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More science data from Chandrayaan-1, and some thermal issues on the spacecraft

Posted by Emily Lakdawalla

27-11-2008 14:27 CST


The Indian Space Research Organisation just posted a few images containing the first publicly released data from two of the spacecraft's 11 instruments. We've previously seen images from its Terrain Mapping Camera and from the imager aboard its Moon Impact Probe. The new images are from the HySI hyperspectral imager -- one of the five Indian-built instruments -- and the RADOM or Radiation Dose Monitor Experiment, which was provided to the mission by Bulgaria.

Here's the new HySI image. They didn't include much in the way of commentary on these images, so I can't really do much scientific interpretation. Judging from the way that they are comparing it to a Terrain Mapping Camera image, I think that probably they plan to combine the color information from the HySI camera with the higher-resolution photographs from the TMC to create a very nice set of color maps of the lunar surface.

Image from Chandrayaan-1's HySI camera


Image from Chandrayaan-1's HySI camera
The HySI hyperspectral camera on the Chandrayaan-1 spacecraft operates primarily in visible wavelengths, extending slightly into the infrared. The two strips on the left in this image are from HySI; the one on the right is from the higher-resolution Terrain Mapping Camera (the data has been downsampled to match the resolution of the HySI images). The strip covers an area near the lunar north pole, centered above 78 degrees north.
They also released two sets of 64 images from HySI covering spots on the lunar surface in each of HySI's different channels; you can download those from the ISRO website. This represents the full spectral resolution of the HySI data; the scientists can do neat tricks with this like taking the ratios of different bands to try to tease out subtleties within the colors of spots on the lunar surface. The Moon is very, very gray, meaning that regardless of what wavelength you take a photo in, the image will look pretty much the same -- bright stuff stays bright and dark stuff stays dark, pretty much regardless of what wavelength you look at the Moon in. But there are tiny little wiggles in the spectrum, places where the brightness dips just a tiny bit, and those wiggles can tell scientists how much iron versus titanium versus other metal ions are present in the volcanic rocks making up the lunar surface. Playing with hyperspectral data like what HySI produces can help scientists tease out those subtleties in the color of the Moon.

I don't know enough about how RADOM works to comment intelligently on the images that ISRO released showing RADOM results. The instrument's goals are pretty basic, but important: to monitor the radiation environment in lunar orbit, which has implications for the long-term health of any future human explorers. I'll just note that Bulgaria is not a member state of the European Space Agency. I don't know anything about Bulgaria's previous contributions to planetary exploration, but I'd guess that its cooperation with India to provide an instrument to a lunar mission is a big deal, and I congratulate the Bulgarians on the successful operation of their instrument!

Finally, there are apparently some thermal issues with the Chandrayaan-1 spacecraft. The BBC quotes the Chandrayaan-1 project director M. Annadurai as saying that the "temperature is a bit higher than anticipated," prompting them to shut off some instruments at times in order to keep the temperature down. Thermal issues are not uncommon with spacecraft, especially when they are operated in space for the first time; it sounds like it may be causing concern with Chandrayaan-1 but no damage. The Hindu, reporting more recently, reports that "India's unmanned lunar spacecraft Chandrayaan the unmanned lunar spacecraft is functioning normally even though there has been a rise in temperature in the moon's atmosphere" and that the rise in temperature is caused by the fact that "it is summer on the moon," an explanation that makes absolutely no sense to me. Hopefully ISRO will step in with a more official statement that will clarify this news!P.S. I wrote this yesterday, just before losing Internet access for a day, and finally found access at my sister-in-law's house after Thanksgiving dinner had been eaten. Happy Thanksgiving to all the Americans -- and to those of you outside the country, think happy thoughts of tummies full of turkey dinner and pie. Now it's time to watch the Cowboys beat the Seahawks.

See other posts from November 2008


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