Dynamics of a failed ISS

Many posts here discuss an ISS failure and breakup like a space borne bomber
dropping it's load on the world. Phrases like modules dropping off and
reentering along the ground track. It has to be a lot more complicated.
Sections breaking off are subject to the rotational dynamics of the station
as a whole as they break free as units plus all sorts connection related
smaller pieces. A detached module will interact with the atmosphere acording
to it's own mass and rotational profile with respect to the orbital velocity
vector. The ISS won't drop them as simple gravity bombs. Some may last
longer in orbit that the main unit. The whole mess is in orbit.

We could have candlelight vigils as the mess passes over us - this should
bring whole neighborhoods together. Might even spawn a new religion or two.

"We pray for a half more orbit
so it doesn't land on us.
Let it cease to fly
in someone else's sky
in some other place on Earth"

Sorry Robert - I just couldn't resist.

The amount of small junk left in orbit could be appreciable. Or the whole
mess may simply come down - breaking up on the way down with debris over
some large ellipse on the ground. If any halfway decent estimate of reentry
can be made the cruise industry might make a fair profit with cruises to
view the event.

It seems the real trade study is How much useful science are we getting from
the ISS vs the Potential for damage to LEO (debris limiting future launches)
and the Earth's surface. Useful science seems to be rapidly remaining at
zero as time goes to any future value. So this is an easy trade.

The next big question has to be - what is the probability that uncontrolled
reentry could cause damage to the extent that the general populace will
never back another effort to explore space. We are witnessing this now where
there is a general backlash against Nuclear Power Stations after the
disaster in Japan. We're considering cutting social security that retired
folks were taxed for their entire working life and continuing to fund a
useless potential disaster. The God's have a sense of humor and they love
us.


Val Kraut

On Sep 1, 7:11*pm, "Val Kraut" wrote:
Many posts here discuss an ISS failure and breakup like a space borne bomber
dropping it's load on the world. Phrases like modules dropping off and
reentering along the ground track. It *has to be a lot more complicated..
Sections breaking off are subject to the rotational dynamics of the station
as a whole as they break free as units plus all sorts connection related
smaller pieces. A detached module will interact with the atmosphere acording
to it's own mass and rotational profile with respect to the orbital velocity
vector. The ISS won't drop them as simple gravity bombs. Some may last
longer in orbit that the main unit. The whole mess is in orbit.

We could have candlelight vigils as the mess passes over us - this should
bring whole neighborhoods together. Might even spawn a new religion or two.

* * * * * * * * "We pray for a half more orbit
* * * * * * * * *so it doesn't land on us.
* * * * * * * * * Let it cease to fly
* * * * * * * * * in someone else's sky
* * * * * * * * * in some other place on Earth"

Sorry Robert - I just couldn't resist.

The amount of small junk left in orbit could be appreciable. Or the whole
mess may simply come down - breaking up on the way down with debris over
some large ellipse on the ground. If any halfway decent estimate of reentry
can be made the cruise industry might make a fair profit with cruises to
view the event.

It seems the real trade study is How much useful science are we getting from
the ISS vs the Potential for damage to LEO (debris limiting future launches)
and the Earth's surface. Useful science seems to be rapidly remaining at
zero as time goes to any future value. So this is an easy trade.

The next big question has to be - what is the probability that uncontrolled
reentry could cause damage to the extent that the general populace will
never back another effort to explore space. We are witnessing this now where
there is a general backlash against Nuclear Power Stations after the
disaster in Japan. We're considering cutting social security that retired
folks were taxed for their entire working life and continuing to fund a
useless potential disaster. The God's have a sense of humor and they love
us.

* * * * * * * * * * * * Val Kraut

ISS ground track is mostly over the most populated part of the
world.... probably any breakup would see some debris impacting
populated areas......

mjor damage or deaths will see demands to end man in space since
theres little science coming from the station even now with a full
crew of 6....... if social security and medicare are being cut, nasas
budget will be shrinking too

the untimely end of ISS might be a good thing, espically if no one
gets hurt.

nasa could move to small robotic explorers and perhaps some sample
return missions........

vehicles that cost far less, and cant risk human life either
astronauts of people on the ground.....

if they took nasas current budget and invested it this way, unmanned
robotics I wonder what we could afford?

