Providing Water for Lunar Outposts
Martin Colianni
Johnny Sun
http://science.nasa.gov/headlines/y2005/28apr_lro.htm
April 28, 2005: The next time you look at the Moon, pause for a moment and let this thought sink in: People have actually walked on the Moon, and right now the wheels are in motion to send people there again.
The goals this time around are more ambitious than they were in the days of the Apollo program. NASA's new Vision for Space Exploration spells out a long-term strategy of returning to the Moon as a step toward Mars and beyond. The Moon, so nearby and accessible, is a great place to try out new technologies critical to living on alien worlds before venturing across the solar system.
Whether a moonbase will turn out to be feasible hinges largely on the question of water. Colonists need water to drink. They need water to grow plants. They can also break water apart to make air (oxygen) and rocket fuel (oxygen+hydrogen). Furthermore, water is surprisingly effective at blocking space radiation. Surrounding the 'base with a few feet of water would help protect explorers from solar flares and cosmic rays.
The problem is, water is dense and heavy. Carrying large amounts of it from Earth to the Moon would be expensive. Settling the Moon would be so much easier if water were already there.
It's possible: Astronomers believe that comets and asteroids hitting the Moon eons ago left some water behind. (Earth may have received its water in the same way.) Water on the Moon doesn't last long. It evaporates in sunlight and drifts off into space. Only in the shadows of deep cold craters could you expect to find any, frozen and hidden. And indeed there may be deposits of ice in such places. In the 1990s two spacecraft, Lunar Prospector and Clementine, found tantalizing signs of ice in shadowed craters near the Moon's poles--perhaps as much as much as a cubic kilometer. The data were not conclusive, though.
To find out if lunar ice is truly there, NASA plans to send a robotic scout. The Lunar Reconnaissance Orbiter, or "LRO" for short, is scheduled to launch in 2008 and to orbit the Moon for a year or more. Carrying six different scientific instruments, LRO will map the lunar environment in greater detail than ever before.
"This is the first in a string of missions," says Gordon Chin, project scientist for LRO at NASA's Goddard Space Flight Center. "More robots will follow, about one per year, leading up to manned flight" no later than 2020.
LRO's instruments will do many things: they'll map and photograph the Moon in detail, sample its radiation environment and, not least, hunt for water.
For example, the spacecraft's Lyman-Alpha Mapping Project (LAMP), will attempt to peer into the darkness of permanently shadowed craters at the Moon's poles, looking for signs of ice hiding there.
How can LAMP see in the dark? By looking for the dim glow of reflected starlight.
LAMP senses a special range of ultraviolet light wavelengths. Not only is starlight relatively bright in this range, but also the hydrogen gas that permeates the universe radiates in this range as well. To LAMP's sensor, space itself is literally aglow in all directions. This ambient lighting may be enough to see what lies in the inky blackness of these craters.
"What's more, water ice has a characteristic spectral 'fingerprint' in this same range of ultraviolet light, so we'll get spectral evidence of whether ice is in these craters," explains Alan Stern, a scientist at the Southwest Research Institute and principal investigator for LAMP.
The spacecraft is also equipped with a laser that can shine pulses of light into dark craters. The main purpose of the instrument, called the Lunar Orbiter Laser Altimeter (LOLA), is to produce a highly accurate contour map of the entire Moon. As a bonus, it will also measure the brightness of each laser reflection. If the soil contains ice crystals, as little as 4%, the returning pulse would be noticeably brighter.
LOLA by itself can't prove that ice is there. "Any kind of reflective crystals could produce brighter pulses," explains David Smith, principal investigator for LOLA at NASA's Goddard Space Flight Center. "But if we see brighter pulses only in these permanent shadows, we'd strongly suspect ice."
One of LRO's instruments, named Diviner, will map the temperature of the Moon's surface. Scientists can use these measurements to search for places where ice could exist. Even in the permanent shadows of polar craters, temperatures must be very low for ice to resist evaporation. Thus, Diviner will provide a "reality check" for LRO's other ice-sensitive instruments, identifying areas where positive signs of ice would not make any sense because the temperature is simply too high.
