Monday, December 17, 2012

Another strange 'cup' on Mars

A Curiosity close-up view of another 'cup' feature like those in my last blog post (contrast stretched to show color variations):
Lava bubble on Mars? Concretion with a soft center?
(original Mastcam image,  0122MR0765000000E2_DXXX.jpg)

The shallow slopes on some sides, and hollowness make me think that they are more lik bubbles, trapped while rising through molten rock. Are these flat outcrops consistent with lava flows? How come they aren't common on earth?

Perhaps the apparent spheroid, below another example of a 'cup', is one of these 'bubbles' that is intact:

JPL and Curiosity request: Please laser blast and and then attempt to pop this bubble with your arm.

Update, 12/18/12:
Chem cam is on the case. Here's a telescopic closeup of the shell-like top edge:
Dammit Jim, I'm a geologist not a doctor! (The Devil in the Dark) These could be Horta egg shells.
Set lasers to stun.

Wednesday, December 12, 2012

Strange 'cups' on Mars

Things are different on Mars: it's generally dry, with a thin breeze blowing dust across most landscapes for billions of years. Many rock formations are recognizable as volcanic or sedimentary formations. But some things big and small are hard to explain. NASA/JPL scientists are having a field day, but they won't say what they might be thinking for fear of being hyperbolic or just wrong. They won't even point out the things they find interesting. We'll have to wait for the papers, or more accurately the press reports after the papers have been published, long after the observations were made.

What is the ring in the photo (below) from the left and right navigation camera photos? It appears to be a thin walled cup-like mineral formation rooted in the rock below, partly filled with sand. I imagine it formed within the rock and is now in the process of eroding out, preserved because it is more resistant to slight sand-blasting over a long period of time.

(stereo pairs, cross-view)

And what formed the small trench to the left of the 'cup'? This surface is undisturbed by Curiosity. There are now hundreds of photos of nearby sufaces, but nothing like this. It looks like suface dust and pebbles are falling into the trench, so maybe there's some kind of sub-surface void between the rock on the left and right (which appear to be from different formations).

A third photo from a slightly different angle doesn't give any more hints.

And one more mystery; what is up with the rounded, pitted, partially buried cobble below the 'cup'? Rounded things are quite rare on Mars. In fact there seems to be more pyramidal rocks, with points straight up, than one would expect from randomly fractured rock, randomly splayed across the surface. In thousands of Curiosity images I don't remember seeing anything quite as spherical as this.

Here's a wider view, with these features at left, just below center:

Is the 'cup' unique? No. Here's another one (bottom-center), very similar in form, at a close by location:

Again, most of the rim has thin walls around most of the circumferance.

There appears to be another one in the mid-distance, left of center, in the same photos. Here's a cropped view, with the 'cup' near dead center.

The only other one I've found is not thin-walled and it's not clear if it is the same type of formation.

But like the others it appears to be embedded in similar type of layered rock, partly filled with sand.

There are many examples of thin structures that are unusual by earth standards. Presumably they would  be too brittle to survive other erosion processes on earth. 

Here's a telephoto close-up view (from the Chemcam) of the edge of a layered rock in this region:

In this case it looks as if the laminations are due to preferential splitting of the source along weaker planes (contrast stretched to show color variations). If it were on earth I would expect it to be the result of freeze-thaw weathering:

Here's a good example of laminations where harder layers are less eroded by sandblasting resulting in thin parallel sheets (contrast stretched to show color variations):

I might be wrong.

Friday, November 2, 2012

Programmers Anonymous notes, 1110

Robot news:

Human edges out robot car on race track (BBC)

The robot car in the race has been developed by researchers at the Centre for Automotive Research at Stanford University (Cars).
Called Shelley, the autonomous vehicle is fitted with sensors that work out its position on the road, feed back information about the grip of its tyres and help it plot the best route around the circuit.
Prof Chris Gerdes, head of the Cars Lab at Stanford, said Thunderhill was chosen because its 15 turns present the car's control systems with a wide variety of challenges. Some corners can be taken at high speed, some are chicanes, others are sharp and come at the end of long straights down which the car hit a top speed of 115mph (185kph).
"As we set up these systems in the future, it's important not to build autonomous vehicles that are merely a collection of systems designed for human support but to think a little bit more holistically about making them as good as the very best human drivers," said Prof Gerdes. "It's not so much the technology as the capability of the human that is our inspiration now."

