Bangalore/New Delhi: India’s maiden lunar mission, Chandrayaan-1, found the strongest evidence yet that the moon isn’t the dry place it was thought to be, a finding that has been validated by a US space probe and which itself supported data that’s a decade old.
While the formation of an earth-like, liquid reservoir on the moon is impossible because of the weak atmosphere on Earth’s only natural satellite, there are chances of fresh and bigger chunks of water-ice forming over several years on the lunar surface.
Water-ice formation: A schematic showing the stream of charged hydrogen ions carried from the sun by the solar wind. One possible scenario to explain hydration of the lunar surface is that during the daytime, when the moon is exposed to the solar wind, hydrogen ions liberate oxygen from lunar minerals to form hydroxyl and water, which are then weakly held to the surface. At high temperatures (red-yellow), more molecules are released than adsorbed. When the temperature decreases (green-blue), hydroxyl and water accumulate. University of Maryland/F Merlin/McREL
Although there’s little evidence to suggest that life existed on the moon ever, water on its surface in any form is necessary to set up a base—both to exploit the moon’s resources such as helium-3, a clean nuclear fuel, and setting up a transit point for possible exploration of planets beyond, such as Mars.
Ice that on heating vapourizes without the intermediary liquid state is called water-ice. Such ice naturally occurs in certain planets and their satellites.
“Certainly, it will increase man’s interest in the moon,” P. Sreekumar, chief scientist of the Chandrayaan-1 mission, said over phone, calling the finding a “major discovery” and adding that the theory of the origin of the moon may have to be re-examined.
The moon mineralogy mapper (M3), an instrument provided by the US National Aeronautics and Space Administration (Nasa) and fitted on board Chandrayaan-1, made the discovery. Scientists validated the finding when Deep Impact probe, another Nasa spacecraft, flew by the moon in June.
Researchers also went back to data sent in 1999 by Cassini, a probe that passed the moon on its journey to Saturn.
India’s first lunar mission, launched on 22 October 2008, was aborted prematurely on 30 August after its power systems failed and it lost contact with earth. Mission objectives included finding evidence of water and minerals such as helium-3.
Scientists found a thin layer of hydrogen and oxygen—the two elements that make up water—bound together.
The finding is a boost for India’s ambitions for deep space exploration. The Indian Space Research Organisation (Isro) will follow up by landing a rover on the moon by 2013 and send probes to asteroids and Mars in the future amid a renewed burst of global interest in exploring outer space.
India is targeting a human spaceflight by 2016 and eventually landing a man on the moon in the 2020s.
The US plans to return a man to the moon by 2020, around when China plans to send a manned mission.
Still, the most powerful evidence of water on the moon is likely to come from the Lunar CRater Observation and Sensing Satellite that will crash into the moon’s south pole on 9 October to sense the presence of water in the resulting debris, Lawrence Taylor of the University of Tennessee and one of the authors of three papers to be published in Science magazine on Friday, said in an email.
In the past, researchers have found signs of ice in the moon’s polar region, located in deep craters that have never seen sunlight, but the latest findings indicate water on its surface.
While the quantity is not precisely known, as much as 1,000 water molecule parts-per-million could be in the lunar soil, according to Carle Pieters, principal investigator of the M3 instrument and the author of one of the papers.
Harvesting one tonne of the top layer of the moon’s surface would yield as much as 32 ounces, or about a cup of water, according to scientists involved in the discovery.
“When we say ‘water on the moon’, we are not talking about lakes, oceans or even puddles,” Pieters said in a statement. “Water on the moon means molecules of water and hydroxyl that interact with molecules of rock and dust specifically in the top millimetres of the moon’s surface.”
Experts are also prescribing caution.
“There’s an expression that describes the moon as dry as a bone. In this case, the bone may be much wetter than the moon,” said Paul Lucey, a physicist at the University of Hawaii, in an email. “Somehow water trapped in the cold regions must be protected from ultraviolet rays (for a chunk of water ice to develop). Liquid water is not possible.”
Lucey has published a commentary on the findings in Science journal.
Last October, Junichi Haruyama of Japan Aerospace Exploration Agency and his team published a report in Science analysing images from the Japanese lunar probe, Selene or Kaguya, and stating that there was no water-ice at least on the surface of the lunar south pole, a region believed to hold water deposits.
Significantly, the latest studies suggest a new theory to explain how water-ice could have formed on the moon. Hydrogen, an essential component of water, comes from solar wind that reacts with the oxygen. Over time, these drops of water gradually move towards the poles and form chunks of water-ice, said Jessica Sunshine of the University of Maryland, and one of the authors of the papers published in Science.