The discovery of water on the moon has always been on top agenda for the scientists who were studying the nearest heavenly body; more so as they plan to colonize it today. As the 300-kilograms of Lunar samples brought during the Apollo program did not yield any conclusive evidence of water on the moon, the hunt continued. Both Clementine in 1994 and The Lunar Prospector in 1998 did find indirect evidence of water; the credit is finally taken by the Indian Lunar mission, Chandrayaan-I launched in October-2008.
Professor Arlin Crotts, an astrophysicist from Columbia University in New York, has recently unfolded the historical developments related to the human pursuit of finding the presence of water on the moon and discovered that the Russians had found a very positive signature of 0.1% (by weight) of water in moon rocks brought by Luna-24 in 1976. Similarly in the recent Chandrayaan mission, the Indian payload CHACE (CHandra's Altitudinal Composition Explorer), a quadrupole mass spectrometer had found abundance amount of water as the "direct evidence" during the CHACE 22-minute descent journey after separating from the mother spacecraft. In the history of lunar exploration, this was for the first time a mass spectrometer has sampled the "lunar atmosphere". The 34-page report (with elaborate 64-references) is an extra-ordinary effort by Prof. Crotts where there were mention about the chronological evolution of scientists thoughts in understanding the Moon and its surroundings, most of the papers published (in the west) on the "presence of water on the moon"; views of few American geologists who argued all along (till 1970s) that the moon is a dry bone land.
As per Prof. Crotts findings ( http://arxiv.org/abs/1205.5597 ), none of the two significant "discoveries" (as mentioned above) were recognized by the scientists in the west. Though the US Apollo mission to the moon brought around 300 kilograms of lunar rock samples; many of them did show (very weak) signatures of water; but NASA believed the water was a contaminant originating on Earth, because lunar dust had clogged the seals of some of the containers and prevented them from being closed properly (as per Prof. Crotts). May be because, the LACE mass spectrometer carried by Apollo-17 placed on the moon and which worked for almost 10-months ( Bob Hodges et al.) but did not find the evidence of water (Author's view).
The Soviet Luna-24 mission drilled a 2-meter hole while extracting the 270-gram lunar sample bringing it back to earth for analysis; while the designers of the experiment (M. Akhmanova, B.Demen'tev and M.Markov) took every possible precaution against any contamination. The Russian scientists found that the water made up 0.1% mass of the soil and published their results in the journal, Geokhimia in 1978, pp-285. Though the journal appears in English, but with a lesser readership, however, it was "never" referred by the western scientist, as per Crotts.
As per Crotts, page-20 of the above mentioned report, it is said that, though the CHACE (MIP-mission) was the first to be completed in the series of Chandrayaan-I experiments, CHACE had to wait for 10-months till the other (two) instruments had their finding published. It was categorically said that the later published data of CHACE (Planetary and Space Sciences, UK) had those gaseous species which were coinciding with the rocket firing and hence were not accepted by the scientists in the west calling it as "contaminated".
The author (of this blog) was the team leader of CHACE payload at ISRO's VSSC (Vikram Sarabhai Space Center). CHACE was a state-of-the quadrupole mass spectrometer with a highest dynamic range ever to leave earth's gravity. As soon as the Chandrayaan spacecraft reached a 100-km lunar polar orbit, as a part of the Moon Impact Probe (MIP) mission; the CHACE instrument during the 22-minute descent journey (Nov-14th, 2008) to the lunar southern pole, the CHACE payload worked immaculately well. The success of CHACE goes to an elaborate planning at ISRO and extra-ordinary hardships of 4-5 young scientists/engineers who had ZERO experience in space borne instrumentation, but did everything RIGHT starting from the selection of the mass spectrometer till the last qualification test where CHACE came up with flying colors .
I recall, my boss was jumping like kid on 14th Nov-2008 when we saw peak#18 "literally pouring out of the CHACE". We sent our work for publication by mid Dec-2008; but neither Nature nor Science would accept it by saying that "the data could be contaminated due to out gassing of surrounding sub systems". Though we have explained by the observations that the just before, during and after the firing of the de-boost motor of the MIP, the CHACE has no blip in its collected spectra as shown here:
We had to wait another one year to have it published in Feb-2010 ( Planetary and Space Sciences,UK, 58, 947-950, 2010) ; while other teams in Chandrayaan-I (Moon Mineralogy Mapper, Mini-SAR: NASA) walked away with the credit of discovering water on the moon.
We took enormous efforts in designing CHACE: I had consulted the senior Hodges (RR) via Alan Stern. It was great to receive postal letter from the same person who had built and successfully sent the first Mass spectrometer (LACE) ever to reach Moon. We took all the inputs from their past experience (LACE) while setting the gain on the mass spectrometer. It was Stern's amazing review paper ("The Lunar Atmosphere", Review of Geo-Physics, 37,453, 1999) which motivated me to do the best for CHACE. My team always walked that "extra mile " to see their baby on the southern pole of the moon. We also took lot of care in avoiding the outgassing which could eminmate either within the space craft or from the propollents; this was done by having UHV sealing all along the probe sensing area. The way the "nose" of the mass spectrometer positioned; during the descent of Moon Impact probe, that it will be the CHACE which would sample lunar environment; this is done by keeping the nose (of CHACE) in ram direction, so that there is no way that the contaminants can reach the sample area.
-S.M.Ahmed, Team leader (Project Manager), CHACE, smahmedhyd@gmail.com
References:
R. Sridharan, S.M. Ahmed,
Tirtha Pratim Das, P.Sreelatha, P. Pradeepkumar, Neha Naik, Gogulapati Supriya
Direct evidence for water (H2O)
in the sunlit lunar ambience from CHACE on MIP of Chandrayaan-I, Planetary and Space Sciences,58, 947-950, 2010
R. Sridharan, S.M. Ahmed,
Tirtha Pratim Das, P.Sreelatha, P. Pradeepkumar, Neha Naik, Gogulapati Supriya
The sunlit lunar atmosphere: A
comprehensive study by CHACE on the Moon Impact Probe of Chandrayaan-1
List of my (recent) Blogs:
http://chace-water-1.blogspot.in/
http://chace-isro.blogspot.com/
http://chace2moon.blogspot.com/
http://co2-on-moon.blogspot.com/
