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What would the moon look like to someone at the South Pole? To a first approximation, it's bisected by the horizon. But how far above and below does it get?
The moon orbits close to the plane of the ecliptic, which is tilted at 23.5 degrees to the equator, the moon is slightly off the ecliptic, and can be about 5 degrees above the ecliptic.
So, on the winter solstice (June 21) if full moon happens to be furthest from crossing the ecliptic, the moon would be 28.5 degrees above the horizon: roughly a third of the way between the horizon and the zenith. It can get the same distance below the horizon, and during summer the full moon would not be seen at all.
Our moon is unique in being close to the plane of the ecliptic, and not in the plane of the equator, which suggests its formation was not like that of other moons in the solar system.
Apr 13th: Why Is The Moon’s South Pole So Important?
Title: Guide To Space – Why Is The Moon’s South Pole So Important?
Organization: Universe Today
As NASA prepares to return to the Moon by 2024 as part of its Artemis program, the agency is focusing its efforts on exploring the Moon’s polar regions. These are areas of the Moon which seem to have a lot of water mixed in with the regolith.
Some of these craters are permanently in shadow, and might still have large quantities of water, that’s accessible to human and robotic explorers. This is a critical resource, and the Moon might be just the place to help humanity as it pushes out to explore the rest of the Solar System.
In addition to filling the atmosphere with oxygen, plants give off a very specific wavelength visible in infrared radiation. It’s the kind of signal that other civilizations could search for as they’re scanning the galaxy. It’s what we’ll be looking for too. But don’t just blame the plants. Other forms of life have been giving off signals too, signals we can search for as we discover new exoplanets and wonder if they have life there.
Bio: Fraser Cain is the publisher of Universe Today
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A concept for a simple radio observatory at the lunar south pole
The lunar south pole may be the most feasible site for the first very low frequency interferometric array. The part of the electromagnetic spectrum below ∼30 MHz remains to be the only unexplored window in astronomy because of significant radio interference of Earth. To avoid such interference, the far side of the Moon has been considered for basing a radio array. However, such an observatory will unlikely be funded until access to the lunar far side becomes inexpensive. This paper presents a potentially affordable observatory concept for performing an initial sky survey at very low frequencies. The south polar region of the Moon was chosen as the observatory site and its radio quietness was examined using a numerical simulation. The simulation shows that the far side of Malapert Mountain near the lunar south pole may be a promising site for radio astronomy. Simple radio antennas could be deployed there as a lightweight payload on any mission to the lunar south pole.
View of moon from South Pole? - Astronomy
Moon 3D Map allows you to view Moon landscape in a new way.
The Moon is in synchronous rotation with Earth, always showing the same face with its near side marked by dark volcanic maria that fill between the bright ancient crustal highlands and the prominent impact craters. It is the second-brightest regularly visible celestial object in Earth's sky (after the Sun), as measured by illuminance on the surface of Earth. Although it can appear a very bright white, its surface is actually dark, with a reflectance just slightly higher than that of worn asphalt. Its prominence in the sky and its regular cycle of phases have, since ancient times, made the Moon an important cultural influence on language, calendars, art, and mythology. The Moon's gravitational influence produces the ocean tides and the slight lengthening of the day. The Moon's current orbital distance is about thirty times the diameter of Earth, causing it to have an apparent size in the sky almost the same as that of the Sun. This allows the Moon to cover the Sun nearly precisely in total solar eclipse. This matching of apparent visual size is a coincidence.
Google Maps API is used in this project.
The Google Maps plug-in allows you to navigate and explore Moon geographic data using a web browser.
Use the new navigation panel to zoom in and zoom out or just press the random button to find a new amazing place.
New interesting places on the map
A drop down menu with a list of interesting places will help you to find where they are.
Still to come are list with popular places on the moon like mountains, landing places and more.
View of moon from South Pole? - Astronomy
The South Pole Telescope (SPT) is a new 10-meter telescope at the Amundsen-Scott South Pole research station. Taking advantage of the exceptionally clear, dry, and stable atmosphere at the South Pole, the SPT will map large areas of the sky with high sensitivity at millimeter and sub-millimeter wavelengths.
The initial goal of the SPT is to explore the nature of dark energy, an unexplained phenomenon responsible for the observed acceleration in the expansion of the universe. The SPT will search for massive clusters of galaxies by looking for spectral distortions in the cosmic microwave background. Dark energy inhibits the growth of galaxy clusters, so studying the population of clusters through cosmic time will constrain models of dark energy.
