ISS needs RotoRooter

David Lesher wrote:
That was the basic idea with the Salyut/Mir airlock trash ejections.
Jettison it with enough velocity to clear the microgravity environment
of the station and let atmospheric drag slow it down till it reentered
several weeks or months later.


I was looking for an approach that didn't waste air on such...


The scientific airlock on Mir was pretty small; it was a sphere around
three feet in diameter with a hemispherical domed hatch making up its
top half and around a two-foot diameter cylindrical ejection hatch
joined to the exterior of the station. Once the trash bag was in the
airlock the total amount of air lost during ejection wouldn't be that high.

I'm thinking torsion catapult, seeing as how a trebuchet might have some
issues without a gravity field...


On Mir, the trash got ejected at a ninety degree angle to the orbital
path so it didn't affect the orbital velocity of the station when used.
One of the plans for Space Station Freedom was going to use a linear
accelerator to fire the crew's solid waste at high velocity backwards to
its orbital path, causing the waste to fall into the atmosphere right
after ejection...while at the same time using the recoil to help prevent
orbital decay via air drag by adding velocity to the station itself.
Although a interesting idea, this concept got a lot of fun poked at it. :-D

Pat

On Mon, 02 Jun 2008 17:23:41 -0500, "Jorge R. Frank"
wrote:

If it doesn't experience enough atmospheric drag on it's first
independent orbit, isn't the baggie going to meet after once around
back at the point of the original impulse, and perhaps go "splat" on a
viewport or solar array?

Only if the designers are silly enough to have the system eject in the
radial or out-of-plane direction.

....And let us not forget that the waste will have been freeze-dried
long before the orbit is complete, which means it wouldn't go "splat",
but more like "*THWACK!!!*" or "*B*A*M*!*", with a "ping!" or twelve
at least.

OM
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On Mon, 02 Jun 2008 17:32:38 -0500, Pat Flannery
wrote:

One of the plans for Space Station Freedom was going to use a linear
accelerator to fire the crew's solid waste at high velocity backwards to
its orbital path, causing the waste to fall into the atmosphere right
after ejection...while at the same time using the recoil to help prevent
orbital decay via air drag by adding velocity to the station itself.
Although a interesting idea, this concept got a lot of fun poked at it. :-D

....Most of them also led straight into the old question as to whether
one could propel themselves by farting in zero-gee.

OM
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wrote:

If it doesn't experience enough atmospheric drag on it's first
independent orbit, isn't the baggie going to meet after once around
back at the point of the original impulse, and perhaps go "splat" on a
viewport or solar array?


The Russians ejected it downwards, so it would end up in a orbit with a
slightly different apogee and perigee.
At least I assume that was the case; when a Soyuz was docking with Mir's
multiple docking adapter, the station was aligned so that the Soyuz
would approach it from above, with the rear Kvant module facing the Earth.
One of the things that led to the Mir/Progress collision was that the
Mir crew were having a hard time seeing the Mir against the Earth from
the television cameras of the approaching Progress, as it came in from
above them.
In that case the ejection would be in a circle around the station,
either increasing, decreasing in velocity in comparison to the
station's orbit, or ending up in a orbit with a slightly different
inclination.
Even if it did go around once a hit the station (and this sounds like
something that's only going in mathematical simulations, not the real
world where the Earth isn't completely homogeneous in density, and
orbits aren't going to be completely perfect) its velocity would be
very low, so it probably wouldn't do any damage.
Which brings up another point...say it exits the Mir at five meters per
second.
Figure out exactly how long it's going to take for it to circle the
Earth and end up where the station is again.
Earth has a diameter of around 12,736 km in Mir's orbit, and we have to
add around 1,000 km to that to match its orbital height (around a 500 km
radius increase) to that, so we are talking about a diameter of 13,736
km, which equals a circumference of around 43,150 km. At a velocity of 5
mps, it's going to take 43,150,000 seconds to get around the Earth once
and re-contact the station. That equals right around 500 days, so it's
probably going to have reentered before it gets to that point again.
Even if it did stay in orbit that long, the station would have been
reboosted by a Progress by then, so the Mir and the trash would no
longer be in the same orbit. Aerodynamic drag on the trash bag would
have moved it into a new and lower orbit also.

Obviously it's a big planet and a small target so the amount of
ongoing influence necessary to insure a miss the first time around
would be slight - but I'd be curious to know if enough occurs that
it's considered safe. I suppose even a hit is likely to be at fairly
low velocity (whatever you accelerated it to on separation) but could
also make approach interesting if a shuttle, soyuz, or progress is due
in the next week or so.

