Category: Moon

The Moon and its dark spots. Image credit: NASA. Click to enlarge.
People of every culture have been fascinated by the dark “spots” on the Moon, which seem to compose the figure of a rabbit, frogs or the face of a clown. With the Apollo missions, scientists found that these features are actually huge impact basins that were flooded with now-solidified lava. One surprise was that these basins formed relatively late in the history of the early solar system – approximately 700 million years after the formation of the Earth and Moon. Many scientists now believe that these lunar impact basins bear witness to a huge spike in the bombardment rate of the planets – called the late heavy bombardment (LHB). The cause of such an intense bombardment, however, is considered by many to be one of the best-preserved mysteries of solar system history.

In a series of three papers published in this week’s issue of the journal Nature, an international team of planetary scientists, Rodney Gomes (National Observatory of Brazil), Harold Levison (Southwest Research Institute, United States), Alessandro Morbidelli (Observatoire de la C?te d’Azur, France) and Kleomenis Tsiganis (OCA and University of Thessaloniki, Greece) – brought together by a visitor program hosted at the Observatoire de la C?te d’Azur in Nice – proposed a model that not only naturally solves the mystery of the origin of the LHB, but also explains many of the observed characteristics of the outer planetary system.

This new model envisions that the four giant planets, Jupiter, Saturn, Uranus and Neptune, formed in a very compact orbital configuration, which was surrounded by a disk of small objects made of ice and rock (known as “planetesimals”). Numerical simulations by the Nice team shows that some of these planetesimals slowly leaked out of the disk due to the gravitational effects of the planets. The planets scattered these smaller objects throughout the solar system, sometimes outward and sometimes inward.

“As Isaac Newton taught us, for every action there is an equal and opposite reaction,” says Tsiganis. “If a planet throws a planetesimal out of the solar system, the planet moves toward the Sun, just a tiny bit, in compensation. If, on the other hand, the planet scatters the planetesimal inward, the planet jumps slightly farther from the Sun.”

Numerical simulations show that, on average, Jupiter moved inward while the other giant planets moved outward.

Initially, this was a very slow process, taking millions of years for the planets to move a small amount. Then, according to this new model, after 700 million years, the situation suddenly changed. At that time, Saturn migrated through the point where its orbital period was exactly twice that of Jupiter’s. This special orbital configuration caused Jupiter’s and Saturn’s orbits to suddenly become more elliptical.

“This caused the orbits of Uranus and Neptune to go nuts,” says Gomes. “Their orbits became very eccentric and they started to gravitationally scatter off each other – and Saturn too.”

The Nice team argues that this evolution of Uranus’ and Neptune’s orbits caused the LHB on the Moon. Their computer simulations show that these planets very quickly penetrated the planetesimal disk, scattering objects throughout the planetary system. Many of these objects entered the inner solar system where they peppered the Earth and Moon with impacts. In addition, the whole process destabilized the orbits of asteroids, which then would have also contributed to the LHB. Finally, the gravitational effects of the planetesimal disk caused Uranus and Neptune to evolve onto their current orbits.

“It’s very convincing,” says Levison. “We have made several dozen simulations of this process, and statistically the planets ended up on orbits very similar to the ones that we see, with the correct separations, eccentricities and inclinations. So, in addition to the LHB, we can also explain the orbits of the giant planets. No other model has ever accomplished either thing before.”

However, there was one more hurdle to overcome. The solar system currently contains a population of asteroids that follow essentially the same orbit as Jupiter, but lead or trail that planet by an angular distance of roughly 60 degrees. Computer simulations show that these bodies, known as the “Trojan asteroids,” would have been lost as the giant planets’ orbits changed.

“We sat around for months worrying about this problem, which seemed to invalidate our model,” says Morbidelli, “until we realized that if a bird can escape from an open cage, another one can come and nest in it.”

The Nice team found that some of the very objects that were driving the planetary evolution, and which caused the LHB, would also have been captured into Trojan asteroid orbits. In the simulations, the trapped Trojans turned out to reproduce the orbital distribution of the observed Trojans, which was unexplained up to now. The total predicted mass of the trapped objects was also consistent with the observed population.

