The event is the highlight of NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) mission. The LCROSS spacecraft flies behind its empty upper stage, which is targeted to strike the floor of Cabeus crater. LCROSS will image the impact and provide direct measurements of the plume before it also plunges into the lunar surface. With LCROSS gone, further measurements of the cloud depend on ground-based observatories around the world.
"This is a completely unique mission that will excavate two large holes dozens of meters across on the lunar surface. It will give us composition measurements we wouldn't otherwise be able to get," said Tim McClanahan, a scientist at Goddard Space Flight Center in Greenbelt, Md.
McClanahan's modeling of the moon's permanently shadowed regions, initially done to support the Lunar Exploration Neutron Detector (LEND) instrument aboard NASA's Lunar Reconnaissance Orbiter (LRO), underscored a problem for ground-based follow-up of the LCROSS impact. "We realized that ground observers would have difficulty identifying the location," he said. "It's near the lunar south pole, where illumination is poor and the ability to distinguish nearly edge-on craters is problematic. On top of that, LCROSS will hit the crater floor, but we can only see its rim from Earth."
To provide the detailed information ground-based telescopes needed, McClanahan approached Goddard's Scientific Visualization Studio (SVS). The goal was to find a "sweet spot" where factors such as lunar topography, lighting from the sun, and the view from Earth provided the earliest, highest-contrast view of the rapidly changing plume.
"Visualization aided two aspects of the LCROSS mission," said Ernie Wright at the SVS. "It helped us understand how visible the plume will be from Earth and whether the targeted terrain was flat and in shadow."
The project prefers a crater floor because slopes tend to be rocky, whereas lighter, fluffier materials fall to the lowest elevations. "LCROSS scientists want to send up a debris cloud as high as they can," Wright explained, "so they want to hit these light materials."
Scientists think that hydrogen detected in lunar soil by several instruments, including LEND, may be either icy leftovers from ancient comet impacts or accumulated from the solar wind, a stream of particles flowing from the sun. Whatever its source, scientists assume hydrogen collects in low polar elevations where the sun never shines. This dictates an impact in the shadowed portion of a crater floor.
On September 11, LCROSS mission planners announced that they had targeted a smaller, more northerly crater named Cabeus A. But later that month, analyses of new data from instruments aboard LRO, together with archival measurements from NASA's Lunar Prospector mission of the late 1990s, indicated that the larger Cabeus crater was a better bet.
"The sweet spot for ground-based telescopes lies about two kilometers above the floor of Cabeus," Wright explained. "There, sunlight streaming through a depression in the crater rim will light up the plume while the rest of the crater remains in shadow."
Francis Reddy | EurekAlert!
Breaking the optical bandwidth record of stable pulsed lasers
24.01.2017 | Institut national de la recherche scientifique - INRS
European XFEL prepares for user operation: Researchers can hand in first proposals for experiments
24.01.2017 | European XFEL GmbH
A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
24.01.2017 | Physics and Astronomy
24.01.2017 | Life Sciences
24.01.2017 | Health and Medicine