Another reality check will come from LRO's Lunar Exploration Neutron Detector (LEND), which counts neutrons spraying out of the lunar surface. Why does the Moon emit neutrons? And what does that have to do with water? The Moon is constantly bombarded by cosmic rays, which produce neutrons when they hit the ground. Hydrogen-bearing compounds like H2O absorb neutrons, so a dip in neutron radiation could signal an oasis ... of sorts. LEND is being developed by Igor Mitrofanov from the Institute for Space Research, Federal Space Agency, Moscow.
"There's a strong synergy between the various instruments on LRO," notes Chin. "None of these instruments alone could provide definitive evidence of ice on the Moon, but if they all point to ice in the same area, that would be compelling."
Chin also points out another reason that finding ice near the Moon's poles would be exciting:
Not far from some permanently shadowed craters are mountainous regions in permanent sunlight, known romantically as "peaks of eternal sunshine." Conceivably, a moonbase could be placed on one of those peaks, providing astronauts with constant solar power--not far from crater-valleys below, rich in ice and ready to be mined.
Wishful thinking? Or a reasonable plan? Lunar Reconnaissance Orbiter will beam back the answer.
http://science.nasa.gov/headlines/y2000/ast02nov_1.htm
November 2, 2000 -- Future astronauts poised to blast off for an extended stay on the International Space Station (ISS) might first consider dashing to the restroom for a quick splash at the lavatory, or better yet, a luxurious hot shower. Once on board the ISS, spacefarers are in for a steady diet of sponge baths using water distilled from -- among other places -- their crewmates breath!
If you're squeamish, read no farther, because the crew will eventually include lab rodents -- and they'll be breathing, too. All of the denizens of the space station lose water when they exhale or sweat. Such vapors add to the ambient cabin humidity, which is eventually condensed and returned to the general water supply.
Sometimes it's better not to think about where your next glass of water is coming from!
Rationing and recycling will be an essential part of daily life on the ISS. In orbit, where Earth's natural life support system is missing, the Space Station itself has to provide abundant power, clean water, and breathable air at the right temperature and humidity -- 24 hours a day, 7 days a week, indefinitely. Nothing can go to waste.
In this article, the first of a series about the practical challenges of living in space, Science@NASA will examine how the Space Station's Environmental Control and Life Support System (ECLSS), under continuing development at the Marshall Space Flight Center, will help astronauts use and re-use their precious supplies of water. Future installments will explore air management, thermal control and fire suppression -- in short, all of the things that will make the Space Station comfortable and safe.
Making a Splash in Space
Before recycling can begin, there has to be some water to start with.
"We have plenty of water on the Space Station now," says Jim Reuter, leader of the ECLSS group at the Marshall Space Flight Center. "The Russian module Zarya is packed with contingency water containers (CWCs) that were carried over from the Space Shuttle during assembly missions earlier this year. They look like duffle bags and each one holds about 90 lbs."
"But it's expensive to ferry water from Earth," he added. "We have to recycle. There's already a Russian-built water processor in orbit that collects humidity from the air. Here at Marshall we're building a regenerative system that will be able to recycle almost every drop of water on the station and support a crew of seven with minimal resupplies."
The ECLSS Water Recycling System (WRS), developed at the MSFC, will reclaim waste waters from the Space Shuttle's fuel cells, from urine, from oral hygiene and hand washing, and by condensing humidity from the air. Without such careful recycling 40,000 pounds per year of water from Earth would be required to resupply a minimum of four crewmembers for the life of the station.
Not even research animals are excused from the program.
"Lab animals on the ISS breath and urinate, too, and we plan to reclaim their waste products along with the crew's. A full complement of 72 rats would equal about one human in terms of water reclamation," says Layne Carter, a water-processing specialist at the MSFC.
It might sound disgusting, but water leaving the space station's purification machines will be cleaner than what most of us drink on Earth.
"The water that we generate is much cleaner than anything you'll ever get out of any tap in the United States," says Carter. "We certainly do a much more aggressive treatment process (than municipal waste water treatment plants). We have practically ultra-pure water by the time our water's finished."
Mimicking Mother Earth
On Earth, water that passes through animals' bodies is made fresh again by natural processes. Microbes in the soil break down urea and convert it to a form that plants can absorb and use to build new plant tissue. The granular soil also acts as a physical filter. Bits of clay cling to nutrients in urine electrostatically, purifying the water and providing nutrients for plants.
Water excreted by animals also evaporates into the atmosphere and rains back down to the Earth as fresh water -- a natural form of distillation.