3D printed custom exoskelteton
Two-year-old Emma wanted to play with blocks, but a condition called arthrogryposis meant she couldn't move her arms. So researchers at a Delaware hospital 3D printed a durable custom exoskeleton with the tiny, lightweight parts she needed. 

"The current methods we have for monitoring or interacting with living systems are limited," said Lieber. "We can use electrodes to measure activity in cells or tissue, but that damages them. With this technology, for the first time, we can work at the same scale as the unit of biological system without interrupting it. Ultimately, this is about merging tissue with electronics in a way that it becomes difficult to determine where the tissue ends and the electronics begin." 
The research addresses a concern that has long been associated with work on bioengineered tissue -- how to create systems capable of sensing chemical or electrical changes in the tissue after it has been grown and implanted. The system might also represent a solution to researchers' struggles in developing methods to directly stimulate engineered tissues and measure cellular reactions.

Robot learns to recognise itself in mirror

So far the robot has been programmed to recognise a reflection of its arm, but ultimately Mr Hart wants it to pass the "full mirror test".
The so-called mirror test was originally developed in 1970 and has become the classic test of self-awareness.
More usually performed on animals, the creature is given time to get used to the mirror and is then anesthetized and marked on the face with odourless, non-tactile dye.
The animal's reaction to their reflection is used as a gauge of their self-awareness, based on whether they inspect the mark on their own body, or react as if it does not appear on themselves.
Increasingly scientists have used similar tests to analyse self-awareness in robots but none have yet programmed a robot to fully recognise itself from appearance alone.To date, only a few non-human species pass these tests, including some primates, elephants and dolphins. Human babies are unable to pass the test until they are 18 months old.

I Made the Robot Do It (NY Times, by Thomas L. Friedman)

And therein lie the seeds of a potential revolution. Rethink’s goal is simple: that its cheap, easy-to-use, safe robot will be to industrial robots what the personal computer was to the mainframe computer, or the iPhone was to the traditional phone. That is, it will bring robots to the small business and even home and enable people to write apps for them the way they do with PCs and iPhones — to make your robot conduct an orchestra, clean the house or, most important, do multiple tasks for small manufacturers, who could not afford big traditional robots, thus speeding innovation and enabling more manufacturing in America.

Thursday, November 1, 2012


" Can't say your narrowmindedness and your comfort with censorship appeals to me

So you're a Human Computer-Interaction Student? Well, well. Let me tell you who I am. I designed a touchscreen interface paradigm that has been copied the world over and covers the globe. Millions of people use it. Just about every touchscreen interface in the world borrows freely and liberally from my work, none of which was patented and none of which requires royalties. And you don't think my mention of touchscreens in a discussion of user interfaces is noteworthy. You can surely understand my position if I think you have your head up your ass.
Every time I walk into a restaurant I see people using touchscreens and the software paradigm that I developed 20 years ago. Every time I go into the post office I see touchscreens. In supermarkets, I see people using touchscreens to cash out their own purchases. In many of the new cars I see people using touchscreens. On all the new consumer electronics gear I see touchscreens replacing buttons, knobs & dials. In the library, I see people checking out materials with touchscreens. The latest airplanes all have touchscreens. And you have the nerve to dismiss all of this? It's clear that you don't get out much. There are 4,000 stories in Google News today worldwide with the word touchscreen or touch-screen in them. I don't think you have any idea what the concept of User Interface means in 2005. And you think you're going to tell us all about user interfaces on the cell phones and the airplanes they're designing and building today without talking about touchscreens? Let us all know how that goes, won't you? It should be quite a laugh. GeneMosher"

The Wikipedia User Interface entry is pretty good too, something for everyone to disagree with.

For reference, I got 25,500 results for "touchscreen" on Google News today.

