Graphic of how the solar wind flows over the Moon. Credit: NLSI
The Moon keeps getting more interesting all the time! But now comes “shocking” news that exploring polar craters could be much harder and more dangerous than originally thought. New research shows that as the solar wind flows over natural obstructions on the moon, such as the rims of craters at the poles, the craters could be charged to hundreds of volts. “In a nutshell, what we’re finding is that the polar craters are very unusual electrical environments, and in particular there can be large surface charging at the bottom of these craters,” said William Farrell from Goddard Space Flight Center, lead author of a new research on the Moon’s environment.
The moon’s orientation to the sun keeps the bottoms of polar craters in permanent shadow, allowing temperatures there to plunge below minus 400 degrees Fahrenheit, cold enough to store volatile material like water for billions of years. And of course, any resources that may lie in those craters are of interest for any future explorers, should astronauts ever return to the Moon.
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“However, our research suggests that, in addition to the wicked cold, explorers and robots at the bottoms of polar lunar craters may have to contend with a complex electrical environment as well, which can affect surface chemistry, static discharge, and dust cling,” said Farrell, who is part of a lunar Dream Team — the Lunar Science Institute’s Dynamic Response of the Environment at the moon (DREAM) project, which is also part of NASA’s Lunar Science Institute.
Solar wind inflow into craters can erode the surface, which affects recently discovered water molecules. Static discharge could short out sensitive equipment, while the sticky and extremely abrasive lunar dust could wear out spacesuits and may be hazardous if tracked inside spacecraft and inhaled over long periods.
The solar wind is a thin gas of electrically charged components of atoms – negatively charged electrons and positively charged ions — that is constantly blowing from the surface of the sun into space. Since the moon is only slightly tilted compared to the sun, the solar wind flows almost horizontally over the lunar surface at the poles and along the region where day transitions to night, called the terminator.
The researchers created computer simulations to discover what happens when the solar wind flows over the rims of polar craters. They discovered that in some ways, the solar wind behaves like wind on Earth — flowing into deep polar valleys and crater floors. Unlike wind on Earth, the dual electron-ion composition of the solar wind may create an unusual electric charge on the side of the mountain or crater wall; that is, on the inside of the rim directly below the solar wind flow.
Since electrons are over 1,000 times lighter than ions, the lighter electrons in the solar wind rush into a lunar crater or valley ahead of the heavy ions, creating a negatively charged region inside the crater. The ions eventually catch up, but rain into the crater at consistently lower concentrations than that of the electrons. This imbalance in the crater makes the inside walls and floor acquire a negative electric charge. The calculations reveal that the electron/ion separation effect is most extreme on a crater’s leeward edge – along the inside crater wall and at the crater floor nearest the solar wind flow. Along this inner edge, the heavy ions have the greatest difficulty getting to the surface. Compared to the electrons, they act like a tractor-trailer struggling to follow a motorcycle; they just can’t make as sharp a turn over the mountain top as the electrons.
“The electrons build up an electron cloud on this leeward edge of the crater wall and floor, which can create an unusually large negative charge of a few hundred Volts relative to the dense solar wind flowing over the top,” said Farrell.
The negative charge along this leeward edge won’t build up indefinitely. Eventually, the attraction between the negatively charged region and positive ions in the solar wind will cause some other unusual electric current to flow. The team believes one possible source for this current could be negatively charged dust that is repelled by the negatively charged surface, gets levitated and flows away from this highly charged region. “The Apollo astronauts in the orbiting Command Module saw faint rays on the lunar horizon during sunrise that might have been scattered light from electrically lofted dust,” said Farrell. “Additionally, the Apollo 17 mission landed at a site similar to a crater environment – the Taurus-Littrow valley. The Lunar Ejecta and Meteorite Experiment left by the Apollo 17 astronauts detected impacts from dust at terminator crossings where the solar wind is nearly-horizontal flowing, similar to the situation over polar craters.”
“This important work by Dr. Farrell and his team is further evidence that our view on the moon has changed dramatically in recent years,” said Gregory Schmidt, deputy director of the NASA Lunar Science Institute at NASA’s Ames Research Center, Moffett Field, Calif. “It has a dynamic and fascinating environment that we are only beginning to understand.”
Next steps for the team include more complex computer models. “We want to develop a fully three-dimensional model to examine the effects of solar wind expansion around the edges of a mountain. We now examine the vertical expansion, but we want to also know what happens horizontally,” said Farrell. As early as 2012, NASA will launch the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission that will orbit the moon and could look for the dust flows predicted by the team’s research.
