SMART-1 view of the crater Pentland area

Credits: ESA/Space-X (Space Exploration Institute)

28 September 2006
This high-resolution image, taken by the advanced Moon Imaging Experiment (AMIE) on board ESA’s SMART-1 spacecraft, shows an area close to crater Pentland on the Moon.

AMIE obtained this sequence on 18 March 2006 from a distance of 573 kilometres from the surface, with a ground resolution of 52 metres per pixel. The imaged area is centred at a latitude of 67.7º South and longitude 18.3º East.
During the course of its mission, Smart-1 orbited the Moon in a highly elliptical orbit, varying its distance to the lunar surface roughly between 500 and over 2000 kilometres. This particular image was taken from really close by.

The image scale makes it possible to clearly see craters as small as 200 metres. This image was taken near a surface feature named ‘Manzinus D’ in the vicinity of Pentland – an impact crater 56 kilometres in diameter, too large to be visible in the AMIE field of view. When seen from Earth these craters are very foreshortened, due to their southern latitudes.

Carlo Manzini (1599-1677), after whom Manzinus D was named, was an Italian philosopher and astronomer. Joseph Barclay Pentland (1797-1873) was a 19th century Irish politician, explorer and geographer.

Source: ESA - Smart-1

Image courtesy of D. Campbell (Cornell), B. Campbell (Smithsonian) and L. Carter (Smithsonian)

This radar image of the south pole region of the moon is about 250 km by 100 km. Shackleton crater ( A ) is 19 km in diameter. The Lunar Prospector orbiter impacted Shoemaker crater ( B ), 51 km in diameter. The south pole is about on the center of the left rim of Shackleton. The image was made in April 2005 by transmitting from Arecibo Observatory in Puerto Rico at 13 cm wavelength and receiving the radar echo with the Robert C. Byrd Green Bank Telescope in West Virginia. The underlying resolution of the image is about 20 m, the highest resolution radar image ever made of the moon.


Oct. 18, 2006

Leave the skates on Earth -- Cornell researchers find no evidence of ice reserves on the moon

By Lauren Gold

Alas, the moon is not for winter sports. Never mind the difficulty of a triple axel in a bulky spacesuit (though the diminished gravity might help) -- ice, it turns out, is hard to come by up there.

That's the latest word from astronomers at Cornell and the Smithsonian Institution, who used high-resolution radar-mapping techniques to look for ice deposits at the lunar poles. Their research appears in the Oct. 19 issue of the journal Nature.


Campbell

The researchers, led by Donald Campbell, professor of astronomy at Cornell, analyzed radar transmitted to the moon from the Arecibo Observatory in Puerto Rico and received 2.5 seconds later at the Robert C. Byrd Green Bank Telescope in West Virginia. Using 20-meter resolution, 13-centimeter wavelength radar, they looked at areas around the lunar south pole where earlier low-resolution images had indicated a high circular polarization ratio (CPR) -- a possible signature of low-temperature water ice.

They found similar high CPR values. But they also found that those values are not confined to areas that stay cold enough to sustain ice; they occurred in sunlit areas as well, where temperatures can reach 243 degrees Fahrenheit (117 degrees Celsius) and ice would evaporate rapidly. That indicates that scattered rocks associated with young impact craters are more likely the causes of the high CPR.

Accessible ice would be a valuable resource for any long-term human presence on the moon, but reserves could only exist in deep, permanently shaded craters at the poles, where the temperature doesn't rise above about -280 F (-173 C), Campbell said.

Previous data had given the search for lunar ice a boost, including 1992 radar data indicating ice deep in craters at the poles of Mercury, 1996 radio data from the moon taken by the Clementine orbiter and the Lunar Prospector Orbiter's 1998 discovery of an elevated amount of hydrogen at the lunar poles.

But the elevated hydrogen level could come from other sources -- solar wind, perhaps -- and subsequent radar data has failed to show any evidence of ice deposits.

Campbell says the new data should close the door on the debate.

"This is much higher resolution than we've ever done before," said Campbell. "We put the nail in the coffin in terms of the fact that these high CPRs are correlated with presence of rocky, blocky material around young impact craters. The assumption of many people is that high CPRs must indicate the presence of water ice. What we're saying is, that might not be the case.

"There is always the possibility that concentrated deposits exist in a few of the shadowed locations not visible to radars on Earth," he added. "But any current planning for landers or bases at the lunar poles should not count on this."

The Arecibo Observatory is operated by the National Astronomy and Ionosphere Center at Cornell for the National Science Foundation (NSF). The Green Bank Telescope is part of the National Radio Astronomy Observatory, which is operated by Associated Universities for the NSF.

##

Source: Cornell University - Chronicle Online

SMART-1 view of Shackleton crater at lunar South Pole

Credits: ESA/Space-X (Space Exploration Institute)

20 October 2006
This image, taken by the advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 spacecraft, shows crater Shackleton on the Moon.

AMIE obtained this image on 13 January 2006 - close to the time of lunar southern Summer - from a distance of 646 kilometres over the surface and with a ground resolution of 60 metres per pixel.

Shackleton crater lies at the lunar South Pole, at 89.54° South latitude and 0° East longitude, and has a diameter of 19 kilometres.

SMART-1 monitored this area almost every orbit. This will allow to produce very high resolution maps of the area as well as illumination maps. The long shadows that surround the crater make it very hard to observe. The analysis of the data obtained allowed a very detailed map of its rim, surrounding ejectas and craters.

SMART-1 also made long repeated exposures to see inside the shadowed areas. The purpose was detecting the very weak reflected light from the crater rims, and therefore study the surface reflection properties (albedo) and its spectral variations (mineralogical composition). These properties could reveal patchy ice surface layers inside the crater.

On the 2-kilometre wide inner edge of the crater ridge, at times barely visible from Earth, astronomers using ground radio-telescopes have recently reported they were not able to detect a distinctive signature of thick deposits of ice in the area. Earlier measurements by NASA's Lunar Prospector reported of hydrogen enhancement over large shadowed areas.

"We still do not know if this hydrogen is due to enhanced trapping of solar wind, or to the water ice brought on the Moon by the bombardment of comets and asteroids," says Bernard Foing, ESA's SMART-1 Project Scientist. "These bodies may have deposited on the Moon patchy layers of ice filling about 1.5 percent of the areas in permanent shadow, down to one metre below the surface."

"We need to analyse all remote sensing data sets consistently. Future lander and rover missions to the Moon will help in the search and characterisation of lunar polar ice, both on the surface and below the subsurface," Foing continues. "In any case, one day we may even be able to simply combine the implanted hydrogen and the oxygen extracted from lunar rocks to produce clean water, like we do in laboratory experiments on Earth.”

The crater is named after Ernest Shackleton (1874-1922), an explorer famous for his Antartic expeditions.

Note

Launched in September 2003, SMART-1 ended its mission through lunar impact on 3 September 2006. The huge data sets it provided are and will be analysed by lunar and planetary scientists, and provide a very important legacy in the history of lunar exploration.

Source: ESA - Smart-1

October 16, 2006 Update
Lunar exploration satellite "SELENE" make its appearance



On Oct. 13, the lunar exploration satellite, Selenological Engineering Explorer (SELENE), introduced itself to the public at the Tsukuba Space Center. The SELENE is 2.1 meters both in length and width, 4.8 meters in height, and three tons in weight including its two sub-satellites (each of which is about 50 kg.) The satellite is scheduled to be launched by an H-IIA launch vehicle from the Tanegashima Space Center in the summer of next year. It then will circulate on a lunar orbit 100 km above the moon for a year to elucidate the mystery of the lunar origin and development by observing the distribution of elements and minerals on the surface of the moon, its geographical features, surface structure, and gravity and magnetic fields in details.

SELENE: The largest lunar mission since the Apollo program -

Mission Overview



The SELenological and ENgineering Explorer "SELENE", Japan’s first large lunar explorer, will be launched by the H-IIA rocket in 2007. The mission, which is the largest lunar mission since the Apollo program, is being keenly anticipated by many countries.

The major objectives of the mission are to understand the Moon’s origin and evolution, and to observe the moon in various ways in order to utilize it in the future. The lunar missions that have been conducted so far have gathered a large amount of information on the Moon, but the mysteries of its origin and evolution have been left unsolved.

SELENE will investigate the entire moon in order to obtain information on its elemental and mineralogical composition, its geography, its surface and sub-surface structure, the remnant of its magnetic field, and its gravity field. The results are expected to lead to a better overall understanding of the Moon’s evolution. At the same time, the observation equipment installed on the orbiting satellite will observe plasma, the electromagnetic field and high-energy particles. The data obtained in this way will be of great scientific importance for exploring the possibility of using the moon for human endeavors.