Above: When water evaporates from the ocean and surface waters, it leaves behind impurities. In the absence of air pollution, nearly pure water falls back to the ground as precipitation.
Water purification machines on the ISS partly mimic these processes, but they do not rely on microbes or any other living things.
"While you try to mimic what's happening on Earth -- which is so
complicated if you really think about it -- we have to use systems that we can
control 100 percent," said Monsi Roman, chief microbiologist for the ECLSS
project at MSFC. ECLSS depends on machines -- not microbes -- because, "if
a machine breaks, you can fix it."
The water purification machines on the ISS will cleanse wastewater in a
three-step process.
The first step is a filter that removes particles and debris. Then the water passes through the "multi-filtration beds," which contain substances that remove organic and inorganic impurities. And finally, the "catalytic oxidation reactor" removes volatile organic compounds and kills bacteria and viruses.
Every Drop Counts
Once the water is purified, astronauts will do everything possible to use it efficiently. "On the ground, people flick on the faucet and they probably waste a couple of liters of water just because it's free and the water pressure is high," notes Carter.
"On the ISS, the water pressure will be about half what you might experience in a typical household," Carter said. "We don't use faucets on the ISS, we use a wash cloth. It's much more efficient. If you're an astronaut, you'll wet the wash cloth with a spray nozzle and then use the cloth to wash your hands."
On the space station, people will wash their hands with less than one-tenth the water that people typically use on Earth. Instead of consuming 50 liters to take a shower, which is typical on Earth, denizens of the ISS will use less than 4 liters to bathe.
Even with intense conservation and recycling efforts, the Space Station will gradually lose water because of inefficiencies in the life support system.
"We will always need resupply, because none of the water reprocessing technology that is available right now for space flight ... is 100 percent efficient. So there's always some minimal loss," said Marybeth Edeen, deputy assistant manager of environmental control and life support at NASA's Johnson Space Center.
Water is lost by the Space Station in several ways: the water recycling systems produce a small amount of unusable brine; the oxygen-generating system consumes water; air that's lost in the air locks takes humidity with it; and the CO2 removal systems leach some water out of the air, to name a few.
Lost water will be replaced by carrying it over from the Shuttle or from the Russian Progress rocket. The Shuttle produces water as its fuel cells combine hydrogen and oxygen to create electricity, and the Progress rocket can be outfitted to carry large containers of water.
NASA scientists will continue to look for ways to improve the life support systems of the Space Station, reducing water losses and finding ways to reuse other waste products. If the water recycling systems can be improved to an efficiency of greater than about 95 percent, then the water contained in the Station's food supply would be enough to replace the lost water, Edeen said.
"It takes processes that are slightly more efficient than we have developed for the space station to do that," Edeen said. "Those are the next generation water processing systems. Those are being developed now, but they're not ready for space flight yet."
The ECLSS life support system will join the Space Station as part of Node 3, which is scheduled to launch in October 2005. Until then, the environment inside the ISS will be maintained primarily by life support systems on the Russian Zvezda Service Module.
http://science.nasa.gov/headlines/y2005/14apr_moonwater.htm
April 14, 2005: The first object in the night sky most of us ever saw, the Moon remains a mystery. Haunted by poets, looked upon by youngsters in love, studied intensely by astronomers for four centuries, examined by geologists for the last 50 years, walked upon by twelve humans, this is Earth's satellite.
And as we look towards the Moon with thoughts of setting up a permanent home there, one new question is paramount: does the Moon have water? Although none has been definitely detected, recent evidence suggests that it's there.
Why should there be water on the Moon? Simply for the same reason that there's water on Earth. A favorite theory is that water, either as water by itself or as its components of hydrogen and oxygen, was deposited on Earth during its early history--mostly during a period of "late heavy bombardment" 3.9 billion years ago--by the impacts of comets and asteroids. Because the Moon shares the same area of space as Earth, it should have received its share of water as well. However, since it has only a tiny fraction of Earth's gravity, most of the Moon's water supply should have evaporated and drifted off into space long ago. Most, but perhaps not all.
In ancient times, observers commonly thought the Moon had abundant water--in fact, the great lava plains like Mare Imbrium were called maria, or seas. But when Neil Armstrong and Buzz Aldrin landed on the Moon in 1969, they stepped out not into the water of the Sea of Tranquillity, but onto basaltic rock. No one was surprised by that--the idea of lunar maria had been replaced by lava plains decades earlier.
