The
first astronauts to walk on the moon in the 1960s and 1970s were inundated by
sticky lunar dust that clung to their spacesuits whenever they ventured
outside. Now, four
decades later, a self-funded study by an Australian physicist has found a link
between the dust's stickiness and the angle of the sun at the time of each
moonwalk.
The
new research, which drew on the personal files and paper charts of physicist Brian O'Brien of Perth, suggests that
future lunar astronauts may have greater problems with dust
adhesion in the middle half of the day than NASA's Apollo missions faced in the
early morning.
"Dust is
the number one environmental
hazard on the moon, yet its movements and adhesive properties are little
understood," said
O'Brien, who was the principal investigator for the Dust Detector Experiment on several Apollo lunar
landing missions between 1969 and 1970. His new research will be detailed in the Geophysical Research Letters.
Sticky
science
The new study
points out that the electrostatic adhesive forces of dust decreases as sunlight
on the moon decreases. Furthermore, O'Brien believes that some sort of lunar
shack for
on-duty moonwalkers may be mandatory to provide for a sunlight-thwarting,
dust-free working environment.
"It follows
that on future lunar expeditions, powerful electrostatic adhesion of lunar dust
during the middle half of each lunar day could cause greater dust problems than
experienced by Apollo astronauts," he relates.
This model by
O'Brien infers that Apollo astronaut problems
from clinging dust, at solar elevations much less than 45 degrees, may have
been driven by other forces. Mechanical bonding properties intrinsic to lunar
dust, he suggests, could explain partial success by moonwalkers in shedding
gear of dust with "moon brushes."
Detecting
moon dust
Invented by
O'Brien, the matchbox-sized detectors for the DDE study were planted on
the moon during the Apollo 11, 12, 14 and 15 missions. O'Brien carried
out that work while serving as a professor of space science at Rice University
in Houston, Texas, from 1963 to 1968.
O'Brien
was one of seven scientists chosen by NASA from 90 applicants to provide
sophisticated instruments in remote scientific stations deployed by Apollo
astronauts. While another of his projects, the Charged Particle Lunar
Environment Experiment, was lost on Apollo 13, it was deployed during the
Apollo 14 moon landing mission.
It turns
out that NASA had misplaced its computer tapes of the experimental data but
O'Brien preserved his copies.
"I started to revisit the
personal Dust Detector Experiment (DDE) data in 2007 after learning in late
2006 that the sole source of data was with me," he told SPACE.com.
Spray of
debris
In another
finding by O'Brien, Apollo 11's DDE made the first measurements suggesting that
rocket exhaust caused significant contamination of deployed equipment.
Apollo 11's dust
detectors, O'Brien said, showed the impact of rocket exhaust spit out from the
departure of the Eagle lunar module's ascent stage. This stage was the home,
hotel and vehicle back into lunar orbit for Neil Armstrong and Buzz Aldrin, and
a key step in returning them to home planet Earth.
Eagle's
liftoff from Tranquility Base caused quite a stir, environmentally speaking.
There
was significant contamination of astronaut-deployed hardware by kicked-up
lunar material. So much so that the spray of debris caused by the departing
rocket motor led to the overheating and early failure of Apollo 11's Passive
Seismic Experiment - the first major scientific experiment put on the moon by
human hands.
A lesson
learned here is where best to place equipment given future landings and
takeoffs of moon vehicles. For Apollo 11's DDE, it was deployed roughly 55 feet
(17 meters) away from the Eagle lander.
"Such damage
was a foreseen possibility... accepted on this first mission in interests of
astronaut safety. These benchmark measurements on the moon appear unused and
unreferenced in theoretical modeling of effects of rocket exhausts," O'Brien
explains.
Considering
NASA's plan to return humans to the lunar surface for longer stints, there's
another lesson underscored by O'Brien's work. That is, the need to better
preserve, dust off, and revisit Apollo data.
Doing so can
teach moonwalkers new tricks to live and work on the old moon.
Leonard
David has been reporting on the space industry for more than four decades. He
is past editor-in-chief of the National Space Society's Ad Astra and Space
World magazines and has written for SPACE.com since 1999.
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