SELENE’s configuration and mission

SELENE consists of the Main Orbiter and two small satellites (Relay Satellite and VRAD Satellite). The Main Orbiter will reach the vicinity of the Moon. Once it has reached the Moon, it will be placed into a peripolar orbit at an altitude of 100 km. The Relay Satellite will be placed in an elliptic orbit at an apogee of 2400 km, and will relay communications between the Main Orbiter and the ground station. The VRAD Satellite will play a significant role in measuring the gravitational field around the Moon. The Main Orbiter will be employed for about one year and will observe the entire Moon.

Source: JAXA - SELENE

The Brown University press release is reproduced below:


Not So Dead After All

Moon’s Escaping Gasses Expose Fresh Surface

A fresh look at Apollo-era images combined with recent spectral data leads researchers to re-examine conventional wisdom about the Earth’s moon. Several lines of evidence suggest that the moon may have seen eruptions of interior gasses as recently as 1 million years ago, rather than 3 billion years ago – the date that had been most widely accepted.



PROVIDENCE, R.I. — Conventional wisdom suggests that the Earth’s moon has seen no widespread volcanic activity for at least the last 3 billion years. Now, a fresh look at existing data points to much more recent release of lunar gasses.

The study, published in the journal Nature by geologists Peter Schulz and Carlé Pieters of Brown University and Matthew Staid of the Planetary Science Institute, uses three distinct lines of evidence to support the assertion that volcanic gas has been released from the moon’s surface within the last 1 to 10 million years. The researchers focus on a D-shaped area called the Ina structure that was first recognized in images from Apollo missions.

Millions of years – not billions
Apollo images of the D-shaped Ina structure indicate that gas releases may have exposed fresh surfaces on the moon. The main image shows very few craters within the depression. Low-angle illumination (inset) reveals sharp features with little evidence of weathering.
Image: NASA

The unusual sharpness of the features first called Schultz’s attention to the area. “Something that razor-sharp shouldn’t stay around long. It ought to be destroyed within 50 million years,” said Schulz. On Earth, wind and water quickly wear down freshly exposed surface features. On the airless moon, constant bombardment with tiny space debris accomplishes a similar result. By comparing the fine-scale surface features within the Ina structure to other areas on the moon with known ages, the team was able to place its age at closer to 2 million years.

The scarcity of asteroid impact craters on the surface within Ina provided a second line of evidence for the feature’s relative youth. The researchers identified only two clear impact craters larger than 30 meters on the 8 square kilometers of the structure’s floor. This frequency is about the same as at South Ray Crater, near the Apollo 16 landing site. The surface material ejected from South Ray Crater has long been used as a benchmark for dating other features on the moon’s surface and most lunar scientists studying these rocks agree on a date of approximately 2 million years, based on cosmic ray exposure.

Far from mature
This false color composite image indicates age and composition of lunar surface features. Titanium basalts (blue) are exposed on the floor of Ina structure and in the ‘fresh’ impact crater. Less mature soils (based on spectral ratios) appear in green.
Image: NASA

The third piece of support for the authors’ hypothesis comes from comparing the spectral signatures of deposits in the Ina depression to those from very fresh craters. As lunar surface deposits weather, the wavelengths of light they reflect change in predictable ways. Overall reflectance, or albedo, gets less bright and the ratio of light at 1,000 nm wavelengths to 750 nm wavelengths increases. Based on these color ratios, the deposits on Ina’s floor are exceptionally young – and possibly even newly exposed.

The appearance of the surface at Ina does not indicate an explosive release of magma, which would result in visible rays of ejecta surrounding a central crater. Rather, it suggests a rapid release of gasses, which would have blown off the surface deposits, exposing less weathered materials. This interpretation is particularly appealing because Ina is located at the intersection of two linear valleys or rilles – like many geologically active areas on Earth.

Ina also does not appear to be alone. The authors identify at least four similar features associated with the same system of rilles, as well as others in neighboring rille systems. Although several kinds of evidence support the authors’ conclusion that the moon is more geologically active than previously thought, the only sure way to resolve the question would be to collect samples at such sites. “Ina and other similar features are great targets for future exploration, by people or robots,” said G. Jeffrey Taylor, a lunar researcher at the University of Hawaii. “They might be the best place to get a good look at the interface between the powdery regolith and the consolidated rock beneath.”

Over the years, says Schultz, amateur astronomers have seen puffs or flashes of light coming from the moon’s surface. Although most professional observers have upheld the conclusion that the moon was inactive, such sightings have kept open a window of doubt. A coordinated observation campaign, including both professional and amateur astronomers, would be one way to build additional evidence for activity, says Schultz. A gas release itself would not be visible for more than a second or so, but the dust it kicked up might stay suspended for up to 30 seconds. With modern alert networks, that’s long enough to move a professional telescope into position to see what’s happening.

NASA’s Planetary Geology and Geophysics Program supported this research. Peter Schultz and Carlé Pieters are professors of geological science at Brown University. Matthew Staid is a research scientist at the Planetary Science Institute.

######

Source: Brown University Press Release

Ever since astronauts returned from another world, scientists have been mystified by some of the moon rocks they brought back. Now one of the mysteries has been solved.

"We learned a great deal about the sun by going to the moon," said Don Burnett, Genesis principal investigator at California Institute of Technology, Pasadena, Calif. "Now, with our Genesis data, we are turning the tables, using the solar wind to better understand lunar processes."


Image above: Don Burnett, Genesis principal investigator,
examines samples upon their return in Utah.

Ansgar Grimberg from ETH Institute of Astronomy in Zurich and coworkers analyzed the composition of neon in a metallic glass exposed on NASA's Genesis mission. The team's findings are reported in a paper published in the Nov. 17 issue of the journal Science. Burnett is a co-author of the paper.

One of the stated goals of the Apollo missions was to understand the history of the sun in time. With no atmosphere or magnetic field to interfere, particles from the sun hit and imbedded themselves into the lunar surface for almost four billion years. This goal was not fully met due to the complexity of lunar materials and processes and to the limited duration of the Apollo field operations.

Many of the lunar sample studies were of the relative amounts of the isotopes of different solar gas elements. Many elements have atoms of different mass. For example, neon has a light isotope (Ne20) and a heavy isotope (Ne22).

One of the major surprises from study of the record of neon from the sun in lunar soil samples was evidence for two solar gas components with distinct isotopic compositions. One has been identified as solar wind, the other as higher-energy solar energetic particles because it was found at greater depths in the mineral grains. But the latter has long been puzzling to scientists because its relative amounts were much too large compared with present-day solar fluxes, suggesting very high solar activity in the past.

To investigate this problem, a bulk metallic glass specially synthesized by Charles Hays at NASA's Jet Propulsion Laboratory, Pasadena, Calif., was exposed to the solar wind for 27 months on NASA's Genesis mission. The advantage of this material is that when it is returned to Earth and analyzed in a laboratory, it can be uniformly etched with nitric acid vapor allowing the depth distribution of the solar wind neon to be measured by stepwise release.

The first experiments at the ETH Institute in Zurich revealed surprising results. Neon isotopic variations were not expected until relatively large depths when the solar energetic particle regime would be reached, but instead they were observed immediately. As etching proceeded, the results were almost identical to those found in many lunar samples, with two major differences.

First, Genesis samples do not contain detectable amounts of neon produced by galactic cosmic ray particles because no appreciable concentrations of such particles accumulated in 27 months. Thus they allowed scientists to analyze pure solar wind samples.

Second, the first gas extractions from the bulk metallic glass showed neon isotopic compositions never seen in lunar sample data. This finding suggests that space weathering and erosion over time reduced the levels of neon on the surface of all lunar samples, which in turn led to a misinterpretation of the lunar data.

The researchers conclude that the Apollo solar energetic particles do not exist. Both the Genesis and Apollo isotopic variations can be quantitatively explained by the fact that the Ne22 isotope is implanted deeper than the Ne20 isotope. Moreover, these findings indicate that there is no evidence for enhanced fluxes of high-energy solar particles billions of years ago compared to today.

Source: NASA - Missions - Genesis

Nov. 6, 2006: Near the end of the mission of Apollo 16, on April 24, 1972, just before returning back home to Earth, the three astronauts released one last scientific experiment: a small "subsatellite" called PFS-2 to orbit the Moon about every 2 hours.

The intention? Joining an earlier subsatellite PFS-1, released by Apollo 15 astronauts eight months earlier, PFS-2 was to measure charged particles and magnetic fields all around the Moon as the Moon orbited Earth. The low orbits of both subsatellites were to be similar ellipses, ranging from 55 to 76 miles (89 to 122 km) above the lunar surface.

see captionInstead, something bizarre happened.