" if they took nasas current budget and invested it this way, unmanned
robotics I wonder what we could afford?

I think you could do even better than you might originally think - the
shuttle is gone that frees up money, with the ISS gone you will free up ISS
and programs related to ISS. Stop NASA funded pork in congressman's
districts like planateriums etc. Congress seems to be already determined to
cancel JWST. I don't have the latest budget numbers - but add this up plus
the money already committed to probes - total has to be big bucks.


Val Kraut

I'm only half in jest when I suggest an abandoned end-of-life ISS serve as a
test platform for a VASIMR. Sending it out unoccupied into solar orbit might
be preferable to having it come down to Earth.

If not VASIMR perhaps a more conventional ion-electric system that feeds off
the solar panels and gradually takes it out of Earth orbit in a controlled
fashion?

If we left in unmanned to pass slowly through the Van Allen belts and then
park it somewhere like L4 / L5 or maybe even L2 you'd have a potential space
platform there waiting for future space cadets to figure out what to do with it.

We are looking for an excuse to re-invigorate manned space. Preventing an
uncontrolled decent of the ISS into populated areas or a decent altogether
sounds like a good enough reason to me.

Think of the ISS as an insurance program for manned space, we won't have
enough time to figure out how to do this all via unmanned systems.

Does life get any more weird?

Dave

David Spain wrote:
I'm only half in jest when I suggest an abandoned end-of-life ISS serve
as a test platform for a VASIMR. Sending it out unoccupied into solar
orbit might be preferable to having it come down to Earth.


If fact, actually, the more I think about it the more this makes sense.
Not necessarily the VASIMR part, but pushing the ISS further out into
cis-Lunar space.

Actually I think this thread would be more interesting if the topic were
instead of "Dynamics of a failed ISS", "Dynamics of the end-of-life ISS".

If you believe Heinlein, the ISS is already halfway to anywhere in the solar
system. So, why send all that hardware back to Earth? Let's park it somewhere
where it might actually have salvage value. Heck we've already paid the
biggest part of the price of the ticket to get it where it is now.

But this also begs the "bigger" question as well. Why build BIG objects in
LEO? Shouldn't we think BIG things should go further out, say to Lagrange and
save LEO for the smaller things?

First it reduces risk of big objects returning to Earth crashing onto
someone's head, second it is easier to loft smaller objects thus easier (less
costly) to station keep in LEO, and third if/when it does return to Earth
there is less hazard of it breaking into small pieces, some of which might
contaminate LEO for decades.

But I really like the idea of using old hardware for feedstock for future
programs. Why not? Why pay the price to get it up there twice?

Think "Junkyard Wars", the "Space" edition... ;-)

Structurally what can the ISS withstand to get it further out, to say a
Lagrange point? Could an ion-engine assist work? Do the solar arrays even
generate enough power to do it if all life-support were shutdown? How hard
would station keep at the Lagrange points be? What are the hazards if station
keeping at Lagrange fails?

Henry doesn't think we have electronics hardened enough to withstand a slow
transit across the Van Allen belts for an un-crewed automated journey, which
is the true shame.

I would postulate that for this idea to have a chance it would require some
retro-fit anyway, if we gave some forethought to this idea maybe we could come
up with something that would work, even if it uses vacuum tubes! ;-D

Dave

David Spain wrote:
Structurally what can the ISS withstand to get it further out, to say a
Lagrange point?

Or just into a higher EO, one where we won't have to deal with it for decades
or centuries rather than "within a decade".

Dave

: Pat Flannery
: You get it into the Van Allen belts long enough, and the metals on it
: might ending up being partially isotopes.

Really? Are there neutrons in the VABs (didn't expect there was anything`
but charged particles) or high enough energy particles (didn't expect they
were much above non-flare solar wind energy)?

