The LCROSS shepherding spacecraft attached to the Centaur upper stage.
An enterprising robotic explorer will smash into the lunar frontier Friday (9th Oct) in search of water ice hidden deep inside the darkest corners of the moon, spewing hundreds of thousands of pounds of dust high above the surface in a celestial event visible from Earth.
Just four minutes will decide the outcome of three years of preparations, four months of space travel, and a $79 million investment put into the bold mission.
Four minutes is the time that nine science instruments on the LCROSS probe will be able to directly study a cloud of dust thrown high above the moon by the impact of an empty Centaur rocket stage.
LCROSS is "a very exciting mission culminating in a real crescendo event," said Dan Andrews, the project manager from NASA's Ames Research Center at Moffett Field, Calif.
The sensors will scan the debris for the chemical signature of water, providing definitive proof for a decade-old hypothesis that ice exists on Earth's inhospitable companion.
The Clementine and Lunar Prospector missions of the 1990s sensed elevated levels of hydrogen at the moon's poles. Scientists believed the hydrogen was from trapped water ice. The high concentrations were centered on permanently shadowed craters, lightless meteor impact sites that are unimagineably cold.
According to scientists, temperatures at the bottoms of the craters could be as low as -240 degrees Celsius, or -400 degrees Fahrenheit. At those temperatures, water tends to freeze instead of sublimating into gas, Colaprete said.
The time scales are just as mind-boggling.
Data from the Lunar Reconnaissance Orbiter, a counterpart to the LCROSS mission, have independently verified the presence of hydrogen, even hinting the potential water ice was more widespread than earlier thought.
Scientists also announced last month that three spacecraft found evidence of water in lunar regions previously thought unable to support it.
Those recent findings have set the stage for an experiment to "reach out and touch the water," said Mike Wargo, chief lunar scientist from NASA's exploration directorate.
If LCROSS proves water resides on the moon, it could be a boon for engineers in the early stages of planning for a human return to the lunar surface.
Water could not only help quench the thirst of astronauts, but also supply oxygen, electricity and even rocket propellant for the return trip to Earth.
NASA says the latest estimates predict impact at exactly 1131:30 GMT (7:31:30 a.m. EDT) Friday morning. That time could shift by a few seconds based on new navigation solutions in the coming days.
Scientists have tapped Cabeus crater for the cosmic collision, a 60-mile-wide depression near the moon's south pole.
Cabeus was the subject of a late crater switch announced last week based on a recent analysis of results from LRO and Japan's Kaguya spacecraft.
Having been drained of its propellant and safed shortly after launch, the 41-foot-long, 10-foot-wide inert Centaur has a mass comparable to a large sports utility vehicle, according to Andrews.
The two vehicles will part ways at about 0150 GMT Friday (9:50 p.m. EDT Thursday), according to NASA.
After separating from the Centaur, the shepherding satellite will fire its engines to back away from the rocket. Lunar gravity will be pulling both objects toward the moon.
The probe will open up to a distance of nearly 400 miles from the Centaur, equivalent to about four minutes of flight time between the vehicles.
That will give the shepherding satellite enough time for its make-or-break chance to detect iron-clad evidence of water inside Cabeus.
When the Centaur slams into the moon at 5,600 mph, it will excavate more than 350 metric tons of lunar regolith, throwing some of the material up to six miles above the surface and 30 miles away from the impact site.
At that altitude, the debris will be exposed to sunlight and illuminated for the first time in ages.
Scientists expect the Centaur to leave a crater some 66 feet wide and 13 feet deep.
Read More
[SOURCE: SPACEFLIGHTNOW.COM]
No comments:
Post a Comment