASA science satellites into space Saturday, the first step in a $496 million mission to map the moon's gravity and probe its hidden interior.

By precisely measuring the distance between the two spacecraft as they orbit the moon - and thus the subtle effects of the moon's gravity as they sail over visible and sub-surface geologic structures - scientists will be able to determine the nature of the moon's enigmatic core and perhaps confirm or refute theories about how the moon formed some 4.5 billion years ago, reports CBS News space analyst Bill Harwood.

"There have been many missions that have gone to the moon, orbited the moon, landed on the moon, brought back samples of the moon," said Maria Zuber, principal investigator of the Gravity Recovery and Interior Laboratory (GRAIL) mission. "But the missing piece of the puzzle in trying to understand the moon is what the deep interior is like.

"Is there a core? How did the core form? How did the interior convect? What are the impact basins on the near-side flooded with magma and give us this man-in-the-moon shape whereas the back side of the moon doesn't have any of this? These are all mysteries that despite the fact we've studied the moon before, we don't understand how that has happened. GRAIL is a mission that is going to tell us that."

GRAIL (Gravity Recovery and Interior Laboratory) Mission (
CBS News: Space Place (Bill Harwood blog)

It also may help inspire school kids to take more of an interest in science. Each satellite is equipped with four cameras sponsored by former shuttle astronaut Sally Ride's science education company that can be used by students around the world to photograph the lunar surface.

"While GRAIL is performing its gravitational experiments, MoonKam will serve as eyes on the moon for Earth's students," said Leesa Hubbard, an educator with Sally Ride Science. "And how they will do that is through the use of these cameras.

Artist's rendition of the twin GRAIL spacecraft mapping the moon's gravity field. Radio signals traveling between the two spacecraft provide scientists the exact measurements required as well as flow of information not interrupted when the spacecraft are at the lunar far side.

"This program is available at no cost to schools, and students are going to be able to take their very own photos. This is what's going to make the difference. We know there are lots of images of the moon out there, but this gives students their own ownership of that."

High winds aloft forced the NASA launch team to pass up two one-second launch windows Thursday and concern about a heater that ran longer than expected during detanking prompted another 24-hour slip.

More high winds Saturday forced NASA to pass up the first of two "instantaneous" launch windows, but a final weather balloon showed conditions were acceptable and at 9:08:52 a.m. EDT (GMT-4), the Delta 2 roared to life and vaulted away from complex 17B at the Cape Canaveral Air Force Station.

It was the 110th and final planned flight of a Delta 2 from Cape Canaveral and while ULA has enough hardware on hand to build a final five medium-lift Delta 2s, any future flights of the workhorse rocket almost certainly will be launched from the West Coast.

As such, the GRAIL launch marked the end of an era after more than 22 years of memorable Delta 2 flights, including 49 Global Positioning System navigation satellites and all of NASA's recent Mars missions, including the enormously successful Spirit and Opportunity rovers.

Equipped with nine strap-on solid-fuel boosters for extra power, GRAIL's Delta 2 was programmed to boost the twin spacecraft onto looping 2.6-million-mile trajectories to the moon, a low-energy approach that allowed the use of a less expensive, medium-lift rocket.

  • William Harwood

    Bill Harwood has been covering the U.S. space program full-time since 1984, first as Cape Canaveral bureau chief for United Press International and now as a consultant for CBS News. He covered 129 space shuttle missions, every interplanetary flight since Voyager 2's flyby of Neptune and scores of commercial and military launches. Based at the Kennedy Space Center in Florida, Harwood is a devoted amateur astronomer and co-author of "Comm Check: The Final Flight of Shuttle Columbia."