Virtually visit the South Pole Telescope and the Amundsen-Scott South Pole Station, which is operated by the National Science foundation via panoramic in Google Street View format.
Issue 6: Autumn 2004 Australian Antarctic Magazine
The rear door of the Hercules lifted, a shaft of bright light illuminated the dark interior of the transport plane, and the first bite of the polar air gripped me. I’d arrived at the South Pole at last. It was January 1994, nearly four years on from when a small group of idealists had dared to dream that Australians could do astronomy in Antarctica. With the encouragement of colleagues from the recently formed US Center for Astrophysical Research in Antarctica, we’d put together two experiments to test our speculations about the conditions we’d encounter. There were two questions we hoped to answer that coming winter. Would the infrared sky be 100 times darker than in Australia, and was there ‘super-seeing’ of the stars?
Jamie Lloyd, who’d just finished his honours year at the University of New South Wales (UNSW), was the advance party, and I was the following infantry division. He’d arrived a week before me, hand-carrying what looked, to anyone else, like a golden dust-bin with him on the plane. It was the IRPS, or Infrared Photometer Spectrometer, the subject of his honours thesis. Ten years previously it had been a state-of-the-art instrument on the Anglo Australian Telescope, used by David Allen to pioneer the fledgling field of infrared astronomy. Now it was about to become Australia’s first experiment at the South Pole, and our first step on the road which we hope will lead to the building of the world’s largest telescopes on the summits of the Antarctic plateau, able to look back in time to the formation of planets, stars and galaxies.
I was bringing with me a second experiment, put together by Rodney Marks, a young graduate student who in the last year had taught himself French, headed off to the Université de Nice on the French Riviera to learn the science of micro-thermal turbulence from its master, Jean Vernin, and returned to UNSW to build his own experiment to measure the turbulence above the South Pole.
The IRPS had been ‘winterised’ over the previous six months by Jamie, working under the supervision of my colleague Michael Ashley, both doing their best to anticipate how it would perform when left outside, at up to minus 75 degrees for six months, while needing to be filled each day with liquid nitrogen (100 degrees colder still), in the winter dark, by winterer John Briggs. Jamie had laboured heroically in the week before I arrived putting the IRPS together, working in a laboratory still under construction, confined to the corner of a desk, with two other telescopes also going up around him. However the IRPS was still in bits when I got there, and we had all of a one hour change-over, for Jamie was to depart on the plane I’d just arrived on!
Jamie tried to brief me on where he’d got up to, while I sat mutely in the galley, trying to take it in while gasping for breath, as all new arrivals to Pole do, unaccustomed to the thin, dry air at a pressure altitude of over 3000m. Then Jamie shot off, and I was left with John Briggs to get the IRPS and the micro-thermal experiments together in this alien environment.
Somehow we did it and, a week later, when I saw the Moon pass through the beam of the 5mm diameter ‘telescope’ that the IRPS effectively was, shining brightly in the infrared ‘L-band’ of 3.8 microns, it was perhaps the most exciting moment of my professional life as an astronomer.
That winter the IRPS confirmed for us that the infrared sky was indeed as dark as we’d anticipated (see Figure 1, and photograph previous page). However, we also found that the boundary layer generated considerable turbulence that disturbs the smooth wave-front arriving from an astronomical source in its last few metres before it would reach a telescope, creating the appearance of an excessive twinkling of the stars.
The infrared observations led us, four years later in 1998, to our first ‘real’ astronomical experiment, when we worked with our US colleagues on the 60cm SPIREX telescope, to image star forming regions in our Galaxy in the thermal infrared wavebands, from 2–4 microns. We were able to view extensive clouds of complex organic molecules enshrouding protostars, still embedded within great clouds of dust, the natal cocoons from which they were being born (see infrared image previous page).
The micro-thermal turbulence measurements, on the other hand, caused something of a puzzle to us as we sought to understand the implications they posed. They led to a series of further experiments over the coming years as we fully characterised the turbulence. Yet, while the measurements caused some dismay at first, they may be leading us to a remarkable, if somewhat abstruse, conclusion, now that we have managed to take them from Dome C.
Dome C is one of the summits of the Antarctic plateau, in the middle of the Australian Antarctic Territory, and the site of the French-Italian Concordia Station. Our measurements suggest that it may be the best site in the world for the next generation of optical/infrared telescopes with diameters of up to 100m. The extremely narrow boundary layer in which all the turbulence is generated greatly simplifies the requirements for adaptive optics correction, an essential element in recovering the diffraction limit of a telescope from distortions caused by the atmosphere, thereby allowing the telescope to image sources with a clarity almost equivalent to being in space.
