Tag: Space Station

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:

  1. Is 1 in 55 (reliability = .982) acceptable? Why?
  2. 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: Probability the Space Station Crashes

Now that the last Space Shuttle has been retired, much debate has focused on the reliability of the Russian Soyez  capsules as the sole means of reaching the $100 billion International Space Station (ISS). Prior to that , our July 11th blog discussed the overall reliability of the Space Shuttle, which at Rs=.98 suggested one fatal crash every 50 missions (and indeed there were 2 crashes in the 135  flight life of the Shuttle). But, interestingly  little has been mentioned in the press about the reliability and safety of the ISS itself.

Today’s Orlando Sentinel (July 25,2011) brings to light 3 important facts: (1) the ISS will be abandoned in any event by 2020 (if it lasts that long), (2) the probability of it taking a disabling strike from space debris is 16.6%, and (3) the probability of  a fatal collision is 1 in 13.  NASA’s own task force found slightly worse odds, with a 0.125 probability that an astronaut will die or the station would have to be abandoned.

The problem is space junk–those 1,000’s of pieces of old rockets  and satellites that were destroyed in space. “The orbit they are flying in is the worst possible. The Russians blew up all kinds of things in that orbit”, says a retired NASA exec. (That 1 in 13 chance of a disastrous collision with space junk is, of course,  the same as what a card player faces in  drawing an Ace from a deck). NASA estimates that there are 500,000 pieces between 1-10 centimeters (large enough to do damage) floating around –and 20,000 more deadly pieces (larger than 10 cm). Just 4 weeks ago, a piece of debris caused a big enough scare to send the 6 astronauts on board the ISS scrambling to Soyez escape capsules. The debris passed within 1,100 feet of the Space Station–the closest near-miss yet.

Discussion questions:

1. Discuss the role of manned space exploration in light of the probabilities given.

2. What are the main operations issues vis-a-vis the ISS?