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posted by janrinok on Saturday November 25 2017, @07:48AM   Printer-friendly
from the forget-the-puncture-kit,-give-me-a-welding-torch dept.

Chainmail tires re-invent the wheel to get future NASA rovers rolling.

NASA has developed chainmail tires with a memory and thinks they'll do the trick for future rovers.

As readers of The Register's coverage of the Curiosity Rover may recall, the vehicle has experienced considerable wheel damage that has led to changes to its route in 2014 and a 2017 software update to preserve the wheels and provide better grip.

Throw in the fact that it's not yet possible to send a spare wheel to Mars and have it fitted, and NASA has a clear need for more robust tires.

Enter a technology called "spring tires" that use a tubular structure of steel mesh – think tire-shaped chainmail - to cushion rovers as they roll. Spring tires have many fine qualities as the mesh forms a pattern that provides good grip on many surfaces. Mesh is also light by nature and can survive some damage. But spring tires don't deform well: if one rolls over a sharp rock, it can acquire a dent - or "plastic deformation" as NASA boffins put it.

The tires use a nickel titanium alloy that can endure plastic deformation.


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  • (Score: 3, Interesting) by takyon on Saturday November 25 2017, @08:39AM (6 children)

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Saturday November 25 2017, @08:39AM (#601319) Journal

    I'm thinking it will cost no less than $500 million to use a new rover flown to Mars for the purpose of changing the tires on Curiosity. Better just to build future rovers with these new tires. Starting with Mars 2020 [wikipedia.org] which is launching in July 2020. NASA should be hounded repeatedly on whether Mars 2020 will use the chainmail tires instead of the originally planned ones. They were the ones who touted their chainmail tire breakthrough after all.

    Where we should have serviceability is our space telescopes. The James Webb Space Telescope is not designed to be serviceable. It will eventually run out of fuel for station keeping [nasa.gov]. Can a small spacecraft be sent to refuel JWST towards the end of its life anyway? Let's hope so. Although better telescopes than JWST will eventually be sent into space, old [wikipedia.org] and partially-broken [wikipedia.org] telescopes still get used as much as possible. There's an essentially infinite number of stars, galaxies, and other objects to point your telescope at, and making repeated or continuous observations can reveal planets, flares, etc.

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  • (Score: 2) by Runaway1956 on Saturday November 25 2017, @09:31AM (5 children)

    by Runaway1956 (2926) Subscriber Badge on Saturday November 25 2017, @09:31AM (#601334) Journal

    Station keeping . . . I've wondered why they don't put something like that into a higher orbit, where it's much easier to maintain station. And, if it does wander a little, the consequences are negligible. In LEO, being ten miles off course can be catastrophic. Somewhere close to the earth/moon Lagrange point, being a thousand miles off course would be almost meaningless. Everyone on earth who wants to see the signal from the satellite simply adjusts his antenna toward the off-course satellite. What, a couple tenths of a second, for 1000 miles at that range? Even if it's a whole minute, point your antenna at it's assigned position, then focus to get the strongest signal.

    That would, however, make it more expensive to perform maintenance, since you have to get a lot further up the gravity well to work on it.

    • (Score: 5, Informative) by takyon on Saturday November 25 2017, @09:42AM (4 children)

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Saturday November 25 2017, @09:42AM (#601336) Journal

      An L2 orbit is meta-stable so it requires orbital station-keeping or an object will drift away from this orbital configuration.

      [...] The JWST will be located near the second Lagrange point (L2) of the Earth-Sun system, which is 1,500,000 kilometers (930,000 mi) from Earth, directly opposite to the Sun. Normally an object circling the Sun farther out than Earth would take longer than one year to complete its orbit, but near the L2 point the combined gravitational pull of the Earth and the Sun allow a spacecraft to orbit the Sun in the same time it takes the Earth. The telescope will circle about the L2 point in a halo orbit, which will be inclined with respect to the ecliptic, have a radius of approximately 800,000 kilometers (500,000 mi), and take about half a year to complete.[14] Since L2 is just an equilibrium point with no gravitational pull, a halo orbit is not an orbit in the usual sense: the spacecraft is actually in orbit around the Sun, and the halo orbit can be thought of as controlled drifting to remain in the vicinity of the L2 point.[107] This requires some station-keeping: around 2–4 m/s per year[108] from the total budget of 150 m/s.[109] Two sets of thrusters constitute the observatory's propulsion system.

      Why is JWST at L2?

      https://space.stackexchange.com/questions/284/why-should-the-james-webb-space-telescope-stay-in-the-unstable-l2 [stackexchange.com]

      1. The distance from the L2 to Earth is only 1.5 million km away. The L4/L5 are 1 AU, or about 150 million km away. That leads to a reduction in link margin of 40 db, or 1/10000. That is quite significant. In order to compensate for that difference, you either need a bigger radio dish, more power, or a loss in data.
      2. As you mentioned, the fuel usage is quite low to maintain that position, only on t.order of 150 m/s delta v for the entire mission. That isn't a whole lot, and in fact, is less than what is required to keep a satellite in geostationary orbit.
      3. The satellite is much closer, reducing the time to command an object. Light only will take 5 seconds to reach James Webb, whereas it will take 9 minutes to reach L4/L5. This limits the ability to do real time commands, which occasionally are useful (Think Gamma Ray Bursts, Super Novas, etc)

      http://en.wikipedia.org/wiki/Lagrangian_point#L2 [wikipedia.org]

      The Sun–Earth L2 is a good spot for space-based observatories. Because an object around L2 will maintain the same relative position with respect to the Sun and Earth, shielding and calibration are much simpler.

      It's important to make sure these instruments never point towards the Sun.

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      • (Score: 2) by frojack on Saturday November 25 2017, @09:02PM (3 children)

        by frojack (1554) on Saturday November 25 2017, @09:02PM (#601494) Journal

        Exactly.

        Its not an easy place to get to either.
        But a simple refueling port on the platform would have been cheap. You could easily justify the cost on a hunch that automated vehicles could be designed in the interim. Its expected life was 5 to 10 years.

        Musk's first flight was in 2008. He's routinely landing rockets today 8 years later. Shit is moving very fast these days, and JWST isn't even scheduled to launch till 2019.

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        • (Score: 2) by takyon on Saturday November 25 2017, @10:16PM (2 children)

          by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Saturday November 25 2017, @10:16PM (#601522) Journal

          It's not an easy place for humans to get to, ala Hubble servicing missions. Or in other words, it would be further away than humans have ever traveled from Earth (although not that far, just ~four times the distance to the Moon). But robotic spacecraft? No problem.

          I hope that despite its lack of serivceable design, it could still be serviced anyway. Even if takes physically ripping into it or having the second spacecraft grab onto JWST and become the new thruster. Because if you are going to let the nearly $10 billion scope go to waste, you might as well try.

          If the scope ends up performing for a full 10 years, by the time we get to year 5 the science value of JWST should be clear in that it will be beating Hubble for many observations. It should be enough to pressure who needs to be pressured to try and make this happen.

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          • (Score: 1) by anubi on Sunday November 26 2017, @08:56AM (1 child)

            by anubi (2828) on Sunday November 26 2017, @08:56AM (#601671) Journal

            (although not that far, just ~four times the distance to the Moon).

            Nor do we get the benefit of the Moon's gravitational field to sling us back.

            So we are gonna spend either a helluva lot of fuel braking and resuming the trip velocity back, or take a helluva lotta time creeping up to it.

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