Knowing where the moon’s gravity is stronger will enable the United States and other countries to better pinpoint landing locations for future explorers, whether robot or human. The gravity on the moon is uneven and about one-sixth Earth’s pull.
“If you want to land right next to a particular outcrop (of rock), you’re going to be able to do it,” Zuber said. “There will be no reason to do another gravity experiment of the moon in any of our lifetimes.”
Zuber said the Grail findings should eliminate cliffhangers like the Apollo 11 landing in 1969 by Neil Armstrong and Buzz Aldrin. They overshot their touchdown site in part because of the subtle gravity changes in the moon’s surface below; they almost ran out of fuel before safely touching down on the Sea of Tranquility.
“It will be easier next time,” Zuber promised.
For now, NASA has no plans to return astronauts to the moon, Earth’s closest neighbor at approximately 240,000 miles away. That program, called Constellation, was canceled last year by President Barack Obama, who favors asteroids and Mars as potential destinations in America’s future without the shuttle.
This is the second planetary mission for NASA since the space shuttle program ended in July, and attracted a large crowd to Cape Canaveral. NASA counted nearly 1,000 guests at Kennedy Space Center on Saturday, nowhere near the 12,000 on hand for the Juno launch to Jupiter at the beginning of August.
Grail was supposed to soar Thursday, but high wind interfered. Then NASA needed an extra day to check the rocket after engine heaters stayed on too long. High wind almost stopped NASA again Saturday; the launch team had to skip the morning’s first opportunity, but the wind dissipated just in time for the second.
The year’s grand finale will be the launch of the biggest Mars rover ever the day after Thanksgiving.
Grail is the 110th mission to target the moon, according to NASA records. Missions have been launched by the United States, Soviet Union, Japan, China and India.
The previous moonshot was two years ago: NASA’s Lunar Reconnaissance Orbiter. Just last month, the moon-circling probe beamed back the sharpest pictures yet of some of the Apollo artifacts left on the moon from 1969 through 1972 _ and even moonwalkers’ tracks. NASA released the photos earlier in the week.
Ride and Zuber will help pick the winning names for the Grail twins later this year, well before the spacecraft reach the moon.
Zuber said she has her own pet names, “but I think I’ll keep those to myself because I don’t want to influence the contestants.” Some of the names used by members of her team over the four-year life of the project: Fred and Ginger, Castor and Pollux, and Tom and Jerry.