Archive | June 2010

Let’s Talk Moon

People take the Moon for granted. It’s familiar. It’s always there. Since the 1950s small American and Russian spacecraft have been sent to orbit it, photograph it and crash into it. Some never made it and blew up on launch, others completely missed it and are now orbiting the Sun but some successfully orbited it or landed on it and took what were back in the day considered to be amazing images.


Luna 3 and the photos it took of the far side of the Moon in 1959 (wikipedia, nssdc.gsfc.nasa.gov)

The first photos taken from the lunar surface by Luna 9 in 1966 (nssdc.gsfc.nasa.gov)

Landing a spacecraft on the Moon represented a very significant achievement. It showed that it was possible to land things on the Moon, that the surface would support the weight of spacecraft and, therefore, astronauts who wouldn’t disappear into lunar quicksand. Apart from these fact finding missions people had looked through telescopes at the Moon, photographed it and sketched it for years before Neil Armstrong took one small step and actually stood on it. This and the following 5 manned missions provided a wealth of data and information which is still being studied today. So several scouting missions, 6 Apollo landing missions and nearly 400kg of lunar rock later what more could there possibly be left to learn? Plenty!

Just looking up at the Moon we can see the familiar dark and light patches so it’s easy for everyone to see that the Moon has two different kinds of terrain. Look through binoculars and we can make out some craters, bright crater rays and bumpy bits and the Moon starts looking a little more complicated. Through even a small telescope the Moon is transformed into a land of mountains, hills, deep shadowy craters some with mountains in the centre, craters within craters, dark areas and incredibly bright areas. Anyone who has done this might then wonder what the mountains and craters look like up close. Now we can find out.

Moon Zoo gives us a chance to get up close and personal with the Moon using bite sized images from the Lunar Reconnaissance Orbiter Camera. The resolution of these images is staggering. Not only can we see craters as small as 1 metre in diameter we can also see individual boulders and rocks. The media has picked up on the fact that it is now possible to identify bits of spacecraft and there are many pictures in magazines, newspapers and on the internet showing the crash sites of various American and Russian spacecraft. Most of the debris has already been found and identified but it’s fun to spot it in the Moon Zoo images too.

What is quite unexpected and sometimes takes your breath away is the sheer variety of the lunar landscape. This is where the Moon Zoo forum comes into its own. Some of the images posted on the forum are just stunning. There is everything from mountain ranges and rugged boulder strewn regions to smooth plains and picturesque valleys. We have found evidence of boulders sliding and bouncing down slopes, volcanic activity and, yes, we have found spacecraft. Every click is contributing to science. We are providing data for lunar scientists to find out more about the Moon, its geology, its past and to help pinpoint areas for future exploration.

Here are just some of our recent finds:

Ina – an unusual volcanic feature A lunar tadpole Boulders close up
. . .
Bouncing, sliding boulder tracks Apollo 17 Lunar Alpine Valley
. . .

So while you are clicking on Moon Zoo please consider contributing to the forum. That’s where you can discuss your finds, post your favourite images and learn more about the Moon. We have boards where you can post images and discuss them and we choose one each week to highlight in our Image of the Week feature. We even have a virtual cafe where you can chat and chill. Don’t let that image with a striking odd feature or the image you think one of the science team should really take a look at go unnoticed — the forum is the place to post it. That’s where the Moon Zoo science team go to look. That’s where you can learn about and discuss the science and that’s where discoveries of the strange and unusual are likely to be made. It’s a mixture of amateur clickers and lunar scientists all with one thing in common — a desire to learn more about the Moon. It’s informal, friendly, and there is no such thing as a silly question. Make one post or become a regular, it’s entirely up to you, but please come and join us — you’ll get a warm welcome!


Jules is the volunteer Moderator of the Moon Zoo Forum

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Why Explore the Moon?

Planetary scientist Ian Crawford presents the case for our return to the Moon.

