Sally Furniss
Well-known member
Moon dust becomes eco hazard to astronauts due to Sun's elevation
Washington, April 19 : A new study has revealed that the Moon dust, which causes hazards like ruining scientific experiments and endangering astronauts' health, is influenced by the Sun's elevation.
Lunar dust has long been described as the No. 1 environmental hazard on the Moon.
It causes miscellaneous havoc: from destroying scientific equipment deployed on the lunar surface, to creating blinding dust clouds that interfere with lunar landings.
It also may be a health hazard to space travelers, since dust clinging to space suits detaches when astronauts reenter their lunar module.
It then floats free in zero gravity, ready to be inhaled, during the 3-day journey back to Earth.
Now, a study reveals that forces compelling lunar dust to cling to surfaces, change during the lunar day with the elevation of the sun.
The study analyzes the interactions on the Moon among electrostatic adhesive forces, the angle of incidence of the sun's rays, and lunar gravity.
It concludes that the stickiness of lunar dust on a vertical surface changes as the sun moves higher in the sky, eventually allowing the very weak lunar gravity to pull the dust off.
"Before you can manage the dust, you have to understand what makes it sticky," said Brian O'Brien, the sole author of the study.
He used data from the matchbox-sized Dust Detector Experiments deployed on the Moon's surface in 1969 during the Apollo 11 and Apollo 12 missions.
O'Brien analyzed the behavior of dust on horizontal and vertical solar cells in one of the Apollo dust-detecting experiments.
On the first morning of the experiment, the lunar module - 130 meters (426 feet) away from the dust detector - took off from the Moon's surface.
The blast of exhaust gases completely cleansed a dusty horizontal solar cell, because it was illuminated only by weak early-morning light and thus the adhesive force of dust was faint.
But, only half the dust covering the vertical cell was removed by the blast, because its surface faced east - into more intense sunlight- and thus the sticky forces were stronger.
O'Brien found that later, as the sun rose and the angle of incidence of the sun's rays on the dusty vertical surface facing east decreased, the electrostatic forces on the vertical cell weakened.
The tipping point was reached when the sun was at an angle of about 45 degrees.
Then, the pull of lunar gravity counteracted the adhesive forces and made the dust start falling off. All dust had fallen by lunar night.
"These are the first measurements of the collapse of the cohesive forces that make lunar dust so sticky," O'Brien said.
http://www.newkerala.com/nkfullnews-1-23836.html
Washington, April 19 : A new study has revealed that the Moon dust, which causes hazards like ruining scientific experiments and endangering astronauts' health, is influenced by the Sun's elevation.
Lunar dust has long been described as the No. 1 environmental hazard on the Moon.
It causes miscellaneous havoc: from destroying scientific equipment deployed on the lunar surface, to creating blinding dust clouds that interfere with lunar landings.
It also may be a health hazard to space travelers, since dust clinging to space suits detaches when astronauts reenter their lunar module.
It then floats free in zero gravity, ready to be inhaled, during the 3-day journey back to Earth.
Now, a study reveals that forces compelling lunar dust to cling to surfaces, change during the lunar day with the elevation of the sun.
The study analyzes the interactions on the Moon among electrostatic adhesive forces, the angle of incidence of the sun's rays, and lunar gravity.
It concludes that the stickiness of lunar dust on a vertical surface changes as the sun moves higher in the sky, eventually allowing the very weak lunar gravity to pull the dust off.
"Before you can manage the dust, you have to understand what makes it sticky," said Brian O'Brien, the sole author of the study.
He used data from the matchbox-sized Dust Detector Experiments deployed on the Moon's surface in 1969 during the Apollo 11 and Apollo 12 missions.
O'Brien analyzed the behavior of dust on horizontal and vertical solar cells in one of the Apollo dust-detecting experiments.
On the first morning of the experiment, the lunar module - 130 meters (426 feet) away from the dust detector - took off from the Moon's surface.
The blast of exhaust gases completely cleansed a dusty horizontal solar cell, because it was illuminated only by weak early-morning light and thus the adhesive force of dust was faint.
But, only half the dust covering the vertical cell was removed by the blast, because its surface faced east - into more intense sunlight- and thus the sticky forces were stronger.
O'Brien found that later, as the sun rose and the angle of incidence of the sun's rays on the dusty vertical surface facing east decreased, the electrostatic forces on the vertical cell weakened.
The tipping point was reached when the sun was at an angle of about 45 degrees.
Then, the pull of lunar gravity counteracted the adhesive forces and made the dust start falling off. All dust had fallen by lunar night.
"These are the first measurements of the collapse of the cohesive forces that make lunar dust so sticky," O'Brien said.
http://www.newkerala.com/nkfullnews-1-23836.html