Monthly Archives: October 2012

Mundane Explosions

Last week I had the opportunity to speak about “Spectacular Spectacles” at MCAD.  I chose to look at software failure as an example of  spectacle.  Software often fails spectacularly, which corresponds well with the theme, but there is also an interesting argument to be made about how software fails.  Software failures are often a result of the most mundane of mistakes.

Photo credit: Unknown

One such spectacular failure is the explosion of the Ariane 5 Rocket.

The rocket was part of a family of  rockets intended to carry a payload into orbit.

The specific payload that the Ariane 5 was supposed to launch was a three-ton satellite.

A $7 billion joint venture of the European Space Agency (ESA) and the Centre national d’études spatiales (CNES), the rocket took ten years to complete.  It was intended to give Europe an edge in the competitive, private space industry.

On its maiden voyage, the unmanned rocket exploded just forty five seconds after lift-off from French Guiana.

The cause of the failure was a software error in the Inertial Reference System.  Worse, the failure is a frequent mistake made in coding:

When programming languages store data, they store it as a particular type of data.  Integers, alphanumeric strings, and  Boolean variables are examples of data types.

Numbers can be stored in a variety of ways, but in the specific case of the Ariane 5 there was an error in the way a particular number was being stored.   The inertial guidance system used an integer type to store the  horizontal velocity.  This had worked perfectly well in the previous Ariane 4 rockets.  But, the Ariane 5 was faster than its predecessors.  *The horizontal velocity exceeded 32,767 – the largest number that should be stored as an integer.  Instead, the value should have been stored as a floating point value.  But, floating point values are less efficient than integers, and since the system was not mission critical, the integer value was overlooked.

 

This caused an error in the Inertial Reference System.  That error message was then interpreted by the on board computer as flight data, at which point it altered its course.  A part of the rocket (the launcher) began to disintegrate because of the steep angle of flight, and that disintegration triggered the self destruct mechanism.

 

This isn’t an esoteric error in computing: typed variables and the limitations of each type of variable is a first year programming topic at any university.  This is certainly not a dig either, the software for this rocket was sophisticated code that had developed over the course of a decade.  Moreover, even if the error had been noticed, this is the metaphorical equivalent of your house falling down around you because you accidentally slammed a door.  But it is remarkable, that such a mundane mistake can have such spectacular consequences.

And this leads us to the point of this post: software fails; it fails frequently and for easily understandable reasons.  The inability to verify that software works as intended has been one of the foremost research topics in computer science since the mid 1960s.  While there has been significant progress, it is still a challenge for the field.

For the public, it should be becoming a greater concern as modern, western society becomes more and more dependent upon computers and the software that drives them.

 

*More information on data types

References:

Lions, J.L. et. al. (1996) ARIANE 5 Flight 501 Failure: Report by the Inquiry Board, Paris

Gleick (1996, Dec. 1) A Bug and a Crash, Sometimes a Bug is more than a Nuisance, New York Times

The Public Trust: What Sesame Street, Honey Boo Boo and the Real Housewives have in common

 

The kerfuffle over Big Bird that came out of last Wednesday’s Presidential debate has been great fodder for the 24 hour news cycle and comedians, but it seems to be considered only in the context of the different policies of the two candidates.

In passing, I saw a post on Facebook about the history of TLC and how it changed after privatization.  And that prompted me to consider the underlying assumptions of this story.  When Romney spoke about this, his underlying assumption was that outside of the addition of commercials, programming would undergo minimal change if PBS was privatized.

“We’re not going to kill Big Bird. But Big Bird is going to have advertisements. Alright?”

The history of TLC really challenges that underlying assumption.  TLC was originally “The Learning Channel”.  That name was not a marketing tool – in 1972  the channel was launched as a joint venture of the federal Department of Health, Education and Welfare and NASA.   It was to be provided free using NASA satellites.  The channel was privatized in 1980.  In the period directly following its privatization, TLC continued to provide educational programming like Ready, Set, Learn and Paleoworld.  After having changed hands a number of times, TLC ended up housed in the Discovery Communications company. With increasing pressure on the channel for ratings share, their programming has devolved into sensationalist fodder for the popular culture mill.  Case in point – Honey Boo Boo.  But this isn’t a criticism of TLC – far be it for me to criticize anyone from watching sensationalistic, voyeuristic crap, I live on that type of programming.