Apollo 14 landing site in 3-D. Image: LRO, Anaglyph by Nathanial Burton-Bradford. Click for larger version.
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Time to grab your 3-D glasses! Just got a note from Nathanial Burton-Bradford, one of the image editing wizards we have featured here at Universe Today. His latest handiwork is creating some 3-D analglyphs of images from the Lunar Reconnaissance Orbiter, and particularly of the Apollo landing sites. As Nathanial wrote me, “In a word, WOW!” Nathanial’s images make the lunar landers really stand out and stand *up* in the images, and other features such as tracks and experiments left by the Apollo astronauts become more visible as well. See more images below, and click on the images for larger versions, or see Nathanial’s flickr page for lots more!
Apollo 15 landing site in 3-D. Image by LRO, Analglyph by Nathanial Burton Bradford. Click for larger version.
Apollo 11 landing site in 3-D. Image: LRO, Anaglyph by Nathanial Burton-Bradford. Click for larger version.
[/caption]Despite the close proximity between the Earth and the Moon, there’s a big difference between the surface of the Moon and of Earth’s. Much of the difference between the two celestial bodies is caused by the absence of the following attributes on the Moon: an atmosphere, bodies of water, and plate tectonics.
Since the Earth’s Moon doesn’t have a significant atmosphere, nothing can stop even the smallest meteoroids from striking its surface. As a result, the lunar surface is heavily cratered. As a matter of fact, tiny craters are quite common even on lunar rocks. This was observed on the Moon rocks brought home by the Apollo missions.
By contrast, small meteoroids that pass through the Earth’s atmosphere are easily vaporized and hence are not able to form craters on the land below.
The absence of liquid water on its surface has allowed the Moon to preserve much of its ancient geological features. Here on Earth, erosion can alter and cover formations over time. Plate tectonics, which is also absent on the Moon, is another big factor that makes the terrain of the two celestial bodies different.
Here on Earth, plate tectonics cause volcanic activities, earthquakes, and sea floor spreading.
Due to the lack of water and atmosphere, the lunar regolith (also called “lunar soil”) is noticeably dry and devoid of air. It also does not contain anything organic. The regolith comes from meteor impacts that has plagued the Moon since its inception.
Impact crater sizes on the lunar surface range from the tiny holes that mark lunar rocks to the really big ones like the South Pole Aitken Basin that has a diameter of approximately 2,500 km. Younger craters are superimposed over older ones. This characteristic is used by scientists to determine the relative ages of impact craters.
Basically, it has been observed that the size of impact craters on the surface of the Moon have decreased over time.
Other prominent geological features found on the surface of the Moon include maria, rilles, domes, wrinkle ridges, and grabens.
The maria, which comprise about one-third of the Moon’s near side, are made up of flows of basaltic lava formed from volcanic activities that occurred in the younger years of the Moon. They were once mistaken for seas on the surface of the Moon, hence the name. Maria is the Latin word for seas. The near side refers to the side of the Moon that is constantly facing Earth.
ISS transit of the Moon. Image Credit: Photo courtesy of Fernando Echeverria
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The NASA Image of the Day is a webpage that everyone should visit everyday, as there are always great images of our explorations of space and Earth. But this one has a wow factor that is off the charts. It was taken just minutes before space shuttle Discovery launched this past Monday on April 5, 2010, as the International Space Station flew across the face of the moon over Kennedy Space Center in Florida. I know people who were there who thought it was an poignant event, but here photographer Fernando Echeverria captures the event at just the right milimoment as the ISS reached the dark area on the Moon. Amazing, and such incredible detail, too! Click the image or this link to go to the NASA Image of the Day site where you can find larger versions — suitable for framing or desktops!
The debate on why humans should or should not return to the Moon has been ongoing for years. Two weeks ago, I had the opportunity to hear astronautRon Garan speak eloquently on a subject he is passionate about, water sustainability on planet Earth. Subsequently, I read an essay Garan wrote about the importance of returning to the Moon. Although Garan originally wrote this essay before the cancellation of the Constellation program was announced, he has amended his thoughts to reflect the likelihood that the US won’t be returning to the Moon anytime soon. With Garan’s permission, we are re-publishing his essay in its entirety.
