Image Specifications
11.26.08
 
A team of scientists, led by Diane Wooden of NASA’s Ames Research Center has created a detailed mosaic image of the moon’s south pole to help observe the dual impacts of the Lunar CRater Observation and Sensing Satellite (LCROSS) mission. Mosaic image of the lunar south pole near the Faustini Crater, a candidate LCROSS impact site. This perspective would reveal the impact debris plume as it rises above the crater rim into sunlight against the dark background of space. Credit: NASA Ames Research Center
Mosaic of 699 images of a candidate impact site on the moon's south pole. The image was collected on Nov. 7, 2008 using the NASA’s Infrared Telescope Facility (IRTF) located atop Mauna Kea on the Big Island of Hawaii. A closer view of the candidate LCROSS impact site with reference craters labeled. Credit: NASA Ames Research Center
The final mosaic image is composed of 699 images taken on 2008 November 7 at 06:30-07:21 UTC using the near-IR SpeX spectrometer and imaging instrument on the IRTF. The spatial resolution in the mosaic is 0.15 arc seconds per pixel, which corresponds to 0.3 km per pixel at the distance of the moon. The densest and brightest part of the LCROSS ejecta plume is expected to extend two to four kilometers above the crater rim, which corresponds to 13 to 26 pixels in these images. Each image was exposed for 0.24 seconds, the shortest integration possible with the SpeX instruments focal plane camera. The images were taken through a 1.5% narrow band filter centered at a wavelength of 2.294 micron (http://irtfweb.ifa.hawaii.edu/~spex/). Due to high cirrus, some, but not all, frames are saturated. A neutral density filter that transmits only one percent has been installed together with the narrow band filter to mitigate the overexposure for the next three half-night observation run on December 6-8 04:00-10:00 UT.

2008 December 6-8 04:00-10:00 UT Observations

Amateur astronomers are encouraged to image the north and south poles of the moon. The goal is to obtain images that determine the scale of recognizable features observed in the wider field of view on amateur telescopes when compared the higher spatial resolution near-infrared IRTF images. A secondary goal is to compare the dynamic range of images to allow the verification of detection of subtle variations in topography and albedo. This exercise also may help amateur astronomers prepare for obtaining images of the impact plumes. The impact plumes will occur in shadowed regions, but these shadowed regions likely will be adjacent to lit regions of the moon.

The LCROSS mission plans to impact the moon when the lunar phase is approximately between 76 degrees and 150 degrees and between 210 and 284 degrees. This avoids the few days surrounding a full moon when the moon’s brightness probably will hamper large telescopic observations. These phases also provide sun avoidance for space-based telescopes, such as the Hubble Space Telescope. Moreover, the shadowing conditions at the planned lunar phases favor identification of small features. At full moon, these features may be more easily confused with albedo variations, rather than surface topography.

The coordinates for preferred locations for LCROSS impacts within permanently shadowed craters, as of October 2008, are given below. Crater A and F are in the north polar region and Faustini and Shoemaker are in the south polar region. Cabeus at 84.9 S, 324.5 E is no longer included as a preferred impact location.

Crater A: 84.45 N, 62.2 E
Crater F: 86.2 N, 38.4 E
Faustini: -87.5 (S), 83.1 E
Shoemaker: -88.3 (S), 43.4 E

The libration during fall season favors observations of the lunar south pole. In addition to observations on 2008 Nov 7-8 04:00-10:00 UT, Wooden and her team will also be obtaining images and spectra of the lunar poles on 2008 December 6-8 04:00-10:00 UTC (calendar days Dec. 5-7) and 2009 January 2 04:00-10:00 UTC (calendar day, Jan. 1).

Amateur astronomers have the opportunity to create a useful reference imaging data set for the LCROSS impact. They can be helpful in the development of an amateur astronomer atlas of the lunar poles at different lighting and libration conditions. Images taken under different phases produce subtle shifts in crater shadows that affect determination of "crater centers" in images. This can affect the determinations in the offsets between these reference craters and a target crater. Furthermore, images taken during phases on the opposite side of full moon may reveal subtle features that are useful in refining the pointing accuracy.

Observations by amateur astronomers will help refine new protocols for observing the moon and increase knowledge about the moon.

For more information about the LCROSS Observation Campaign, visit:

http://lcross.arc.nasa.gov/observation.htm

For a library of photographic images of the moon, visit:

http://www.lpi.usra.edu/resources/lunar_orbiter/