Taken in total, the Nice team’s new model naturally explains the orbits of the giant planets, the Trojan asteroids and the LHB to unprecedented accuracy. “Our model explains so many things that we believe it must be basically correct,” says Mordibelli. “The structure of the outer solar system shows that the planets probably went through a shake up well after the planet formation process ended.”

Original Source: SWRI News Release

Astronauts in a lunar base will need a lot of air. Image credit: NASA. Click to enlarge.
NASA, in collaboration with the Florida Space Research Institute (FSRI), today announced a new Centennial Challenges prize competition.

The MoonROx (Moon Regolith Oxygen) challenge will award $250,000 to the first team that can extract breathable oxygen from simulated lunar soil before the prize expires on June 1, 2008.

For the MoonROx challenge, teams must develop hardware within mass and power limits that can extract at least five kilograms of breathable oxygen from simulated lunar soil during an eight-hour period. The soil simulant, called JSC-1, is derived from volcanic ash. The oxygen production goals represent technologies that are beyond existing state-of-the-art.

NASA’s Centennial Challenges promotes technical innovation through a novel program of prize competitions. It is designed to tap the nation’s ingenuity to make revolutionary advances to support the Vision for Space Exploration and NASA goals.

“The use of resources on other worlds is a key element of the Vision for Space Exploration,” said NASA’s Associate Administrator for the Exploration Systems Mission Directorate, Craig Steidle. “This challenge will reach out to inventors who can help us achieve the Vision sooner,” he added.

“This is our third prize competition, and the Centennial Challenges program is getting more and more exciting with each new announcement. The innovations from this competition will help support long-duration, human and robotic exploration of the moon and other worlds,” said Brant Sponberg, NASA’s Centennial Challenges program manager.

“Oxygen extraction technologies will be critical for both robotic and human missions to the moon,” said FSRI Executive Director Sam Durrance. “Like other space-focused prize competitions, the MoonROx challenge will encourage a broad community of innovators to develop technologies that expand our capabilities,” he added.

The Centennial Challenges program is managed by NASA’s Exploration Systems Mission Directorate. FSRI is a state-wide center for space research. It was established by Florida’s governor and legislature in 1999.

For more information about Centennial Challenges on the Internet, visit: http://centennialchallenges.nasa.gov

For more information about NASA and agency programs on the Internet, visit: http://www.nasa.gov/home/index.html

For information about the Florida Space Research Institute on the Internet, visit: http://www.fsri.org

Original Source: NASA News Release

NASA is gearing up to send humans back to the Moon. Image credit: Pat Rawlings / SAIC. Click to enlarge.
The next time you look at the Moon, pause for a moment and let this thought sink in: People have actually walked on the Moon, and right now the wheels are in motion to send people there again.

The goals this time around are more ambitious than they were in the days of the Apollo program. NASA’s new Vision for Space Exploration spells out a long-term strategy of returning to the Moon as a step toward Mars and beyond. The Moon, so nearby and accessible, is a great place to try out new technologies critical to living on alien worlds before venturing across the solar system.

Whether a moonbase will turn out to be feasible hinges largely on the question of water. Colonists need water to drink. They need water to grow plants. They can also break water apart to make air (oxygen) and rocket fuel (oxygen+hydrogen). Furthermore, water is surprisingly effective at blocking space radiation. Surrounding the ‘base with a few feet of water would help protect explorers from solar flares and cosmic rays.

The problem is, water is dense and heavy. Carrying large amounts of it from Earth to the Moon would be expensive. Settling the Moon would be so much easier if water were already there.

It’s possible: Astronomers believe that comets and asteroids hitting the Moon eons ago left some water behind. (Earth may have received its water in the same way.) Water on the Moon doesn’t last long. It evaporates in sunlight and drifts off into space. Only in the shadows of deep cold craters could you expect to find any, frozen and hidden. And indeed there may be deposits of ice in such places. In the 1990s two spacecraft, Lunar Prospector and Clementine, found tantalizing signs of ice in shadowed craters near the Moon’s poles–perhaps as much as much as a cubic kilometer. The data were not conclusive, though.

To find out if lunar ice is truly there, NASA plans to send a robotic scout. The Lunar Reconnaissance Orbiter, or “LRO” for short, is scheduled to launch in 2008 and to orbit the Moon for a year or more. Carrying six different scientific instruments, LRO will map the lunar environment in greater detail than ever before.