The Importance of Returning to the Moon
(The 8th Continent)
By Ron Garan
NASA Astronaut
On May 10th, 1869, a golden spike joined two railways at Promontory Point, Utah, and the first transcontinental railroad was completed. On January 14th, 2004, a new vision for our Nation’s space exploration program was announced that committed the United States to a long-term human program to explore the solar system starting with a return to the moon. On February 1st 2010, those plans to return to the moon were put on hold. Although our Nation has decided to postpone a return to the moon it is still important to acknowledge the moon’s relevance to life on Earth.
There is no doubt that the railroad changed the world. It opened up frontiers to discovery, settlement, and commerce. The railroad was the backbone for the industrial revolution that provided the largest increase in life expectancy and improvement in quality of life in history. Just as the industrial revolution brought about unprecedented improvements in quality of life so can a new age of space exploration and development, but this time with a positive impact on the environment. To begin a period of sustainable space exploration, both the public and private sectors of our Nation must seize the opportunity and continue on a path to the moon. Artist impression of humans on the Moon. Credit: NASA
Since the Vision for Space Exploration was announced in 2004, there has been an on-going debate about the importance of taking the next step in space exploration, a return to the moon. The reasons for making this the next step include: fulfilling a compelling human need to explore; gaining a foothold on the moon to prepare for journeys to other worlds; easing the world’s energy problems; protecting the planet from disasters; creating moon-based commercial enterprises that will improve life on Earth, conducting scientific research; inspiring young people toward higher education, and utilizing space resources to help spread prosperity throughout the world.
We should not return to the moon for any one of these reasons, but for all of them and more. By first establishing the basic infrastructure for a transportation system between the Earth and the moon and a sustainable, semi-autonomous, permanent human settlement, we will open the door to significant benefits for all. Of course, any permanent lunar base must be economically and politically sustainable and therefore must provide tangible benefits and a return on investment. Ron Garan ready for an EVA in June 2008. Credit: NASA Exploration: Great nations accomplish extraordinary endeavors that help to maintain their leadership in the world. America’s history is built on a desire to open new frontiers and to seek new discoveries. NASA’s vision for space exploration acknowledges that, “Mankind is drawn to the heavens for the same reason we were once drawn into unknown lands and across the open sea. We choose to explore space because doing so improves our lives and lifts our national spirit.”
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Establishing a lunar infrastructure will challenge us to improve the reliability of space transportation and allow us to demonstrate exploration systems and concepts without leaving the relative safety of near-Earth space. Testing systems and concepts at a location that’s a three-day journey from Earth is a logical step before we make the leap of a six-month journey to Mars. Establishing a permanently occupied lunar base also will open the way to detailed study and use of lunar resources, which likely are significantly more economical than lifting all required exploration resources from the Earth’s surface.
Energy: Today, about 1.6 billion people on the Earth don’t have access to electricity. The World Bank estimates that 1.1 billion people live in extreme poverty which leads to 8 million premature deaths every year. In developed countries, higher quality of life is achieved only through a high rate of energy use. Increased energy supply is needed for economic and social development, improved quality of life, and to grow enough food to provide for the citizens of the developing world.
Unless something is done soon, the world will be faced with a crisis of enormous proportions. The United Nations estimates that world population will be approximately 9.1 billion by 2050 with virtually all growth in the 50 poorest countries. The choices that the global society makes to provide for future energy needs will have a profound effect on humanity and the environment.
The moon can supplement Earth-based renewable energy systems to meet future energy demand. Ample energy from the Sun reaches the moon and is not interrupted by weather, pollution or volcanic ash. Solar energy farms on the moon can “beam” limitless clean energy down to where it is needed on Earth or to satellites for relay to the Earth. There are also other potential sources of energy including platinum for fuel cells and an isotope called helium-3, which could be used in fusion reactors of the future.
Supplying energy from the moon will enable us to help provide the Earth’s energy needs without destroying our environment. Artists impression of an asteroid flying by Earth. Credit: NASA Protect the Planet from Disasters: There is a real risk to the Earth’s inhabitants from asteroid impacts and super-volcano eruptions. If a large object the size of Comet Shoemaker-Levy 9 that recently slammed into Jupiter were to hit the Earth, civilization could be destroyed. Much smaller asteroids could cause tremendous damage and loss of life. The moon is a superb location for early detection systems.
A super-volcano eruption is a geologic event of enormous explosive power to affect the global climate for years. Scientists estimate the last such eruption happened 74,000 years ago, and was 10,000 times more powerful than Mount St. Helens. Tremendous amounts of rock and ash were ejected into the air causing a six year long volcanic winter and a 1,000-year instant Ice Age, massive deforestation, disastrous famine, and near extinction of humankind. Scientists estimate that such a super-eruption will occur about once every 100,000 years.
