Notched Cavities or INA-like?
User placidstorm posted some Ina-like formations in the Dark Halo Craters thread in December 2011.
I think these look more like “notched cavities” than INA-like formations – see end of posting for references to these features.
These cavities appear to be associated with lava which covers a lava tube or rille, part of which later collapses leaving depressions. I don’t know if that’s what has happened here but this whole region is full of interesting features.
The LPOD Lunar Photo of the Day for 10 August 2007 mentions this area:
A feature, previously unknown to me, is the degraded linear rille segment that extends westward from between Arago Beta and Manners. A similar short but more subtle rille is nearly perpendicular to the Sosigenes Rilles between Beta and Sosigenes A. These two rilles must relate to structures that are now covered by the Tranquillitatis lavas – perhaps whatever is under Lamont. Linear collapse troughs just north of Sosigenes A is evidence for a buried lava tube, another feature from the past of this mare area.
An overview of the features that placidstorm found. This area is in Mare Tranquillitatis north of Sosigenes A crater at approximate coordinates, latitude = 8.1 longitude = 19.0.
Left image: M177508146LE Right image: M177508146RE
Closeup of one of the “bays”.
The image below gives some context to this feature – the area inside the orange oval is the approximate site of the images above. It shows that there is a rille running underneath the feature and this could help explain how the “notched cavities” were formed. The “feature” crossing the rille is a secondary crater chain.
The Lunar Networks article referenced below the image is well worth a read but does contain a mistake where it refers to “linear rille system in the northeast Mare Tranquillitatis” it should say “southwest”.
Full two kilometer width segment of LROC NAC frame M146858595LE as shown on Lunar Networks 16 Sep 2011
[NASA/GSFC/Arizona State University]
More information about INA features will be found here: TLP Project – INA-like Features and here: INA Images
“Notched Cavities” are discussed here: TLP Project – Notched Cavities in Lava
Strange Whites
Forum member Ewan, otherwise known as Dynamo Duck, found some strange looking craters on the South-East edge of Mare Crisium at Latitude: 12.275° Longitude: 62.1034°. They appear to have unusually high albedo floors and possibly some ejecta of the same high albedo material.
Searching around the area I found some more of these “strange whites.”
Here are two. |
And closer… |
And then they were everywhere.
At the moment they remain a puzzle. They look like bench/concentric craters but why are the floors so “white”? What is this high albedo material and why are there so many of these craters in this region of Mare Crisium?
While we work out the answers here are some NACs for you to peruse showing the “strange whites” under different illumination.
M137136039RE
M119449091RE
M144212439LE
Hadley Rille
Continuing the rille theme from last week, Hadley Rille has been a bit of a forum feature this week. Forum regular kodemunkey sent me a interesting couple of NAC (Narrow Angle Camera) images he had come across while exploring a “wandering rille”. Here they are:
M104504818LE |
.. | M144612571RE |
He thought he might have spotted a volcanic vent but wasn’t sure. This turned out to be the start of the Hadley Rille-Apennine region shown here on the ACT-REACT Quick Map.
We can now check the topography of any feature we see using the new ACT-REACT line tool to produce a map of surface elevation. The “vent-like” trench kodemunkey spotted on the NAC images is Běla, an elongated crater thought to be either a collapsed magma chamber or a volcanic vent. Hadley Rille itself is thought to be a either a volcanic vent or a collapsed lava tube. There is more about the volcanic nature of the region in this LROC article Layers near Apollo 15 landing site. Using the ACT-REACT tool produced the following plot of Běla revealing a vent or tube -like “V” shaped dip in the terrain:
Newcomer to the forum Dynamo Duck asked if we could view the tracks around Hadley Rille from the Apollo 15 mission. Here is the location of the Apollo 15 landing site and a map of the various routes and tracks. Click on the images to enlarge.
From LROC article “Follow the Tracks” |
From ACT-REACT |
The latest batch of NACs taken from a lower orbit, 25-30 kilometres above the surface, show these tracks – but you need a keen eye. Here’s what you are looking for:
NASA/GSFC/Arizona State University
The new NACS are now available to examine! Enjoy.
Jules is a volunteer moderator on the Moon Zoo forum
Schiller Crater
The Image of the Week for 20th February 2012 featured exploding boulders, discovered by Dr Anthony Cook, in Schiller crater which is located in the southwestern region of the Moon, south of Oceanus Procellarum at coordinates 51.8 S / 40.0 W. This crater is interesting in its own right apart from the exploding boulders!
Schiller crater is one of the most uniquely shaped craters on the Moon and its formation is still a bit of a mystery. It is elongated as if it had been stretched lengthwise at some point but was probably created by a grazing (oblique) impact or is a secondary impact crater. At least one article claims that it was created by a multiple impact, i.e. the impacting object broke up just before hitting the Moon (see Formation of Irregular Craters on the Moon below).
