GRAIL: the story

1. GRAIL: Ebb & Flow

   NASA Discovery Program · 2011 – 2012

   To peer deep inside the Moon, NASA launched twin identical spacecraft. Named Ebb and Flow by fourth-grade students in Bozeman, Montana, they flew in tandem around the Moon like high-wire acrobats.

2. Delta II Heavy launch

   10 September 2011 · Cape Canaveral SLC-17B

   In the final flight of the Delta II Heavy rocket from Cape Canaveral, Ebb and Flow climbed toward space, traveling on a low-energy trajectory through the Earth-Moon Lagrange point.

3. The 0.02-micrometer microwave link

   15 to 55 km Lunar Altitude

   Flying 75 to 225 kilometers apart, the twins beamed Ka-band microwaves back and forth. They could measure changes in their separation speed down to 0.02 micrometers per second—less than the width of a single red blood cell per second.

4. Rewriting lunar geology

   38-Kilometer Lunar Crust

   GRAIL revealed the Moon's crust was far thinner and more fractured than anyone realized—only 34 to 43 km thick, shattered by billions of years of impacts, and crisscrossed by 500-km-long magma dikes from an ancient thermal expansion.

5. MoonKAM & Dr. Sally Ride

   119,830 Student Photographs

   Under the leadership of Dr. Sally Ride, over 100,000 middle school students requested and examined Moon images taken by cameras on Ebb and Flow. GRAIL gave the Moon's wonders directly to classrooms.

6. Sally K. Ride Impact Site

   17 December 2012 · 22:28 UTC

   With fuel exhausted, Ebb and Flow crashed into a 2,500-meter mountain ridge near the lunar north pole at 6,050 km/h, thirty seconds apart. NASA named the site in eternal honor of Sally Ride.

NASA Discovery Program · 2011 – 2012

GRAIL: Ebb & Flow

To peer deep inside the Moon, NASA launched twin identical spacecraft. Named Ebb and Flow by fourth-grade students in Bozeman, Montana, they flew in tandem around the Moon like high-wire acrobats.

10 September 2011 · Cape Canaveral SLC-17B

Delta II Heavy launch

In the final flight of the Delta II Heavy rocket from Cape Canaveral, Ebb and Flow climbed toward space, traveling on a low-energy trajectory through the Earth-Moon Lagrange point.

15 to 55 km Lunar Altitude

The 0.02-micrometer microwave link

Flying 75 to 225 kilometers apart, the twins beamed Ka-band microwaves back and forth. They could measure changes in their separation speed down to 0.02 micrometers per second—less than the width of a single red blood cell per second.

38-Kilometer Lunar Crust

Rewriting lunar geology

GRAIL revealed the Moon's crust was far thinner and more fractured than anyone realized—only 34 to 43 km thick, shattered by billions of years of impacts, and crisscrossed by 500-km-long magma dikes from an ancient thermal expansion.

119,830 Student Photographs

MoonKAM & Dr. Sally Ride

Under the leadership of Dr. Sally Ride, over 100,000 middle school students requested and examined Moon images taken by cameras on Ebb and Flow. GRAIL gave the Moon's wonders directly to classrooms.

17 December 2012 · 22:28 UTC

Sally K. Ride Impact Site

With fuel exhausted, Ebb and Flow crashed into a 2,500-meter mountain ridge near the lunar north pole at 6,050 km/h, thirty seconds apart. NASA named the site in eternal honor of Sally Ride.

RoverVilla / GRAIL

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20112012