But, we also need our broccoli.  And, in this analogy, PBS is the broccoli.  Public television is a national trust, one that we need to protect.  It provides reliable sources that inform our understanding of the world.  It helps to create an engaged, informed citizenry.  And, it uses a modern technological achievement to contribute to the education of children – particularly in lower income demographics who can’t afford to purchase cable packages that provide  dedicated child-centric networks.  In short, public television raises the bar of social discourse for a very reasonable price.

TLC is not the only example of how programming can decline in the face of the constant competition for ratings:  Bravo and A&E also gave up their highbrow focus in favor of less educational, more sensationalist programming.  And again, not a criticism of those choices – I will watch Andy Cohen and the Real Housewives of [any city large enough to house a camera crew]  every day of the week.  But, surely, the stories of these channels’ intellectual demise challenges the underlying assumption that privatization will not change the nature of PBS.

You can argue that we don’t need to subsidize educational programming.  I believe we do, but at least that could be a discussion rooted in reality.  What we can’t do is pretend that PBS will survive in its present incarnation if we decide to change its underlying principles.

For more information about the transformation of TLC see this great article at Modern Primate.
For details about the benefits of public broadcasting, see Brown, A. (1996). Economics, Public Service Broadcasting, and Social Values. Journal Of Media Economics, 9(1), 3

 

 

 

How did the Dinosaurs Die?

Image credit: Don Davis, NASA

Since we are celebrating the discovery of a new dinosaur, the Pegomastax africanus, I thought about the Alvarez (meteorite impact) theory of Dinosaur extinction.  This theory was hotly contested in the scientific community, but it has gone on to be almost universally accepted.  And it doesn’t just describe the demise of the dinosaurs – in fact, the Alvarez team argued that the giant meteorite wiped out half of all species of plants and animals, including the mighty dinosaurs.  Before the Alvarez team published the article in Science in 1980, scientists had given little serious consideration to the demise of the dinosaurs.

R. P. Walker, S.T. Smith, and S. M. Smith, USGS
The K-T boundary layer in Caravaca, Spain

The theory stemmed from the work of Walter Alvarez, a geologist, on the clay layer that separates the Cretaceous and Tertiary geologic eras, commonly referred to as the KT boundary.  This boundary is approximately sixty-five million years old and is defined by a distinct change in the earth’s flora and fauna: it marks the disappearance from the fossil record of about fifty percent of the Earth’s species at that time.   In the mid-1970s geologists had not dated the KT layer precisely, which led to confusion about the amount of time it represented.  Alvarez proposed to determine the rate of the clay’s deposition, in a bid to understand the Cretaceous extinctions.

He enlisted the help of his father, nuclear physicist and Nobel laureate, Luis Alvarez.  Luis and his associate Frank Asaro decided to measure the amount of Iridium in a clay sample from Gubbio, Italy—a location where the KT boundary was exposed.  Iridium is a metal found in trace quantities in Earth’s crust, deposited steadily and slowly as meteorite dust.  If no Iridium was found in the clay layer, the Alvarez team could assume that the layer had been deposited in a relatively short amount of time-less than one thousand years.  A trace amount of Iridium (approximately 0.03 parts per billion) suggests that the clay layer had been deposited over a longer period of time—more than one thousand years.  The test results took the Alvarez team by surprise.  The sample yielded three parts per billion of Iridium.   It seemed incredible that such a thin layer could correspond to a period of one hundred thousand years!

After waiting nine months for the results of the Iridium test, the Alvarez team was finally able to go to work.  Asaro tested layers above and below the KT boundary to make sure that the high Iridium content was unique to the KT layer.  Walter Alvarez looked for other locations where the KT layer was exposed to make sure that the high Iridium content was not an anomaly local to Gubbio.  In time, they determined that high levels of Iridium were unique to the KT layer and not confined to the Gubbio sample.

