Scientists
are plotting out a "crash course" in learning what happens when a European
lunar probe slams into the Moon.
The
European Space Agency's (ESA) SMART-1 spacecraft--now circling the Moon--is
headed for a planned early September impact with Earth's celestial neighbor.
The
ESA probe would plow into the lunar surface, giving it a glancing blow as it
speeds in at nearly 5,000 miles per hour (2 kilometers per second).
SMART-1
is Europe's first robotic lunar mission. The name SMART stands for Small
Mission for Advanced Research in Technology
The
spacecraft was launched on September 27, 2003. Making use of its ion-propulsion
engine to slowly nudge it outward from Earth, the probe powered its way into
lunar orbit on November 15, 2004.
Outfitted
with miniaturized instruments, SMART-1's goal has been to gauge key chemical
elements in the lunar surface, as well as look into the theory that the Moon
was formed following the violent collision of a smaller planet with Earth long
ago.
ESA's
lunar probe completes a loop around the Moon every five hours--but that's
about to end later this year.
Rehearsal mode
Engineers
and scientists are now targeting SMART-1 for possible impact on the
Moon around September 1-2. The current uncertainty range for the exact
time of impact is 15 hours.
At
the end of June, SMART-1 is slated to carry out two maneuvers. These will fine-tune
the exact time of impact. Those slight thrust firings will lead to the
spacecraft flying over the Moon at its lowest point at below186 miles (300
kilometers) in altitude.
In
early July, the plan calls for assessing the success of the maneuver and
determining the spacecraft's orbit and expected impact time. Later that month,
the probe will zip as close as 124 miles (200 kilometers) from the barren lunar
landscape.
In
early August, SMART-1 will make an overflight of its eventual impact site,
racing over that area at just 75 miles (120 kilometers) height in what's termed
as "rehearsal" mode for the early September run-in with the Moon.
According
to Bernard Foing, ESA SMART-1 project scientist, an inventory is being made of
the composition and mechanical properties of the spacecraft--including
aluminum, copper, titanium, and other materials, as well as the probe's remaining
hydrazine fuel.
That
data will be used to support observations of what is kicked up from the Moon
itself on impact, contrasted to bits, pieces, and fuel tossed into the mix due
to SMART-1's high-speed slap.
Boom and bust finale
Here
on Earth, sky watchers worldwide are getting ready for the projected September
1-2 lunar boom and bust finale of SMART-1.
Foing
told SPACE.com that he is now engaged in assembling a "coordinated
campaign" of ground-based observations. This activity would support SMART-1
measurements and monitor the artificial crash that mimics in a small way, an
asteroid or comet hit on the Moon.
Numbers
of observatories around the world have indicated interest in watching the
outcome from SMART-1's collision with the Moon, Foing has reported.
At impact, the ESA spacecraft will weigh a
little over 628 pounds (285 kilograms), punching the Moon at a grazing
incidence near 37 degrees south latitude. The near-side impact is timed so that
it will be illuminated to assist in observations from Earth.
A
current orbit simulation of the SMART-1 impact for September 2 is at lunar
longitude 44.54 degrees West and 36.22 South in Lacus Excellentiae, 10 degrees south
of Mare Humorum. A far more refined target point will come as the event draws closer.
Crater-making crash
Back
on July 31, 1999, the Moon was on the receiving end of NASA's Lunar Prospector.
That
farewell fall of space hardware struck within a crater near the lunar south
pole--in an attempt to detect water ice stirred up by the wallop. No visible
debris plume was reported.
According
to Foing, the hope is that those Earth-based observers intending to take part in
September's thump of the Moon can make pre-hit predictions of SMART-1's impact
magnitude, cloud ejecta dynamics, exospheric effects and other observable
manifestations brought about by the crash.
Coordinated
measurements by observers here on Earth are high on the priority list, Foing
noted. Impact observations would include: Infrared imaging of thermal flash;
visible/infrared imaging of ejected clouds; hydrazine flame detection;
post-characterization of ejecta; as well as exospheric effects if lunar
material is blasted high off the Moon's surface.
In
addition, Foing said, there is also intent to conduct follow up searches for
the crater produced by SMART-1's crash into the Moon via the sensor eyes of future,
follow-on lunar orbiters.
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