After a long hiatus following the Apollo missions forty years ago, the scientific exploration of the Moon is undergoing something of a renaissance. In the last few years a flotilla of robotic spacecraft has been sent to orbit the Moon by the space agencies of China, Europe, India, Japan, and the United States. This international concentration of effort is unprecedented in the history of space exploration. In part it reflects a renewed scientific interest in the Moon in its own right, and in part the aspirations of new space-faring nations to demonstrate their growing technical capabilities.

The primary scientific importance of the Moon arises from the fact that it has an extremely ancient surface, mostly older than 3 billion (i.e. 3 thousand million) years, with some areas extending almost all the way back to the origin of the Moon 4.5 billion years ago. It therefore preserves a record of the early geological evolution of a terrestrial planet, which more geologically active bodies, such as Earth, Venus and Mars, have long lost. The ancient lunar surface also preserves a record of everything that has fallen on it throughout the history of the Solar System. This includes fragments of meteorites and comets, as well samples of the ancient solar wind and, possibly, samples of the Earth’s oldest crust, blasted into space by giant meteorite impacts on our planet and collected by the Moon. Taken together, this is potentially a very rich scientific record of Solar System history which, with the possible exception of the much less accessible surface of Mercury, is unlikely to be preserved anywhere else. And it lies only three days away with current spacecraft technology.

Harrison Schmitt

The first, and so far only, geologist to visit the Moon: Harrison Schmitt stands next to a large boulder in the Taurus-Littrow Valley, visited by Apollo 17 in December 1972.

The idea that samples of the Earth’s earliest crust might be preserved on the Moon is particularly intriguing. Although we have strong grounds for believing that the Earth, like the rest of the Solar System, is 4.5 billion years old, the oldest actual Earth rocks found to-date are only 3.5 to 3.8 billion years old. All older rocks have been destroyed or buried by Earth’s active geology and climate. The oldest Earth rocks already show tantalising evidence for life having been present on our planet by that early time, but as we don’t have access to any older rocks we cannot be sure exactly how or when life first appeared on our planet. However, as noted above, ancient Earth rocks, blasted into space by meteorite impacts, may be preserved on the Moon. Perversely, therefore, our natural satellite may preserve fragments of Earth’s earliest crust, along with a record of the origin and evolution of life on our planet, which the Earth itself has destroyed. Finding such samples could become a holy grail of future lunar exploration.

The airless surface of the Moon has other scientific advantages as well. It is a superb site for some types of astronomical observation. The lunar far-side, in particular, is probably the best site for radio astronomy anywhere in the inner Solar System, as it is permanently shielded from artificial radio transmissions from Earth, and also shielded from solar radio emissions during the 14-day lunar night. Optical astronomy may also benefit from the establishment of lunar observatories. As the Moon lacks any obscuring atmosphere, the lunar surface is a much better site for astronomical telescopes than the surface of the Earth.

Altair lunar lander

The proposed Altair lunar lander. Although NASA's plans to return people to the Moon in the near future are currently in a state of flux, significant scientific advantages would follow from a renewed period of human lunar exploration.

To fully exploit the scientific potential of the Moon, to access the geological record of early Solar System history it undoubtedly contains, and to establish astronomical observatories on its surface, will require us once again to land astronauts on the lunar surface – and this time to stay. This must be the next step in lunar exploration, hopefully in the context of a fully international exploration programme, and science will be a major beneficiary. The Apollo missions demonstrated that human beings are highly efficient as explorers of planetary surfaces, and it is difficult to see how we will ever learn all that the Moon has to teach us about the history of the Solar System, and of our own planet, until people are once again actively exploring its ancient battered surface. Looking to the longer term, the human exploration of the Moon will also help develop essential experience that will be required for the human exploration of other locations in the Solar System, not least the planet Mars which also has much to tell us about the evolution of the Solar System and our place within it.

By helping to identify scientifically interesting places on the Moon, which may be explored when people do eventually return its surface, Moon Zoo participants can make a significant contribution to these exciting future activities.


Ian Crawford is a planetary scientist in the Department of Earth and Planetary Sciences, Birkbeck College London, and a member of the Moon Zoo Science Team.