Now if they left out the antiseptic, fitted the bag with a nozzle
sealed by a low-pressure membrane, and stored it for *just* the right
amount of time before jettisoning...


In space no one can hear you fart.

Pat

"OM" wrote in message
...
...Most of them also led straight into the old question as to whether
one could propel themselves by farting in zero-gee.

Somewhere in storage I have a paperback, one of a series of generic novels,
this one "Science Fiction", which came with a space cadet, a plucky heroine
and a mad scientist. Don't recall a personality-filled monkey. However, I do
recall the space cadet getting caught in a zero-g tunnel, having let go of
the hand rail, and being unable to get back to the rail. Said cadet ended up
using bits of uniform as reaction mass and had just tossed his underwear
when the visiting admiral entered the tunnel...


** Posted from http://www.teranews.com **

"OM" wrote in message
...
...Most of them also led straight into the old question as to whether
one could propel themselves by farting in zero-gee.

If one intends to ignite said fart, consider this:
http://firechief.com/training/appare...-defense-0101/


** Posted from http://www.teranews.com **

Jorge R. Frank wrote:

Only if the designers are silly enough to have the system eject in the
radial or out-of-plane direction.

I don't know if they changed Mir's orientation for trash ejection, but
the airlock jettisoned the trash out of the bottom of the main module in
relation to the crew's operating orientation in orbit.
The scientific/trash ejection airlock is the spherical thing in the
bottom of the large diameter part of the station core module in this
cutaway:
http://www.astronautix.com/graphics/m/mircut.jpg


If the designers have enough rudimentary smarts to have the system
eject retrograde, the resulting orbit will have a shorter period so
that by the time the trash returns to apogee, it will be considerably
ahead of the station.

The Nudelman space cannon* was fired retrograde on the Almaz/Salyut-3
station during the on-orbit firing tests:
http://www.russianspaceweb.com/almaz_ops2.html ...to allow the shells to
fall into the atmosphere very shortly after firing - which must have
generated one mighty impressive artificial meteor shower, particularly
after the explosives in the shells detonated due to atmospheric heating
and fragmented the casings of the shells.

* Either 23mm or 30mm depending on the source.

Pat

OM wrote:
...And let us not forget that the waste will have been freeze-dried
long before the orbit is complete, which means it wouldn't go "splat",
but more like "*THWACK!!!*" or "*B*A*M*!*", with a "ping!" or twelve
at least.


Considering that Mir got rammed by a Progress and somehow survived, I
wouldn't be too concerned about a low-velocity impact by a bag of
freeze-dried turds.
(Of course, if one were to soak those turds in hydrogen peroxide and
leave the bag of them burning just outside the ISS airlock door, it
would be a pretty good joke.) :-D

Pat

OM wrote:
One of the plans for Space Station Freedom was going to use a linear
accelerator to fire the crew's solid waste at high velocity backwards to
its orbital path, causing the waste to fall into the atmosphere right
after ejection...while at the same time using the recoil to help prevent
orbital decay via air drag by adding velocity to the station itself.
Although a interesting idea, this concept got a lot of fun poked at it. :-D


...Most of them also led straight into the old question as to whether
one could propel themselves by farting in zero-gee.


One of the problems with this concept is the system that's going to take
up the recoil of the launcher and transmit to the main station structure
in a way that doesn't over-stress it in such short period of time as the
"turd cannon" gets fired.
If you want to aid the station in maintaining its orbital altitude
without frequent reboosts, then to me it would seem like ion engines
would be the way to go. Any electrical energy from the solar arrays the
station wasn't using at the moment could be diverted to the ion engines,
and at the same time one could try out new ion engine designs.
That concept seems so straightforward that I find it odd it wasn't
incorporated in the ISS design.

Pat

On Tue, 03 Jun 2008 00:32:00 -0500, Pat Flannery
wrote:

(Of course, if one were to soak those turds in hydrogen peroxide and
leave the bag of them burning just outside the ISS airlock door, it
would be a pretty good joke.) :-D

[Cut to: Cosmonaut outside of airlock in Orlan suit, trying to stomp
out the fire]

Cosmonaut: "Bozhemoi! Shtool!"

Cosmonaut 2: "Comrade! Remember, wipe feet before reentering airlock!"


OM
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] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
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