The systems and technology that will be developed for life and work on the moon can be used to develop habitats and systems that could preserve Earth’s inhabitants in the event of a devastating eruption. These systems will also improve our ability to live in extreme environments and can be used to learn how to overcome limited resources and other environmental issues. Astronaut Ron Garan takes a moment to pose for a picture during training for his April 3-20 stay inside the Aquarius Underwater Laboratory off the coast of Key Largo, Florida. Credit: NASA Moon-Based Commercial Enterprises: When the early pioneers headed west and expanded our Nation, they did not carry everything with them that they would need for their journey. They “lived off the land” and we will also need to use those resources available to us along our journey, starting with the moon.
There are numerous moon-based commercial activities that could significantly offset the cost of a moon base. Just a few of these are lunar refueling or servicing stations for satellites, lunar mining and space tourism. These commercial activities would allow us to return national treasures from space and provide a significant return on our space investment.
Scientific research: The moon offers an incredible opportunity to further human understanding and discovery. Since the moon’s ancient surface is relatively undisturbed, study of its geology can help us better understand the geological history of Earth. Further, the moon’s vacuum environment can’t be duplicated on the Earth or in low-Earth orbit, and could lead to new materials, advanced alloys, medicines and innovative ways to deal with limited resources on Earth. Radio telescopes on the far side of the moon would be shielded from all radio signals (noise pollution) from Earth, allowing tremendous sensitivity increases and telescopes pointed at the Earth could identify and predict weather and climate changes.
If we return to the moon just for science and exploration then activities will be limited by the amount of money our nation is willing to devote. But, if we establish a sustainable, economically viable lunar base then our science and exploration will be limited only by our imagination.
Education: Our children are our best investment for the future, and our space program is a tremendous motivator. Our Nation has seen a steady decline in the number of students studying math and science. The space program can help turn this trend around. I can personally attest to the ability of the space program to encourage students based on the fact that I enrolled in math and science courses and began the pursuit of an engineering degree the day after the first space shuttle mission landed. The creation of a permanent lunar base will inspire millions of young people toward higher education and help maintain our Nation’s technological leadership. Astronaut Ron Garan, STS-124 mission specialist, participates in the mission's first EVA in June 2008. Credit: NASA Resources and Other Benefits: Since we live in a world of finite resources and the global population continues to grow, at some point the human race must utilize resources from space in order to survive. We are already constrained by our limited resources, and the decisions we make today will have a profound affect on the future of humanity.
Using resources and energy from space will enable continued growth and the spread of prosperity to the developing world without destroying our planet. Our minimal investment in space exploration (less than 1 percent of the U.S. budget) reaps tremendous intangible benefits in almost every aspect of society, from technology development to high-tech jobs. When we reach the point of sustainable space operations we will be able to transform the world from a place where nations quarrel over scarce resources to one where the basic needs of all people are met and we unite in the common adventure of exploration. The first step is a sustainable permanent human lunar settlement. Artist concept of the Orion capsule in orbit around the Moon. Credit: NASA
How should we go about this important undertaking? A good analogy to look at is the U.S. railroad system. The greatest obstacle for the first railroad developers was financial risk. Purchasing right of way, paying wages for large workforces and buying materials and equipment were prohibitively expensive. But the federal government stepped in, orchestrating massive land grants and other incentives. Once initial government investment was assured, enterprising developers invested enormous sums to bridge vast valleys and tunnel through enormous mountains.
Today we are faced with similar obstacles in the development and use of space for the benefit of humanity. Potential space developers face enormous up-front costs for high-risk, long-term returns on investment. To capitalize on the tremendous moon-based opportunities, our nation should establish the basic infrastructure for a transportation system between the Earth and the moon and a sustainable human settlement on the moon. Once this initial investment is made, commercial revenue-generating activities can be established. Just as our investment in the railroad, interstate road system, hydro-electric dams and other large federal projects have been paid back many times over by increased productivity and quality of life, so will our investment in lunar infrastructure.
We are poised on the doorstep of an incredible opportunity to benefit all of humanity. We have the technology and the ability to make this a reality — we need only the will to see it through. We need to choose a course toward the utilization of space to increase our available resources, global prosperity, quality of life, technological advancement, and environmental stewardship. Just as we look back and thank those before us for developing things most of us take for granted such as railroads and highways, the generations to come should be able to look back and thank us for committing to sustainable space exploration.
