Date: April 29, 2010
Title: Water on the Moon!
Podcaster: NASA Lunar Science Institute (NLSI)
Organization: NASA Lunar Science Institute (NLSI)
Description: In this podcast from the NASA Lunar Science Institute, Dr. Carle Pieters and Dr. Jessica Sunshine talk about their roles in finding water on the Moon.
Bio: The NLSI brings together leading lunar scientists from around the world to further NASA lunar science and exploration.
Dr. Carle Pieters is from Brown University and is the Principal Investigator for the Moon Mineralogy Mapper (M Cubed) instrument on the Chandrayaan-1 spacecraft.
Dr. Jessica Sunshine is from the University of Maryland, and is a co-investigator for M Cubed, and also the repurposed Deep Impact spacecraft, designated as the EPOXI mission, with a dual purpose to study extrasolar planets and comet Hartley 2.
Nancy Atkinson is a science journalist and is the Senior Editor for Universe Today
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Donald Hoverson. Many years ago I tried to stump my poor game players with a Tolkienesque riddle, the answer to which I need not give to the listeners of this podcast: Brightly cold and very old. Rubies beyond price. Diamonds beyond measure, and sapphires all comprise, the bounty of this treasure.
Voice: You are listening to the NASA Lunar Science Institute podcast which highlights the latest news information of the Moon, on the Moon and from the Moon. It is produced from the NASA Lunar Science Institute at the Ames Research Center in Moffett Field, California.
Nancy Atkinson: Water on the Moon? Until recently, this idea would have been considered almost a fairy tale. Hi, this is Nancy Atkinson for the NASA Lunar Science Institute. In September of 2009, scientists from three different spacecraft announced they had found water molecules across the surface of the moon in low concentrations. This was completly unexpected, and although its not a fairy tale, it still is a great story. To tell that story, we visited with two of the scientists involved, Dr. Carle Pieters from Brown University who is the Principal Investigator for the Moon Mineralogy Mapper instrument or M cubed, on the Chandrayann-1 spacecraft, and also Dr. Jessica Sunshine from the University of Maryland, a co- investigator with M Cubed and also with the Deep Impact Mission.
We asked Dr. Pieters to tell us about her role in finding water on the Moon and how exciting it was.
Dr. Carle Pieters: Oh, that’s a wonderful story, I’m not even sure where to begin! First of all I have a wonderful team who worked very, very hard on this for months and months. From the beginning of when we first started working receiving M Cubed data back from the Moon to the point where we were ready to publish it we spent many months and extension discussion and debates among ourselves trying to understand why there was this water feature in our spectra. It should not be there, and it took us a lot of probing and arguing among ourselves to convince ourselves it was real.
Nancy: And as Dr. Sunshine explains, the spacecraft were the main characters in this story.
Dr. Jessica Sunshine: Water on the Moon is a tale of three spectrometers. There’s a Moon Mineralogy Mapper, M Cubed which is on Chandrayaan-1, VIMS, Visible Infrared Mapping Spectrometer which is on Cassini and the Deep Impact High Resolution Spectrometer which is on the Deep Impact spacecraft, and it took all three of us working together to ultimately present the whole story. The neat thing about it was that we had three different spectrometers that had different characteristics that took different data at different times. And by the time we were done we realized we were all seeing the same thing, which was water on the Moon in sunlight, which was quite a surprise. Having all three instruments come to the same conclusion makes it very solid and there’s no other way to explain the data, and we can’t contribute it to a calibration problem or something we didn’t do right. So I got to work pretty heavily on two out of three of these legs of this process.
Nancy: Dr. Pieters echoed the importance of teamwork in sorting out this story.
Pieters: A key point in this is that we weren’t alone.. People on our team, in particular Roger Clark from the Cassini VIMS team also analyzed data from an early pass that that instrument made by the Moon and when the calibration of that data was sufficiently appropriate, he was able to examine the lunar data for the same properties, and early on we had both the VIMS and the M Cubed data, and we knew that both of those instruments saw the water on the Moon, but we were still puzzled. We were – about half of our team was ready to go to press and the other half said, “Well, we’re still not quite sure.”
About that time Jessica Sunshine recognized that the Deep Impact experiment was going to fly by the Moon and do some calibration and she suggested that maybe, we should see what comes out of the Deep Impact spacecraft.
Nancy: We’ll let Dr. Sunshine pick up on this part of the story.
Sunshine: And with Deep Impact, we happened to be taking calibration data to calibrate our instrument just when all this happened and the Deep Impact spectrometer was designed to look for water in various phases in comets, so I knew without question that if there was water on the Moon, the Deep Impact spectrometer would see it.
And until I got that data, our team here worked on it and 24 hours later we turned it around and had recalibrated the instrument and had done everything we needed to do. And we could at least preliminarily look at the data and it was very obvious to me at that point that there was something there and it was real. And then it got to be very exciting! Until then I think skepticism had overwhelmed most of us!
Nancy: And Dr. Pieters confirmed it took a combination of spacecraft to convince the science teams.
Pieters: When we have all three components together there’s no question we see OH and H2O on the surface of the Moon and its very widespread. So we were thrilled when we had sufficient information that convinced literally everyone on the team with this highly unusual and completely unexpected result.
Nancy: Dr. Sunshine explained some of the reasons of why the teams were so skeptical.
Sunshine: You know, of the goals of M Cubed was to look for evidence of water but we thought we would see it as ice in heavily shadowed, permanently shadowed craters and that if we took enough data in these relatively dark areas nearby we might see scattered light coming in from the ice, for example, or some chemistry that might be associated with ice deposits. None of went in thinking , oh we’re just going to find – we went looking for evidence of water in the near-dark because you can’t see in the complete dark. I don’t think any of us went in thinking we would see water in broad daylight. And ultimately from the Deep Impact data we were able to show that all parts of the Moon, the entire surface of the Moon at some point in the lunar day has water on the surface – water and OH.
Nancy: But this story is far from complete. Dr. Pieters explains.
Pieters: Carrying it further, the other thing we’re still in the middle of, is that M Cubed has high spatial resolution, and although the Indian mission ended early, we have data over a large area of the Moon in high spatial resolution and we’re currently in the process of trying to eke out of that data more properties that will provide us clues as to the origin and history and fate of this surfacial water we now know is clearly widespread across the surface.
Nancy: So what is the next chapter in this story
Pieters: Well, my perspective is that some of the issues that have been raised now really require additional data. It really does require a spectrometer around the Moon that can measure the surface with high precision through the water band to about 3.6 microns, but can measure the time variation. That is the key issue that we have to be able to resolve in order to be able to link it to processes that are currently active in this part of the solar system. We have some hints of that in the data we have at hand but we don’t have it documented well enough to explicitly identify the processes that are working. From my perspective, one of the interesting questions that we don’t have an answer for is how rapidly does this OH and H2O develop on the Moon and is it a renewable resource, and is it something that is ongoing and if harvested will we be able re-harvest it? These are questions we can’t answer with the data in hand, but are really very exciting in terms of understanding how small scale processes work when a silicate body in the space environment. And in the longer term it allows us to ask questions about the resources and in particular lunar resources.
Nancy: So stay tuned to the continuing saga of water on the Moon!
Voice: To find out more about this topic, visit our website at www.lunarscience.nasa.gov. Any opinions expressed are the individuals and do not necessarily reflect the opinion of NASA or the NASA Lunar Science Institute. This podcast is produced for educational purposes only. On behalf of the NASA Lunar Science Institute, thanks for listening.
End of podcast:
365 Days of Astronomy
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