What did the Alvarez team make of these results?  While they could have adopted several alternative explanations, they concluded that some extra-terrestrial event had produced the Iridium spike and that this event was also the cause of the mass extinction seen in the fossil record.  They put these conclusions in the form of a provocative question—

What extra-terrestrial even could have caused the sudden extinction of half the genera on earth, while depositing the tell-tale Iridium anomaly?

By 1979, the Alvarez team had definitively settled on the impact of a meteorite the size of Mount Everest.
With this answer in hand the Alvarez group focused on how a meteorite could have caused the mass extinction—what became known as the killing mechanism.  The first mechanism they proposed, inspired by the 1883 eruption of Krakatoa, was that the impact had launched a giant dust cloud into the upper atmosphere.  This dust would choke of sunlight, end photosynthesis, and create a deadly rift in the food chain.

However, this was quickly discounted because some of the affected species lived in dark artic regions.   Instead, impact supporters proposed global wildfires and an ‘impact winter’ (similar to nuclear winter), with accompanying acid rain, which would disrupt the food chain causing the mass extinction.   This killing mechanism was accepted because it explained the selectivity seen in the K2 extinction event.  While there is still debate, there is by now a broad, if by no means complete, consensus that a meteorite impact is the likely cause of the mass extinction at the KT boundary.

For more information about the demise of the dinosaurs, check out Alvarez’s book.  In it, he details the many anomalies that supported the theory – including the shocked quartz found at the boundary.  Walter Alvarez, 1997. T. rex and the crater of doom. Princeton University Press, Princeton, N.J

Tiny, beaked dinosaur fossil found in South Africa

Pegomastax africanus
Illustration by Todd Marshall

Earlier this month Paul Sereno and the University of Chicago announced that a new fossilized dinosaur, the Pegomastax africanus (a tiny, beaked dinosaur) had been discovered in a slab of rock found in South Africa.
Paul Sereno believes the Pegomastax would have looked like a cross between a chicken and a porcupine.

Recreation of the Pegomastax
Image Credit: Tyler Keiller

The quills are inferred from an earlier discovery in China of the Tianyulong dinosaur.  The Tianyulong was found buried in lake sediment and covered in volcanic ash.  This burial preserved the appearance of quills spread across the diminutive dinosaurs’ body.  Sereno’s Pegomastax has similar quills, which, when combined with the beak-like mouth and sharp, stabbing canines, produces a formidable looking dinosaur.  However, unlike the mighty T-rex, the Pegomastax is thought to have been about two feet tall.

The rock slab was found in the 1960s by the famous paleontologist Alfred Crompton.  Crompton identified the first of these miniature dinosaurs – the heterdontosaurus.  Yet, the creature in the slab remained undiscovered, first sitting in the Harvard Museum of Natural History and then later when it was returned to South Africa.

Sereno, a professor at the University of Chicago (and currently, an explorer in residence for National Geographic) published the discovery in the peer reviewed, online journal ZooKeys on October 3, 2012.

This dramatic video by paleontological reconstructionist, Tyler Keiller, illustrates how paleontologists recreated the appearance of the the Pegomastax.

For more information on the Pegomastax see the University of Chicago Newsletter or the original article in ZooKeys.

Geeks and Gadgets at Gaylaxicon!

 

I’m speaking this evening at Gaylaxicon about Geeks and Gadgets, so I did some homework to get in the mood.  Here is my line up of the top (or at least randomly discovered) 17 things* all good geeks should know exist:

1.  The Hi-Call Gloves: awesome gloves that let you talk to your hand!

2.  The Fancy app – like Pinterest, but it lets you actually buy stuff!

3.  Simpl: I haven’t used this, but it promises me I can design websites from my tablet – why you need a website so quickly that you can’t use a real computer, I have no idea – but here we are.

