2020托福听力练习：太空船自我修复挽救宇航员性命（下载）

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　　It's a scenario straight out of Hollywood:

　　You're up in a spacecraft, "you've got this capsule around you," and a loose bolt, a piece of space junk, is zooming your way.

　　"And it's going really fast.

　　It's going to very likely pass through your spacecraft and leave both entry and exit holes.

　　So all of a sudden now your atmosphere is rushing out those holes, and you want them sealed right away."

　　That's Timothy Scott, a polymer scientist at the University of Michigan, Ann Arbor.

　　He and his team have devised a potential solution to this space disaster:a material that patches itself up, less than a second after impact.

　　Think of an ice-cream sandwich.

　　"The central part, the ice cream of our sandwich, is a liquid resin."The cookie parts are sheets of thermoplastic.

　　When a projectile—or piece of space junk—punctures the sandwich,it exposes the liquid part to the ship’s oxygen, which causes it to solidify, patching the hole.

　　The researchers tested sheets of the self-healing material at a firing range, filming the results with high-speed video.

　　And indeed, the material worked fine here on Earth,but they say the findings will have to be replicated under pressure conditions like those you'd find in space.

　　The results are in the journal ACS Macro Letters.

　　The space station is already well protected by bumpers that vaporize particles on impact.

　　But protection doesn't come cheap.

　　"It turns out that robust things are also very heavy.

　　The intent of this is really to provide a backup that's very low weight."

　　It costs some 10,000 a pound to launch equipment into space today.

　　So a lighter weight material could save money—and lives.