This January marks for us a decade of astronomy on the Antarctic plateau. The early site testing experiments were soon followed by a more sophisticated approach, that of the ‘automated astrophysical site testing observatory’ or AASTO (see image on previous page), and involving scientists from the ANU. Driven by the enthusiasm and vision of John Storey, leader of the UNSW group, a series of increasingly sophisticated experiments were built for the AASTO: sky monitors to measure the sky at optical, infrared and sub-millimetre wavebands, and instruments to characterise the turbulence profiles at all heights through the atmosphere.
Working with the AASTO has been an eventful experience, for the trials of winterising and automating experiments are not trivial ones! The greatest challenges have been caused not by the experiments, but by the need to provide reliable power to run them in a warm but autonomous environment. Perhaps reminiscent of the challenge faced by Mawson’s men in 1911 trying to get their ‘air tractor’ working to haul their equipment, the problem of reliable power generation almost proved our nemesis.
Perseverance paid off, and the AASTO produced a string of results. The site testing program at the South Pole is now virtually over we expect measurements there to finish after this coming winter. Our work at the Pole is not over, however. One of the experiments is already being adapted to a new use, the search for exoplanets, orbiting around other stars! That story will have to wait for another day.
We have now reached the next stage of the journey to an Antarctic observatory, Dome C. With the rapid development of Concordia station by the French and Italians, a new frontier is opening here for Antarctic science. Extreme cold, dryness, absence of katabatic winds, and high elevation hold the promise of providing the best Earth-based site for observing the distant Cosmos.
Jon Lawrence, a postdoctoral fellow in our group, redesigned the AASTO into the AASTINO (automated astrophysical site testing international observatory), complete with a new, improved power generator, a Whispergen engine (see image above). Originally designed for ocean yachting but now transformed for Antarctica, and working on the principle of a Stirling thermodynamic engine, it has proved far more reliable than the propane-fuelled thermoelectric generator used on the AASTO. This last winter the AASTINO operated, completely autonomously, for over 100 ‘days’ at Dome C. While we communicated with it via Iridium telephone, it was sited over 1000km away from the nearest human being. See for yourself the amazing results from the webcam at http://www.phys.unsw.edu.au/southpolediaries/– hardly a day of cloud was seen during the entire period!
The first scientists will be wintering at Concordia Station in two seasons’ time. The initial results from the first full season of winter measurements there exceeded expectations, and interest in the site as the possible location for an ‘extremely large telescope’ (ELT) is growing rapidly, especially in Europe. A few parameters for the site still need to be ascertained before such a decision would be made, in particular the characteristics of high-altitude turbulence. We are building an instrument, a ‘multi-aperture scintillation sensor', or MASS, in conjunction with NASA’s Jet Propulsion Laboratory, in order to make the necessary measurements this coming winter. If the results turn out as we anticipate, there may be only one logical place to build the ELT — a prospect that has one salivating!
How Saturn's Moon Got Its Stripes
By: Monica Young December 9, 2019 0
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Astronomers have struggled to understand the origin of the parallel fractures on Saturn’s icy moon Enceladus, known as “tiger stripes,” from which water-ice spews into space. Now, a single explanation ties all the pieces together.
The tortured surface of Saturn's moon Enceladus includes four rifts, sometimes called "tiger stripes," near its south pole. These are the source of its gas-and-particle plumes. Blue tints in this false-color view from Cassini indicate an icy surface covered with coarse grains and boulders.
NASA / JPL / Space Science Institute / CICLOPS
Saturn’s moon Enceladus is famous for its water-spewing geysers, an outward sign of an underground saltwater ocean. But the region that hosts the geysers — an area of so-called “tiger stripes” etched into the icy crust— has long puzzled astronomers.
The parallel stripes, about 35 kilometers (21 miles) apart, are located only at the moon’s south pole, and they’re unlike any features found on other icy moons. No scenario has simultaneously explained all of the stripes’ characteristics.
Now, Douglas Hemingway (Carnegie Institution for Science and University of California, Berkeley) and his colleagues publish an explanation in Nature Astronomy that covers all the bases.
The idea is simple in concept: Once a crack forms in Enceladus’s icy crust, it creates a cascade of fractures next to it.
Enceladus is known to go through cooling periods that thicken its icy crust. As its belowground water ocean freezes, it expands, exerting pressure from the inside. Because Enceladus’s crust is thinnest at its north and south poles, where Saturn’s gravitational pull creates the most heat, that’s where the crust breaks when it begins to pull apart.
