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  • [intro]

  • Space missions don't always go quite as planned.

  • And by the time something goes wrong, your spacecraft is a hundred million kilometers

  • from home

  • too far away to dash out and repair it.

  • Consequently, space science can get...improvisational.

  • If a tool is no longer capable of carrying out its original purpose,

  • maybe it can still do something.

  • Your adjustable wrench's threads bound up?

  • Now you've got a normal wrench!

  • Oh, it's stuck closed entirely?

  • Well, then you've got a very oddly-shaped hammer!

  • The folks at NASA have had to apply this school of thought to far more sophisticated equipment,

  • and sometimes it works out really well for them.

  • Here are a few such examples.

  • The Hubble Space Telescope has been serviced by astronauts five times since 1990.

  • But it's the exception.

  • Because it's in low Earth orbit, we've actually been able to go there and fix it.

  • Other telescopes are less lucky.

  • The Kepler space telescope was meant to find exoplanets by continuously watching faraway

  • stars for transit events:

  • a slight dimming of a star's brightness for a specific amount of time, indicating

  • that a planet is passing in front of it.

  • Through this method, Kepler aimed to identify as many Earth-sized exoplanets as possible,

  • while looking at a patch of about 150,000 stars.

  • It had four gyroscopic stabilizersone stabilizer for each three-dimensional axis,

  • plus a spare if one of them should fail.

  • These were to protect the probe from being pushed around too much by pressure from the

  • solar wind.

  • In 2013, four years into the mission, two of the stabilizers had failed.

  • Which made it too hard to keep the telescope steady

  • so NASA put it in sleep mode and went back to the drawing board.

  • After a few months of hard work, scientists realized they could use the solar wind instead

  • of fighting it,

  • basically bracing the spacecraft against it and using the other two gyros to keep it in

  • place.

  • It would mean they'd need to re-align the telescope every 80 days as it orbited the

  • sun and slowly shifted its angle relative to the solar wind.

  • Which meant pointing it at a new field of stars every few months, instead of studying

  • the same patch continuously.

  • But these limitedcampaignsreturned fantastic resultsand buckets of exoplanets

  • for researchers here at home.

  • And this isn't the only telescope NASA has had to save.

  • Spitzer is an infrared space telescope designed to operate slightly above absolute zero to

  • see distant objects that optical telescopes can't,

  • such as low temperature and dim objects far away.

  • Spitzer initially had a life expectancy of two and a half years, which it easily outstripped.

  • But in 2009, after five and a half years of operating, its liquid helium coolant finally

  • ran out.

  • Spitzer could no longer look at some of the very cool and dim objects it had been designed

  • to spot.

  • But at its new temperature, the telescope could still look at asteroids and comets in

  • our own solar system, as well as far-off, ancient galaxies.

  • This was the start of its so-calledwarm mission” —

  • which, at minus 241 degrees, was still pretty chilly.

  • As a result of this repurposing,

  • Spitzer has subsequently observed countless amazing objects in our own solar system, and

  • it's expected to keep going into 2020.

  • But space missions obviously aren't all about looking at things from afar.

  • Sometimes we want to get up close and personal.

  • To that end, the Deep Impact mission was designed to slam a probe into a comet while the probe's

  • mothership watched.

  • In 2005, the 370-kilogram impactor probe successfully smashed into Comet Tempel 1 at 37,000 kilometers

  • per hour,

  • and in so doing, revealed a lot about the nature of comets.

  • That, and dinosaurs in their graves maybe felt a twinge of catharsis.

  • The mission was complete, but while the probe had very much crash-landed, there was still

  • a perfectly functional mothership out there.

  • So mission managers sent it to do more cool comet science elsewhere.

  • During its new mission, dubbed EPOXI, the probe flew by another comet, made observations

  • of Earth and Mars, and even searched for exoplanets.

  • Eventually though, NASA lost contact in August of 2013.

  • Then there's the part where NASA used a totally different probe to get more mileage

  • out of Deep Impact's results.

  • The Stardust spacecraft, which flew through the tail of comet Wild 2 in 2004,

  • was similarly successful enough to be given new tasks.

  • One of these was a flyby of Tempel 1.

  • Stardust's visit in 2011 gave NASA the opportunity to observe their handiwork, and to make further

  • observations of the unfortunate comet.

  • And while we've covered it before, no discussion of spacecraft doing more than their planned

  • workload would be complete without a mention of the Mars rover Opportunity.

  • Oppy lasted sixty times longer than its planned lifetime of 90 days,

  • spending nearly 15 years searching for signs of water and collecting other data on the

  • red planet.

  • Opportunity is a pretty extreme example,

  • but its success speaks to the careful planning and engineering that goes into every device

  • we launch into space.

  • Space travel is difficult and expensive, so the scientists responsible really care about

  • getting it right.

  • Whether it's coming up with clever fixes from afar,

  • or just making the most of their funding, scientists have gotten pretty adept at getting

  • everything they can out of their outer space investments.

  • Thanks for watching this episode of SciShow Space.

  • This episode, along with every other episode we make, was supported by our patrons on Patreon.

  • If you're interested in helping us do what we do, check out patreon.com/scishow.

  • [ outro ]

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5個獲得新生命的航天器 (5 Spacecraft That Got a New Lease on Life)

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    林宜悉 發佈於 2021 年 01 月 14 日
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