Wednesday, October 31, 2012

Mars surface pics

Most of the rock surfaces in Gale Crater are covered by dust, making many photos have very low contrast and with little variation in color. By stretching each color to near the full range available, small differences are emphasized. The bluish tones here are not near the true colors, but are blue only in comparison to other surfaces; because the dust is redish, blues and greens are stretched more.

Most of the variation appears to be due to differing thickness of dust on the surfaces.

These Curiosity photos are from the mast cameras.

Original imagetaken: 2012 SEP 29 09:12:44 EDT
river gravel?
Original imagetaken: 2012 SEP 29 09:13:36 EDT

Tuesday, October 23, 2012

Programmers Anonymous notes, 1101

Cellular automata are implemented as rules on a discrete grid. This seems to limits the range of possible behaviors, as the rules depend on a finite number of neighbors. SmoothLife is also implemented on a (rectangular) grid, but the rules approximate continuous functions on a large set of neighbors. Finding parameter sets that display interesting behavior is more difficult, but this example shows that motion of coherent structures (gliders) in any direction is possible. Source code. Paper describing the implementation.

Learnable Programming

A visual interface designer with a huge ego criticizes the way everyone else programs:
The goals of a programming system should be:
  • to support and encourage powerful ways of thinking
  • to enable programmers to see and understand the execution of their programs
A live-coding Processing environment addresses neither of these goals. JavaScript and Processing are poorly-designed languages that support weak ways of thinking, and ignore decades of learning about learning. And live coding, as a standalone feature, is worthless.
Alan Perlis wrote, "To understand a program, you must become both the machine and the program." This view is a mistake, and it is this widespread and virulent mistake that keeps programming a difficult and obscure art. A person is not a machine, and should not be forced to think like one.

Relatively Prime's Chinook podcast

Chinook is the greatest checkers player in the world, in fact it is impossible to beat. The product of an 18 year project in computer artificial intelligence, Chinook represents one of the greatest breakthroughs in computer game playing and was the first machine to ever hold a human world championship. (Relatively Prime, stories from the mathematical domain)

Chinook's story is a bittersweet and moving tale, a modern account of John Henry and the steam-drill, though this version is told from the point of view of the machine and its maker, Jonathan Schaeffer, a University of Alberta scientist who led the Chinook team. Schaeffer's quest begins with an obsessive drive to beat reigning checkers champ Marion Tinsley, but as the tale unfolds, Tinsley becomes more and more sympathetic, so that by the end, I was rooting for the human. (Cory Doctorow's description)

"...a time-ordered stream of documents that functions as a diary of your electronic life; every document you create and every document other people send you is stored in your lifestream. The tail of your stream contains documents from the past (starting with your electronic birth certificate). Moving away from the tail and toward the present, your stream contains more recent documents --- papers in progress or new electronic mail; other documents (pictures, correspondence, bills, movies, voice mail, software) are stored in between. Moving beyond the present and into the future, the stream contains documents you will need: reminders, calendar items, to-do lists."Eric Freeman, David Gelemter in Lifestreams Project Home Page
Lifestreams represent a source of information about people's intents that can be mined.[3] 

Numerical approximations of pi
The English amateur mathematician William Shanks, a man of independent means, spent over 20 years calculating pi to 707 decimal places. This was accomplished in 1873, although only the first 527 were correct. His routine was as follows: He would calculate new digits all morning; and then he would spend all afternoon checking his morning's work. This was the longest expansion of pi until the advent of the electronic digital computer three-quarters of a century later.

Stern–Brocot tree
In number theory, the Stern–Brocot tree is an infinite complete binary tree in which the vertices correspond precisely to the positive rational numbers, whose values are ordered from left to right as in a search tree.
The Stern–Brocot tree was discovered independently by Moritz Stern (1858) and Achille Brocot (1861). Stern was a German number theorist; Brocot was a French clockmaker who used the Stern–Brocot tree to design systems of gears with a gear ratio close to some desired value by finding a ratio of smooth numbers near that value.

Monday, October 22, 2012

Blue capped pillars on Mars

An extraordinary rock formation, photographed with a Curiosity mast camera a few days ago, recieved and released today.

[10/26/12: See update at bottom, from a JPL video that gives a better but incomplete description of what they know about this feature they call "Zephyr" or "Stonehenge".]