“This is the first in a string of missions,” says Gordon Chin, project scientist for LRO at NASA’s Goddard Space Flight Center. “More robots will follow, about one per year, leading up to manned flight” no later than 2020.

LRO’s instruments will do many things: they’ll map and photograph the Moon in detail, sample its radiation environment and, not least, hunt for water.

For example, the spacecraft’s Lyman-Alpha Mapping Project (LAMP), will attempt to peer into the darkness of permanently shadowed craters at the Moon’s poles, looking for signs of ice hiding there.

How can LAMP see in the dark? By looking for the dim glow of reflected starlight.

LAMP senses a special range of ultraviolet light wavelengths. Not only is starlight relatively bright in this range, but also the hydrogen gas that permeates the universe radiates in this range as well. To LAMP’s sensor, space itself is literally aglow in all directions. This ambient lighting may be enough to see what lies in the inky blackness of these craters.

“What’s more, water ice has a characteristic spectral ‘fingerprint’ in this same range of ultraviolet light, so we’ll get spectral evidence of whether ice is in these craters,” explains Alan Stern, a scientist at the Southwest Research Institute and principal investigator for LAMP.

The spacecraft is also equipped with a laser that can shine pulses of light into dark craters. The main purpose of the instrument, called the Lunar Orbiter Laser Altimeter (LOLA), is to produce a highly accurate contour map of the entire Moon. As a bonus, it will also measure the brightness of each laser reflection. If the soil contains ice crystals, as little as 4%, the returning pulse would be noticeably brighter.

LOLA by itself can’t prove that ice is there. “Any kind of reflective crystals could produce brighter pulses,” explains David Smith, principal investigator for LOLA at NASA’s Goddard Space Flight Center. “But if we see brighter pulses only in these permanent shadows, we’d strongly suspect ice.”

One of LRO’s instruments, named Diviner, will map the temperature of the Moon’s surface. Scientists can use these measurements to search for places where ice could exist. Even in the permanent shadows of polar craters, temperatures must be very low for ice to resist evaporation. Thus, Diviner will provide a “reality check” for LRO’s other ice-sensitive instruments, identifying areas where positive signs of ice would not make any sense because the temperature is simply too high.

Another reality check will come from LRO’s Lunar Exploration Neutron Detector (LEND), which counts neutrons spraying out of the lunar surface. Why does the Moon emit neutrons? And what does that have to do with water? The Moon is constantly bombarded by cosmic rays, which produce neutrons when they hit the ground. Hydrogen-bearing compounds like H2O absorb neutrons, so a dip in neutron radiation could signal an oasis … of sorts. LEND is being developed by Igor Mitrofanov from the Institute for Space Research, Federal Space Agency, Moscow.

“There’s a strong synergy between the various instruments on LRO,” notes Chin. “None of these instruments alone could provide definitive evidence of ice on the Moon, but if they all point to ice in the same area, that would be compelling.”

Chin also points out another reason that finding ice near the Moon’s poles would be exciting:

Not far from some permanently shadowed craters are mountainous regions in permanent sunlight, known romantically as “peaks of eternal sunshine.” Conceivably, a moonbase could be placed on one of those peaks, providing astronauts with constant solar power–not far from crater-valleys below, rich in ice and ready to be mined.

Wishful thinking? Or a reasonable plan? Lunar Reconnaissance Orbiter will beam back the answer.

Original Source: Science@NASA Story

This is a true story.

In 1972, Apollo astronaut Harrison Schmidt sniffed the air in his Lunar Module, the Challenger. “[It] smells like gunpowder in here,” he said. His commander Gene Cernan agreed. “Oh, it does, doesn’t it?”

The two astronauts had just returned from a long moonwalk around the Taurus-Littrow valley, near the Sea of Serenity. Dusty footprints marked their entry into the spaceship. That dust became airborne–and smelly.

Later, Schmidt felt congested and complained of “lunar dust hay fever.” His symptoms went away the next day; no harm done. He soon returned to Earth and the anecdote faded into history.

