GRAIL Launch Milestones

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE 818-354-5011
http://www.jpl.nasa.gov

DC Agle 818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov

News release: 2011-278 Sep. 7, 2011

GRAIL Launch Milestones

PASADENA, Calif. -- NASA's GRAIL spacecraft are set to launch to the moon aboard a
United Launch Alliance Delta II rocket on Sept. 8, 2011, from Cape Canaveral Air Force
Station, Fla. There are two instantaneous (one-second) launch windows at 5:37:06 a.m.
and 6:16:12 a.m. PDT (8:37:06 a.m. and 9:16:12 a.m. EDT). The launch period extends
through Oct. 19. The launch times occur approximately four minutes earlier each day.

GRAIL's primary science objectives are to determine the structure of the lunar interior,
from crust to core, and to advance understanding of the thermal evolution of the moon.
The lunar orbiters are nestled inside the top of a United Launch Alliance Delta II 7920H-
10C rocket, the most powerful Delta rocket in NASA's inventory.

On launch day, Sept. 8, NASA TV commentary coverage of the countdown will begin at
3 a.m. PDT (6 a.m. EDT). The coverage will be webcast at http://www.nasa.gov/ntv .
Live countdown coverage on NASA's launch blog also begins at 3 a.m. PDT (6 a.m.
EDT) at http://www.nasa.gov/mission_pages/grail/launch/grail_blog.html .

Coverage features real-time updates of countdown milestones, as well as streaming
video clips highlighting launch preparations and liftoff. To access these features, and for
more information on GRAIL, visit http://www.nasa.gov/grail and http://grail.nasa.gov
.
The launch will also be online, with a live chat available, on Ustream TV, at
http://www.ustream.tv/nasajpl2 . To follow the GRAIL launch on Twitter, visit
http://twitter.com/NASAJPL and http://twitter.com/NASA .

Here is a timeline of expected launch milestones:

Launch

At liftoff, the rocket's first-stage engine and six of its nine strap-on solid rocket motors
will ignite, and the rocket will be airborne, carrying GRAIL up and over the Atlantic
Ocean.

First six solid rocket motors are jettisoned
GRAIL's Delta II is carrying nine strap-on graphite-epoxy motors. The first six will be
ignited at the time of liftoff. The remaining three will be ignited shortly after the first six
strap-on motors burn out.

Fairing separates

After the Delta's first stage completes its tour of duty, its second stage, which will
provide 9,645 pounds of kick for GRAIL, will begin the first of two scheduled burns.
Shortly after ignition of the rocket's second stage, the Delta's 30-foot-long (8.88-meter-
long) nose cone, or fairing, will separate and be jettisoned as planned, providing the
GRAIL twins with their first taste of exo-atmospheric existence.

Parking at 17,500 miles per hour

The Delta's second stage will temporarily stop firing, as planned, and the rocket and
GRAIL will begin a planned coast phase, also known as a "parking orbit" at about 90
miles (nearly 167 kilometers up).

GRAIL heading from Earth to the moon

The Delta's second stage will begin a second burn. This approximately four-and-a-half-
minute-long burn will place GRAIL on its desired trajectory to the moon.

Spacecraft begin to separate from second stage

The GRAIL-A spacecraft begins separation process from the Delta's second stage. The
GRAIL-B spacecraft separates about 8 minutes later. At this point, the moon is three-
and-a-half months away.

-end-

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