Water on the moon

Plans for a habitable moon are too much too soon

Published: Saturday 31 October 2009


IT’S CONFIRMED: the moon has water on its surface. This does not mean lakes, oceans or even puddles. It means water molecules and hydroxyl—a hydrogen and oxygen atom bound together. This find, by India’s Chandrayaan I and NASA’s Cassini and Deep Impact spacecraft, has raised hopes of rocket fuelling stations and swanky buildings on the moon. But to achieve these, scientists will first have to overcome several engineering challenges. Observations from the three spacecraft suggested water was distributed over a thin layer of the lunar surface and not just concentrated in the permanently shadowed craters at the poles, as was suspected earlier. An imaging spectrometer, the moon mineralogy mapper, or M3, in Chandrayaan I detec - ted an infrared absorption at a wavelength of three micrometres, which is typical of water or hydroxyl on silicate surfaces, such as the moon. M3 analyses the constitution of the soil on the moon by studying reflection of light off the lunar surface. Light from different minerals is reflec - ted in different wavelengths and these differences are used to detect minerals in the upper layer of the soil. This is how water and hydroxyl were found. The M3 data was crosschecked with the Visual and Infrared Mapping Spectrometer on the Cassini and the High Resolution Infrared Imaging Spectrometer on the Deep Impact. “We postulate hydrogen ions from the sun are carried by the solar wind to the moon and they interact with oxygen- rich minerals in the lunar soil to produce water and hydroxyl molecules that spectral analysis unequivocally shows,” said Jessica Sunshine, co-author of the paper that analyzed data from M3 in the study published in Science on September 24. “In a cycle that occurs in daylight, this water is formed in the morning, substantially lost by lunar mid-day, and formed again as the lunar surface cools towards evening,” she added. Sunshine was also the lead author of the study on Deep Impact spacecraft. The abundance of water on the lunar surface is not yet known. The scientists involved in the discovery said one tonne of the top layer of the moon’s surface would yield about one litre of water. “At about US $50,000 per kg (estimated) to transport material (water) from the earth to the moon’s surface, even a litre of lunar water would be of great value,” said Lawrence Taylor, director of Planetary Geosciences Institute of the University of Tennessee in the US. He explained hydroxyl ions could be converted into water by the addition of protons through the solar wind. The find is crucial because carrying water increases the load of the vehicle and if hydroxyl is converted to water, astronauts would not need to recycle their urine into potable water, said Ajey Lele, research fellow on space strategy at the Institute of Defence Studies and Analyses. Taylor added the hydroxyl molecules could also be a source of liquid oxygen and liquid hydrogen for rocket fuel. Nearly 85 per cent of the fuel in a spacecraft is used to escape the Earth’s gravity. Setting up a base on the moon and converting hydroxyl to liquid hydrogen and oxygen would provide the requisite fuel. “It remains to be seen whether it will be possible to overcome the engineering challenges in producing water and at what cost,” said Subrata Ghoshroy, research associate at the Massachusetts Institute of Technology (MIT) in the US. What about residential colonies? Lunar Embassy, a private company in the US, is selling land on the moon at US$36 per acre (see ‘2008: A lunar odyssey’, Down To Earth, November 16- 30, 2008). Lele called the property business bunkum and colonization a farfetched idea. A study published in the journal Acta Astronautica in March 2009 said the first step towards colonization would be to create a micro environment by introducing microbes such as algae. “Due to the high silica content on the surface, the algae can tolerate radiation of different kinds,” said Satadal Das, the lead author of the paper. Das is a microbiologist in Peerless hospital in Kolkata. Since the moon experiences extreme diurnal temperatures, between -200°C and 300°C, algae should be introduced in the lunar craters at the poles first. There, the temperature is minimum because it is permanently shadowed. At that temperature, the algae can metabolize despite being frozen. Microbes like streptococci and bacillus spores, according to Das’s study, are among those that can survive on the moon. “The atmosphere layer around the moon is very thin. Even minute algal growth would thicken the layer and it can be retained for nearly 100,000 years,” said Das. Low lunar gravity could be a hindrance to colonization, said Haym Benaroya of the Centre for Structures in Extreme Environment at the Rutgers University in New Jersey, USA. To begin with, colonization would imply staying on the moon for a few months for research. Benaroya suggested cylindrical structures like soup cans with enough space for six people to sleep, clean up, eat and research. A lot more needs to be done on the technological front. “We need heavy-lift launch vehicles, reliable means of launching crew to orbit, life support systems even more reliable than those on the International Space Station. We also need to design elements such as habitation modules, power sources, rovers to make any return to the moon a reality,” said Scott A Uebelhart, research asso ciate at MIT. Benaroya added while engineering would cater to structures to protect inhabitants from radiation and micrometeorites, it is not clear yet how humans would react to gravity that is one sixth of the Earth. The question is: how long will it take for colonization to begin on moon? Uebelhart said at present it is impossible to predict a date. According to Ghoshroy, “When colonization would appear as something real, some form of moon treaty is likely be adopted to control activities on the moon. We are nowhere near that.” Who owns the water? At present, nobody. As per the UN Moon Treaty of 1979, an international authority would supervize the development, extraction and management of resources on moon and divert profits if any to developing countries. Most countries, including the US and the then Soviet Union, that did not sign the treaty pursued moon missions independently. India and France signed the treaty but have not ratified it. “Power structures on Earth will impact ownership on the moon as well. If moon becomes economically useful, there will be fights between nations. But it doesn’t seem to be happening anytime soon,” said Yash Pal, scientist and chancellor of Jawaharlal Nehru University in New Delhi. India and China have been close in the race in lunar missions. While India, with Chandrayaan I launched in October 2008, had plans to send a manned mission to the moon by 2015, China’s target is 2020. “There is a lot of hype about an India-China race but at the moment one should talk about collaboration rather than race. It is one thing to land a lunar rover and another to talk about colonization,” said Ghoshroy. There is also confusion on how much credit India should take for the find. Pat on the back Brown University in Rhode Island, US, first issued a press release on September 23, claiming water on moon. Science reported it. Indian space agency, ISRO, which sent Chandrayaan I, was criticized for not publishing the results first. ISRO maintained that the delay in announcing the find was because of several rounds of peer reviews that happened between NASA, ISRO and other scientists. Chandrayaan I carried the spectrometer M3, a NASA instrument. “Many feel India was a carrier but it is important for the craft to be reoriented and manoeuvred to get data. ISRO operated Chandrayaan I so due credit should be given to ISRO,” said Lele. Uebelhart stressed it was a collaborative effort and that any delay in announcing the results did not take away any credit from India. Data from Chandrayaan I, which carried probe instruments from different countries, is still under review. “More research needs to be done,” said Yash Pal. “What we have now is a few buckets of water.




Nobody owns the
moon yet. If it
becomes economically
useful, several nations
might stake claims




Types of water on moon

EXOGENIC: Water from external sources such as comets striking the moon’s surface. ENDOGENIC: Water that originates on the moon is called endogenic. The rocks and soil on the moon contain 45 per cent oxygen combined with silicate. The hydrogen component comes from the solar wind. As a result of nuclear fusion, the sun constantly emits a stream of particles, mostly protons, which are positively charged hydrogen atoms. The wind strikes the soil on the surface of the moon, which has no magnetic field or atmosphere to protect it, and stimulates chemical reactions in which oxygen atoms in the soil combine with hydrogen nuclei to form water and hydroxyl ions.

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