But Russell Kerschmann never forgot. He’s a pathologist at the NASA Ames Research Center studying the effects of mineral dust on human health. NASA is now planning to send people back to the Moon and on to Mars. Both are dusty worlds, extremely dusty. Inhaling that dust, says Kerschmann, could be bad for astronauts.

“The real problem is the lungs,” he explains. “In some ways, lunar dust resembles the silica dust on Earth that causes silicosis, a serious disease.” Silicosis, which used to be called “stone-grinder’s disease,” first came to widespread public attention during the Great Depression when hundreds of miners drilling the Hawk’s Nest Tunnel through Gauley Mountain in West Virginia died within half a decade of breathing fine quartz dust kicked into the air by dry drilling–even though they had been exposed for only a few months. “It was one of the biggest occupational-health disasters in U.S. history,” Kerschmann says.

This won’t necessarily happen to astronauts, he assures, but it’s a problem we need to be aware of–and to guard against.

Quartz, the main cause of silicosis, is not chemically poisonous: “You could eat it and not get sick,” he continues. “But when quartz is freshly ground into dust particles smaller than 10 microns (for comparison, a human hair is 50+ microns wide) and breathed into the lungs, they can embed themselves deeply into the tiny alveolar sacs and ducts where oxygen and carbon dioxide gases are exchanged.” There, the lungs cannot clear out the dust by mucous or coughing. Moreover, the immune system’s white blood cells commit suicide when they try to engulf the sharp-edged particles to carry them away in the bloodstream. In the acute form of silicosis, the lungs can fill with proteins from the blood, “and it’s as if the victim slowly suffocates” from a pneumonia-like condition.

Lunar dust, being a compound of silicon as is quartz, is (to our current knowledge) also not poisonous. But like the quartz dust in the Hawk’s Nest Tunnel, it is extremely fine and abrasive, almost like powdered glass. Astronauts on several Apollo missions found that it clung to everything and was almost impossible to remove; once tracked inside the Lunar Module, some of it easily became airborne, irritating lungs and eyes.

Martian dust could be even worse. It’s not only a mechanical irritant but also perhaps a chemical poison. Mars is red because its surface is largely composed of iron oxide (rust) and oxides of other minerals. Some scientists suspect that the dusty soil on Mars may be such a strong oxidizer that it burns any organic compound such as plastics, rubber or human skin as viciously as undiluted lye or laundry bleach.

“If you get Martian soil on your skin, it will leave burn marks,” believes University of Colorado engineering professor Stein Sture, who studies granular materials like Moon- and Mars-dirt for NASA. Because no soil samples have ever been returned from Mars, “we don’t know for sure how strong it is, but it could be pretty vicious.”

Moreover, according to data from the Pathfinder mission, Martian dust may also contain trace amounts of toxic metals, including arsenic and hexavalent chromium–a carcinogenic toxic waste featured in the docudrama movie Erin Brockovich (Universal Studios, 2000). That was a surprising finding of a 2002 National Research Council report called Safe on Mars: Precursor Measurements Necessary to Support Human Operations on the Martian Surface.

The dust challenge would be especially acute during windstorms that occasionally envelop Mars from poles to equator. Dust whips through the air, scouring every exposed surface and sifting into every crevice. There’s no place to hide.

To find ways of mitigating these hazards, NASA is soon to begin funding Project Dust, a four-year study headed by Masami Nakagawa, associate professor in the mining engineering department of the Colorado School of Mines. Project Dust will study such technologies as thin-film coatings that repel dust from tools and other surfaces, and electrostatic techniques for shaking or otherwise removing dust from spacesuits.

These technologies, so crucial on the Moon and Mars, might help on Earth, too, by protecting people from sharp-edged or toxic dust on our own planet. Examples include alkaline dust blown from dry lakes in North American deserts, wood dust from sawmills and logging operations, and, of course, abrasive quartz dust in mines.

The road to the stars is surprisingly dusty. But, says Kerschmann, “I strongly believe it’s a problem that can be controlled.”

Original Source: Science@NASA Story

The first object in the night sky most of us ever saw, the Moon remains a mystery. Haunted by poets, looked upon by youngsters in love, studied intensely by astronomers for four centuries, examined by geologists for the last 50 years, walked upon by twelve humans, this is Earth’s satellite.