The orbit of PFS-2 rapidly changed shape and distance from the Moon. In 2-1/2 weeks the satellite was swooping to within a hair-raising 6 miles (10 km) of the lunar surface at closest approach. As the orbit kept changing, PFS-2 backed off again, until it seemed to be a safe 30 miles away. But not for long: inexorably, the subsatellite's orbit carried it back toward the Moon. And on May 29, 1972—only 35 days and 425 orbits after its release—PFS-2 crashed.


Above: An Apollo subsatellite leaves the Service Module,
an artist's concept. [More]

What happened? The Moon itself plunged the subsatellite to its death. That's the conclusion of Alex S. Konopliv, planetary scientist at NASA's Jet Propulsion Laboratory in Pasadena. He and several colleagues have been analyzing the orbits of various Moon-orbiting satellites since PFS-2, notably the 1998–99 mission of Lunar Prospector.

"If the Moon were a uniform sphere, you could have an orbit that was perfect ellipse or circle," Konopliv explained. "The Moon has no atmosphere to cause drag or heating on a spacecraft, so you can go really low: Lunar Prospector spent six months orbiting only 20 miles (30 km) above the surface."

So why did PFS-2, which was inserted into an elliptical orbit that originally carried it from 52 miles (97 km) to 66 miles (120 km), end up as a kamikaze blast of broken aluminum struts and solar panels?

"The Moon is extraordinarily lumpy, gravitationally speaking," Konopliv continues. "I don't mean mountains or physical topography. I mean in mass. What appear to be flat seas of lunar lava have huge positive gravitational anomalies—that is, their mass and thus their gravitational fields are significantly stronger than the rest of the lunar crust." Known as mass concentrations or "mascons," there are five big ones on the front side of the Moon facing Earth, all in lunar maria (Latin for "seas") and visible in binoculars from Earth.

The mascons' gravitational anomaly is so great—half a percent—that it actually would be measurable to astronauts on the lunar surface. "If you were standing at the edge of one of the maria, a plumb bob would hang about a third of a degree off vertical, pointing toward the mascon," Konopliv says. Moreover, an astronaut in full spacesuit and life-support gear whose lunar weight was exactly 50 pounds at the edge of the mascon would weigh 50 pounds and 4 ounces when standing in the mascon's center.


Above: Mascons on the Moon that make its gravitational field so lumpy, as mapped by the Lunar Prospector
mission, are shown in orange-red. The five largest all correspond to the largest lava-filled craters or lunar
"seas" visible in binoculars on the near side of the Moon: Mare Imbrium, Mare Serenitatus, Mare Crisium,
Mare Humorum and Mare Nectaris. Image reference: Konopliv et al, Icarus 150, 1–18 (2001).

"Lunar mascons make most low lunar orbits unstable," says Konopliv. As a satellite passes 50 or 60 miles overhead, the mascons pull it forward, back, left, right, or down, the exact direction and magnitude of the tugging depends on the satellite's trajectory. Absent any periodic boosts from onboard rockets to correct the orbit, most satellites released into low lunar orbits (under about 60 miles or 100 km) will eventually crash into the Moon. PFS-2 released by Apollo 16 was simply a dramatic worst-case example. But even its longer-lived predecessor PFS-1 (released by Apollo 15) literally bit the dust in January 1973 after less than a year and a half.

So what does this mean for eventual lunar exploration?

Be careful of the orbit chosen for a low-orbiting lunar satellite. "What counts is an orbit's inclination," that is, the tilt of its plane to the Moon's equatorial plane. "There are actually a number of 'frozen orbits' where a spacecraft can stay in a low lunar orbit indefinitely. They occur at four inclinations: 27º, 50º, 76º, and 86º"—the last one being nearly over the lunar poles. The orbit of the relatively long-lived Apollo 15 subsatellite PFS-1 had an inclination of 28º, which turned out to be close to the inclination of one of the frozen orbits—but poor PFS-2 was cursed with an inclination of only 11º.

Alternatively, if there are mission reasons for choosing a non-frozen orbital inclination, plan to do frequent course corrections. Lunar Prospector had to do a maneuver every two months to keep itself in its initial circular orbit of 60 miles (100 km)—and more often than once a month when it was orbiting at only 20 miles (30 km) altitude. When its fuel tank was nearly empty, the scientists knew its end was near, so they deliberately crashed it on July 30, 1999, near the Moon's south pole to observe its plume of lunar dust. After a year and a half, the Moon had claimed the spacecraft for its own.

Bottom line, says Konopliv: "Carry plenty of fuel."

Author: Trudy E. Bell | Editor: Dr. Tony Phillips | Credit: Science@NASA

More to the story...

Lunar mascons are a mystery. Although scientists generally agree they resulted from ancient impacts billions of years ago, it’s unclear how much of the excess mass is due to denser lava material filling the crater or how much is due to upwelling of denser iron-rich mantle material to the crust. Regardless of composition or origin, the mascons make the Moon the most gravitationally "lumpy" body known in the solar system. Although mascons also exist on Mars, none have been found on Venus or Earth; those two larger planets, however, have had an active tectonic (geological) past that has drawn their crusts down into their interiors several times in the past few billion years, homogenizing the distribution of mass.

Details about the subsatellites of both Apollos 15 and 16, including their orbital parameters, appear on p. 5-5 of Apollo 16 Mission Report.

A paper detailing the weird behavior of mascons on low lunar orbits (of about 100 km altitude) by Alex Konopliv and four coauthors is "Recent Gravity Models as a Result of the Lunar Prospector Mission" published in Icrarus, vol. 150, pp. 1-18, 2001 (available online only by subscription).

More about the mascons in the context of the gravitational lumpiness of the moon is "Improved Gravity Field of the Moon from Lunar Prospector," by Konopliv and colleagues.

An account of the deliberate crashing of Lunar Prospector into the Moon may be found here.

The Vision for Space Exploration

Source: Science@NASA

November 30, 2006: It's 2015. You're NASA's chief engineer designing a moonbase for Shackleton Crater at the Moon's south pole. You're also designing a com-system that will allow astronauts constant radio contact with Earth.

see captionBut you know that direct transmissions won't work--not always. As seen from Shackleton Crater, Earth is below the horizon for two to three weeks each month (depending on the base's location). This blocks all radio signals, which travel line of sight.


Above: Artist Pat Rawling's concept of a manned lunar base. [More]

The solution seems obvious. Simply place a satellite in a high, circular orbit going almost over the Moon's poles. Better yet, place three satellites into the same orbit 120 degrees apart. Two would always be above the lunar horizon to relay messages to and from Earth.

There's just one problem.

"High-altitude circular orbits around the Moon are unstable," says Todd A. Ely, senior engineer for guidance, navigation, and control at NASA's Jet Propulsion Laboratory. "Put a satellite into a circular lunar orbit above an altitude of about 430 miles (1,200 km) and it'll either crash into the lunar surface or it'll be flung away from the Moon altogether in a hyperbolic orbit." Depending on the specific orbit, this can happen fast: within tens of days.

Why? Earth is responsible. The gravity of massive Earth only 240,000 miles from the Moon constantly tugs on lunar satellites. For a lunar orbit higher than 430 miles, Earth's pull is actually strong enough to whisk a spacecraft out of the game.

Satellites in Earth orbit don't experience this sort of interference from the Moon. The Moon has just 1/80th Earth's mass—scarcely more than 1%. Relatively speaking, the Moon is a gravitational pipsqueak. Indeed, to any satellite in Earth orbit, the gravitational pull of the Sun is 160 times stronger than any lunar influence.

Any satellite in orbit around the Moon higher than about 430 miles, however, finds itself in a kind of celestial tug-of-war between Moon and Earth. Earth's pull can actually change the shape of an orbit from a circle to an elongated ellipse.

Stable circular lunar orbits do exist below an inclination of 39.6º, says Ely, but they spend so much time near the equator that "they are terrible orbits for covering the poles."

NASA wants to explore the Moon's polar regions for many reasons--not least is that deep polar craters may contain ice, which astronauts could harvest and melt for drinking or split into hydrogen and oxygen for rocket fuel and other uses. The instability of polar orbits poses a real problem for exploration.


An elliptical orbit around the moon

Now for the good news. Ely and several colleagues have discovered a whole new class of "frozen" or stable high-altitude lunar orbits. Pictured right, they are all inclined at steep angles to the Moon's equatorial plane so they get far above the horizon at the lunar poles, and--surprise--they are all also quite elliptical.

"For better South Pole coverage, you want an ellipse with an eccentricity of about 0.6, which is pretty oval," Ely says. An eccentricity of 0 is a circle, along which a satellite travels at a constant speed around a primary body (say, the Moon) at its center. With Earth nearby, that's out of the question: "An inclined circular orbit is kind of a blank canvas where Earth can quickly work its will," Ely says.

