NASA – The OM Blog by Heizer, Render, & Munson

OM in the News: What Is a “Digital Twin”?

A digital twin is a virtual representation of an object or system that spans its lifecycle, is updated from real-time data, and uses simulation, machine learning and reasoning to help decision-making.

NASA tested an early iteration of a digital twin in response to the Apollo 13 disaster in 1970, using training simulators to match the conditions on the crippled spacecraft and test potential strategies for bringing the astronauts home safely. Today’s digital twins are much more advanced, writes The Wall Street Journal ( March 20, 2023). Not only do they pull in real-time data, but also use AI to capture insights and make predictions, such as identifying potential problems before they happen. The technology also can eliminate the need for physical prototyping of products such as automobiles, and offer a way to test different configurations for spaces such as warehouses and stores, potentially saving time and money.

Companies in every industry are looking at the technology to help them improve processes, reduce costs, conserve resources, boost employee safety and productivity: 17% said they have or plan to deploy digital twins.

San Francisco Airport’s digital twin of its Terminal 2.

For example, the massive San Francisco Airport relies on a digital twin to keep the facility running smoothly. It is a 3-dimensional virtual replica of the airport that is continuously updated with data gathered from embedded sensors throughout the airport. If the maintenance team were to receive a request to change door locks, for example, it could consult the digital twin to find the locations of all the doors that need service.

Another growing area is construction. Modern buildings are already layered with sensors and data-gathering systems that building operators can combine in a digital twin to help them improve a structure’s efficiency, sustainability and security. Building managers can use digital twins to keep track of systems—such as EV charging, smart glass that darkens to reduce energy costs and even soap dispensers with built-in sensors that know when it’s time for a refill—all in one place.

Other complicated systems might benefit from connected digital twins, too. A collection of twins representing everything from stadiums to freeways to public parks has the potential to change the way governments build cities and provide services. Cities might use the technology to create more efficient trash-pickup schedules and routes, for example, or to change traffic patterns when there is a spike in additional people getting on the road from, say, a stadium event.

Classroom discussion questions:

How might a digital twin be used at your university?
Why are twins so useful?

OM in the News: Getting Mac and Cheese to Mars

Washington State University scientists have developed a way to triple the shelf life of ready-to-eat macaroni and cheese, a development that could have benefits for everything from space travel to military use. If human beings go to Mars, they need food. Food that won’t spoil during the long travel between planets, and while they’re on the surface.

Currently, plastic packaging can keep food safe at room temperature for up to 12 months. The WSU researchers demonstrated they could keep ready-to-eat macaroni and cheese safe and edible with selected nutrients for up to 3 years. “We need a better barrier to keep oxygen away from the food and provide longer shelf-life similar to aluminum foil and plastic laminate pouches,” said the research team in WSU Insider (Sept. 24, 2019). “We’ve always been thinking of developing a product that can go to Mars, but with technology that can also benefit consumers here on Earth.”

In addition to having space travel in mind, the researchers are working closely with the U.S. Army, who want to improve their “Meals Ready to Eat” (MREs) to stay tasty and healthy for 3 years. In taste panels conducted by the Army, the mac and cheese, recently tested after 3 years of storage, was deemed just as good as the previous version that was stored for 9 months. NASA will require storage of up to 5 years for food, so that’s what the team is working on now. They are currently aging other recipes that will be taste tested once they reach the 5-year mark. When humans are involved and they travel over great distances spanning long periods of time, the supply and transport of fresh nourishment can present a significant challenge.

The food itself is sterilized using a process called the microwave-assisted thermal sterilization (MATS) system. Adding a metal oxide coating to a layer of the plastic film significantly increases the amount of time it takes for oxygen and other gases to break through.

Classroom discussion questions:

What other OM applications could benefit from such technologies?
What additional logistics challenges will need to be solved before humans can embark on a trip to Mars?

OM in the News: NASA’s “Failed Mission” Probabilities

NASA is working with Elon Musk’s SpaceX to redesign part of the fuel system for the company’s Falcon 9 rockets and then will demand at least 7 successful unmanned flights before allowing astronauts on board. With routine flights ferrying U.S. astronauts to the orbiting international space station slated to begin in fall of 2019, the agency has raised new questions about potential hazards and longstanding NASA safety standards, writes The Wall Street Journal (Jan.18, 2018). Ending current U.S. reliance on Russian capsules for crew transportation may “require decisions to accept a higher risk” on next-generation U.S. systems than anticipated, says NASA.

NASA’s statistical limit for a “failed mission” remains 1 in 55 launches, despite several years of intense development, NASA expenditures of about $5 billion and significant additional investment by the two companies bidding for contracts–Boeing and SpaceX. That limit applies to mission failures in which the vehicle doesn’t reach the space station but the crew uses emergency procedures to survive.

NASA’s statistical standard for crew fatalities is no greater than one in 270 flights, though neither Boeing nor SpaceX is on track to meet that precise mandatory benchmark. By contrast, the global airline industry has achieved fatal accident rates for jetliners of 1 crash for several million flights.

System reliability is an old, but crucial issue at NASA. During the long era of the Space Shuttle, which I was proud to be a part of, mission reliability was set at 98%. This meant a critical failure was anticipated every 50 flights. And indeed, the first Shuttle exploded on flight no. 25 (Challenger), and the 2nd loss on flight 113 (Columbia) . The Shuttle program ended with flight no. 135, as a 3rd crash was viewed as unsustainable.

