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posted by Fnord666 on Friday December 15 2017, @10:43PM   Printer-friendly
from the how-many-astronauts-does-it-take dept.

Three astronauts on Thursday landed back on Earth after nearly six months aboard the International Space Station.

A Russian Soyuz capsule with NASA's Randy Bresnik, Russia's Sergey Ryazanskiy and Paolo Nespoli of the European Space Agency descended under a red-and-white parachute and landed on schedule at 2:37 p.m. local time (0837 GMT; 3:37 a.m. EST) on the vast steppes outside of a remote town in Kazakhstan.

The three were extracted from the capsule within 20 minutes and appeared to be in good condition.

Bresnik, Ryazansky and Nespoli spent 139 days aboard the orbiting space laboratory. The trio who arrived at the station in July contributed to hundreds of scientific experiments aboard the ISS and performed several spacewalks.

They left Alexander Misurkin, commander of the crew, and two Americans, Joe Acaba and Mark Vande Hei, in charge.

Do you think astronauts on the ISS play a drinking game where they try to land toilet bombs on earth-bound targets? I would.


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  • (Score: 2) by unauthorized on Saturday December 16 2017, @12:34AM (6 children)

    by unauthorized (3776) on Saturday December 16 2017, @12:34AM (#610572)

    Everything in LEO is in a decaying orbit because there there is a bit of atmosphere up there, the only reason that the ISS stays up is that it occasionally uses it's thrusters to maintain it's orbit. That said, you can't actually eject things to make them fall, in space the only way to move things is to expel matter in the opposite direction of your desired motion. If you shoot a cannonball out of a cannon located on the ISS, the ball will just settle into an orbit that is very similar to the ISS, at least until orbital decay causes it to diverge significantly.

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  • (Score: 2) by Immerman on Saturday December 16 2017, @09:57AM (5 children)

    by Immerman (3985) on Saturday December 16 2017, @09:57AM (#610667)

    To clarify a little further - no matter how fast you launch something all you'll accomplish is to put it in a new new orbit that still intersects your own at that point. Unless you can somehow impart a several km/s speed difference to drop it below orbital speed (or alternately boost it beyond escape velocity), the most likely thing you'll end up hitting is yourself at some point in the future.

    • (Score: 0) by Anonymous Coward on Saturday December 16 2017, @10:29AM (1 child)

      by Anonymous Coward on Saturday December 16 2017, @10:29AM (#610672)

      Looking down from the ecliptic, draw your orbit around the earth. Work out how fast you are travelling in that orbit. Fire a connonball in the reverse direction to your orbit, at your orbital speed. It is effectively stationary with respect to earth and, from the point of view of earth, will fall straight down. Not much of an orbit there, hey.

      • (Score: 2) by Immerman on Sunday December 17 2017, @04:14AM

        by Immerman (3985) on Sunday December 17 2017, @04:14AM (#610851)

        Certainly. However, very few cannons fire projectiles at ~8 km/s, which is orbital speed in low orbit.

    • (Score: 2) by Arik on Saturday December 16 2017, @06:18PM (2 children)

      by Arik (4543) on Saturday December 16 2017, @06:18PM (#610752) Journal
      "Unless you can somehow impart a several km/s speed difference to drop it below orbital speed "

      Exactly.

      And that's something that's not all that hard to do. The biggest problem is that when you fire a projectile off in one direction the entire station will accelerate in the other direction. As long as it's a relatively small object at a relatively low speed the change will be negligible, but depending on just how much the projectile weighs and how much velocity is required it might be a big deal. But in no way is it true to say it can't be done.

      --
      If laughter is the best medicine, who are the best doctors?
      • (Score: 2) by Immerman on Sunday December 17 2017, @04:21AM (1 child)

        by Immerman (3985) on Sunday December 17 2017, @04:21AM (#610853)

        Not *incredibly* difficult, in theory, but there's not a whole lot of devices out there for firing projectiles at Mach 24 (~8km/s), which is approximately Low Earth Orbit orbital speed. In fact, that's basically the entire purpose of massive rockets like the Falcon. Altitude is only responsible for about 5-10% of orbital energy, the rest is the insane speeds things travel at.

        • (Score: 2) by Arik on Sunday December 17 2017, @11:22AM

          by Arik (4543) on Sunday December 17 2017, @11:22AM (#610957) Journal
          Hah, I was waiting for someone to catch that.

          Yeah, that was a case of should have hit preview again, I lost an edit.

          Actually firing something at that velocity is still far from trivial. But it's not actually required to do the job.

          There are a couple of possible ways around it. One, of course, is to strap a rocket on the thing and fire it later. Still would need quite a powerful rocket, at least in proportion to the mass of the projectile, but clearly not all of the necessary deceleration has to come at the start. So we can add these things together, at least, the initial velocity, and some later impulse as well.

          But neither is going to easily add up to the full amount we want if we're thinking of it as fully kicking it out of orbit, countering the orbital velocity and bringing it to a standstill. But our goal is just to see it fall to earth, and to do that we don't need to make it stop on a dime. It would be sufficient just to nudge it into a more eccentric orbit, if that results in a perigee a little lower in the atmosphere, where drag can do the rest.
          --
          If laughter is the best medicine, who are the best doctors?