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  • Late January and early February are a tough time for the spaceflight industryreally,

  • for anyone who's passionate about the exploration of space.

  • Over the course of one week, we mark the anniversaries of the only two fatal NASA accidents to happen

  • during flight: the destruction of Space Shuttles Challenger and Columbia.

  • Traveling to space continues to be one of the most dangerous things humanity's ever

  • done, and space agencies want to do everything they can to minimize that risk.

  • So, after each of the Shuttle accidents, NASA grounded flights for years, while they figured

  • out exactly what went wrong, and how to stop it from happening again.

  • Here's what we learned from those disasters.

  • At 11:38 AM Eastern Time on January 28, 1986, Challenger lifted off from the launch pad

  • in Cape Canaveral, Florida, with seven crew on board -- including one civilian, a teacher

  • named Christa McAuliffe.

  • 73 seconds later, the Shuttle broke apart.

  • The cabin landed in the Atlantic Ocean about two minutes later with enough force to crush

  • everything inside.

  • We know that the accident was caused by a leak in one of the solid rocket boosters.

  • We also know that if it had been up to the engineers, Challenger would never have launched

  • that day.

  • Before this, the coldest it had ever been when the Shuttle launched was about 10.5 degrees

  • Celsius.

  • But on January 28th, it was more like 2 degrees.

  • And some of the engineers working on the Shuttle knew that colder weather was a problem for

  • the O-rings, the rubber seals that hold together the four sections of each solid rocket booster.

  • When it got too cold, the rubber wasn't as flexible, which meant that the fuel could

  • leak.

  • They warned management of the danger, with at least one engineer refusing to sign off

  • on the paperwork for the launch.

  • NASA went ahead with it anyway, and seven people died.

  • After that accident, all shuttles were grounded until 1988, and in the meantime, NASA made

  • two important changes to the program.

  • First, they fixed the problem with the O-rings, adding an additional ring to each link between

  • sections, as well as heating pads that made sure they stayed above 24 degrees no matter

  • how cold it was outside.

  • But they also spent those years changing policies and management structure, in the hope that

  • a warning against a launch would never be ignored again.

  • Those changes seem to have helped, at least for the next 17 years.

  • Then the Space Shuttle Columbia exploded.

  • This time, it was a completely different sort of accident.

  • Seven astronauts launched at 10:39 AM on January 16, 2003, and they made it to space just fine.

  • There was some concern, because it looked like a piece of foam insulation had broken

  • off the external fuel tank, and no one knew if Columbia had been damaged.

  • But on every previous flight, Shuttles had been damaged by debris, and they'd come

  • back safely.

  • So while at least a few engineers were worried, the mission went ahead as usual, with the

  • astronauts working on more than 80 experiments.

  • Then came February 1st, the day Columbia was supposed to land.

  • As it re-entered the atmosphere, the crew lost sensor readings from the left wing.

  • Then NASA lost contact with the crew.

  • It turns out, the foam had punctured a hole in the left wing.

  • During re-entry, extremely hot atmospheric gas pushed through, into the damaged wing,

  • first disabling the sensors and then destroying the ship.

  • Columbia exploded somewhere over Texas and Louisiana, leaving a field of debris about

  • 400 kilometers long and 8 kilometers wide.

  • Again, shuttles were grounded for about two years -- there were no more flights until

  • 2005.

  • And in the meantime, the fuel tank was redesigned so it no longer had that piece of foam.

  • But the committee that reviewed the accident made another recommendation: NASA still needed

  • the Shuttles for a few more years, until the International Space Station was completed.

  • But after that, it was time to ground the fleet.

  • They pointed out that the shuttle program had always been kind of experimental.

  • They were now more than 30 years old, and it wasn't safe to keep using spaceships

  • that were essentially still in development.

  • So the very last Space Shuttle flight touched down on July 21, 2011, and NASA astronauts

  • have been flying to space on the Russian Soyuz ever since.

  • In the end, it's difficult to calculate everything we learned from the shuttle program.

  • It enabled us to conduct hundreds of scientific experiments that we could never have done

  • on Earth

  • It launched the Hubble Space Telescope

  • ...and then repaired it.

  • Five times.

  • And it gave us our first real lesson in how to build and operate a re-useable spacecraft

  • -- the world's first.

  • But maybe the hardest lesson we learned was how much risk we were willing to take, in

  • order to keep the shuttle flying.

  • In the end, we decided that we didn't want to learn any more about that.

  • So, today, spaceflight continues -- all around the world! -- and new astronauts are training

  • to fly new spacecraft, from the Dragon capsule by SpaceX, to NASA's Orion.

  • And every time we send astronauts into space, they travel with the lessons that we learned

  • from the Shuttle, and the fourteen people who died flying it.

  • Everyone who goes to space, goes thanks to them.

  • Thanks for watching this episode of SciShow Space, and thanks especially to our patrons

  • on Patreon who help make this show possible.

  • If you want to help us keep making episodes like this, just go to patreon.com/scishow.

  • And don't forget to go to youtube.com/scishowspace and subscribe!

Late January and early February are a tough time for the spaceflight industryreally,

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What We Learned from Challenger and Columbia

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    joey joey に公開 2021 年 04 月 18 日
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