Classroom discussion questions:

Is 1 in 55 (reliability = .982) acceptable? Why?
Why is NASA seeking this alternative to Russia’s Soyuz ferrying rockets?

OM in the News: 3-D Printing Heads for the Moon and Mars

The European Space Agency's proposed moon colony to be built on site by a robotic 3-D printer using lunar dust as ink — The European Space Agency’s proposed moon colony to be built on site by a robotic 3-D printer using lunar dust as ink

Dutch television producers chose 100 contestants in February to vie for a one-way trip to Mars. If all goes as advertised, winners might be landing there sometime in 2027. They’ll quickly need permanent shelter. The nearest Home Depot will be 140 million miles away. The only readily available construction material on Mars is sand.

That might be all they need if a plan by NASA works out, reports The Wall Street Journal (April 13, 2015). NASA is experimenting with a 3-D printer that would make bricks suitable for airtight buildings and radiation-proof shelters using the grit that blows across Mars’s red surface. In Huntsville, NASA’s 3-D printer is starting to print curved walls and other structures using imitation Martian sand as an ink.

And engineers at the European Space Agency (ESA) are exploring ways to use lunar dust as an ink to print out an entire moon base. On a recent trial run, ESA used a 3-D stereo-lithography printing process that can print objects up to 19 feet long on each side. They mixed simulated lunar dust with magnesium oxide and printed out stone-like building blocks weighing one-and-a-half tons each. That could reduce the need to launch raw materials into orbit at a cost of thousands of dollars per pound. “It would be economically impossible to send all these bricks from Earth to the Moon,” said an engineer at ESA.

And if astronauts ever do reach Mars, they may survive the journey by eating pizza made with a 3-D-printed food system for long duration space missions. Aboard the international space station last December, one astronaut printed out a ratchet wrench—the first tool to be printed in orbit. Typically, an astronaut might have to wait a year or more for a new tool to be shipped into orbit. In all, the crew printed 25 experimental parts.

Classroom discussion questions:

1. Will 3-D printing revolutionize space travel?

2. How can this technology be used by operations managers on earth?

OM in the News: Neil Armstrong and Reliability

To most Americans, especially those of us who used to work at NASA, Neil Armstrong’s death was the loss of an American hero, and a sad ending to our Moon exploration days. But the reason we mention the astronaut in today’s blog is his speech about the topic of Chapter 17, reliability. Surely someone who risked his life in every launch and who studied engineering understood the mathematics of reliability.

As reported in The Wall Street Journal (Aug. 26, 2012), here are Armstrong’s remarks: “Each of the components of our hardware were designed to certain reliability specifications, and far the majority, had a reliability requirement of 0.99996, which means that you have four failures in 100,000 operations. If every component met its reliability specifications precisely, a typical Apollo flight would have about 1,000 separate identifiable failures.”

“In fact, we had more like 150 failures per flight, substantially better than statistical methods would tell you that you might have. I can only attribute that to the fact that every guy in the project, every guy at the bench building something, every assembler, every inspector, every guy that’s setting up the tests, cranking the torque wrench, is saying, ‘If anything goes wrong here, it’s not going to be my fault, because my part is going to be better than I have to make it.’ And when you have hundreds of thousands of people all doing their job a little better than they have to, you get an improvement in performance.”

I appreciate Armstrong’s observations–and think your students may as well. In those days, you could stand outside a NASA Space Center and never tell when quitting time was. Engineers simply stayed each day till they felt their work was done–maybe at 6 pm or even 9 pm. When we work on projects we are all interested in and dedicated to, there is nothing we cannot accomplish.

Discussion questions:

1. What was the reliability of each Shuttle flight, given that 2 Space Shuttles crashed in about 140 flights?

2. In what other industries is reliability equally important?

OM in the News: NASA’s Last Space Shuttle Launch

When the final Space Shuttle launch took place on July 8th, an era of tragedy and triumph that dominated space travel for a generation drew to a close. I worked at NASA headquarters in the late 1970’s during the planning for the 1981 inaugural launch of Columbia, and always followed the program closely–to this day I can watch every launch from my backyard in Central Florida! In 1982, Prof. Paul Meising (SUNY-Albany) and I published four OM-related cases about the Shuttle, which appeared in earlier editions of the Heizer-Render OM text. They dealt with Shuttle reliability (Ch.17), astronaut assignment (Ch.15), forecasting demand (Ch.4), and ordering external tanks (Ch.12).

Looking back on the Shuttle program 30 years and 135 missions later, several facts stand out. First, with a 98% reliability rate (Rs=.98), one would expect a major problem every 50 launches. And indeed, with the explosions of Challenger in 1986 and Columbia in 2003, NASA was almost statistically due for a 3rd disaster. The Wall Street Journal (July 9-10, 2011) quotes Duke space historian Roger Launius as follows: “It was a magnificent failure. It was the most technologically sophisticated launch vehicle ever, but it never made human spaceflight safe, reliable, or economical”.

Launius was correct. Our 1979 forecasts at NASA for 500 flights within the 1st decade–basically a launch a week starting in 1986–were off by 90%. Our pricing structure assumed that private companies, foreign governments, and the Defense Dept. would cover all the bills as full-paying customers. We budgeted each launch at $15 million, when in reality the average cost rose to $1.5 billion–100 times the promised price. Now, as the Russians are charging us $20-30 million per seat to ride to the Space Station, a piece of American history draws to a close.

Discussion questions:

1. Was the Shuttle program a success overall?

2. Why did the program never reach its budget and schedule targets?