Lunar Landscape. Credit: LROC; Goddard Space Flight Center and U of AZ, 3-D modeling and rendering by Bernhard Braun.
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You may recall Bernhard Braun as the wizard from UnmannedSpaceflight.com who created the amazing 3-D images of the Mars avalanche. Now he’s created incredible planetary landscapes for a different world: the Moon. “Actually, this has been my very first attempt with lunar imagery after my previous work has almost been exclusively devoted to Mars,” Braun said. The special software he developed can create three dimensional images from one 2-dimensional picture, but he says the real stars are the spacecraft that gather the data, the Lunar Reconnaissance Orbiter and the Mars Reconnaissance Orbiter. “It is the unprecedented quality together with the unprecedented availability of the raw data that opens the door for everyone to explore new ideas and processing techniques,” Braun said.
See below for more stunning from-the-surface 3-D looks at the Moon – no special 3-D glasses needed!
Lunar Landscape. Credit: LROC; Goddard Spaceflight Center, U of AZ, 3-d rendering and modeling by Bernhard Braun.
I asked Braun if working with images from the Moon was different than working with Mars images. “Creating the single-image shading-derived DEMs from the Moon imagery is both easier and more difficult at the same time when compared to the same process applied to Mars images,” he said. “It’s easier because the lunar surface does not vary as much in its intrinsic albedo, i.e. the visible brightness variations are almost exclusively caused by variations in surface topography, especially at low illumination angles, which can be exploited by the reconstruction algorithm to derive high precision 3D geometry.”
But the work is more difficult because of the totally black shadows on the Moon due to lack of any atmosphere. “So on the Moon any shadows are virtually featureless areas where the 3-D reconstruction algorithm cannot infer anything about the structure of the invisible shadowed surface,” Braun said. “This is different on Mars, where the shadowed areas are usually lit indirectly by considerable amounts of ambient light scattered by dust particles suspended in the atmosphere. So the 3-D models of the Mars surface can be more complete, showing surface details even in shadowed areas.”
Lunar Landscape. Credit: LROC; Goddard Spaceflight Center, U of AZ, 3-d rendering and modeling by Bernhard Braun.
“All in all it’s a lot of fun to play around with both camera and sun positions until an interesting landscape shot is found,” Braun said. “I would like to add that much of the credit must really go to those true wizards at NASA/JPL for not only making and bringing to orbit these almost unearthly powerful cameras like LROC and HiRISE … but also for sharing the whole image catalog via the internet with everyone in the world!”
Braun said he hopes to tackle 3-D views of the Apollo landing sites — which we cannot wait to see!
Before the invention of the telescope in the early 1600’s, man just knew of the Moon — a round, mysterious astronomical object that people would gaze up to in the night sky. As time progressed however, astronomers discovered that the moon isn’t exactly unique to earthlings, and other planets had their own moons. So exactly what is a moon?
A moon is defined to be a celestial body that makes an orbit around a planet, including the eight major planets, dwarf planets, and minor planets. A moon may also be referred to as a natural satellite, although to differentiate it from other astronomical bodies orbiting another body, e.g. a planet orbiting a star, the term moon is used exclusively to make a reference to a planet’s natural satellite.
The first moons to be discovered outside of the Earth’s moon were the Galilean moons of Jupiter, named after astronomer and discoverer Galileo Galilei. The moons Io, Europa, Ganymede, and Callisto are Jupiter’s largest and only the first four to be revealed, as to date, the planet has 63 moons.
Other than the four Galilean moons, Saturn’s Titan and Neptune’s Triton are two other moons which are comparable in size to the Earth’s Moon. In fact, these seven moons are the largest natural satellites in the solar system, measuring more than 3,000 kilometers in diameter. Only the inner planets Mercury and Venus have no moons.
An interesting fact about some of the solar system’s largest moons that most people may not be aware of is that a few of them are geologically active. While we may not see the Moon spewing lava or displaying any evidence of tectonic activity, Jupiter’s Io and Europa, Saturn’s Titan and Enceladus, and Neptune’s Triton have been found to be volcanically active bodies.
If the moon count had a grand total of just one in the olden times, that number has ballooned to 336 as of July 2009, with 168 moons orbiting the six planets, while the rest are moons of dwarf planets, asteroids moons, and natural satellites of Trans-Neptunian objects.