And as we look towards the Moon with thoughts of setting up a permanent home there, one new question is paramount: does the Moon have water? Although none has been definitely detected, recent evidence suggests that it’s there.

Why should there be water on the Moon? Simply for the same reason that there’s water on Earth. A favorite theory is that water, either as water by itself or as its components of hydrogen and oxygen, was deposited on Earth during its early history–mostly during a period of “late heavy bombardment” 3.9 billion years ago–by the impacts of comets and asteroids. Because the Moon shares the same area of space as Earth, it should have received its share of water as well. However, since it has only a tiny fraction of Earth’s gravity, most of the Moon’s water supply should have evaporated and drifted off into space long ago. Most, but perhaps not all.

In ancient times, observers commonly thought the Moon had abundant water–in fact, the great lava plains like Mare Imbrium were called maria, or seas. But when Neil Armstrong and Buzz Aldrin landed on the Moon in 1969, they stepped out not into the water of the Sea of Tranquillity, but onto basaltic rock. No one was surprised by that–the idea of lunar maria had been replaced by lava plains decades earlier.

As preparations were underway in the mid 1960s for the Apollo program, questions about water on the Moon were barely on the radar screen. Geologists and astronomers were divided at the time as to whether the lunar surface was a result of volcanic forces from beneath, or cosmic forces from above. Grove Carl Gilbert in 1893 already had the answer. That famous geologist suggested that large asteroidal objects hit the Moon, forming its craters. Ralph Baldwin articulated the same idea in 1949, and Gene Shoemaker revived the idea again around 1960. Shoemaker, almost alone among geologists of his day, saw the Moon as a fertile subject for field geology. He saw the craters on the Moon as logical impact sites that were formed not gradually in eons, but explosively in seconds.

The Apollo flights confirmed that the dominant geological process on the Moon is impact-related. That discovery, in turn, ushered in a new question: Since Earth’s water was probably delivered largely by comets and asteroids, could this process have done the same for the Moon? And could some of that water still be there?

In 1994, the SDI-NASA Clementine spacecraft orbited the Moon and mapped its surface. In one experiment, Clementine beamed radio signals into shadowed craters near the Moon’s south pole. The reflections, received by antennas on Earth, seemed to come from icy material.

That makes sense. If there is water on the Moon, it’s probably hiding in the permanent shadows of deep, cold craters, safe from vaporizing sunlight, frozen solid.

So far so good, but… the Clementine data were not conclusive, and when astronomers tried to find ice in the same craters using the giant Arecibo radar in Puerto Rico, they couldn’t. Maybe Clementine was somehow wrong.

In 1998, NASA sent another spacecraft, Lunar Prospector, to check. Using a device called a neutron spectrometer, Lunar Prospector scanned the Moon’s surface for hydrogen-rich minerals. Once again, polar craters yielded an intriguing signal: neutron ratios indicated hydrogen. Could it be the “H” in H2O? Many researchers think so.

Lunar Prospector eventually sacrificed itself to the search. When the spacecraft’s primary mission was finished, NASA decided to crash Prospector near the Moon’s south pole, hoping to liberate a bit of its meager layer of water. Earth’s satellite might briefly become a comet as amounts of water vapor were released.

Lunar Prospector crashed, as planned, and several teams of researchers tried to detect that cloud, but without success. Either there was no water, or there was not enough water to be detected by Earth-based telescopes, or the telescopes were not looking in precisely the right place. In any event, no water was found from Prospector’s impact.

In 2008, NASA plans to send a new spacecraft to the Moon: the Lunar Reconnaissance Orbiter (LRO), bristling with advanced sensors that can sense water in at least four different ways. Scientists are hopeful that LRO can decide the question of Moon water once and for all.

Our interest is not just scientific. If we are indeed to build a base on the Moon, the presence of water already there would offer a tremendous advantage in building and running it. It’s been 35 years since we first set foot on the Moon. Now ambitious eyes once again look toward our satellite not just as a place to visit, but as a place to live.

Original Source: Science@NASA

ESA?s SMART-1 mission to the Moon has been monitoring the illumination of lunar poles since the beginning of 2005, about two months before arriving at its final science orbit.