It appears to be a row of harder bluish rock blobs with the underlying substrate rock partially eroded away. Is it a ventrifact? Presumably most erosion is due to wind driven abrasion. These pillars are vertical and sandblasting would be expected to undercut harder material, but it's strange that the pillars survived. The bluish caps have a slightly specular surface, and look like they may be translucent with a distinct lower boundary and opaque supporting rock.

The three dark "holes" in the sand behind the pillars are remains after Curiosity laser blasting.

blue capped pillars
There doesn't appear to be any sort of continuation of the form, as you might see in an eroded dyke.

I'm guessing they are agate:
Most agates occur as nodules in volcanic rocks or ancient lavas where they represent cavities originally produced by the disengagement ofvolatiles in the molten mass which were then filled, wholly or partially, by siliceous matter deposited in regular layers upon the walls.
In the formation of an ordinary agate, it is probable that waters containing silica in solution—derived, perhaps, from the decomposition of some of the silicates in the lava itself—percolated through the rock and deposited a siliceous coating on the interior of the vapour-vesicles.  

Original image

JPL is on it. Here's a ChemCam photo. Notice that the three "holes" (and a fourth, less visible) in the sand behind the formation don't appear in this shot (see below for comparison after shot), but the shadows are in a similar position (a slightly higher sun angle). A close-up photo is needed, if only for the beauty and mystery.

Original imagetaken: 2012 OCT 17 20:45:59 EDT

Original imagetaken: 2012 OCT 17 21:03:22 EDT, 17 minutes and 22 seconds after the above image. There are also disturbances below the pillars, near the shadow line.

Drat, it missed!! More target practice required, autonomous mode. Don't these robot overlords practice with shoot-em-ups?

I count six misses, including a couple at the base of the pillars, and some pebbles scattered.

1/23/12 New photo that's more in focus showing that Curiosity had a direct hit, although it is close to the boundary between the blue cap rock and substrate.

Original imagetaken: 2012 OCT 23 00:37:01 EDT

Here's the comparison, coregisteed to the single "before" image.

No word yet from JPL on whether they saw a silica signal to be expected from an agate.

From 10/26/12 JPL podcast and YouTube video:

This feature is really only an inch long and we're shooting this from about 8 feet away, making the pointing very difficult.  So that's why we decided to do 9 points instead of just 2, just to make sure we would hit the material of interest. We ended up hitting both the dark and the light material and we found that there was indeed a compositional difference. 
1" scale bar

This feature is really only an inch long and we're shooting this from about 8 feet away, making the pointing very difficult.
JPL marking of laser hits
You can see that this isn't a good representation of where the laser actually hit: two or three of them are just wrong. It's irritating that JPL hasn't released data or results of the spectroscopy.

Saturday, October 20, 2012

Bit of trash on Mars, stereo pair

Stereo pair of a patch of pebbles, dust and a scrap of distressed pastic (about 13mm long), using Curiosity's Mars Hand Lens Imager (MAHLI). The camera was shifted by about 7mm between the views.

NASA speculates that the plastic was part of the delivery vehicle, presumeably shredded during landing and carried by Curiosity to this location about a half-kilometer from the landing site. But if they know what part it is from, they aren't saying.

(stereo pairs, cross-view)

The trash was unexpectedly spotted at bottom center of this photo of the first scoop of soil. It is more visible in the original full size image.

It was a good opportunity to get a high resolution shot of the pebbles covered, and interspersed with, dust.

The two images were taken about 5 minutes apart, with indirect sunlight.

Thursday, October 4, 2012

Closeups on Mars

Photography by Curiosity in Gale Crater:

One corner of a pyramidal rock named Jake Matijevic.
Original: 0044MR0204022000E1_DXXX
Nice wider view
Composition and other information

Sand ripple on patch of ground named Rocknest. I don't know the exact scale, but it looks to be about 30-60 cm wide. The small blobs of texture seem to be pebbles coated in dust.

After a scoop from near the ripple.

The ripple above extends into the foreground of this navigation camera photo, looking to the rim of Gale Crater.

