This undated artist rendering shows the twin Grail spacecraft mapping the lunar gravity field.
Cape Canaveral, FL (Florida Today) -- Twin NASA spacecraft will crash
deliberately into a mountain on the moon today, ending a successful
mission that is shedding light on the evolution of the solar system's
Each about the size
of compact washing machines, the Ebb and Flow spacecraft are low on
fuel, and they've finished a $496 million mission aimed at making the
most accurate gravitational map of the moon to date.
the spacecraft will be directed on a shallow dive into a mile-high
mountain near the moon's north pole - a controlled crash-landing that
will occur in the lunar night.
Expected velocity at impact is 3,760 mph. But don't expect anything dramatic here on Earth.
are not expecting a big splash or a big explosion, OK?" said Maria
Zuber, a professor of geophysics at Massachusetts Institute of
Technology and the mission's principal scientific investigator.
"These are two small spacecraft ... with empty fuel tanks. So we are not expecting a flash that is visible from Earth."
Lunar Reconnaissance Orbiter will zoom over the crash site not long
after impact, but no imagery is expected because the mountainous region
will be in shadow at the time.
Still, it will be a destructive end to NASA's Gravity Recovery and Interior Laboratory, or GRAIL, mission.
going to make a crater on the moon, and they are going to be completely
blown apart at the time," said GRAIL project manager David Lehman of
NASA's Jet Propulsion Laboratory in Pasadena, Calif.
You wouldn't want to be standing at the crash site.
"It would be like a washing machine coming in and landing on you, and it would be a very bad day for you," Lehman said.
Ebb and Flow spacecraft blasted off on Sept. 10, 2011, aboard a United
Launch Alliance Delta II rocket at Cape Canaveral Air Force Station's
an era-ending finale for the venerable Delta II, a workhorse rocket
designed and developed after the 1986 Challenger accident to fly Navstar
Global Positioning System (GPS) spacecraft into orbit. The GRAIL twins
arrived in lunar orbit three months later - on Dec. 31, 2011, and Jan.
Flying in formation, they zoomed around the moon at an altitude of
34 miles and trained scientific instruments on its surface, making the
highest-fidelity gravitational maps of any rocky body in the solar
system - including Earth.
Data from the spacecraft show the lunar crust is much thinner than scientists had believed before.
more, the lunar surface - which has been bombarded by asteroids and
comets for billions of years - is much more pulverized than previously
found is just how broken up and fractured the crust of the moon is,"
Zuber said. "There is evidence that fracturing extends maybe several
tens of kilometers into the upper mantle."
that finding could go a long way toward explaining one of the great
mysteries of the solar system - where all the water that once was awash
on the surface of Mars might have gone.
planetary crusts have been bombarded in a similar way. Earth has ...Mars
has. With Mars, there's a lot of questions about where did the water
that we think was on the surface of Mars go," Zuber said.
if a planetary crust is that fractured, these fractures provide a
pathway deep inside the planet, and it's very easy to envision now how a
possible ocean at its surface could have found its way deep into the
crust of a planet."
One other key finding relates to the origin of the moon - where it came from; how it was created.
Zuber said instruments on GRAIL determined that the amount of aluminum in the crusts of the moon and Earth are nearly equal.
that observation provides additional support for the theory that the
moon formed by a giant impact of a Mars-sized body into Earth," she
Bottom line: the moon is a chip off the old block.