Exploring the Eighth Continent

This image is a Mini-RF synthetic aperture radar (SAR) strip overlain on an Earth-based, Arecibo Observatory radar telescope image. Taken Nov. 17, 2008, the south-polar SAR strip shows a part of the Moon never seen before: a portion of Haworth crater that is permanently shadowed from Earth and the sun.
Credit: ISRO/NASA/JHUAPL/LPI/Cornell University/Smithsonian

In orbit around the Moon, the Chandrayaan-1 spacecraft is making new discoveries about the chemical composition of our cosmic neighbor. This information will teach us more about the current lunar environment, and also help us better understand the formation of the Moon from an asteroid collision with Earth 4.5 billion years ago.

The Mini-SAR instrument, a lightweight, synthetic aperture radar, has sent back data that gives scientists a look inside the Moon’s coldest, darkest craters. The images show the floors of permanently-shadowed polar craters on the Moon that aren’t visible from Earth. Scientists are using the instrument to map and search the insides of the craters for water ice.

"The only way to explore such areas is to use an orbital imaging radar such as Mini-SAR," said Benjamin Bussey, deputy principal investigator for Mini-SAR, from the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "This is an exciting first step for the team which has worked diligently for more than three years to get to this point."

The two north-polar strips have been mosaicked to show the western rim of Seares crater. The mosaic covers an area roughly 80 kilometers (50 miles) long by 20 kilometers (12.5 miles) wide.

The images, taken on Nov. 17, 2008, cover part of the Haworth crater at the Moon’s south pole and the western rim of Seares crater, an impact feature near the north pole. Bright areas in each image represent either surface roughness or slopes pointing toward the spacecraft. Further data collection by Mini-SAR and analysis will help scientists to determine if buried ice deposits exist in the permanently shadowed craters near the Moon’s poles. If ice deposits do exist, they could be an important resource for future human missions to the Moon.

"During the next few months we expect to have a fully calibrated and operational instrument collecting valuable science data at the Moon," said Jason Crusan, program executive for the Mini-RF Program for NASA’s Space Operations Mission Directorate in Washington.

Mini-SAR is one of 11 instruments on the Indian Space Research Organization’s Chandrayaan-1 and one of two NASA-sponsored contributions to its international payload. The other is the Moon Mineralogy Mapper, a state-of-the-art imaging spectrometer that will provide the first map of the entire lunar surface at high spatial and spectral resolution. Data from the two NASA instruments will contribute to the agency’s increased understanding of the lunar environment as it implements America’s space exploration plan, which calls for robotic and human missions to the Moon.

The C1XS X-ray camera, jointly developed by the UK’s STFC Rutherford Appleton Laboratory and the Indian Space Research Organisation (ISRO), has successfully detected its first X-ray signature from the Moon. This is the first step in its mission to reveal the origin and evolution of our Moon by mapping its surface composition.

C1XS detected the X-ray signal from a region near the Apollo landing sites on December 12th 2008 at 02:36 UT. The solar flare that caused the X-ray fluorescence was exceedingly weak, approximately 20 times smaller than the minimum C1XS was designed to detect.

A permanent human presence on the Moon would teach us many lessons about living and working away from the protection of the Earth.
Credit: NASA Glenn Research Center

"C1XS has exceeded expectations as to its sensitivity and has proven by its performance that it is the most sensitive X-ray spectrometer of its kind in history," said Shyama Narendranath, Instrument Operations Scientist at ISRO.

The X-ray camera collected 3 minutes of data from the Moon just as the flare started and the camera finished its observation. The signal reveals the X-ray fingerprint of a part of the lunar surface. As the mission continues, C1XS will build up a detailed picture of the ingredients that have gone into the Moon – our eighth continent.

Barry Kellett, instrument scientist from STFC’s Space Science and Technology Department said "Despite the small quantity of data, our initial analysis and modelling shows that C1XS has identified the chemistry of this area of the Moon."

Manuel Grande, Principal Investigator, Aberystwyth University, concluded, "The quality of the flare signal detected from the moon clearly demonstrates that C1XS is in excellent condition and has survived the passage of Chandrayaan-1 through the Earth’s radiation (or van Allen) belts with very little damage. This is excellent news for the rest of the Chandrayaan-1 mission."