In contrast, an eccentricity of 0.6 is an ellipse about as oval as an American football minus the pointed ends; the Moon would be at one focus of the ellipse. "The ellipse effectively 'locks in' the satellite's behavior to make it tougher for Earth to change," Ely explains. [See the appendix below for details.] How stable are they? Ely and his colleagues calculate that certain elliptical, high-inclination, high-altitude lunar orbits may remain stable for periods of at least a century. Indeed, Ely hypothesizes the orbits could last indefinitely.

For lunar communications and navigation, Ely recommends spacing three satellites 120º apart in the same elliptical orbit at an inclination of 51º. Each satellite in turn would go screaming down past periapsis (closest approach to the lunar surface) only 320 miles (700 km) above the north lunar pole, but would each linger fully 8 hours of its 12-hour orbit at 4,800 miles (8,000 km) above the horizon over the south lunar pole. In this configuration, two of the three satellites would always be in radio line-of-sight from a South Pole moonbase.

High-inclination, highly elliptical orbits being cheapest and most stable for communications satellites around the Moon? To Earth-centered satellite engineers used to thinking in terms of circular equatorial orbits, "it's a new paradigm," Ely declares.

Editor's note: This story describes problems keeping satellites in high orbit around the Moon. Low-orbiting satellites have problems, too. Lunar "mascons" tug on them and cause them to crash into the ground. Earth affects high orbits, mascons affect low orbits. For more information read Science@NASA's Bizarre Lunar Orbits (see above).

Author: Trudy E. Bell | Editor: Dr. Tony Phillips | Credit: Science@NASA

More to the story...

Two recent papers by Ely describe stable high-altitude lunar orbits and their challenges:

• Stable Constellations of Frozen Elliptical Inclined Lunar Orbits, Journal of the Astronautical Sciences, vol. 53, No. 3, July-Sept 2005, pp. 301-316
• Constellations of Elliptical Inclined Lunar Orbits Providing Polar and Global Coverage (by Ely and Erica Lieb), Paper AAS 05-343, AAS/AIAA Astrodynamics Spe*spam filter*ts Conference, August 7-11, 2005.

APPENDIX: THE STABILITY OF HIGH LUNAR ORBITS

The stability of high lunar orbits (as well as of stars and black holes) is all about angular momentum—the force that keeps a top or gyroscope or ice skater spinning upright, even if perturbed slightly from the side.

For anything that's spinning, physicists use the right hand rule. Curl the fingers of your right hand to point in the direction of the spin. Then your thumb will point along the axis of spin. More importantly, it will point in the direction of what physicists call the angular momentum vector, which has one absolute direction in space.

You can actually feel the angular momentum vector. Try this. Take off the front wheel of a bicycle. Hold it horizontally by the axle, with one arm above and one arm below, leaving the wheel free to spin. Have a friend get the wheel spinning as fast as possible. Once the wheel is spinning, try to tilt it at a different angle or even to turn it over. You will find that the spinning wheel resists you with surprising force. Indeed, the angular momentum of bicycle wheels is what makes it easier to balance a bicycle when riding fast than when riding slowly.

One last brief primer before turning to orbits: The magnitude of the angular momentum vector depends on three quantities: the rate of spin, the mass of the spinning object, and the distance of the mass from the axis (the lever arm distance). Moreover, angular momentum is conserved—that is, absent any losses such as friction or applied external torques (twisting motions), the angular momentum vector will remain constant. Thus, if rate of spin, mass, or lever arm changes, then the remaining quantities must change in some compensating way to keep angular momentum constant. Example: if a spinning skater brings her arms in close to her body (shortens the lever arm distance), she starts spinning faster. The constancy of the angular momentum vector is also why gyroscopes are used to stabilize the orientation of spacecraft (such as the Hubble Space Telescope) in space.

What does all this have to do with lunar orbits? Every orbit has angular momentum. Satellites can be fairly massive (kilograms), and the lever arms can be hundreds or thousands of kilometers long. Now, if a lunar orbit is circular with the Moon at the center, the satellite travels with constant velocity—a situation that makes it vulnerable to Earth's gravitational pull.

The effect of all these fascinating dynamics is not to speed the satellite up in its orbit, but to apply a torque (twisting motion) that alters the inclination (tilt) of the plane of the satellite’s orbit. Such a change in tilt is resisted by the angular momentum vector, just as the spinning bicycle wheel resisted your attempts to change its tilt. The only way the orbit can compensate to conserve angular momentum is to change its shape or eccentricity: specifically, to become less circular (eccentricity = 0) and more elliptical (eccentricity > 0 but < 1). If the original circular orbit was steeply inclined, however, the change in shape can be so radical that the satellite is thrown into a hyperbola (eccentricity > 1) and flies completely away from the Moon.

Below a critical inclination of 39.6º, the orbital plane of a lunar satellite wobbles up and down with the line joining the ellipse’s apoapsis (farthest point from the Moon) and periapsis (closest point to the Moon) being dragged around by Earth as if it were attached by a leash. Such low-inclination elliptical orbits circulate around the Moon. Above that critical inclination of 39.6º, the line joining the orbit's periapsis and apoapsis stays relatively fixed in space, providing a stable orbit for communications and navigation satellites with minimum fuel needed for periodic course corrections.

The Vision for Space Exploration

Source: Science@NASA

Dec. 1, 2006: Meteoroids are smashing into the Moon a lot more often than anyone expected.

That's the tentative conclusion of Bill Cooke, head of NASA's Meteoroid Environment Office, after his team observed two Leonids hitting the Moon on Nov. 17, 2006. "We've now seen 11 and possibly 12 lunar impacts since we started monitoring the Moon one year ago," says Cooke. "That's about four times more hits than our computer models predicted."


Above: Each red dot denotes a meteoroid impact observed
since Nov. 2005 by members of the NASA Meteoroid
Environment Office. [More]

If correct, this conclusion could influence planning for future moon missions. But first, the Leonids:

Last month, Earth passed through a "minefield" of debris from Comet 55P/Tempel-Tuttle. This happens every year in mid-November and results in the annual Leonid meteor shower. From Nov. 17th to Nov. 19th both Earth and the Moon were peppered with meteoroids.

Meteoroids that hit Earth disintegrate harmlessly (and beautifully) in the atmosphere. But the Moon has no atmosphere to protect it, so meteoroids don't stop in the sky. They hit the ground. The vast majority of these meteoroids are dust-sized, and their impacts are hardly felt. But bigger debris can gouge a crater in the lunar surface and explode in a flash of heat and light. Some flashes can be seen from Earth.

During the passage through Tempel-Tuttle's debris field, Cooke's team trained their telescopes (two 14-inch reflectors located at the Marshall Space Flight Center) on the dark surface of the Moon. On Nov. 17th, after less than four hours of watching, they video-recorded two impacts: a 9th magnitude flash in Oceanus Procellarum (the Ocean of Storms) and a brighter 8th magnitude flash in the lunar highlands near crater Gauss.

"The flashes we saw were caused by Leonid meteoroids 2 to 3 inches (5 to 8 cm) in diameter," says Cooke. "They hit with energies between 0.3 and 0.6 Giga-Joules." In plain language, that's 150 to 300 pounds of TNT.

Click to view the movie: gif, wmv or mpeg.
Above: An 8th-magnitude Leonid flash near crater Gauss. The movies play in 7x slow motion; otherwise the explosion would be nearly invisible to the human eye. [More]

How do you get so much energy out of a 3-inch meteoroid? "Leonids travel fast—about 144,000 mph," he explains. "At that speed, even a 3-inch rock packs tremendous energy."

For comparison, the ESA's SMART-1 probe crashed into the Moon on Sept. 2nd, delivering 0.6 Giga-Joules of energy to the lunar surface—the same as the brighter of the two Leonids.

"Leonid impacts are as energetic as the crash of a 700-lb spacecraft!" says Cooke.

With these latest detections, Cooke's group has tallied a dozen "lunar meteors" since Nov. 2005. Most were sporadic meteoroids--meaning they are part of no annual shower like the Leonids, but just random chips of asteroids and comets floating around in space. Cooke estimates that for every four hours they observe the Moon, they see one bright flash caused by the impact of a large meteoroid.

And that's surprising. "Our best models of the lunar meteoroid environment predict a much lower rate—only 25% of what we are actually seeing." The problem may be with the computer models: "They're based on observations of meteors in the skies of Earth," and those data may not translate well to the Moon.


Above: The lunar meteoroid impact observatory at the
Marshall Space Flight Center. Inset is one of two 14-inch
telescopes used to observe the Moon. [Larger image]

The solution? "We need to spend more time watching the Moon," says Cooke. "With more data, we can draw stronger conclusions about the impact rate."