As more and more discoveries are made however, astronomers may find it more difficult to put a really defining line on what can or what can’t be classified as a moon. For instance, can you consider a 10-inch rock that’s orbiting Jupiter a moon? If yes, then there could be thousands or even millions of moons out there. If not, then where do you draw the line? Obviously, even the size of an “official” moon is still up for debate, so other than the simple definition of it being a natural satellite of a planet, there really is no clear cut answer to the question, “What is a moon?”.
Here in Universe Today, we have a nice collection of articles that explain why the Moon landings could not have been faked. Here are some of them:
Moon Rocks – Discusses how the Moon rocks are one of the most tangible objects that prove the landings took place.
Moon Landing Hoax – An explanation that counters some of the points raised by skeptics
Apollo 11 Hoax – another point for point discussion by Jerry Coffey
TV – Alert: Mythbusters and the Moon Hoax Myth – a teaser for the Mythbusters episode featuring the so-called hoax. You’ll find the comments below that article equally interesting, by the way.
Here’s an article from NASA that debunks the hoax theory using the Moon rock arguments. Another article about Moon rocks from the same site.
Episodes about the moon from Astronomy Cast. Lend us your ears!
Annotated graphic of Lunokhod 2's travels from Phil Stooke's International Atlas of Lunar Exploration.
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The saga of the Soviet Union’s Lunokhod moon rovers keeps getting more interesting! If you missed the update on our article about finding the “missing” Russian landers and rovers among the newly released Lunar Reconnaissance Orbiter images, the Lunokhod 2 rover was not exactly where one researcher initially thought – so there’s now an updated image, which you can see at this link. But among all the research and poring over images that has been done since NASA released six month’s worth of LRO data to the public earlier this week, Emily Lakdawalla from the Planetary Society uncovered an interesting tidbit about the Lunokhods which she generously passed on to me. After a little research, I found out more about an “extracurricular activity” the two Lunokhod rovers were commanded to do along their traverses on the lunar surface. They each created “memorials” to women on the Moon.
Since the early 1900’s, International Women’s Day has been observed each year by several countries around the world on March 8. The day marks the economic, political and social achievements of women. Russia has been celebrating this holiday since 1913, and in the 1970’s the crews who “drove” the Lunokhod rovers decided to honor women by commanding the rovers to create figure 8’s in the lunar regolith — 8 as in March 8.
Lunokhod 1. Credit: Goddard Spaceflight Center
Lunokhod 1 landed on the Moon November 17, 1970 and roved the surface for nearly a year (322 days.) Lunokhod 2 landed on January 15, 1973 and operated four months.
Apparently both rovers made a figure 8 in the regolith, although the documentation is a little fuzzy. A Russian scientist recalls that Lunokhod 1 made the figure 8, and one of the newly released LRO images shows a faint figure 8 in the regolith (see image left), which could only have been made by Lunokhod 1, but there is better documentation for Lunokhod 2’s memorial.
“To the extent I know, that was Lunokhod 1 which the crew made an 8 by Lunokhod tracks to congratulate our women on March 8 1973,” said Alexander “Sasha” Basilevsky, a veteran Russian planetary scientist, who responded to my queries about the significance of the figures 8’s. “Even in that Soviet time March 8 practically lost its political significance and we men just congratulated our women with little gifts. We continue to do this even now when our political system is far from communistic. For us it is just Women’s Day.”
Also, after scanning through all of Lunokhod 1’s panoramic images, I found this possible image of the figure 8, but I have not yet confirmed this is it:
Possible figure 8 in a Lunokhod 1 panoramic image. Credit: Laboratory of Comparative Planetology. Click image to see all the panoramas from Lunokhod 1.
Dr. Phil Stooke from the University of Western Ontario compiled “The International Atlas of Lunar Exploration.” “In my atlas I show a feature like this at Lunokhod 2’s site,” he said in response to my questions. “I didn’t know about this one at Lunokhod 1, but apparently it’s there as well.”
Here’s what Stooke wrote about the Lunokhod 2’s figure 8:
“On 18 January Lunokhod 2 was driven to a point on the north rim of the 25 m crater where it photographed the landing stage and the hill Le Monnier Alpha in the distance to the southwest. Here it was turned in place to create a circular mark with its wheels, and then moved a few meters where it made a second circle. The resulting figure 8 marking was later described as a memorial to commemorate International Women’s Day, 8 March, which was a holiday in the Soviet Union and is in Russia today.”