4.  Shoes with GPS! I need these.  I am always lost.

5.   PDF Pro – write your notes right on the pdf

6.  Google Goggles: take a photograph of something and let it guide your search! 

7.    This is a Transparent Glass Toaster.

8.  Also the toaster that prints the weather on your toast:

9.   Cool new mind mapping software from Exobrain

10.  You know you wish you could use the Facebook in your shower!

11.  Haiku Deck – okay, so again – really?! You are so busy you need to create your presentation on the bus – but yeah, maybe you are.  Or maybe you forgot about it all weekend and now you’re up the proverbial creek.  Either way, this app looks pretty cool.

 

12.  Glow in the dark fingernails?  Hell yeah.

13.  I have handy man envy and often wish I was better at building stuff.  Well, at least now I can safely hammer a nail.

 

 

14.   Prismatic:  Sticks all your social media stuff in one spot. 

15.  Project Glass – We know this one – Google’s making glasses that overlays virtual information on your vision.

16.  Wanna watch tv on your wall?

17. And…drum roll please…this is the most awesome thing I’ve ever seen.  Turn your smart phone into a robot.  ZOMG, I want this.

*Yes, 17.  Because it is an awesome number not seen often enough in our popular culture.

Curiosity gets a taste of Martian Soil

Have you been following the new Mars rover, Curiosity, as it explores our nearest planetary neighbor?  Well then, you won’t want to miss out on the rover’s first use of its complex, on-board, chemistry lab!


Rover Gets Set to Scoop, Credit: NASA/JPL-Caltech

The lab is central to Curiosity’s mission, because the mobile lab will allow NASA scientists to figure out if this region of Mars could have ever sustained life.  There are a lot of different environmental conditions that have to be present for a planet to have life – even tiny, microscopic life.  According to NASA the fundamental requirements for life as we know it are liquid (not frozen) water, organic compounds and an energy source for metabolism (all the chemical reactions that organisms go through).  So, Mars would have needed to be a lot warmer to sustain life.   And, its current atmosphere is too thin for liquid water to exist on the surface of the planet.  But, there is evidence that there once was running water on Mars.

Tools at Curiosity’s ‘Fingertips’
Image credit: NASA/JPL-Caltech

And so, Curiosity is going to use its robotic arm to scoop up a little bit of Martian sand and dust and then test it to find out its chemical composition.  Curiosity performs these experiments with three instruments – collectively called the Sample Analysis at Mars instrument suite, better known as SAM.

Sample Analysis at Mars Instrument
Image Credit: NASA

NASA describes these three instruments: a mass spectrometer, gas chromatograph, and a laser spectrometer.  The mass spectrometer separates elements and compounds using their mass.  This helps scientists identify them.  The gas chromatograph heats soil and rock samples until they vaporize.  It then separates these gases into their components for analysis. The laser spectrometer measures the different isotopes of  carbon, hydrogen, and oxygen in atmospheric gases. Understanding the ratios of these elements is crucial to the mission because they indicate whether Mars could have supported life.

This image from NASA’s Curiosity rover shows the open inlet where powered rock and soil samples will be funneled down for analysis.
Photo Credit: NASA

Curiosity is also going to look at the minerals in the soil using an instrument called the CheMin.  The CheMin is an X-ray Diffraction (XRD) instrument that also has X-ray Fluorescence (XRF) capabilities. That data will be sent back to Earth and NASA scientists will analyze it. Because minerals indicate the environmental conditions that existed when they formed, scientists will be able to see if water was involved when the minerals were formed, deposited or altered.

View of Rocknest
Credit: NASA/JPL-Caltech/MSSS

Right now, Curiosity is just in the testing phase – NASA scientists wanted to test the rover’s arm at a sand dune that Curiosity is currently exploring, called Rocknest.  The entire analysis will take two to three weeks, before Curiosity begins its 325 foot journey to its next stop: Glenelg Intrigue.  This location is unique because it is where three types of Martian terrain meet.

Eventually, Curiosity is heading to Mount Sharp to test the clay at its base.  That clay might hold clues to Mars’ past.