NASA needs that kind of information to decide, e.g., if it's safe for astronauts to go moonwalking during a meteor shower; and to calculate the necessary thickness of shielding for lunar spacecraft and habitats.

Next up: The Geminid meteor shower on December 13th-14th. Once again Earth and Moon will be peppered with meteoroids—this time from the asteroid 3200 Phaethon. Says Cooke, "we'll be watching."

Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

More Information

Lunar Impact Monitoring -- home page of the NASA Meteoroid Environment Office

Previous stories about lunar impacts:

A Meteoroid Hits the Moon -- (Science@NASA) a sporadic meteoroid hit Mare Nubium, the lunar Sea of Clouds, resulting in the best video yet of a lunar explosion.

The Sky is Falling -- (Science@NASA) NASA researchers are mining old Apollo seismic data for clues to lunar meteoroid impacts

An Explosion on the Moon -- (Science@NASA) A piece of Comet Encke hit Mare Imbrium and exploded like 70 kg of TNT.

The Vision for Space Exploration

Source: Science@NASA

The Lunar Reconnaissance Orbiter (LRO) successfully completed its Critical Design Review (CDR) on Thursday, November 9, 2006.

The review was held to present the complete system design developed at NASA's Goddard Space Flight Center, and to make sure that technical issues have been properly addressed. Additionally, it ensured that the design maturity justifies the start of manufacturing mission hardware and software. As a result of this major assessment, NASA's independent review board provided a green light for proceeding into the fabrication and integration phase of the project.


Image above: This is an artist's concept of the LRO spacecraft in orbit around the moon.
Credit: NASA
Print-resolution copy

The first in a series of robotic missions to the moon, the lunar orbiter is scheduled for launch in October 2008. It will carry six science instruments and a technology demonstration. The mission goal is to expand the coverage and accuracy of lunar maps and environmental data, enabling selection of landing sites for future robotic and human lunar missions.

"LRO will lead the way for NASA to reduce many of the major physical uncertainties in the basic definition of the moon itself, especially filling in gaps in our understanding of lunar topography, temperature, and resources including potential hydrogen and water, and in the information about the lunar poles," said Tony Lavoie, NASA's Lunar Precursor and Robotic Program Manager. "A solid performance as a result of this CDR review allows us to have high confidence that the LRO team at Goddard will make it to the launch pad on time for this crucial launch." LRO is part of NASA's Lunar Precursor and Robotic Program, located at the Marshall Space Flight Center, Huntsville, Ala.

The LRO Critical Design Review began November 6, 2006 at NASA Goddard in Greenbelt, Md., where LRO will be built. The independent review board, comprised of reviewers from NASA and several external organizations, heard presentations on all aspects of LRO design. Presentations included the spacecraft construction and systems integration, the science operations center, testing, and safety requirements.

Critical Design Reviews are one-time programmatic events that bridge the design and manufacturing stages of a project. A successful review means that the design is validated and will meet its requirements, is backed up with solid analysis and documentation, and has been proven to be safe. LRO's CDR completion grants Goddard permission to begin manufacturing hardware.

Source: NASA/GSFC - News

Dec. 28 , 2006: Life is tough for a humble grain of dirt on the surface of the Moon. It's peppered with cosmic rays, exposed to solar flares, and battered by micrometeorites--shattered, vaporized and re-condensed countless times over the billions of years. Adding insult to injury, Earthlings want to strip it down to oxygen and other elements for "in situ resource utilization," or ISRU, the process of living off the land when NASA returns to the Moon in the not-so-distant future.

But, as Robert Heinlein famously observed, "the Moon is a harsh mistress." Living with moondust and striping it down may be trickier than anyone supposes.


Above: A speck of Moon dirt. The strange shape tells
a tale of violence: It results from the welding of rock,
mineral and glass by the heat of micrometeoroid
impacts.
Image credit: David S. McKay, NASA/JSC.

To find out how tricky, researchers would like to test their ideas for ISRU and their designs for lunar rovers on real lunar soil before astronauts return to the Moon. But there's a problem:

"We don't have enough real moondust to go around," says Larry Taylor, director of Planetary Geosciences Institute at the University of Tennessee in Knoxville. To run all the tests, "we need to make a well-qualified lunar simulant." And not just a few bags will do. "We need tons of it, mainly for working on technologies for diggers and wheels and machinery on the surface," adds David S. McKay, chief scientist for astrobiology at the Johnson Space Center (JSC).

Taylor and McKay are lead members of a small group of self-styled "lunatics" whose careers have focused on lunar soil and rocks. They are among several consultants to NASA's Marshall Space Flight Center (MSFC), which manages the Lunar Regolith Simulant Development Program.

Carole McLemore is the program manager at Marshall. Back in the 1990s, she explains, researchers used a lunar simulant called JSC-1 developed at JSC. But "there is no more JSC-1 available." So, to get started, researchers at Marshall are working with the Astromaterials Research and Exploration Science office at Johnson to create a replica of the JSC-1 simulant: JSC-1A. It comes in three types based on grain size (fine, medium and coarse). MSFC has also begun work on more demanding simulants representing various locations on the Moon.

Until the Apollo astronauts brought lunar soil samples to Earth during 1969-72, the belief was that the Moon's dry, airless environment left the soil largely undisturbed. Reality is much harsher.

Micrometeorites, many smaller than a pencil point, constantly rain onto the surface at up to 100,000 km/hr (about 62,000 mph), chipping off materials or forming microscopic impact craters. Some melt the soil and vaporize and re-condense as glassy coats on other specks of dust. Impacts weld debris into "agglutinates." Complicated interactions with the solar wind convert iron in the soil into myriads of "nano-phase" metallic iron grains just a few nanometers wide.


Above: The lunar surface is exposed to solar wind and constantly pounded by micrometeorites.
Credit: Larry Taylor, Univ. of Tennessee. [More]

These processes form the "regolith" -- Greek for stone blanket (litho + rhegos) -- covering the Moon's surface. What greets astronauts and spaceships is a complex material comprising "sharp, abrasive, interlocking fragile glass shards and fragments," Taylor says. It grinds machinery and seals, and damages human lungs.

"Some of the stuff that got into the Apollo spacecraft was very finely ground," McKay said. Dust was everywhere and impossible to brush off. All the lunar astronauts had lung reactions to this dust, some more than others, like Harrison H. (Jack) Schmitt's "lunar dust hay fever."

The Apollo specimens are America's Crown Jewels and are doled out in ultra-small samples to scientists who can demonstrate that nothing else will do for high-value experiments. Renewed interest in lunar exploration in the late 1980s meant that lunar simulants were needed to test schemes for building structures on the Moon or for extracting oxygen and other materials.

That led to JSC-1 in 1993, made of basaltic volcanic cinder cone deposits from a quarry near Flagstaff, AZ. The 25-ton lot -- distributed in 50-pound bags -- proved popular.

"We're totally out, but that's soon to be corrected," said McKay. MSFC has a Small Business Innovative Research (SBIR) contract with Orbitec of Madison, WI, to manufacture about 16 metric tonnes of three types of JSC-1A: 1 tonne of fines (delivered); 14 tonnes of moderate grains (being delivered); and 1 tonne of coarse grains (coming soon). The U.S. Geological Survey in Denver and the University of Colorado at Boulder -- key partners -- are checking the chemical, mineralogical, and geotechnical properties.


Above: This photomicrograph of soil from a lunar
mare hints at the underlying variety of genuine Moon
dirt and the difficulty of reproducing it. [Larger image]

MSFC is developing three new simulants. Two will represent mare and polar highlands regions. A third will represent the glassy, sharp, jagged edges of regolith that test the best of hardware and humans. But matching every location on the Moon would require large numbers of small, unique, expensive batches.

"Instead, we will develop root simulants and manufacture specific simulants from these, but also enable investigators to enhance the products as needed," McLemore added. "I liken this process to baking a cake: depending on the type of cake you want, you need certain ingredients for it to come out right and taste right. Getting the recipe right whether for a cake or lunar simulants is critical."

For example, the new mare simulant will be enriched with ilmenite, a crystalline iron-titanium oxide. Source materials used to produce the three simulants will potentially come from locations as diverse as Montana, Arizona, Virginia, Florida, Hawaii, and even some international sites.

Initial lots will weigh just tens of pounds to ensure that the simulant is made correctly. "Eventually we will scale up to larger quantities when we can make sure that there is little variation from batch to batch," McLemore said.

Once NASA understands how to make the various simulants, plans are to farm the work out to companies to produce larger batches. "We will have certification procedures in place for vendors to follow so users know that the simulants meet the NASA standards," McLemore said.

And that will be the best way to tell it's a "true fake." Accept no substitutes.