As preparations were underway in the mid 1960s for the Apollo program, questions about water on the Moon were barely on the radar screen. Geologists and astronomers were divided at the time as to whether the lunar surface was a result of volcanic forces from beneath, or cosmic forces from above. Grove Carl Gilbert in 1893 already had the answer. That famous geologist suggested that large asteroidal objects hit the Moon, forming its craters. Ralph Baldwin articulated the same idea in 1949, and Gene Shoemaker revived the idea again around 1960. Shoemaker, almost alone among geologists of his day, saw the Moon as a fertile subject for field geology. He saw the craters on the Moon as logical impact sites that were formed not gradually in eons, but explosively in seconds.
The Apollo flights confirmed that the dominant geological process on the Moon is impact-related. That discovery, in turn, ushered in a new question: Since Earth's water was probably delivered largely by comets and asteroids, could this process have done the same for the Moon? And could some of that water still be there?
In 1994, the SDI-NASA Clementine spacecraft orbited the Moon and mapped its surface. In one experiment, Clementine beamed radio signals into shadowed craters near the Moon's south pole. The reflections, received by antennas on Earth, seemed to come from icy material.
That makes sense. If there is water on the Moon, it's probably hiding in the permanent shadows of deep, cold craters, safe from vaporizing sunlight, frozen solid.
So far so good, but... the Clementine data were not conclusive, and when astronomers tried to find ice in the same craters using the giant Arecibo radar in Puerto Rico, they couldn't. Maybe Clementine was somehow wrong.
In 1998, NASA sent another spacecraft, Lunar Prospector, to check. Using a device called a neutron spectrometer, Lunar Prospector scanned the Moon's surface for hydrogen-rich minerals. Once again, polar craters yielded an intriguing signal: neutron ratios indicated hydrogen. Could it be the "H" in H2O? Many researchers think so.
Lunar Prospector eventually sacrificed itself to the search. When the spacecraft's primary mission was finished, NASA decided to crash Prospector near the Moon's south pole, hoping to liberate a bit of its meager layer of water. Earth's satellite might briefly become a comet as amounts of water vapor were released.
Above: Hydrogen deposits measured by Lunar Prospector. [More]
Lunar Prospector crashed, as planned, and several teams of researchers tried to detect that cloud, but without success. Either there was no water, or there was not enough water to be detected by Earth-based telescopes, or the telescopes were not looking in precisely the right place. In any event, no water was found from Prospector's impact.
In 2008, NASA plans to send a new spacecraft to the Moon: the Lunar Reconnaissance Orbiter (LRO), bristling with advanced sensors that can sense water in at least four different ways. Scientists are hopeful that LRO can decide the question of Moon water once and for all.
Our interest is not just scientific. If we are indeed to build a base on the Moon, the presence of water already there would offer a tremendous advantage in building and running it. It's been 35 years since we first set foot on the Moon. Now ambitious eyes once again look toward our satellite not just as a place to visit, but as a place to live.
Martin Colianni
Johnny Sun
Lunar Water Utilities
I. Potential Lunar Water Sources
1. Lunar crust composition
a. Composition of crust
b. Molecular breakdown of lunar crust
2. Create water from elements on moon
a. Isolate oxygen from rocks
b. Power to combine hydrogen and oxygen to water
c. Options to augment hydrogen and oxygen supplies from earth
3. Polar hydrogen sources
a. Determine if there is water ice in permanently shadowed craters.
b. Infrastructure to mine hydrogen or water from poles
c. Viability of mining in crater regions
II. Water Purification
1. Recycling of all available water supplies
a. Humidity to potable water
b. Urine
c. Water for hygiene use
2. Filtering
a. Particulate filters
b. Multi-filtration beds
c. Catalytic oxidation reactor
3. Machinery
a. Substances required for filters.
b. Ways to improve efficiency of current filtration systems
III. Uses for water
1. Personal
a. Drinking
b. Hygiene
2. Mechanical
a. Cooling
b. Radiation absorbance
http://oregonstate.edu/~atwaterj/apco.htm
http://www.lenntech.com/water-purification-steps-FAQ.htm
http://en.wikipedia.org/wiki/Dehumidifier
http://en.wikipedia.org/wiki/Water_purification
http://oregonstate.edu/~atwaterj/mf.htm