Ever since, the AMIE on-board camera has been taking images which are even able to show polar areas in low illumination conditions. Images like these will help identify if peaks of eternal light exist at the poles.

SMART-1 took views of the North Polar Region from a distance of 5000 km during a pause in the spiralling descent to the science orbit. One can see highland terrains, very highly cratered due to their old age. The rims of the large craters project very long shadows even on surrounding features. SMART-1 is monitoring the polar shadows cast during the Moon rotation, and their seasonal variations, to look for places with long-lasting illumination.

The image shows a 275 km area close to the North pole (upper left corner) observed by SMART-1 on 29 December 2004 from a distance of 5500 km. This shows a heavily cratered highland terrain, and is used to monitor illumination of polar areas, and long shadows cast by large crater rims.

SMART-1 also observated a North polar area 250 km wide on 19 January 2005 (close to North winter solstice) from a distance of 5000 km. The illuminated part of crater rim is very close to the North pole and is a candidate for a peak of eternal sunlight.

?This shows the ability of SMART-1 and its camera to image even for low light levels at the poles and prospect for sites for future exploration?, says AMIE camera Principal Investigator Jean-Luc Josset, (SPACE-X, Switzerland).

?If we can confirm peaks of eternal light?, adds Bernard Foing, SMART-1 Project Scientist, ?these could be a key locations for possible future lunar outposts?.

The existence of peaks of eternal light at the poles, that is areas that remain eternally illuminated regardless of seasonal variations, was first predicted in the second half of the nineteenth century by the astronomer Camille Flammarion. Even if for most of the Moon the length of the day does not vary perceptibly during the course of seasons, this is not the case over the poles, where illumination can vary extensively during the course of the year. The less favourable illumination conditions occur around the northern winter solstice, around 24 January. There are areas at the bottom of near-polar craters that do not see direct sunshine, where ice might potentially be trapped. Also there are areas at higher elevation on the rim of polar craters that see the Sun more than half of the time. Eventually, there may be areas that are always illuminated by sunlight.

Original Source: ESA News Release

Image credit: ESA
On 17 March the ESA Council, at its meeting in Paris, unanimously approved a cooperation agreement between ESA and the Indian Space Research Organisation for India?s first moon mission ? Chandrayaan-1.

The Indian Space Research Organisation (ISRO), founded in 1969, launched its first satellite in 1975. Since then it has developed a number of launch vehicles as well as satellites for Earth observation, remote sensing, telecommunications and weather forecasting. India has its own launch site at Sriharikota but has also used Europe?s Spaceport in French Guiana to launch its satellites. Chandrayaan-1 marks its first venture into planetary space science.

Under the agreement Europe will coordinate and support the provision of three instruments: CIXS-2, the Chandrayaan-1 Imaging X-Ray Spectrometer; SARA, a Sub-keV Atom Relecting Analyzer; and SIR-2, a Near-Infrared Spectrometer. It will also support the hardware for the High-Energy X-ray Spectrometer (HEX). Direct ESA in-kind contributions are also foreseen under this historical agreement. In return, all data resulting from the instruments will be made immediately available to ESA Member States through ESA.

The instruments requested are identical to those on ESA?s SMART-1. Launched in 2003, SMART-1, having demonstrated a new solar electric propulsion motor and tested other technologies on its way to the moon, has just started its science phase. It will make the first comprehensive inventory of key chemical elements in the lunar surface.

ISRO plans to send a 1050 kg (523 kg initial orbit mass and 440 kg dry mass) remote sensing satellite to help unravel mysteries about the origin and evolution of the solar system in general and the Moon in particular. The satellite, which is expected to have an operational life of two years, will be launched by India?s Polar Satellite Launch Vehicle in 2007/2008.

ESA will give ISRO the benefit of its experience with SMART-1 and will further assist in operations facilitation as well as providing the science instruments.

ESA’s SMART-1 put Europe in the lead in the new race back to the Moon. As well as India and Japan, China and the USA also intend to launch lunar missions in the coming years. The cooperation with India will keep European scientists in the forefront.

The ESA Director of Science, David Southwood, said: “One should also see the cooperation in a wider context. Space science is a natural area for space agencies to learn to work together in technical matters. Such cooperation remains a strategic element in the Director General’s wider agenda for the Agency.”

