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Forty Years Ago: Apollo 13

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The number 13 had a bad reputation long before 1970, but it only got worse on April 13 of that year. Just eight months earlier, Neil Armstrong set foot on the moon. Apollo 12 had a successful mission to the moon in November. But Apollo 13 had that number. Lift off two days earlier was at 1:13 PM, or 13:13 in military time. Apollo 13 commander Jim Lovell noticed the coincidence of the time, but he is not a superstitious man. Besides, lift-off was on April 11th. He, Jack Swigert, and Fred Haise were on their way to the moon to explore the Fra Mauro highlands and bring back moon samples.

On the 13th, two days into the flight, there was a loud bang. Lovell and Swigert looked at Haise, who had startled the crew members before by actuating a lunar module relief valve. But this was no prank. A liquid oxygen tank had exploded, which blew out the side of the service module. Power went down. Oxygen leaked out.

Swigert and Lovell radioed Mission Control with those understated words, "Houston, we've had a problem." The crew at Mission Control who had complained of boredom over the previous two days would never do so again. The original mission was aborted; the new mission was to get the three crewmen back to earth alive. Flight director Gene Kranz and his team hunkered down to figure out how to stretch the spaceship's available resources.

To conserve energy, all but essential systems were shut down. The astronauts moved into the lunar module, which had enough resources for two days for two men. Now, those resources would have to last four days for three men. There was backup oxygen on board, but power and water had to be conserved. And carbon dioxide buildup would be a problem.

Mission Control worked on the filter problem. The canisters of lithium hydroxide used to filter carbon dioxide in the lunar module were a different size from the available canisters in the command module. On directions from Houston, the crew rigged up a system using duct tape and hosing, to adapt the command module's canisters for lunar module use. The contraption they built was called the "mailbox".

Also to conserve energy, on board television cameras were turned off, and NASA used miniatures and animations to keep the public informed of Apollo 13's progress.

With critically low resources, there was no way the crew could land on the moon, but they continued on the trajectory to the moon in order to pass around it and gain momentum from the moon's gravity to coast back to earth. This picture was taken from Apollo 13's lunar flyby.

On approach to earth, the crew jettisoned the damaged service module, then moved into the command module and jettisoned their "lifeboat", the lunar module. They splashed down in the Pacific on April 17th, four days after the tank explosion.

An investigation into what went wrong with Apollo 13 found that a heating wire inside the liquid oxygen tank had lost its insulation, which led to the explosion. The cause was a combination of mistakes in design, testing, and implementation. The report is available online. The entire Apollo 13 operations team was awarded the Presidential Medal of Freedom as a group.

Mission number 13 may have been unlucky to have experienced the explosion, but an entire series of lucky breaks and intelligent decisions contributed to the crew's safe return. Lovell wrote a book about the mission, Lost Moon in 1994.  It became a best seller. Ron Howard made the book into the 1995 movie Apollo 13.

Tom Hanks was nervous about his role as commander Jim Lovell, because an actor  rarely gets the chance to play one of his childhood heroes. But the movie introduced a new generation to the real-life suspense of the Apollo 13 mission.

Jim Lovell and Fred Haise got together yesterday with Gene Krantz and other members of the Apollo 13 team at the Adler Planetarium in Chicago to mark the 40th anniversary of the flight. Jack Swigert died in 1982. Jim Lovell, now 82, owns a restaurant in Lake Forest, Illinois. Fred Haise, now 76, is building a science museum in Mississippi. See a video of the two retired astronauts speaking about the mission.

For more of the story, follow the highlighted links in this overview. Almost all images courtesy of NASA.

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iStock // Ekaterina Minaeva
technology
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Stephen Missal
crime
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New Evidence Emerges in Norway’s Most Famous Unsolved Murder Case
May 22, 2017
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A 2016 sketch by a forensic artist of the Isdal Woman
Stephen Missal

For almost 50 years, Norwegian investigators have been baffled by the case of the “Isdal Woman,” whose burned corpse was found in a valley outside the city of Bergen in 1970. Most of her face and hair had been burned off and the labels in her clothes had been removed. The police investigation eventually led to a pair of suitcases stuffed with wigs and the discovery that the woman had stayed at numerous hotels around Norway under different aliases. Still, the police eventually ruled it a suicide.

Almost five decades later, the Norwegian public broadcaster NRK has launched a new investigation into the case, working with police to help track down her identity. And it is already yielding results. The BBC reports that forensic analysis of the woman’s teeth show that she was from a region along the French-German border.

In 1970, hikers discovered the Isdal Woman’s body, burned and lying on a remote slope surrounded by an umbrella, melted plastic bottles, what may have been a passport cover, and more. Her clothes and possessions were scraped clean of any kind of identifying marks or labels. Later, the police found that she left two suitcases at the Bergen train station, containing sunglasses with her fingerprints on the lenses, a hairbrush, a prescription bottle of eczema cream, several wigs, and glasses with clear lenses. Again, all labels and other identifying marks had been removed, even from the prescription cream. A notepad found inside was filled with handwritten letters that looked like a code. A shopping bag led police to a shoe store, where, finally, an employee remembered selling rubber boots just like the ones found on the woman’s body.

Eventually, the police discovered that she had stayed in different hotels all over the country under different names, which would have required passports under several different aliases. This strongly suggests that she was a spy. Though she was both burned alive and had a stomach full of undigested sleeping pills, the police eventually ruled the death a suicide, unable to track down any evidence that they could tie to her murder.

But some of the forensic data that can help solve her case still exists. The Isdal Woman’s jaw was preserved in a forensic archive, allowing researchers from the University of Canberra in Australia to use isotopic analysis to figure out where she came from, based on the chemical traces left on her teeth while she was growing up. It’s the first time this technique has been used in a Norwegian criminal investigation.

The isotopic analysis was so effective that the researchers can tell that she probably grew up in eastern or central Europe, then moved west toward France during her adolescence, possibly just before or during World War II. Previous studies of her handwriting have indicated that she learned to write in France or in another French-speaking country.

Narrowing down the woman’s origins to such a specific region could help find someone who knew her, or reports of missing women who matched her description. The case is still a long way from solved, but the search is now much narrower than it had been in the mystery's long history.

[h/t BBC]

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