Robot wheel impression across the ridge. The body of the ripple appears to be very fine grained, more like flour than sand.

Top of wheel print above, but with different sun angle (time of sol). Original.

Closeup of part of this wheel-print. Original. The straight horizontal bands are impressions of the wheel surface (see wheel image below).

And closer. Original.

Closer view at edge of imprint:
"The largest grains ... are about 0.04 to 0.08 inches (1 to 2 millimeters) in size. The bulk of the sand in the ripple is smaller, in the range below 0.002 to 0.008 inches (50 to 200 microns).

Wheels of Curiosity that made the impressions. Each is about 40 cm wide. Notice the fine linear texture of the left wheel in the highlight. This pattern is seen as horizontal bands in the dust (two images above, top).

Tuesday, August 28, 2012

Laser blasting request

JPL: Please instruct your robot to laser blast and spectro-analyze the rock face causing saturated luminance.

Is this due to an unusually high albedo? It might be just a flat face with high specular relflectance, but there is no other like it in any other field of view, so it seems statistically unlikely. Perhaps it is a boundary between radically different sediment layers, deposited as ejecta from some meterorite hit. An evaporite?

The shadowed side is consistent with the lightness extending through the body of the rock. And there appears to be a darker band between the top and bottom portions.

These exposures at different times of day (note the shadows) show that there is not a lot of specular reflection.


Just curious. Thanks in advance.

Thursday, August 23, 2012

Skycrane jet wash

When landing on Mars, the MSL skycrane held a fixed position while lowering Curiosity. There happened to be a lot of unconsolidated dust and pebbles, some of which got blown onto Curiosity.

The navigation cameras (Navcam) take beautiful 1000 x 1000 pixel stereo pairs. These views, with the shallow pits caused by the jet wash, are from sol 16 after Curiosity moved a short distance from its landing position.

Navcam A, stereo pair (cross-view)

Navcam A, stereo pair (cross-view)
Here's the plan view of these features, and Curiosity, from this vantage point:

"And then... Try to imagine all this sequence of landing and preparations as you were standing there and watching. Friggin metal spider with rocket engines lowers this car sized rover, flies away and crashes. This rover then sits there for couple sols without any movement. But from time to time it makes some tiny sounds, moves it's robotic arm, turns camera. And sits there again for hours. Zaps a tiny rock with laser. On one sol it starts moving. Moves couple meters here and there, turns around, goes silent again. It's like from some sci-fi book, except we actually are (let's get back to Earth) here and experience it. Not directly, but.. Hey, how cool is that every day we commute to work, hang out with friends and have new pictures coming to our pockets from another friggin planet hundreds of millions kilometres away. I think I need a drink now." Tadas Jelinek, comment on Boing Boing post.

Original pictures:

Navcam: Left and Right A (NAV_LEFT_A, NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 16 (2012-08-22 15:02:31 UTC):

Navcam: Left and Right A (NAV_LEFT_A, NAV_RIGHT_A) onboard NASA's Mars rover Curiosity on Sol 16 (2012-08-22 15:00:53 UTC):

A gallery of several of the first stereo pairs taken by the navigation cameras:

Wednesday, March 14, 2012

Half Tau Day

Half tau is not imaginary, but logarithms of negative numbers can be.

Secnarf got me interested in the function x^x, which is real valued for positive values of x, but wonderfully complex for negative x.
Functions that are powers of a variable are often more simple after taking a logarithm of the function, so I was curious what ln(x^x) might look like:
Sure enough, the imaginary part of this function is piecewise linear. What are the slopes of these segments? For that we just need the derivative with respect to x, d( ln( x^x) )/dy (function in blue, derivative in magenta):
The imaginary part of the derivative (bottom, magenta), shows that the slope is constant, a bit more than 3. In fact, the slope is exactly half tau.

Something similar happens (for the same reason) when we take the logarithm of both sides of Euler's identity:

ln( e^i*τ/2 ) = ln( -1 )

which can be used as defining the logarithm of a negative number. This reduces to:

i * τ/2 = ln( -1 )

So half tau is the magnitude of the imaginary part of the natural logarithm of -1:

τ/2 = ln( -1 )/i