This map shows the active south polar region of Saturn's moon Enceladus. The long, linear, bluish features are the “tiger stripe” fractures, from which a plume of water vapor and other molecules erupts. White circles and crosses represent locations identified by scientists as source locations for dozens of geyser-like jets along the fissures. The red curve is the ground track of Cassini’s October 28, 2015, flyby at the time of the spacecraft's closest approach.
NASA / JPL-Caltech / Space Science Institute / CICLOPS / Porco et al., Astronomical Journal, 2014
Hemingway and colleagues suggest that Baghdad Sulcus, a stripe that cuts directly through the geographic south pole, formed in this way, a crack at the surface that eventually penetrated all the way through the ice shell. Water fills most of the crack, boiling off at the top in geyser-like fashion where it meets the vacuum.
This first crack relieved the pressure from the cooling, expanding ocean — that’s why there are no like fractures at the north pole. But the geyser erupting from this fracture snows water-ice down onto its flanks, building up a ridge on either side over time. The ridge becomes heavy enough to bend, and eventually break, the icy crust, creating another crack at a specific distance — 35 kilometers — from the first one.
This process continued to create stripes in symmetric pairs around Baghdad Salcus: first Cairo and Damascus, then Alexandria and a feature informally named “E.” Eventually, though, the cascade ends, either because there’s not enough eruption “snow” to build up ridges or because the ice crust becomes thick enough not to bend and break.
A closeup of the four 80-mile-long rifts(dubbed "tiger stripes") near Enceladus's south pole (white cross). These are the source of its gas-and-particle plumes. Blue tints in this false-color view from Cassini indicate an icy surface covered with coarse grains and boulders.
NASA / JPL / Space Science Institute / CICLOPS
All In One
Scientists are commending this all-encompassing scenario. “[This study] corrals a host of observations of Enceladus' south polar terrain and its geysering activity with a rather simple idea,” says Carolyn Porco (Space Science Institute), who was not involved in the study but led the Cassini imaging team that discovered the stripes.
The plumes of Enceladus, captured spewing from the moon's surface by the Cassini spacecraft at a distance of 14,000 kilometers (9,000 miles) in 2010.
NASA / JPL / Space Science Institute / CICLOPS
Frank Postberg (Free University Berlin), an expert on Enceladus who was also not involved in this study, agrees: “I think this is another important ‘milestone’ paper that solves one of the long-standing riddles Enceladus has been puzzling us with since the discoveries by Cassini in 2005.”
Not only that, Postberg adds, but the explanation that the authors propose also explains why such regular fractures occur only on Enceladus and not on other icy moons.
Hemingway explains that the cracks can only form on icy worlds with weak gravity. “After the secondary fracture starts to form, the load (the snow piled up on the edge of the previous fissure) is still there,” he explains. “That load has to be supported by an increasingly broken and therefore weaker ice shell.” So once a crack forms, it will break all the way through the ice unless something counteracts the stress. While tiny Enceladus doesn’t have enough gravity to hold a crack together, other icy moons — such as Europa, Callisto, and Ganymede — do.
The new scenario may help scientists understand other facets of Enceladus’s geology. Porco, for one, is excited to see whether this process for creating regularly spaced cracks can also explain the regularly spaced geysers within those cracks. “I have long suspected that the geyser spacing is related to the ice shell structure,” Porco adds. “This may be a hint at exactly how that comes about. Another puzzle awaits the intrepid!”
Huge Mass Found Under Moon's Largest Basin
By: J. Kelly Beatty June 21, 2019 0
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Does the massive metallic core of a primordial impactor lie buried under the South Pole-Aitken basin on the lunar farside?
One of the Moon's most fascinating features — one hidden from our view on its farside — is a huge impact basin known as South Pole-Aitken (SPA). It's so named because its 2,400-km (1,500-mile) diameter extends from the crater Aitken on its north rim to the lunar south pole. It's immense, second only to Mars' Hellas basin as the largest impact in the solar system.
The near side (left) and far side of the Moon, as recorded by the Lunar Reconnaissance Orbiter Camera. An oval indicates the location of South Pole-Aitken basin.
NASA / Arizona State Univ.
SPA isn't particularly obvious in spacecraft photos — a somewhat darker center hints of metal-rich material dredged up from the Moon's deep crust or uppermost mantle. But topographically it's an unmistakable pit up to 9 km deep. Early this year China's Chang-e 4 lander dropped onto one particularly deep spot near the basin's center.
Geologists have long suspected that oval-shaped SPA resulted from the slow, oblique collision of an object roughly 200 km across that didn't penetrate the Moon very deeply.
Now an analysis of gravity and topography data has identified a huge mass buried under the basin. A team led by Peter B. James (Baylor University), which announced the discovery in Geophysical Research Letters, combined topographic maps of the basin with the best-available data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission. The team suspects that the impactor's iron-rich core might have dispersed itself in the Moon's upper mantle, leaving behind a concentrated blob with roughly five times the mass of the Big Island in Hawai'i.
Mass concentrations (or mascons) are nothing new — they're typically found under many other lunar basins. But those tend to have a bull's-eye structure with a deeply buried ring of lower-density material sandwiched between a denser core and outer ring. This tells researchers that that the impact removed enough overlying crust to allow a "plume" of dense, metal-rich mantle to rise toward the surface under the basin's center.
This false-color graphic shows the topography of the far side of the Moon. Reds and yellows indicate high elevations, blues and purples the lowest terrain (dominated by South Pole-Aitken basin at center). A dashed circle shows the location of the huge mass buried under the basin.
NASA / Goddard Space Flight Center / Univ. of Arizona
But the massive blob buried some 400 km under SPA has a different gravitational fingerprint. James and his colleagues posit that it could be a holdover from the Moon's formation, a concentration of dense metallic oxides created as the last of a deep, global magma ocean cooled and solidified. But why aren't these vestiges seen elsewhere? And why would such a huge one just happen to lie beneath the largest lunar impact basin?
A more plausible explanation for this excess mass, James notes in a Baylor press release, is that "the metal from the asteroid that formed this crater is still embedded in the Moon’s mantle." The SPA impactor most likely would have had a differentiated (layered) structure with a silicate exterior and an iron-nickel core. The team's computer simulations show that, after striking the Moon with a glancing blow, the impactor's metallic core could have ended up as a lump beneath the basin — concentrated enough to create the gravity anomaly recorded by GRAIL, but dispersed enough that it didn't sink en masse toward the lunar core.
Researchers are still gauging how the largest and deepest lunar impact basin affected the rest of the Moon when it formed some 4 billion years ago. For sure, it redistributed huge volumes of crust all around the lunar globe. And it's been implicated in creating magnetic anomalies all over the lunar surface. SPA's formation might also have altered the Moon's rotation. Now dynamicists will be looking closely to see what role this massive, newly discovered lump might have played in altering lunar history.
NASA’s VIPER rover to seek water ice at Moon’s south pole
Water ice is key to any permanent settlement on the Moon. NASA's new VIPER rover is tasked with seeking it out.
This competition is now closed
Published: October 29, 2019 at 8:46 am
NASA is to send a mobile robot – dubbed VIPER – to the Moon’s south pole to find where the highest concentrations of water ice are and how far beneath the surface they’re hiding.
Planned to touchdown on the lunar surface in December 2022, the Volatiles Investigating Polar Exploration Rover (VIPER) mission will be the first step in forming a global map of the Moon’s water resources and – ultimately – will inform future dreams of a permanent human settlement on the Moon.
Read more rover stories:
Part of NASA’s Artemis crewed spaceflight program, the rover will roam several miles and use a 1-metre drill to take soil samples.
It will collect data on different kinds of soil environments, from those in complete darkness and occasional light to those in direct sunlight, detecting any ‘wet’ areas below the surface with its Neutron Spectrometer System, known as NSS.
Drill samples will be analysed by two instruments: the Mass Spectrometer Observing Lunar Operations, or MSolo, developed out of NASA’s Kennedy Space Center, and the Near InfraRed Volatiles Spectrometer System, known as NIRVSS, developed by Ames. VIPER’s mission is expected to last 100 days.
The lunar poles are frontrunners for harbouring water in significant concentrations because, thanks to the Moon’s tilt, they have areas that are permanently in shadow, thus preserving any ice.
There’s also the evidence from LCROSS, a rocket that NASA crashed into Cabeus crater near the Moon’s south pole in 2009. It confirmed the crater floor to be 5.6 per cent water ice by mass, about twice as wet as Sahara Desert soil.
The presence of water will be the cornerstone of all future plans for long-term Moon settlement, as well as for any onward missions tdeeper into space and other planets such as Mars.
“The key to living on the Moon is water – the same as here on Earth,” said Daniel Andrews, the project manager of the VIPER mission and director of engineering at NASA’s Ames Research Center.
“Since the confirmation of lunar water ice ten years ago, the question now is if the Moon could really contain the amount of resources we need to live off-world.
“This rover will help us answer the many questions we have about where the water is, and how much there is for us to use.”
Radar provides first 3-D views of moon's frigid poles, indicating sites for ice deposits, say Cornell astronomers
The hidden poles of the moon have been revealed by Cornell University and Jet Propulsion Laboratory researchers working with the radar antennas of NASA's Deep Space Network at Goldstone, Calif. The south pole image, in particular, reveals a chaotic surface, with deep craters that are in permanent shadow from the sun and which are potential repositories for water ice.
These first three-dimensional topographic images of the lunar polar regions will provide essential data for the proposed crash of the orbiting Lunar Prospector spacecraft into the lunar south pole in late July. If NASA approves, the controlled, high-speed dive into a massive crater, 50 kilometers (32 miles) across and 2.5 kilometers (1.5 miles) deep, will attempt to provide absolute proof of the existence of water on the moon.
The new images, obtained through a technique called radar interferometry, are published in the latest edition (June 4) of Science magazine. They are a leap forward in settling the "significant argument" about the existence of water ice on the moon, says Donald Campbell, professor of astronomy at Cornell, and one of the paper's authors.
In the solar system, ice has a unique, and not totally understood, "signature" when probed by radar beams. This was first discovered by Campbell and others when they used the radar system of the Cornell-operated Arecibo Observatory in Puerto Rico to get radar echoes from the icy Galilean satellites of Jupiter.
In 1996, researchers working with radar data from the orbiting lunar spacecraft Clementine reported indications of ice at the south pole of the moon. However, in 1997 researchers, Campbell among them, published a paper in Science reporting on Arecibo's radar imaging of the lunar poles that showed no evidence of ice. Both the Clementine and Arecibo radars would only have detected ice if it had been in the form of large chunks or slabs. The absence of an Arecibo radar detection did not preclude ice being present in small chunks or crystals mixed in with the lunar "soil."
Last year, the neutron spectrometer aboard the Lunar Prospector orbiter, launched in January 1998, detected significant deposits of hydrogen at the moon's north and south poles. This was interpreted as indicating the presence of water ice, since hydrogen in water molecules is thought to be the most likely source of the element at the poles. However, without detailed topographic maps of the poles, it was not possible to identify potential ice-containing regions -- so-called cold traps, or areas where the sun never shines and the temperature hovers around 100 degrees Kelvin (minus 280 degrees Fahrenheit).
Using these new topographical maps, NASA is considering trying to settle the debate about the existence of water on the moon with a controlled crash of the Lunar Prospector spacecraft, which is nearing the end of its useful life. The orbiter has detected significant amounts of hydrogen in the chosen south pole crash site, the informally named Mawson crater. The hope is that the kinetic energy from the plunge into the crater will evaporate the water ice into a plume detectable from terrestrial and space telescopes. "In order to impact the spacecraft at the desired location, very accurate knowledge of the topography is needed," says Campbell, who is also the associate director of the National Astronomy and Ionosphere Center, headquartered at Cornell, which operates Arecibo for the National Science Foundation.
Says Margot: "The argument for targeting that particular crater is that it is both in permanent shadow, as shown by our radar data, and also has a high hydrogen abundance, as shown by new Lunar Prospector data. This makes it a prime candidate for water ice deposits."
To obtain the topographic features of the hidden lunar polar regions, Margot, Campbell and Martin Slade and Raymond Jurgens of JPL used the Goldstone 70-meter antenna to transmit the radar signals. Two separate 34-meter antennas, 20 kilometers (12 miles) apart at the Goldstone site, received the echoes. By comparing the images from the two antennas, Margot derived a three-dimensional digital elevation model of the lunar poles, with
measurements every 150 meters (500 feet) over the imaged area and a height accuracy of 50 meters (165 feet).
To calculate which areas were in permanent shadow, Margot wrote a computer program that calculated whether each point in the three-dimensional image would be in shadow for any allowed position of the sun. "The program simulated light rays from the sun to each point on the map and tested to see if the ray was intercepted by the surrounding topography," Margot says. "If a single light ray was received, that point was in sunlight. If not, it was in shadow."
This detailed topography, says Margot, also has applications in cratering and other, studies. "The data is of such fine resolution that we can find out much about crater shape and impact mechanics," he says.
Related World Wide Web sites: The following sites provide additional information on this news release. Some might not be part of the Cornell University community, and Cornell has no control over their content or availability.