Friday, September 25, 2009
The press conference on the confirmation of water (and hydroxyl) in large quantities on the Moon happened last night and it was very interesting, particularly the explanation of how the discovery was confirmed using a number of probes over the years. The three main probes that contributed to the discovery were actually Deep Impact, Cassini, and Chandrayaan-1. Cassini actually had an Earth flyby almost a decade ago, but the observations of the Earth and Moon system couldn't even begin to be used for the purposes of detecting water at least until 2004 when it arrived at Saturn and had something to compare the first observations to, and the entire discovery wasn't able to take place until they had the long-term Chandrayaan-1 observations to compare with the others, so this is the explanation on why it ended up taking so long.
As for the process by which water is created on the surface of the Moon: it has to do with the day and night cycle there - 14 days of day, then 14 days of night. The greatest concentrations of water occur both at the higher latitudes away from the equator (those are the blue regions in the image to the right), and also around morning and evening. This is the reason why the rocks the Apollo astronauts brought back were so dry, because they went to the driest part of the Moon at the driest part of the day, when the heat from the Sun eliminates the majority of the water from the rocks, and that's why the total amount of water they brought back from the Moon only amounted to one teaspoon.
The water and hydroxyl itself is created by the interaction of the solar wind (charged hydrogen ions) with the oxygen in the rocks themselves, and it's a process that should occur not just on the Moon but any other object in the Solar System (and other solar systems as well) with a similar makeup, which even includes asteroids. One question I have about that (might have been answered in the Q&A but not sure as I went to bed before that as it was 4 am here in Korea) is whether the slow rotation speed also contributes to this.
One other interesting note is that the presence of water they discussed is located right at the surface, in the top two millimetres of soil. What the areas below are like are still a matter of debate, but having confirmed the presence of water right at the top is very good news for future colonization given how easy it would be to gather soil for purposes of water collection compared to having to dig huge trenches.
The subject of LCROSS (the probe that will impact the Moon's south pole two weeks from now) also came up, and the presence of ice there is probably a different phenomenon from the water discovery announced yesterday, though they still may have something to do with each other. The south pole though is likely to have water ice that simply arrived through events such as cometary impacts, which then settled into the permanently shadowed craters down there and remained undisturbed ever since. Before this discovery was made the idea was to build a colony on the peaks of eternal light at the south pole and then venture into the shadowed craters to harvest ice water to be used, but with yesterday's news that water is already present in significant amounts at higher latitudes, it may not even be necessary to venture into them; simply going from the peaks of eternal light where the colony is located into a region with a normal day/night cycle to collect water during the morning and evening periods may be enough.
As for the future implications of this: it has become quite clear that Mars simply doesn't offer any significant advantages over the Moon anymore that would justify a journey there instead. Up until about a few years ago Mars was touted as the only reasonable place for human colonization due to the presence of water and other resources needed to live off the land, while the Moon was thought to be a dry dustball in which we would have to ferry all of our supplies from Earth. Since the Moon seems to have the resources we need to colonize though, waiting 2+ years for a launch window, travelling six months there and six more months back simply isn't worth doing.
Another argument made for Mars is that its higher gravity (0.38g compared to 0.16g for the Moon) would be more suitable for human colonization due to the long-term effects of low gravity on human physiology, but this is questionable for a few reasons. One reason is that we simply have never experienced low gravity in the long term - the only gravity besides 1g that we have ever experienced has been 0g. At the moment the person that has spent the longest period of time in space is Valery Polyakov, who spent 437 days and 18 hours in space at one time. He was also healthy when he returned, even after more than a year in 0g. This means that even without any testing we are certain that humans will be able to remain in a 0.16g environment for at least two years or so, maybe more, without any physiological damage.
The other point to bear in mind is that in spite of its larger gravity, Mars necessitates a trip there and back of a year in duration, a year of no gravity at all. To the Moon this is a mere three days. Even in the worst case scenario where low gravity turns out to be damaging to human physiology and we have not yet constructed a 1g simulator on the Moon it will still be easily possible to return to the Earth within a few days. So the problem of gravity simply isn't a problem.
Micrometeorite impacts will be a problem in the short term. My eventual solution is detailed here. Since human civilization on the Moon will naturally result in the creation of waste gases, it would probably be a good idea to work towards the creation of an extremely thin atmosphere (a Triton-like atmosphere perhaps) that would keep the smallest of micrometeorites from hitting the ground. Until then extremely fortified dwellings are probably the only solution. We have no detailed knowledge of the frequency of very tiny micrometeorite impacts on the surface though so this is still an unknown factor.
Focus: it's now time to shift our focus away from Mars and back towards the Moon. No current missions on Mars should be cancelled though (such as the rovers) since they are already there and gathering valuable data, nor should any scheduled to launch soon (Mars Science Laboratory, Phobos-Grunt) be cancelled. However, completely new missions to Mars based on the idea of eventually paving the way for human settlement need to be rethought. Concepts like the Mars Gravity Biosatellite for example (MGB was cancelled, but just as an example) need to be switched to a Moon-centred concept, testing 0.16g instead of 0.38g. To name a few more examples: Germany should reinstate its lunar mission. Canada may want to rethink its Northern Light mission. India should concentrate on lunar objectives instead of its long-term plans for Mars. You can see that there are a fair amount of resources being devoted to long-term plans for Mars that could easily be diverted to the Moon instead.
As for the upcoming missions to the Moon, you can see them in this chart from Wikipedia. There are a total of eight scheduled missions by 2013, compared to five for Mars during the same time period, two of which seem a bit vague. If we are able to launch so many missions to the Moon without even a firm focus on colonizing there, what more could we accomplish if we put our minds to it?
|USA||GRAIL||September 6 2011|
|USA||ILN Node 1||2013|
|USA||ILN Node 2|
|Future missions||Launch schedule||—|
| Phobos-Grunt (Russia) ||2011-2012|
| Yinghuo-1 (China) |
| MSL Curiosity (US) ||December 2011|
| Northern Light (Canada) ||2012|
| MAVEN (US) ||2013|
| Mars mission (India) ||Between 2013-2015|
Here's the press conference from yesterday in full, including the Q&A session afterwards.