The crater is approximately 180 km in length and 70 km wide.
The image below is an LROC WAC Global 100 meter mosaic draped over the laser altimetry (LOLA) digital elevation model as seen from an imaginary point 65 kilometers over the elongated crater’s southeast.
Credit: NASA/GFSC/Arizona State University
Useful Links
An interesting article about boulders and boulder tracks around the central peak complex of Schiller crater. Some worthwhile images in the article.
LROC: A Recent Journey
Geologic Studies of the Schiller-Schickard Region of the Moon – PDF
Formation of Irregular Craters on the Moon – PDF
Exploding Boulders!
We are used to seeing boulder tracks on Moon Zoo and often come across (or actively go hunting for!) the boulder that caused them. Usually we find something like these large intact boulders having come to rest at the end of their tracks.
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highlighted by placidstorm and kodemunkey
Moon Zoo team member Dr Anthony Cook recently sent me this picture of two boulder tracks in Schiller crater:
In this case the boulders are far from intact and appear to have “exploded” at the end of their journeys. What might have caused these boulders to fracture and fragment? One theory Tony suggested was that due to being under tension the boulders might have fractured before they rolled down the slope and that the movement further weakened them. Then over time the extreme temperature variations between lunar day and night could have fragmented the weakened rocks resulting in the appearance we see in the image.
Tony said:
I’m a bit puzzled though why the one on the top left has rock debris so far away from the centre. The boulder that looks like a skull rock on the bottom right has debris a lot closer to it, that could simply be explained by bits falling off as one would expect from the explanation above.
An alternative theory is that the boulders did roll down the hill intact, but were of sufficient size, area and age to be impacted by later meteorites, and these high velocity impacts split the rocks into many pieces. However, as Tony points out, the chances of this happening to two large rocks next to each other seem a bit remote.
Here is the NAC image M109502471L and the LROC article “A Recent Journey.”
In order to study this process in more detail we need more examples. So if you find any exploded (or partly exploded) boulders please post them on the forum here.
A new void in the melt?
One of the many types of features we are looking out for on Moon Zoo are the Lava tube skylights – ceiling collapses in lava tubes in regions which have been subjected to lunar volcanism.
Marius Hills Lava Tube Sky Light –65 metres wide |
~ | Mare Ingenii Tube Sky Light –130 metres wide |
These pits or caves would provide ready made shelters for any future manned missions. There’s more information in these LROC news articles: Marius Hills Pit – Lava Tube Skylight? and How Common are Mare Pit Craters?.
Forum member JFincannon started discovering similar looking features in non-volcanic regions and called them “collapsed voids.” These appear to be holes in impact melt possibly as a result of the melt cooling rapidly and cracking. However the regular round morphology of these “voids” still has us puzzled. There are more details in JFincannon’s blog post Potential Caves and Sink Holes in Copernicus Crater
Here are some of his Copernicus finds:
M102293451LC |
M111728277RC |
M119985215LC |
There was much discussion on the forum about how these voids might have formed but their origins are still unresolved. However, they are clearly not craters. They do not display typical crater morphology, having flat, boulder-filled bottoms and very distinctive sharp “rims” without the familiar crater walls and without any ejecta.
Impact melt can crack in spectacular ways as this LROC article featuring Giordano Bruno shows: Fragmented Impact Melt. JFincannon referred to another source describing collapsed features in melt ponds: Lunar Caves in Mare deposits imaged by the LROC Narrow Angle Cameras which stated that:
“Collapse features over probable lava tubes within mare (skylights) may provide points of ingress to larger “trunk” cave passages. Collapse features over areas of melt pond drainage suggest additional sublunarean voids. Both types of cave offer intriguing exploration and habitation opportunities.”
We thought JFincannon’s latest potential impact melt void was similarly intriguing and worth highlighting. It is much smaller than previous examples at around 24m diameter and is situated at latitude 72.468 : longitude -31.393 in Philolaus Crater. As JFincannon points out, this far north the Sun never gets higher than 18 degrees above the horizon. This means the bottom of any pits are unlikely to be illuminated making visual confirmation impossible. It also makes spotting them at all very challenging as shadows at this latitude are very long and black. However, this latest candidate does bear all the hallmarks of a potential void which JFincannon describes as:
“… a sharply dark area surrounded by a lighter, grayer one. In these images, the crater-like feature has a steep enough inner slope to brighten this Sun facing side, while the darkness does not seem to be due to a hill or raised crater rim. Also, other craters around it seem shallower. So it could be a deep small crater or a pit.”
Here it is:
M109452586RC
Other views can be found in M168399883RC and M170754606LC”
Time for a Moon Base?