Author: Dave Dooling | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

More Information

Lunar Regolith Simulant Materials Workshop -- the online proceedings of this 2005 workshop held at the Marshall Space Flight Center include, e.g.:

• Physical and Chemical Characteristics of Lunar Regolith: Considerations for Simulants by Larry Taylor (U. Tennessee)
• Evolution of the Lunar Regolith by David McKay (NASA/JSC)
• Biological Effects of Lunar Surface Mineral Particulates by Russ Kerschmann (NASA/Ames)
• The Moon as a Beach of Fine Powders by Masami Nakagawa (Colorado School of Mines)

Above: A vial of simulated moondust, fine-
grained, produced by Orbitec of Madison, Wisconsin.
Photo credit: Dr. Tony Phillips.

How do you know when the fake is true? McLemore answers: "We use Apollo core samples and other lunar data to define the figures of merit (FOMs) that we have generated as a mathematical reference to compare the 'goodness' of the simulants against known lunar regolith data." NASA also confers with other groups who have developed their own simulants, such as Japan's FJS-1 and MKS-1 and Canada's OB-1.

Dust, in particular, is a critical simulant need. Mark Hyatt of Glenn Research Center is working to characterize dust for development of a simulant by MSFC. Even Martian soil simulants will need to be developed in time.

"No matter who made the simulant, unless all simulants' properties are understood, there is no way to ensure 'apples to apples' comparison of research performed by scientists and engineers," she cautions. Thus, even the same tests with the same tools can produce conflicting results.

The Vision for Space Exploration

Source: Science@NASA

January 3, 2007: Another meteor shower, another bunch of lunar impacts...

"On Dec. 14, 2006, we observed at least five Geminid meteors hitting the Moon," reports Bill Cooke of NASA's Meteoroid Environment Office in Huntsville, AL. Each impact caused an explosion ranging in power from 50 to 125 lbs of TNT and a flash of light as bright as a 7th-to-9th magnitude star.


Above: Lunar impacts since Nov. 2005. Numbers 14-16 and 19-20 are Geminids. Number 18 is a probable Geminid.
Credit: NASA Meteoroid Environment Group. [More]

The explosions occurred while Earth and Moon were passing through a cloud of debris following near-Earth asteroid 3200 Phaethon. This happens every year in mid-December and gives rise to the annual Geminid meteor shower: Streaks of light fly across the sky as rocky chips of Phaethon hit Earth's atmosphere. It's a beautiful display.

The same chips hit the Moon, of course, but on the Moon there is no atmosphere to intercept them. Instead, they hit the ground. "We saw about one explosion per hour," says Cooke.

How does a meteoroid explode? "This isn't the kind of explosion we experience on Earth," explains Cooke. The Moon has no oxygen to support fire or combustion, but in this case no oxygen is required: Geminid meteoroids hit the ground traveling 35 km/s (78,000 mph). "At that speed, even a pebble can blast a crater several feet wide," says Cooke. "The flash of light comes from rocks and soil made so hot by impact that they suddenly glow."

Cooke's group has been monitoring the Moon's nightside (the best place to see flashes of light) since late 2005 and so far they've recorded 19 hits: five or six Geminids, three Leonids, one Taurid and a dozen random meteoroids (sporadics). "The amazing thing is," says Cooke, "we’ve done it using a pair of ordinary backyard telescopes, 14-inch, and off-the-shelf CCD cameras. Amateur astronomers could be recording these explosions, too."

Indeed, he hopes they will. The NASA team can't observe 24-7. Daylight, bad weather, equipment malfunctions, vacations—"lots of things get in the way of maximum observing." Amateur astronomers could fill in the gaps. A worldwide network of amateurs, watching the Moon whenever possible, "would increase the number of explosions we catch," he says.


Above: The lunar meteoroid impact observatory
at the Marshall Space Flight Center. Inset is one of two
14-inch telescopes used to observe the Moon.
[Larger image]

To that end, Cooke plans to release data reduction software developed specifically for amateur and professional astronomers wishing to do this type of work. (The release will be announced on Science@NASA in the near future.) The software runs on an ordinary PC equipped with a digital video card. "If you have caught a lunar meteor on tape, this program can find it. It eliminates the need to stare at hours of black and white video, looking for split-second flashes."

More data will help NASA assess the meteoroid threat as the agency prepares to send astronauts back to the Moon. Ready to assist? Stay tuned to Science@NASA for further instructions.

Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

More Information

NASA's Lunar Impact Monitoring Program

The 2006 Geminid Meteor Shower -- (Science@NASA)

The Vision for Space Exploration

Source: Science@NASA

January 8, 2007: If you think in pounds and miles instead of kilograms and kilometers, you're in the minority. Only the United States, Liberia, and Burma still primarily use English units -- the rest of the world is metric. And now the Moon will be metric too.

see captionNASA has decided to use metric units for all operations on the lunar surface when it returns to the Moon. The Vision for Space Exploration calls for returning astronauts to the Moon by 2020 and eventually setting up a manned lunar outpost.


Above: NASA astronauts on the Moon will use the metric
system. [Larger image]

The decision is a victory not only for the metric system itself, which by this decision increases its land area in the solar system by 27%, but also for the spirit of international cooperation in exploring the Moon. The decision arose from a series of meetings that brought together representatives from NASA and 13 other space agencies to discuss ways to cooperate and coordinate their lunar exploration programs. Standardizing on the metric system was an obvious step in the right direction.

"When we made the announcement at the meeting, the reps for the other space agencies all gave a little cheer," says Jeff Volosin, strategy development lead for NASA's Exploration Systems Mission Directorate. "I think NASA has been seen as maybe a bit stubborn by other space agencies in the past, so this was important as a gesture of our willingness to be cooperative when it comes to the Moon."

The meetings, which began in April 2005, included representatives from the Australian, Canadian, Chinese, European, French, German, British, Indian, Italian, Japanese, Russian, South Korean and Ukrainian space agencies, all of which are either planning or considering some form of lunar exploration. "Of course there's some competitiveness and national pride involved," Volosin says, "but we want to find areas where our goals overlap and see if cooperating in certain areas would be best for everyone."

Going metric was one of those areas. Agreeing to use a single measurement system will make the human habitats and vehicles placed on the Moon by different space agencies more compatible with each other. That could come in handy if, say, one agency's moonbase needs emergency spare parts from another agency's base. No need to worry about trying to fit a 15 millimeter nut onto a 5/8 inch bolt.

Emergencies aside, a metric standard will make it easier for countries to form new partnerships and collaborations after their lunar operations are already in place. All data will be in compatible units, whether it's scientific data or operational data -- such as how far a rover must travel to reach the edge of a crater. A single measurement system will make sharing this data and merging operations more seamless.


Above: In this map, gray areas denote metric territory. English units are used primarily in red zones. The
Moon is shown to scale. [More]

Although NASA has ostensibly used the metric system since about 1990, English units linger on in much of the U.S. aerospace industry. In practice, this has meant that many missions continue to use English units, and some missions end up using both English and metric units. The confusion that can arise from using mixed units was highlighted by the loss of the Mars Climate Orbiter robotic probe in 1999, which occurred because a contractor provided thruster firing data in English units while NASA was using metric.

NASA is considering adopting other standards for its lunar operations as well. For example, another idea that has been discussed informally by the space agencies is using the same type of internet protocols that we all use here on Earth today for communications systems developed for the Moon. "That way, if some smaller space agency or some private company wants to get involved in something we're doing on the Moon, they can say, hey, we already know how to do internet communications," Volosin says. "It lowers the barrier to entry."

In all, this push toward standards and cooperation gives the return to the Moon a very different feel than the Cold War space race of the 1950s and '60s. This time around, competition may help motivate nations to reach for the Moon, but cooperation will help to get them there.

Author: Patrick L. Barry | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

More Information

The Metric System -- from Wikipedia

NASA's Future: The Vision for Space Exploration

Source: Science@NASA

January 23, 2007: If you stare at the Moon long enough, you start seeing things. "82 things to be exact," says Bill Cooke, leader of NASA's Meteoroid Environment Group. That's how many "transient phenomena" the group has video-taped since they started monitoring the night side of the Moon in Nov. 2005.

"In 107 hours of observing, we've tallied 20 lunar meteors + at least 60 Earth-orbiting satellites + one airplane + one terrestrial meteor = 82 in all."


Above: The NASA Meteoroid Environment Group's
lunar observatory at the Marshall Space Flight Center
in Huntsville, Alabama. Inset is one of two 14-inch
telescopes simultaneously trained on the Moon during
the group's observing sessions.
[Larger image]

This is the first systematic count of lunar night-side phenomena. "It gives astronomers an idea of what to expect when they undertake a lunar monitoring program from Earth."

