SMART-1 (Part Three)
Published on Sep 3, 2006 at 10:59 am.
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Filed under moon, space exploration.
Well, the SMART-1 mission is over. At least the operational phase of it is over. Data analysis will go on for years to come. Early this morning, ESA’s SMART-1 plunged into the Moon. I’ve spoken about this in my previous two postings, so if you are just tuning in, go back and read them first to see what this is all about.
Around here, it was hopeless to try to see anything. Besides clouds, which made it impossible, the Moon was so low on the horizon that there was no way to see any impact of this size. The lower an object is in the sky, the more of Earth’s atmosphere that you look through. That dims the light of the thing that you are trying to see in a process that astronomers call atmospheric extinction. We don’t just say dimming, because it is a bit more complicated than that. Different wavelengths are dimmed by different amounts. The blue is dimmed more than the red. That is why the Sun or Moon low on the horizon looks dimmer than it does high in the sky, and also redder. As low as the Moon was in the sky from here, it would have nearly taken a nuclear explosion on the Moon to be bright enough to see from here, even if there were no clouds.
Early reports, though, indicate that the flash was far less spectacular than had been hoped, though probably about what was expected. I am accompanying this posting with an image taken by the Canada-France-Hawaii telescope atop Mauna Kea in Hawaii. You can see the flash. But, this telescope is a major instrument, and all it got was a small flash. It had been hoped that the dust cloud might extend high enough to catch sunlight and make a bright fuzzy spot that observers in small telescopes might see. I have not heard of any such observations yet, but it is still early. Personally, I don’t expect much.
In another day or so, the impact site will swing into view. Likely the crater itself will be too small for any telescope on Earth to actually image. However, it may be possible to observe the ejecta blanket from the impact. All of the observations, and lack thereof, are of interest to NASA, too. The next lunar mission may include an impactor to deliberately slam into craters in the Moon’s polar regions to see if there is any ice there. After the amazing success of the Deep Impact mission to blow a hole in a comet, hopes are up for making craters. However, as should be expected, we are finding the Moon to be a lot tougher than a comet. But, crashing SMART-1 into the Moon was a sort of add-on to the mission. That was not its original purpose, and the craft was designed for scientific study, not to make a big crater. That we got anything useful from the impact is probably more than we really should have expected.
The next step is to wait for the Sun to rise over the impact site. Even if the crater is too small to directly see from Earth, we know where it is. So, later lunar orbiting missions can study the crater. Even with its demise, SMART-1 still isn’t through giving us data!
-Astroprof
(Image Credit:Â C. Veillet, CFHT)
