Observing the Moon with the Hubble Space Telescope

Observing the Moon with the Hubble Space Telescope.

Yes, it can be done, but it takes some persuasion and has some limitations. The following images were obtained through John Caldwell's Guarenteed Time Observer program 7717, and were presented at the Lunar and Planetary Science Conference a few years ago. Note that these are scanned from slides taken off a computer screen. Its amazing any information survived this treatment.

This is the first image, which targets Copernicus crater, shows that the initial pointing (under gyro control) was right on. (51 kb JPEG)

This is the second image, which shows Copernicus off-center-- we weren't able to exactly compensate for HST's motion around the Earth. (50 kb JPEG)

This image shows the region around the crater Milichius, halfway between Copernicus and Kepler. (76 kb JPEG) This is the region for which we had overlap in three images, enabling us to make a mineralogical map, shown in this image (172 kb JPEG). The red color indicates old surface with a "space weathered" steep red continuum, while blue indicates fresh material. Green (or yellow) shows where iron (Fe) rich material is found.

Note that the inner slopes of the craters are blue-- moonquakes send stuff sliding down the steep sides of the craters, exposing fresh material. Note how the ejecta blanket around Milichius is easily seen in the black and white image, but disappears in the mineralogical map. This indicates that the ejecta is the same stuff as the surrounding mare basalts, but ground into smaller particles which reflect better. This is as expected. Note also some green/yellow flecks just inside the lip of Milichius, indicating outcrops of more iron-rich material. This could be due to the different scattering properties of bare rock outcrops compared to the talus slope below them, or a phase effect (unlikely, the spots appear all around the inside of the rim), or the presence of more Fe rich material in the top layers of the mare basalt. Gotta go back and take a core...

This image is a composite of images from the Clementine spacecraft. These were made through filters similar to the HST mineralogical image (above) and displayed in a similar way. Clementine was looking straight down, however, while HST was necessarily looking in from Earth's direction. (211 kb JPEG)

This image compares HST resolution with Clementine, for the southeastern part of Copernicus crater. The HST image is on the left, and contains some bright points due to "cosmic rays", solar protons that impact the detector during the exposure. The Clementine image is at right. The resolution is quite comparable. Clementine's big advantage is that it looks straight down, and covers the whole Moon, including the far side. HST's big advantage is cleaner optics and the ability to reimage areas if necessary, with a wider range of filters. (69 kb JPEG)

This last image is a plot of the bandpasses of the HST filters used, along with a generic reflectance spectrum showing the red continuum slope at short wavelengths, and the 1 micron absorption feature due to silicate minerals. (355 kb JPEG)