Cooke's prime target is lunar meteors--flashes of light that occur when meteoroids hit the Moon's surface: video. "Of the 20 lunar meteors we've seen so far, about half come from well-known meteor showers such as the Leonids and Geminids. The other half are random meteoroids that take us completely by surprise." NASA is preparing to send astronauts back to the Moon and the agency is understandably interested in how often this happens.

"Everything else we've seen is just a coincidence, something flying in front of the Moon while we happen to be watching." Leading this category are Earth-orbiting satellites and pieces of space debris. This Orbcomm A4 communications satellite is a typical example:

Above: An Orbcomm communication satellite passes in front of the Moon on Nov. 17, 2006: video.

NORAD tracks more than 10,000 Earth-orbiting objects wider than 10 cm. "Some of them are bound to cross in front of the Moon while we're watching," he says. Objects like Orbcomm are easy to identify as satellites. Tumbling space debris, on the other hand, can be trickier: "A sudden glint of sunlight from a flat surface looks an awful lot like a lunar meteor flash," he explains. "So we have to be very careful. When we see a flash of light on the Moon, we always double-check that there was no piece of space junk passing by at that exact moment."

Back in days of Apollo, astronomers who monitored the Moon didn't have this problem. "There were very few satellites in Earth orbit, and a lunar transit was rare," he says. "But now we see one or two every night."

Here's a mystery: "Can you identify this object?" laughs Cooke. "Airplanes are my favorite."

So far, they have detected only one terrestrial meteor—that is, a meteoroid disintegrating in Earth's atmosphere: video. This may seem puzzling. During a typical meteor shower, novice sky watchers see dozens of shooting stars. Why has NASA counted only one? "The telescope's field of view is too narrow," explains Cooke. The human eye is much better for terrestrial meteor watching.

He's more interested in the Moon, anyway. Exploding meteoroids, tumbling satellites and jet airplanes: "It's a great show." What's next? "We plan to keep watching, so stay tuned."

Author: Dr. Tony Phillips | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

____________________________________________

More to the story...

NASA's Lunar Impact Monitoring Program

Videos: an Orbcomm A4 communication satellite, lunar airplane, lunar meteor, terrestrial meteor. Credit: The NASA Meteoroid Environment Group, MSFC.

Farside vs. Nightside: This article tells what was seen during a survey of the lunar night side. The night side shouldn't be confused with the farside. "We can never see the farside of the Moon," Cooke says. "But we often see the night side. It's any lunar terrain not lit up by the Sun, like the dark half of a quarter Moon."

The Vision for Space Exploration

Source: Science@NASA

An another conspiricy is started , Aircraft launched from the MOON. Hey, it did surprise me the way it shot across the screen.

January 26, 2007: With binoculars, examine the rugged face of the Moon. It is pocked with thousands of impact craters from interplanetary asteroids and comets. Ever wonder why Earth, a much bigger target, apparently has so few craters? They're so rare that a pristine example, the Barringer Meteor Crater in Arizona, is actually a tourist attraction. Did Earth just get lucky and dodge the heavy artillery?

No, throughout the history of the solar system, Earth was bombarded even more than the Moon. But Earth is so geologically active that earthquakes, volcanoes, and plain old weather are continually crushing, melting, and reshaping its crust. In short, Earth is continually destroying evidence of its past, including evidence of ancient impact craters. Almost all the terrestrial craters that have been identified—only some 170 at last count—have been so eroded that essential clues have been erased.



Not so the Moon. In fact, according to Paul Spudis, a senior planetary scientist at Johns Hopkins University's Applied Physics Laboratory, one of NASA's best reasons for returning to the Moon is to learn more about Earth.

"The Moon is a witness plate for Earth," declares Spudis, borrowing an apt term from weapons research. When scientists want to measure the type, amount, and pattern of damage done by an explosion, they set up diagnostic "witness plates" of various materials nearby to register the impact of shrapnel and radiation.

"Earth and the Moon occupy the same position in the solar system," Spudis explains. "While Earth is a very dynamic planet, the Moon is a fossil world with no atmosphere. So the Moon preserves a record of the early history of the solar system that is no longer readable on Earth."

That's not just speculation. In the early 1970s, the astronauts on the last three Apollo missions (15, 16, and 17) returned deep-drill core samples from three different sites on the Moon. The cores drilled more than 2 meters into the lunar regolith (the layer of broken rock and dust covering the Moon).

"The deepest samples brought up by those drill cores were 2 billion years old, and largely unchanged since they were laid down," Spudis says. And what a surprise recent re-analysis has revealed. "The lunar regolith traps particles from the solar wind. And drill cores show that the solar wind had a different chemical composition 2 billion years ago than it does today. There's no known explanation for that in solar theory. But that discovery is crucial for understanding the formation of Earth—and also the evolution of stars."


Above: Apollo 16 astronaut Charlie Duke (feet shown)
drives a core sample tube into the lunar regolith. [More]

Another big question a return to the witness-plate Moon might help answer is, What caused the sudden mass extinctions of life forms on Earth that mark the ends of different geological eras?

The most famous is the so-called K-T extinction that wiped out the dinosaurs 65 million years ago, marking the end of the Mesozoic Era (the age of reptiles) and the beginning of the Cenozoic Era (the age of mammals). Much evidence suggests that an asteroid some 10 km wide slammed into Earth, creating such catastrophic climate change that photosynthesizing green plants died, starving more than half of all living beings worldwide; indeed, ground zero has been identified on Mexico's Yucatán Peninsula as the Chicxulub Crater, 160 km across.

There's evidence in the fossil record that such impacts occur periodically, "once every 26 million years," says Spudis. "Not everyone agrees, but I think it is pretty convincing."

Why would this happen? "Some theories are wild!" There might be a dark, distant companion of the sun that periodically perturbs comets in the Oort Cloud, and the comets rain down on Earth. Or perhaps the solar system as a whole is moving in and out of the plane of the Milky Way galaxy, and this somehow triggers periodic episodes of bombardment.

Before we get carried away with theory, however, "we need to establish whether this really happens," Spudis cautions. Is Earth truly subjected to periodic bombardment? Again, the Moon holds the key: Close-up study of the floors of several hundred lunar craters could confirm or falsify a 26-million year period. "We have to sample the stuff that got melted by the shock of impact, and determine the craters' ages."

The Moon is a harsh—and reliable—witness for Earth.

Author: Trudy E. Bell | Production Editor: Dr. Tony Phillips | Credit: Science@NASA

____________________________________________

Web Links

Metric Moon (Science@NASA) -- NASA is returning to the Moon, and the agency has decided to use metric units for all future lunar operations.

The title of this story was inspired by Robert Heinlein's sci-fi classic The Moon is a Harsh Mistress.

The Vision for Space Exploration

Source: Science@NASA

How three remote-sensing instruments on SMART-1 are scanning the Moon's surface
during one pass. Repeated passes will gradually fill in the picture.

SMART-1 is the first of ESA’s Small Missions for Advanced Research in Technology.
It headed for the Moon using solar-electric propulsion and carrying a battery of
miniaturised instruments.

As well as testing new technology, SMART-1 is making the first comprehensive
inventory of key chemical elements in the lunar surface. It is also investigating the
theory that the Moon was formed following the violent collision of a smaller planet
with Earth, four and a half thousand million years ago.

Credits: ESA - AOES Medialab

31 January 2007
A unique way to travel to the Moon, new technologies successfully tested and brand-new science: a few months after the end of the SMART-1 mission scientists and engineers gathered to recap on these and all the other achievements of the first European mission to the Moon.

The innovative SMART-1 Moon mission has taught ESA, European space industry and institutes a lot about how to perform its missions even more efficiently. For example, the operational tools developed and the lessons learned are already being used on ESA missions such as Rosetta and Venus Express. The SMART-1 experience has also been used to prepare future ESA missions, such as Bepi-Colombo, which will visit the inner planet Mercury.

Between 16-17 January 2007, engineers and scientists met at ESA's space technology centre, ESTEC, in the Netherlands, to discuss the success of SMART-1 and how to apply the achievements to current and future missions.

"SMART-1 proved that, with a sense of innovation and commitment, Europe can perform highly complex missions efficiently," says Bernard Foing, SMART-1's project scientist. "From the start it was designed to both test new technologies and perform useful science," he says.

Ten years ago, he began designing the mission with Giuseppe Racca, SMART-1's Project Manager. "SMART-1 was new and unique. We demonstrated innovative technologies for spacecraft and instruments," says Racca.


SMART-1 first orbits the Earth in ever-increasing ellipses. When it reaches the Moon,
its orbit is altered by the Moon's gravitational field. It uses a number of these lunar
'gravity assist' manoeuvres to position itself for entering orbit around the Moon.

Credits: AOES Medialab, ESA 2002.