Lunar Meteorites – bits of the Moon found here on Earth

This post is a little off track from Moon Zoo images of the lunar surface, but I want to share some information about my particular favourite Moon related subject — lunar meteorites.

What are lunar meteorites?
Thousands of meteorites have been found all over the Earth — the vast majority are thought to have originated from the asteroid belt — but very rarely some are identified that come from bodies like Mars, the Moon, and large asteroids.

Lunar meteorites are chunks of the Moon that were blasted off its surface by meteorite impacts, that then flew through space from the Moon and were captured by Earth’s gravity. The rocks then fell through the Earth’s atmosphere — often losing some mass on the way — and then land here on Earth.

Allan Hills 81005 - the first lunar meteorite to be recognised. This rock was picked up in Antarctica in 1981. Credit: NASA

Allan Hills 81005 - the first lunar meteorite to be recognised. This rock was picked up in Antarctica in 1981. Credit: NASA

How many have been collected so far?
So far (as of 2010) Dr. Randy Korotev, a lunar meteorite researcher from Washington University in St. Louis, states that 136 individual lunar meteorite stones have been collected. As some fell through the atmosphere at the same time, these samples actually represent only 66 meteorites! It is likely that many many more lunar meteorites than this have fallen onto the Earth through time, but because of high weathering rates (wind, rain, organic disaggregation, etc.) they have most likely been weathered away and could no longer be identified as having a lunar origin. We are lucky to have the ones that we have!

How do we know they have come from the Moon (and are not just chunks of grey concrete!)?
Proof of lunar origin can be taken from several lines of evidence that often requires analysis in a laboratory.

  1. The presence of a glassy crust suggests that the sample is of meteoritic origin and has passed through the Earth’s atmosphere causing frictional melting of the surface.
  2. The rock does not have chondrules and therefore can be classified as an anchondrite.
  3. The rock is poor in metal and therefore is classified as stony.
  4. Typical bulk rock elemental ratios and mineral chemistries that are similar to those of the Apollo and Luna Moon samples.
  5. An oxygen isotope ratio corresponding that of the Earth-Moon trend.
  6. Typical mafic mineral Mn/Fe ratios are indicative of the volatile-poor nature of lunar samples that trend on a ‘lunar line’ distinct from terrestrial rocks and samples from Mars and asteroids.
North West Africa 4472 - a lunar meteorite collected in Africa in 2006.

North West Africa 4472 - a lunar meteorite collected in Africa in 2006. I have been studying this sample and you can find out more information about my study in this document. Image: K. Joy.

When did they land on Earth?
All lunar meteorites are thought to have been launched from the Moon in the last 20 million years. As there are believed to have been no large craters generated on the Moon during this period, it is assumed that all lunar meteorites are launched from craters only a few kilometres in diameter (all craters in the last 1 million years or so are thought to be <3.6 km in diameter). This implies that lunar meteorites have been ejected from relatively shallow depths, and so represent the upper layer of lunar crustal material.

What do they tell us about the Moon?
Manned (Apollo) and unmanned (Luna) missions to the Moon have returned about 382 kg of lunar rocks and soils. These were all collected from rather atypical regions on the lunar near-side, within and around the central lunar nearside, or from equatorial latitudes on the eastern limb. Therefore interpretations of the nature of the lunar crust and mantle have been made from a dataset from geographically restricted areas of the Moon. Lunar meteorites, in contrast, are derived from random sample sites on the surface, and thus provide a wealth of new information about the nature of the Moon, even though their precise provenance is as yet unknown.

Some cool lunar meteorite findings:

  • Lunar meteorite Kalahari 009 provides a sample of the oldest basalt (volcanic lava) found on the Moon — it is 4.35 billion years old.
  • Lunar meteorite NWA 032 is the youngest basalt (volcanic lava) found on the Moon — it is 2.9 billion years old.
  • Many lunar meteorites that are rich in a mineral called plagioclase are believed to have originated from the farside of the Moon. These important stones provide information about how the lunar crust formed.

Some good lunar meteorite resources you might like to check out: