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Earth Space Science

SpaceX Launch Last Year Punched Huge, Temporary Hole In the Ionosphere (arstechnica.com) 76

The Falcon 9 rocket that launched last August reportedly ripped a temporary hole in the ionosphere due to its vertical launch, which Ars Technica notes as being rather unusual: Contrary to popular belief, most of the time when a rocket launches, it does not go straight up into outer space. Rather, shortly after launch, most rockets will begin to pitch over into the downrange direction, limiting gravity drag and stress on the vehicle. Often, by 80 or 100km, a rocket is traveling nearly parallel to the Earth's surface before releasing its payload into orbit. However, in August of last year, a SpaceX Falcon 9 rocket launch from California did not make such a pitch over maneuver. Rather, the Formosat-5 mission launched vertically and stayed that way for most of its ascent into space. The rocket could do this because the Taiwanese payload was light for the Falcon 9 rocket, weighing only 475kg and bound for an orbit 720km above the Earth's surface. As a result of this launch profile, the rocket maintained a nearly vertical trajectory all the way through much of the Earth's ionosphere, which ranges from about 60km above the planet to 1,000km up. In doing so, the Falcon 9 booster and its second stage created unique, circular shockwaves. The rocket launch also punched a temporary, 900-km-wide hole into the plasma of the ionosphere.
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SpaceX Launch Last Year Punched Huge, Temporary Hole In the Ionosphere

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  • by Barnoid ( 263111 ) on Friday March 23, 2018 @03:05AM (#56311135)

    Why does a perpendicular penetration create a bigger hole than a (much longer) almost parallel traversal?

    • It 's the shock wave being generated by the passage of the rocket at high speed through the atmosphere. If the rocket curves/turns, the shock wave generated in the previous direction has an opportunity to dissipate instead of continuing to build up.

      So same amount of force exerted on the atmosphere, but not as concentrated in one direction and shorter duration.

      Interestingly, they apparently also managed to minorly disrupt GPS signals in the area as well, similar to a magnetic sun storm, but much more localized.

    • by Chas ( 5144 ) on Friday March 23, 2018 @06:19AM (#56311591) Homepage Journal

      Think of crawling out from under a pile of progressively larger blankets.

      Sure, you can rip your way straight up and out. But that damages the blankets. You also push a certain amount of blanket up and out with you.
      Instead you follow the blankets, slowly making your way upward and outward.
      However, as you pass, gravity and ambient pressure causes the blanket that's being displaced to collapse back in on the path of travel.

      So your shockwave pops open an area of atmosphere in front of you, you move into it, and the space you just left rapidly returns to normal atmospheric pressure.

  • ... still they are damaging to our eco system. Time for the space elevator inventions? Back in the '60 they were already being a vision of modern surface to space freighters.

    • by AC-x ( 735297 )

      One does not simply invent a space elevator!

    • by Rei ( 128717 ) on Friday March 23, 2018 @05:30AM (#56311473) Homepage

      Space elevators require unobtanium to have reasonable masses (they also have serious problems with damping oscillations, and their throughput is tiny in comparison to their mass, and they're inefficient, and slow, and about fifty other things). If you want something along that vein which doesn't require unobtanium, try a launch loop [wikipedia.org].

      • by jabuzz ( 182671 )

        No space elevators require "unobtanium" just to fricking work. Now in theory carbon carbon bonds are sufficiently strong that a carbon nanotube would work as the cord. Anything else and the cord snaps under it's own weight.

        Small snag is that nobody has created a carbon nanotube that is several hundred km long yet. As such they still require unobtanium aka. carbon nanotubes that are a few hundred km long.

        • by lurcher ( 88082 )

          "No space elevators require "unobtanium" just to fricking work."

          I think you will find they all do. Would you like a spare comma?

          • Only the "beanstalk style", there's lots of orbital alternatives. Not quite so convenient to get on, but something like a "space wheel" is a lot easier to build and has its own benefits (e.g. 100% efficient and no moving parts)

        • but isn't part of the space elevator theory is that the thing at top uses centrifugal force to keep the rod straight as it orbits along with earth?

          • It is. Think of it not a tower rising up from the Earth, but a "rope" being dropped from geostationary orbit, all the weight is supported from above - you couldn't hope to keep it from crumbling under its own weight as a tower. And as you climb the rope, it has to keep getting thicker. At the bottom, it only has to support your weight. A mile up it has to support your weight, plus the weight of a mile of rope. Let's say it's ultralight, so that that mile of rope only weighs as much as you - then at that

        • by Rei ( 128717 )

          This is simply not correct. The specific strength of the cable material determines the taper ratio. For anything with a worse specific strength than carbon nanotubes, you get a very high taper ratio that yields completely unreasonable masses - but you still can get a space elevator if you can magic all of that mass into existence in space. Even with carbon nanotubes the infamous Edwards analysis has to "fudge" a lot to make things work (and he assumes CNTs nearly twice as strong as individual CNTs have e

          • The problem is the taper rate is actually exponential rather than linear, and if your strength-to-weight ratio isn't high enough, like steel for instance, then before you reach geostationary orbit your cable has to be wide enough to completely encase the Earth in a giant steel shell just to be able to support it's own weight.

            Which, admittedly would then be much more capable of supporting its own weight, so you COULD do it if you were able to magic up several times the Earth's mass in steel. But I would hav

        • by Ranbot ( 2648297 )

          Your carbon nanotubes cord is a "theory" and the cord is only part of the space elevator problem.

          The other problem is anchoring the cord to something in orbit (e.g. space station or captured asteroid) to keep it from falling back to Earth. The orbiting anchor would have to be perfectly synchronized to the earth's rotation and regularly corrected for orbit decay. The cord will also be deflected by differential air drag at various elevations, high altitude global air currents, and the occasional hurricane/typ

        • And even using flawless multiwalled carbon nanotubes (even higher strength-to-weight ratio), it would only be *barely* strong enough to support its own weight - and no engineer worth their certification would sign off on a structure with a safety margin probably measured in single-digit percentages - especially not considering the devastation it would cause if it fell to Earth (some designs suggest designing it to vaporize in the atmosphere, but I'm not sure that would actually be a dramatic improvement.)

          Th

    • by dcw3 ( 649211 )

      ".. still they are damaging to our eco system."

      Are they? I didn't see anything indicating that in the article, nor anything stating how long the hole remained except to call it temporary. What damage are you claiming? Should California sue SpaceX?

    • ... still they are damaging to our eco system.

      Just about everything humans do is damaging to our ecosystem.

      Time for the space elevator inventions? Back in the '60 they were already being a vision of modern surface to space freighters.

      Time for the Star Trek space transporter inventions? Back in the '60 they were already being a vision of modern surface to space freighters . . . on television.

      I guess we could also ask if it's time for flying cars and fusion power . . . which have been just 10 years away, since the '60s . . .

    • Get in touch with Mr. Musk. He would probably do it.......

      That said, the groups working on launching rockets from high altitudes are interesting, much less fuel, but certainly the same impact on the atmosphere.

    • by Anonymous Coward

      Good Lord you're a moron. You can't just throw tech ideas around like that if you don't have the slightest understand of the requirements to build such a thing.

      There are far more reasonable ways humans and stop harming the ecosystem without resorting to lunacy and "omg do something!" type thinking.

    • A space elevator is a universally terrible idea. It would not only leave a permanent hole in the ionosphere, it would also:

      • Act as a surface for air to adhere to and escape the atmosphere altogether via surface tension.
      • Act as an electrodynamic tether, resulting in a radical change to the Earth's orbit around the sun.
      • Act as an electrodynamic tether, resulting in a lower orbital velocity of the moon (and if left long enough, deorbiting of the moon.)
      • Be a huge risk to ground structures if it snapped.

      People who

      • you're hilarious, your hat must be made of space elevator grade carbon nanotube to have so much tension from cinching it up, tinfoil, or even 5mm aluminum bar, would have broken; not one corpuscle of blood remained to nourish neurons.

      • Only beanstalks - there are many other kinds of space elevators that would be much less challenging and dangerous.

        Is it still a hole if you have a space elevator plugging it?

        I've never heard of air flowing along solids more freely than it moves on its own - air molecules are escaping into orbit constantly.

        Why would the Earth's orbit change noticeably? Any electromagnetic forces should average out - whatever forces the cable experiences as it moves away from the sun will be balanced by those it experiences

        • Air sticks to solids, it also has a surface tension like effect that helps it drag along other air molecules. The effect of a space elevator would be similar to capillary action - it's not such a big deal with it escaping normally because between atomic decay in the Earth and solar winds the air gets replenished to a stable level, but when you increase the height it can obtain with the aforementioned boundary effect of the solid and gas you will effectively create a pipe pumping air up where it takes much
          • There IS drag certainly, as intermolecular collisions create fluid boundary layers as it moves past a solid (or vice-versa). But a beanstalk is stationary - any drag effects will be slowing down the wind, lowering the kinetic energies of the molecules and tending to cause them to fall lower into the atmosphere.

            I'm pretty sure gases don't exhibit surface tension to any appreciable amount - gas molecules have only a very weak attractive force between them, which is why they can change volume so readily. Ther

            • You don't have to reach a stable orbit to lose gas, you just need to expand the atmosphere enough for the solar wind to knock it further out - that already happens and it's a balance between escaping and new particles - any change to the system changes where the balance point is.
              • True, but there is no stable balance point - the rates are always changing along with solar activity and the Earth's magnetic field - neither of which are themselves stable. So the real question is, is any change large enough to make a noticeable difference before the sun expands to consume the Earth anyway?

  • by Anonymous Coward

    First we were destroying the ozone layer with aerosol, and now we're destroying the Ionosphere with rockets. And next we'll be destroying another layer with something else.

    The 20th and 21st centuries have been best described by: let's innovate without worrying about the consequences; let's claim to be supporters of science, without applying its principles.

    An application of modern philosophy that destroys our world. And a rejection of classical/medieval philosophy, which is the underpinning of true science.

    • Troll - go back to your doctor and ask for some more blood letting, and while you are there play with his nifty magical table cloth made from asbestos.
    • by Rei ( 128717 )

      Obvious troll is obvious.

  • Contrary to popular belief, most of the time when a rocket launches, it does not go straight up into outer space.

    I've never known anyone who thought that satellite launches went straight up. Did any Slashdot readers have that belief before reading this article, or know people who think that?

    • Most people who watch rocket launches watch the first 30 seconds when the rocket is going straight up. It is safe to assume that the rockets continues to go straight up. After all, a straight line is the shortest way to get to space.
  • This has happened before. If you google 'skylab ionosphere' you'll find that a large hole was made in the ionosphere during the launch of the Skylab space habitat. After a bit if study it was decided that this was due to the injection of water and other materials into the ionosphere which caused the sudden large decrease in ionization. Basically, this injection changed the electron loss rate in the area to the point where it was much greater than the solar EUV-driven electron production rate. The shock
  • Here's the link to the actual paper:

    https://agupubs.onlinelibrary.... [wiley.com]

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