Perhaps the most obvious new technology was the way SMART-1 travelled to the Moon. SMART-1's electric propulsion system applied a small thrust over a long period. Although this meant that SMART-1 took 13.5 months to reach the Moon, plus an extra 4 months to reach its working science orbit, for deep space missions electric propulsion is more efficient than traditional rockets, in terms of flight time.

"SMART-1 will open the door for new missions because electric propulsion makes it possible to transport more instruments, with lower propellant mass, on affordable rockets with more flexible launch and navigation constraints, in shorter periods of time," says Giorgio Saccoccia, ESA's Head of Propulsion Division.

Using electric propulsion, ESA can send Bepi-Colombo to Mercury in just six years, whereas traditional rockets would take at least seven. Electric propulsion will also be able to transport much more scientific equipment to Mercury than a traditional spacecraft. "With SMART-1, we learned how to drive an electric propulsion spacecraft," says Foing.

"With SMART-1 some dreams became reality. Budget and time pressure originated innovation in spite of the low cost of the mission", says Octavio Camino, Smart-1 Operations Manager at ESOC, "SMART-1 allowed us to test new concepts relevant for future ESA infrastructure for operations automation".



This image, taken by the advanced Moon Imaging Experiment (AMIE) on board ESA’s
SMART-1 spacecraft, shows crater Lomonosov on the Moon’s far side.

AMIE obtained the image on 30 January 2006 from a distance of about 2100 kilometres
from the surface, with a ground resolution of 190 metres per pixel. The imaged area is
centred at a latitude of 27.8º North and a longitude of 98.6º East.

Crater Lomonosov is a nice example for a large crater (92 kilometres in diameter) which
was filled by lava after the impact, thus exhibiting a flat floor. The terraced walls indicate
'slumping', that is sliding of the rocks downwards due to gravity after the end of the
impact. The small craters inside Lomonosov are the result of impacts into this lava floor
which happened after the formation of Lomonosov.

Credits: ESA/Space-X (Space Exploration Institute)

The SMART-1 team also found out how to squeeze the most out of scientific instruments. Originally, the team had planned to take four images per 14.5–hour orbit with the SMART-1 camera, AMIE. As the mission progressed, the team lowered the orbit of SMART-1, so that it circled the Moon in just five hours.

This meant that they had to reprogram the camera to work much faster, as the lunar surface was now rushing by below. In the end, AMIE was supplying 100 images per orbit. The software tools they developed, to schedule this massive upgrade in usage, are now being employed on Venus Express and Rosetta.

The flood of image data has allowed the teams to construct highly detailed maps of the lunar surface. "We have already used the maps to identify possible landing sites for future landers, rovers and even manned bases," says Foing.

Even the instruments on SMART-1 were special. They were miniaturized to be ten times lighter than their traditional counterparts. The camera weighed just 2 kilograms. As a result, two of the instruments (D-CIXS and SIR), which mapped the Moon's elemental composition and minerals, are being upgraded and rebuilt to fly on the 2008 Indian Moon mission Chandrayaan-1.

Whilst the SMART-1 mission is over, Foing thinks there is no room for complacency. He describes the mission as 'a bridge to the future' and says, "We cannot rest on our laurels. By analysing data and lessons learned, we have to carry the SMART-1 legacy forward."


Note

SMART-1, the first European mission to the Moon, concluded its exploration adventure in the early morning of 3 September 2006 through a small impact on the lunar surface,in the 'Lake of Excellence' area. The whole story of this technology-demonstration mission - which also provided great scientific data of the Earth's only natural satellite - began on 27 September 2003 with an Ariane 5 launch from Kourou, French Guiana.

Source: ESA - Smart-1

The press release is reproduced below:

Feb. 2, 2007

Beth Dickey/J.D. Harrington
Headquarters, Washington
202-358-2087/5241

John Bluck
Ames Research Center, Moffett Field, Calif.
650-604-5026/9000

RELEASE: 07-021

NASA Moon-Impactor Mission Passes Major Review

WASHINGTON - NASA's drive to return astronauts to the moon and later probe deeper into space achieved a key milestone recently when agency officials approved critical elements of a moon impact mission scheduled to launch in October 2008. NASA's unmanned Lunar Crater Observation and Sensing Satellite, known as LCROSS, will strike the moon near its south pole in January 2009. It will search for water and other materials that astronauts could use at a future lunar outpost.

Scott Horowitz, associate administrator of the agency's Exploration Systems Mission Directorate, led a confirmation review panel that recently approved the detailed plans, instrument suite, budget and risk factor analysis for the satellite.

NASA's Ames Research Center in Moffett Field, Calif., manages the mission. The mission is valued at $79 million, excluding launch costs. The mission will help NASA gain a new foothold on the moon and prepare for new journeys to Mars and beyond.

The confirmation review authorized continuation of the lunar impactor project and set its cost and schedule. Another mission milestone, the critical design review, is scheduled for late February. That review will examine the detailed Lunar Crater Observation and Sensing Satellite system design. After a successful critical design review, the project team will assemble the spacecraft and its instruments.

"The Lunar Crater Observation and Sensing Satellite project represents an efficient way of doing business by being cost capped, schedule constrained and risk tolerant," said Daniel Andrews, project manager at Ames for the lunar impactor mission.

The lunar impactor will share a rocket ride into space with a second satellite, the Lunar Reconnaissance Orbiter. After the orbiter separates from the Atlas V launch vehicle for its own mission, the LCROSS will use the spent Centaur upper stage of the rocket as a 4,400-pound lunar impactor, targeting a permanently shadowed crater near the lunar South Pole.

According to scientists, the Centaur's collision with the moon will excavate about 220 tons of material from the lunar surface. The Lunar Crater Observation and Sensing Satellite will observe the plume of material with a suite of six instruments to look for water ice and examine lunar soil. The satellite will fly through the plume, also impacting the lunar surface. That second impact will be observed from Earth.

The prime contractor for the satellite is Northrop Grumman Space Technologies of Redondo Beach, Calif.

For information about the Lunar Crater Observation and Sensing Satellite on the Web, visit:

http://lcross.arc.nasa.gov

For information about NASA's Exploration Systems Mission Directorate on the Web, visit:

http://www.nasa.gov/exploration

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/

- end -

--------------------------------------------------------------------------------

Source: NASA Press Release 07-021

February 2, 2007: If you woke up tomorrow morning and found yourself on the moon, what would you do? NASA has just released a list of 181 good ideas.

Ever since the end of the Apollo program, "folks around the world have been thinking about returning to the moon, and what they would like to do there," says Jeff Volosin, strategy development lead for NASA's Exploration Systems Mission Directorate. Now, NASA is going back; the agency plans to send astronauts to the Moon no later than 2020. "So we consulted more than 1,000 people from businesses, academia and 13 international space agencies to come up with a master list of 181 potential lunar objectives."

For example, the moon could be a good location for radio astronomy. A radio telescope on the far side of the Moon would be shielded from Earth's copious radio noise, and would be able to observe low radio frequencies blocked by Earth's atmosphere. Observations at these frequencies have never been made before and opening up a window into this low frequency universe will likely lead to many exciting new discoveries.


Above: A radio telescope on the moon
uses a crater to support its giant primary
dish.
Artist's concept by Pat Rawlings.
[More]

The moon would also be an excellent place to study the high-energy particles of the solar wind, as well as cosmic rays from deep space. Earth's magnetic field and atmosphere deflect many of these particles, so even satellites in low-Earth orbit can't observe them all. The moon has virtually no atmosphere, and it spends most of its 28-day orbit outside of Earth's magnetosphere. Detectors placed on the moon could get a complete profile of solar particles, which reveal processes going on inside the sun, as well as galactic cosmic radiation from distant black holes and supernovas.

Bonus: These particles are trapped by lunar regolith, the layer of crushed rock and dust covering the moon's surface. This means that lunar regolith contains a historical record of solar output: core samples could tell us about changes in solar output over billions of years. "We believe that the moon's preservation of this solar record is unique and can provide us with insights on how past fluctuations in the solar output have affected, for example, the history of life on Earth," says Volosin. In particular, it could shed light on the extent to which solar variability and galactic cosmic radiation influence climate change.

But the moon would be far more than just a platform for scientific instruments gazing into space. The moon itself is a scientific gold mine, a nearby example of planetary formation largely unaltered by the passage of time. Some scientists call it "a fossil world." The moon is a small, non-dynamic planetary body and its interior state is largely preserved since the early days of solar system history. Studying its interior would tell scientists a lot about how a planet's internal layers separate and solidify during planetary formation.

Even something as simple as establishing the dates when various craters on the moon were formed can provide us with a unique picture of how the flux of meteoroids in the vicinity of Earth has changed over time. (For more information see Science@NASA's "