Original Source: ESA News Release

Illustration credit: ESA
ESA’s SMART-1 mission was extended by one year, pushing back the mission end date from August 2005 to August 2006.

ESA’s Science Programme Committee endorsed unanimously the proposed one-year extension of SMART-1 on 10 February 2005.

The extension by one year of the mission will provide opportunities to extend the global coverage, compared to the original six-month mission, and to map both southern and northern hemispheres at high resolution. The new orbit will also be more stable and require less fuel for maintenance.

The extension also gives the possibility to perform detailed studies of areas of interest by performing stereo measurements for deriving topography, multi-angle observations for studying the surface ‘regolith’ texture, and mapping potential landing sites for future missions.

Implementation of this mission extension will be in two periods of six months that correspond to different orbital parameters and illumination conditions. During the first period, the southern survey study is to be completed and dedicated pointings made for multi-angle, stereo and polar illumination studies.

In the second period, high-resolution coverage of the Moon on the equator and part of the northern hemisphere will take place due to the favourable illumination conditions. High resolution follow-up observations of specific targets will also be made, as well as observations relevant for the preparation of future international lunar exploration missions.

Between 10 January and 9 February, SMART-1’s electric propulsion system (or ‘ion engine’) was not active. This allowed mission controllers to accurately determine the amount of fuel remaining, as well as ensure accurate planning for a mission extension, and obtain reconnaissance data from an orbit at 1000-4500 kilometres above the lunar surface.

All the instruments have been performing well from this orbit. As the ion engine is now active again, SMART-1 will spiral down to arrive at the lunar science orbit by the end of February.

The cruise and lunar approach has permitted the demonstration of a number of technologies, such as spacecraft, navigation, operations and instruments, which will be useful for future missions. The SMART-1 mission has now fulfilled its primary objective ? to demonstrate the viability of solar electric propulsion, or ‘ion drives’.

Original Source: ESA News Release

Image credit: ESA
ESA’s SMART-1 captured its first close-range images of the Moon this January, during a sequence of test lunar observations from an altitude between 1000 and 5000 kilometres above the lunar surface.

SMART-1 entered its first orbit around the Moon on 15 November 2004. It has spent the two months following spiralling down to the Moon and testing its array of instruments.

The first four days after being captured by the lunar gravity were very critical. There had been the risk, being in an ‘unstable’ trajectory, of escaping the Moon’s orbit or crashing onto the surface. Because of this, the electric propulsion system (or ‘ion engine’) started a thrust to stabilise the capture.

The ion engine was switched on until 29 December, allowing SMART-1 to make ever-decreasing loops around the Moon. The engine was switched off between 29 December and 3 January 2005 to allow scientists to start observations. At this point, the AMIE camera took the close-up lunar images. The engine was switched off again to optimise fuel consumption on 12 January, and SMART-1 will spend until 9 February making a medium resolution survey of the Moon, taking advantage of the favourable illumination conditions.

ESA’s SMART-1 Project Scientist Bernard Foing said “A sequence of test lunar observations was done in January at distances between 1000 and 5000 kilometres altitude, when the electric propulsion was paused. We are conducting more survey test observations until the electric propulsion resumes from 9 February to spiral down further towards the Moon. SMART-1 will arrive on 28 February at the initial orbit with altitudes between 300 and 3000 kilometres to perform the first phase of nominal science observations for five months.”

The first close-up image shows an area at lunar latitude 75? North with impact craters of different sizes. The largest crater shown here, in the middle left of the image, is Brianchon. The second largest, at the bottom of the image, is called Pascal.

At low illumination angles, the crater shadows allow scientists to derive the height of crater rims.

“This image was the first proof that the AMIE camera is still working well in lunar orbit,” says AMIE Principal Investigator Jean-Luc Josset of Space-X.

The composite images shown here were created to show larger-scale features. The first mosaic shows the complex impact crater Pythagoras and the strip of images (bottom) was produced from images taken consecutively along one orbit.

Starting with this mosaic, SMART-1 scientists expect to build up a global medium-resolution context map, where high-resolution images later observed from lower altitude can be integrated.

Original Source: ESA News Release