Addendum: Stooke told me that after seeing the new images from LRO, he will likely have to re-do the map of Lunokhod’ 2’s travels (top image). “Lunokhod images were often printed mirror-imaged left to right, and it’s often hard to know which is which,” he said. “In this case that map was constructed using at least one image the wrong way round, so it has to be corrected.”
So, it is unclear whether the decision to create these two memorials was in any way political, or simply a kind gesture by the Soviet space agency, or a unique choice made by the rover drivers, or – as was suggested to me by a couple of people – a visual play on an anatomical feature unique to women.
But more importantly, the accomplishments of the Lunokhod rovers are amazing considering the era in which they operated. While the Soviet Union’s exploration of the Moon was not well publicized outside of Russia — and now is often downplayed when compared to the Apollo missions – the ground-breaking technological achievements should be lauded for the innovative sample return missions and rovers that to this day hold the distance record that any vehicle has traveled on another celestial body. Together, they roved further than even the long-lasting Mars Exploration Rovers.
Lunokhod 1 Rover in its final parking spot, as seen by LRO. Credit: NASA/GSFC/Arizona State University. Click for larger version
Lunokhod 1 traveled 10.5 km (6.5 miles) and returned more than 20,000 TV images and 206 high-resolution panoramas. In addition, it performed twenty-five soil analyses with its x-ray fluorescence spectrometer and used its penetrometer at 500 different locations.
Lunokhod 2 covered a whopping 37 km (23 miles) of terrain, including hilly upland areas and rilles. It sent back 86 panoramic images and over 80,000 TV pictures. Many mechanical tests of the surface, laser ranging measurements, and other experiments were completed during this time.
Many thanks to Emily Lakdawalla, Phil Stooke and Alexander Basilevsky for helping me learn more about this interesting piece of space exploration history!
In case you are wondering, International Womans Day is an official holiday in Angola, Azerbaijan, Belarus, Burkina Faso, Cambodia, Equatorial Guinea, Eritrea, Georgia, Guinea Bissau, Kazakhstan, Kyrgyzstan, Laos, Moldova, Mongolia, Nepal, Russia, Tajikistan, Turkmenistan, Uganda, Ukraine, Uzbekistan.
Representing what may be the first long term lunar environmental impact study, recent laser ranging data from the Apache Point Observatory in New Mexico suggests the Lunar Ranging Retro Reflectors (LRRRs) left on the Moon by Apollo missions 11, 14 and 15 are beginning to shows signs of age.
Apache Point Observatory’s Lunar Laser-ranging Operation (the acronym says it all) has been collecting ranging data from the LRRRs since 2006, using a 3.5 metre telescope and a 532 nm laser.
A typical APOLLO observing session involves shooting the laser at the largest of the LRRRs (Apollo 15’s) over a ‘run’ of four to eight minutes. Each shot sends about 1017 photons to the Moon, from which only one returned photon per shot may be detected. This is why the laser is shot thousands of times at a 20 Hz repetition rate during each run.
If the return signal from the Apollo 15 LRRR is good, the laser is then directed to fire at the Apollo 11 and 14 reflectors. The laser can even be directed to the Russian Lunokhod 2 reflector, landed on the Moon in 1973, although this reflector does not return a reliable signal if it is in sunlight, probably because heating affects the reflectors’ refractive index and distorts the return signal.
Lunokhod 2 (moon walker in Russian), an 840 kg rover that landed on the Moon on January 15, 1973 and undertook scientific investigations on the lunar surface until May 1973.
The Apollo LRRRs were designed to remain isothermal, even in direct sunlight, to avoid the problem apparently suffered by Lunokhod 2. But a review of current and historical data has revealed a noticeable decline in their performance at each Full Moon. Since the reflectors are directed straight at Earth, they experience the most direct sunlight at a Full Moon.
Recent Apache Point Observatory data has been compared to historical data collected by earlier observatories involved in lunar laser ranging. For the period 1973 to 1976, no Full Moon deficit was apparent in data records, but it began to emerge clearly in a 1979 to 1984 data set. The research team estimate that return signal efficiency at Full Moon has degraded by a factor of 15 over the approximately forty years since the Apollo reflectors were placed on the Moon.
While heating effects may play a part in the performance degradation of the LRRRs, lunar dust is suggested to be the more likely candidate, as this would be consistent with the very gradual performance degradation – and where the most substantial performance loss occurs right on Full Moon. These findings may require careful consideration when designing future optical devices that are intended to remain on the lunar surface for long periods.
