Date: January 2, 2010
Title: Water on the Moon
Podcaster: Nancy Atkinson
Links: Universe Today, Astrosphere New Media Association. LCROSS mission info, and links to download the song “Water On the Moon” by John Marmie
Description: 2009 was a “watershed” year for lunar exploration, as five different spacecraft were involved in discoveries of water on the Moon. Let’s take a look back at the discoveries and look ahead to what explorations lie ahead.
Bio: Nancy Atkinson is the Senior Editor for Universe Today, and works with the Astronomy Cast podcast and 365 Days of Astronomy.
Today’s sponsor: This episode of “365 Days of Astronomy” is not sponsored. Please consider sponsoring a podcast in 2010.
Music from “Water On The Moon”
Dr. Carle Pieters: Well, the Moon continues to surprise us. Widespread water has been detected on the surface of the Moon. You have to think outside the box on this. This is not what any of us expected a decade ago. But widespread water has been detected on the surface of the Moon.
Nancy Atkinson: That was Dr. Carle Pieters at a press conference on September 23, 2009 announcing that three different spacecraft had confirmed there is water on the Moon. But the news of water on the Moon didn’t end there in 2009. Later on, two other spacecraft were involved in more scientific findings that has given us a whole new outlook on our closest companion in space. Hi, this is Nancy Atkinson from Universe Today. We’re starting a whole new year for the 365 Days of Astronomy in 2010, but I’m taking this opportunity to look back at one of the biggest space news stories from 2009 – which actually ended up being two big news stories.
Let’s start with the first one: In September, data from three spacecraft –indicated that water exists diffusely across the moon as hydroxyl or water molecules — or both — adhering to the surface in low concentrations. Additionally, there may be a water cycle in which the molecules are broken down and reformulated over a two week cycle, –the length of a lunar day. This finding did not constitute ice sheets underneath the lunar surface, but actually water directly on the Moon’s surface. However, the amount of water in a given location on the Moon isn’t much more than what is found in a desert here on Earth, perhaps a few teaspoons across an area about the size of a football field. But there’s more water on the Moon than originally thought.
The spacecraft involved were the the Chandrayaan -1 lunar orbiter and its Moon Mineralogy Mapper instrument, or M cubed, which found evidence of hydroxyl- and water-bearing materials, then there was the re-purposed Deep Impact probe, on its way to rendezvous with another comet in 2010. In June of 2009, the spectrometer on board also showed strong evidence that water is ubiquitous over the surface of the moon. And then archived data was reanalyzed from the Cassini spacecraft that flew by the moon in 1999 on its way to Saturn, and that data as well agreed with the finding that water appears to be widespread across the lunar surface.
If the data was there before, how could we have missed this previously?
Robert Green, project instrument scientist for the M cubed instrument gives this response to that question:
Robert Green: It’s quite fascinating that no one has found this before because Apollo was there for decades, we’ve had robotic missions, the Japanese were there and the Chinese were there and they didn’t see it. We saw it because we went there with the right instrumentation. The Moon Mineralogy Mapper has an extended spectrometer footprint region that was sensitive to the variety of water we are finding.
And what about the Moon rocks returned from Apollo missions? How could we have missed seeing the water in those rock, which we actually have here on Earth to study? Robert Green again provides insight into what happened:
Robert Green: The Apollo astronauts many important samples which includes soils and rocks, and all those rocks and soils were brought into the command module which had a humid atmosphere which the astronauts were living. So the water in the atmosphere interacted with those rocks, and put a signature in those rocks, which is just like the signature that we are seeing, but by the time they came back to Earth we assumed that signature was due to terrestrial contamination; from being in the command module, on Earth and in the Pacific. So those rocks have those signatures but up until today we assumed it was all associated with contamination. But now we’ve measured this signature directly on the Moon, there’s no question of contamination and so that’s the difference between what we’ve discovered and the extraordinary work that was done in the age of Apollo.
Nancy Atkinson: And the process for how water can actually be on the moon’s surface is a little complicated, so I’m going to let Robert Green explain it:
Robert Green: One of the hypotheses were are working with is that there is oxygen in the rocks on the surface of the Moon, there is hydrogen coming from the sun hitting those rocks. Oxygen and hydrogen together make water, so there could be a process with the solar wind carrying the hydrogen which makes water on the surface of the Moon.
Nancy Atkinson: Ok, now let’s move on to the second part of our water on the Moon news from 2009. On October 9, , the LCROSS mission, or the Lunar CRater Observation and Sensing Satellite successfully crashed an impactor into a permantley shadowed crater near the moon’s south pole. Even though the impact didn’t create a plume that was much hoped for by those attempting to observer the impact from Earth, the science team from LCROSS announced on Nov. 13 that they had hit paydirt, or pay-regolith, perhaps. Here’s Tony Colaprete, principal investigator for LCROSS:
Tony Colaprete: Indeed yes, we found water. We didn’t find just a little bit, we found a significant amount. If you remember about a month ago we were talking about teaspoons into glasses from an area about the size of a football field, well now I can say today in the 20-30 meter created by LCROSS, we have maybe about a dozen of these two gallon buckets worth of water.
Nancy Atkinson: Colaprete said they also found signatures of other compounds as well in the impact site in Cabeus Crater, including sodium and carbon dioxide, which they are still analyzing.
There are potentially two types of water on the moon: exogenic, meaning water from outside sources, such as comets striking the moon’s surface, and endogenic, meaning water that originates on the moon. The LCROSS team says that where the water in Cabeus crater came from is yet to be determined, whether it was delivered there by comets and meteorite hits or if some process within the Moon or on the surface is creating the water. The M cubed team, suspects that the water they’re seeing on the moon’s surface is endogenic, that it is coming from the process on the Moon itself that Robert Green talked about.
Mike Wargo, NASA’s chief lunar scientist, said the cold traps in the permanently shadowed craters of the Moon are like the dusty attics or junk drawers of the solar system, and that they collect stuff from the solar system’s evolution. And he added, We’re only just begun to tap into our understanding of the Moon.
The other spacecraft that played a part in the LCROSS findings was the Lunar Reconnaisaince Orbiter, that newest lunar orbiter, which made observations of the crater and plume created by LCROSS.
Mike Wargo talked about how LCROSS and LRO will help our future explorations of the Moon:
Wargo: Well overall both of these missions have been highly successful, so far. The fact that LCross was able to confirm the presence of water in these permanently shadowed regions has significant scientific implications. It confirms prior theories and it gives us potential to have resources to us when we continue to explore beyond lower earth orbit.
The real beauty of both of these missions is that NASA is using the best it has to get the information it needs to continue to explore we knew that the scientific community was the place to go to get the experts and about how to make the measurements on the moon that we’ll need to explore safely and effectively as we go beyond lower earth orbit and LRO is delivering in spades.”
Nancy Atkinson: As another member of the LCROSS team said, these new findings have really turned our understanding of lunar water on its head, and that we need to keep our minds open of what this is telling us. It’s no longer Apollo’s Moon, its our Moon.
As we look ahead to what new information we’ll garner from our explorations of the Moon in 2010 and the years beyond, I’ll leave you with a clip from a song called “Water on the Moon” written by LCROSS Deputy Project Manager John Marmie.
End of podcast:
365 Days of Astronomy
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