GRAIL Twins Launched on Lunar Gravity Mapping Mission

by Dr. Ken Kremer

NASA renewed its focus on ground breaking science with the deafening Sept. 10 blastoff of a pair of lunar bound probes sailing on a unique path ‘From the Earth to the Moon’, for a truly challenging mission to do extraordinary science. GRAIL will map the moons interior with unparalleled precision, which will

GRAIL A and B gravity mappers rocket to the moon atop a Delta II Heavy booster on Sept. 10 from Cape Canaveral, Florida. Credit: Ken Kremer

fundamentally alter our understanding of how the moon and other rocky bodies in our solar system formed and evolved over 4.5 billion years time.

“GRAIL simply put, is a ‘Journey to the Center of the Moon’,” said Ed Weiler, NASA Associate Administrator of the Science Mission Directorate at a prelaunch briefing for reporters at KSC on Sept. 6.

GRAIL will probe the interior of the moon from crust to core and map its gravity field 100 to 1000 times better than ever before during a three-month science phase. We will learn more about the interior of the moon with GRAIL than all previous lunar missions combined.

GRAIL Launch 2

GRAIL and Delta II rocket soar to space. Credit: Ken Kremer

“Precisely knowing what the gravity fields are will be critical in helping to land future human and robotic spacecraft. The moon is not very uniform. So it’s a dicey thing to fly orbits around the moon,” Weiler noted.

NASA’s dynamic duo finally blasted off for the Moon at 9:08 a.m. EDT on Sept. 10, 2011 from Space Launch Complex 17B at Canaveral Air Force Station in Florida after a two-day weather delay.


Delta II arcs over atop long exhaust plume casting shadow for long lunar journey. Credit: Ken Kremer

The nearly identical $496 Million Gravity Recovery and Interior Laboratory (GRAIL) probes were mounted side-by-side inside the nose cone atop a Delta II Heavy rocket. It thundered to life and soared into a gorgeous blue sky sprinkled with scattered clouds on a low-energy, 3.5-month journey to the moon.

This was the most powerful version of the Delta rocket family and generates 1.3 million pounds of thrust. The venerable Delta is being retired after more than 50 years of stellar service. Delta’s have launched numerous NASA science satellites including Spirit and Opportunity, Dawn, Stardust, Deep Impact and MESSENGER.

Photo Journalists

Photojournalists watch as Mobile Service Tower is retracted from around Delta II rocket at Pad 17B. Credit: Ken Kremer

Liftoff of the GRAIL duo marked the last scheduled launch of a United Launch Alliance Delta II from Florida and also the last launch from Space Launch Complex 17. This was the 356th Delta launch since the first one in 1960.

NASA’s twin GRAIL Lunar Science Probes - GRAIL B (left) and GRAIL A (right) spacecraft are readied for flight inside the clean room at Astrotech Space Operations facility before launch. Credit: Ken Kremer

On this historic occasion the media, including myself, were permitted to a observe the liftoff from a viewing location just 1.5 miles away with an unobstructed view of the launch pad, which magnified the tremendous roar and flames spewing from the 1st stage rocket engines.

GRAIL A and GRAIL B will fly in tandem formation in a nearly circular, polar orbit at an altitude of about 50 km above the lunar surface as the moon rotates beneath three times.

NASA has announced an essay writing contest to name the GRAIL probes. The contest is open to students in Grades K – 12 at schools in the United States. The deadline is November 11, 2011.

Check my GRAIL features online at Universe Today:
Student Alert: GRAIL Naming Contest – Essay Deadline November 11
GRAIL Lunar Blastoff Gallery
GRAIL Twins Awesome Launch Videos – A Journey to the Center of the Moon
NASA launches Twin Lunar Probes to Unravel Moons Core
GRAIL Unveiled for Lunar Science Trek — Launch Reset to Sept. 10
Last Delta II Rocket to Launch Extraordinary Journey to the Moon, Sept. 8
NASAs Lunar Mapping Duo Encapsulated and Ready for Sept. 8 Liftoff
GRAIL Lunar Twins Mated to Delta Rocket at Launch Pad
GRAIL Twins ready for NASA Science Expedition to the Moon: Photo Gallery

Astronomy Outreach      by Ken Kremer

Amateur Astronomers Association of Princeton:  Princeton University, Princeton, NJ, Nov 8, 8 PM  “Atlantis, the End of Americas Shuttle Program and What’s Beyond for NASA”Website:

Washington Crossing State Park:  Titusville NJ, Saturday, Nov 12, 1 PM. The Grand Finale of  Americas Shuttle Program and What’s Beyond for NASA”. Website:

Gloucester County College Astronomy Club: Sewell, NJ, Wednesday, Nov. 16, 8 PM. “7 Years of Mars Rovers — Mars and Vesta in 3 D”.


Ken Kremer:  Spaceflight magazine & Universe Today

Please contact Ken for more info or science outreach presentations:

Email:   website:

This entry was posted in November 2011, Sidereal Times and tagged , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s