“to develop and protect potential United States interests on the moon; to develop techniques in moon-based surveillance of the earth and space, in communications relay, and in operations on the surface of the moon; to serve as a base for exploration of the moon, for further exploration into space and for military operations on the moon if required; and to support scientific investigations on the moon.”
In this wide view an arrow marks the proposed site.
In terms of lunar exploration it would have made a great site with opportunities to sample the rays of Copernicus Crater and explore Eratosthenes Crater and the pyroclastic deposits of Rima Bode yielding valuable dating and geologic information. More details can be found on the the LROC News system site where these pictures are taken from and which featured the proposed lunar base last year. Thanks to forum regular kodemunkey for providing that link.
The “Project Horizon” document is lengthy and makes fascinating reading. It’s easy to forget that it was written half a century ago and 2 years before Yuri Gagarin made his historic spaceflight. But the plan never progressed beyond this feasibility study and lunar bases have remained the stuff of science fiction. Will this new attempt to revive the idea meet the same fate?
Here’s the NAC of the Sinus Aestuum region: M129350565L
New Moon Zoo Scientist Position Available
Moon Zoo Science Position Advertised
Dear all
Since it’s launch, Moon Zoo has been an enormous success, with 76,960 people contributing more than 2,858,389 classifications of craters (as of last night!). What we haven’t done, yet, is turn those clicks into results which we can share with the rest of the scientific community. As I noted on my blog from the recent American Astronomical Society conference, that’s the real test of any citizen science project.
An early look at the data looks extremely promising, and I’m pleased to say we’ve just taken two major steps towards that goal. Firstly, thanks to the sterling efforts of Ian Crawford at UCL we’ve obtained funding from The Leverhulme Trust for a three-year postdoctoral position working exclusively on Moon Zoo science. This sort of effort is exactly what we need, and we’ve already got a job ad. out looking for the right person. Having someone working on Moon Zoo full time will also help us investigate some of the weird and wonderful terrains and images uncovered by the Moon Zoo forum.
Secondly, the first paper from Moon Zoo’s sister site, the Milky Way Project, is nearly accepted. As the Milky Way Project uses a modified version of the Moon Zoo interface, the techniques we used there to combine classifications should be easily adapted to the larger Moon Zoo dataset. For example, we have to account for inevitable problems caused by adopting a particular tool – for example, the tendency of classifiers to repeatedly mark craters at the smallest allowed size – but we can do this through careful database manipulation.
We’re tentatively targeting having early results to share by April, and we’ll keep you informed by the blog.
Chris
P.S. Pamela Gay and Stuart Robbins, who had been working with us on Moon Zoo have decided to launch their own, competing, project. Pamela in particular has put a lot of time into the Zooniverse over the last few years, and we’re grateful for her help. Competition in science is usually a good thing, and I hope we’ll see papers from both groups before too long.
Light and Dark
We are used to seeing different kinds of craters on the Moon Zoo forum. In particular we collect dark haloed craters and fresh white craters. Impacts can excavate rocks and material beneath the lunar regolith and this “fresher” material forming the ejecta blanket sometimes looks a very different colour to the rest of the surrounding area due to its higher or lower albedo.
Forum member kodemunkey recently found a couple of impacts which at first glance were hard to classify – you could say they were impacts of two halves. Are they fresh whites or dark haloed? Or is it just a trick of light and shadow? I think that’s exactly what we are seeing in the first crater. The combination of a high Sun, uneven terrain and a deep impact has produced an image of a crater half in shadow. The second crater is slightly more difficult to call. Both make striking images. Why not have a closer look and see what you think.
They are located near to lat: 5.12 Lon: 351.6 in the Schroter / Sinus Medii region.
Here’s the NAC image for a close up view.
Neighbouring regions show more of the two-toned Moonscape:
New Look for Moon Zoo
Moon Zoo launched more than 18 months ago and we’ve been meaning to make some changes to the site. Later today our refreshed site will go live! You’ll notice that we’ve had the decorators in – the website looks a little different and a new tutorial (see below). On the back end, we’ve added new images and retired some old ones.
Tutorial
We have created a new interactive tutorial for Moon Zoo. This tutorial guides you through the basic interface of Moon Zoo and teaches you how to avoid some of the common pitfalls that we’ve seen since the project began. Even if you’ve classified on Moon Zoo before you might need to take the tutorial just once to get back on track – you should find it’s no problem. The tutorial has lists of known craters against which your markings are compared. If you’re too far off the mark with your crater drawing, we’ll ask you to try again. There’s nothing to worry about, just our way of ensuring maximum results from the site by bringing everybody up to speed.
Images
We are retiring the Moon images we used at launch in 2010. But we have some great, new ones that allow us to study secondary craters and volcanic regions of the Moon. These will help us study interesting features and crater types, building on the work that has already been done by Moon Zoo volunteers.
So Moon Zoo: Phase 2 has begun – and will go live today – take a look!