On the bright side – all the reflectors, including Lunokhod 2’s, are still functioning on some level. Hopefully, decades before their slow and steady decline progresses to complete failure, even more efficient replacement devices will be landed on the lunar surface – perhaps carefully positioned by a gloved hand or otherwise by robotic means.
Artist impression of LCROSS approaching the Moon. Credit: NASA
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Almost five months ago, the LCROSS spacecraft had an abrupt end to its flight when it impacted a crater on the Moon’s south pole. But that was only the beginning of the work of principal investigator Tony Colaprete and the rest of the science teams, who have since been working non-stop to get their initial results out to the public. Look for a flood of ‘water on the Moon’ news to be announced at the Lunar and Planetary Science Conference this week.
“The data set from LCROSS is a lot more interesting that we thought it would be,” said Colaprete, speaking on a “My Moon” webcast, sponsored by the Lunar and Planetary Institute. “A big part of our time has been making sure the data is properly calibrated. That takes a lot of time and effort, but the other side of the equation is understanding all the stuff you don’t understand in the data, and there was a lot we didn’t initially understand.”
The LCROSS team will present six papers, 11 posters and several oral sessions at the LPSC.
While the results are still under embargo, Colaprete was able to discuss the basics of what the science teams have found. LCROSS impact site. Credit: NASA
One surprise for the teams was the low “flash” produced by the impact of the spacecraft. “We didn’t see a visible flash, even with sensitive instruments,” Colaprete said. “There was a delayed and muted flash and the impactor was essentially buried, with all the energy apparently deposited at a depth. So it is very likely that there were volatiles in the vicinity.”
The second surprise was the morphology of the impact plume. “We had reason to believe there would be high angle plume,” said Colaprete. “But we had a lower angle plume. We had a signal of a debris curtain in the spectrometers in LCROSS all the way down in the four minutes following the impact of the Centaur stage. That was corroborated with DIVINER measurements with LRO (a radiometer on the Lunar Reconnaissance Orbiter.) They were able to make some great observations of the ejecta cloud with DIVINER, and we had good signals with our instruments all the way down to impact.”
Most surprising, Colaprete said, was all the “stuff” that came up from the impact. “Everyone was really excited and surprised about all the stuff that we threw up with the impact.”
The LRO spacecraft was able to be tilted in orbit so the LAMP (Lyman-Alpha Mapping Project) instrument could observe impact plume. It observed a plume about 20 km tall, and observed a “footprint” of a plume up to 40 km above the Moon’s surface.
“They saw vapor cloud fill the ‘slit’ of the spectrometer’s observations at about 23 seconds after impact and it remained there through the entire flyby,” Colaprete said. “What that corresponds to is a hot vapor cloud of about 1000 degrees that was observed.” A closer view of the moon as the LCROSS spacecraft approaches impact. Credit: NASA
Two exciting species found in the cloud were molecular hydrogen and mercury. “What is fantastic about that, is that there was an article written a couple of decades ago, regarding the possibility of mercury and water at the poles, and they said don’t drink the water!”
Colaprete said observing molecular hydrogen is spectacular because normally it doesn’t stay stable even at 40 Kelvin. The teams are still speculating how it was trapped and what form it was in. They found about 150 kg of molecular hydrogen in the plume.
All the elements found in the plume must be coming from cometary and asteroidal sources, Colaprete said. They also found water ice, sulfur dioxide, methane, ammonia, methanol, carbon dioxide, sodium and potassium. “We haven’t identified everything yet, but what we’re seeing is similar to what you would see in an impact of a comet, like what happened with the Deep Impact probe, which is exciting and surprising. The mineralogy in the dust itself that we kicked up corresponds to what was seen by M Cubed instrument, and also what we see in chondrite asteroids.”
One of the most pleasing aspects of this scientific process, Colaprete said, was the different teams being able to verify what other teams were finding.
“The concentration of hydrogen we saw in the regolith was higher than expected,” Colaprete said. “We ran the numbers again, and we said, ‘Oh, we can’t wiggle out of this answer.’ Then the PI for the LEND (Lunar Exploration Neutron Detector on LRO, which can acquire high-resolution neutron datasets) instrument confirmed that their numbers were entirely consistent with what we got. It was surprising because it wasn’t what we expected. But that is why you make measurements.”
“This should be a fun year as we pull this all together, and get it released to the public so we can get a lot more neurons looking at this,” Colaprete said. “I think this will really change our understanding of the Moon and how we think about it.”