Wayne Throop wrote:
: Pat Flannery

: You get it into the Van Allen belts long enough, and the metals on it
: might ending up being partially isotopes.

Really? Are there neutrons in the VABs (didn't expect there was anything`
but charged particles) or high enough energy particles (didn't expect they
were much above non-flare solar wind energy)?

No, not really. There aren't enough neutrons so there aren't enough
particles to induce much change. Some impacts from cosmic ray primaries
will happen, though, and those can trigger isotope changes (the source
of carbon-14). Some of the Van Allen belt shielding deflects cosmic
ray primaries but nearly all of that happens in the atmosphere. How
high the orbit is makes very little difference.

On 9/6/2011 8:59 AM, David Spain wrote:
David Spain wrote:
But this also begs the "bigger" question as well. Why build BIG objects
in LEO? Shouldn't we think BIG things should go further out, say to
Lagrange and save LEO for the smaller things?

In a word, radiation. The ISS is about as high as you can go before the
crew needs radiation shielding to protect them from the inner Van Allen
belt, especially during solar storms.
Other than that, the further out you go your orbital lifetime increases
dramatically between needing velocity boosts.
If you could get it in a 1,000 mile high orbit, the air drag would be so
low that it could stay up for decades, if not centuries.

First it reduces risk of big objects returning to Earth crashing onto
someone's head, second it is easier to loft smaller objects thus easier
(less costly) to station keep in LEO, and third if/when it does return
to Earth there is less hazard of it breaking into small pieces, some of
which might contaminate LEO for decades.

By the time it would be getting enough heating and aerodynamic stress to
start breaking up on reentry all the parts of it would be going slow
enough that none would stay in orbit, and they all would reenter also.

But I really like the idea of using old hardware for feedstock for
future programs. Why not? Why pay the price to get it up there twice?

Think "Junkyard Wars", the "Space" edition... ;-)

Structurally what can the ISS withstand to get it further out, to say a
Lagrange point? Could an ion-engine assist work?

At it's present altitude, the low thrust that a ion engine could provide
may be less than the aerodynamic drag on it, so that although using ion
motors on it would extend its orbital lifetime, they may not be able to
increase it orbital height. The ISS' big solar arrays turn out a lot of
electrical power, but they add a lot of air drag also.
If you could figure out some other way to get the orbit higher, then the
air drag would be low enough to make the ion engine alternative work for
getting into a yet higher orbit... but there's still the radiation of
the inner and outer Van Allen belts to contend with, and until you are
higher than those, the station will be a very unhealthy place for human
crew. Apollo got around the problem by going very fast during the early
phase of the flight and on lunar return, so that the time spent in the
belts wasn't long, and the crew could take the radiation exposure, but a
ion engine climbing station is a whole other ball of wax and will be
spending weeks or months in the belts.
Then once it's above them, it will be facing solar storm radiation
requiring the crew to have some sort of shielded "Solar Storm Shelter"
they can retreat to for the hours or days until the storm passes

even generate enough power to do it if all life-support were shutdown?
How hard would station keep at the Lagrange points be?

At two of them it should be long term stable, with no energy needing to
be expended to keep it there - L-4 and L-5.
It would slowly make a small orbit around the center of the point in
space each month as the Sun-Earth-Moon positions changed.
The other points (L-1, L-2, and L-3) are unstable, so you would have to
fire up your ion engines to stay in position at them.

What are the
hazards if station keeping at Lagrange fails?

It depends how far out of synch it gets, if it gets way out of synch at
L-1 or L-2 it could either impact the Moon or get tossed into solar
orbit by the Moon's gravitational effects in combination with those of
the Sun and Earth as their geometry changes in comparison with each other.
At L-3, it would end up drifting in Earth orbit at the same distance as
the Moon, but on the other side of the Earth... eventually it might
drift around to the side the Moon's on, and possibly either hit it or be
catapulted into solar orbit as it passed through the lunar gravity field.


Henry doesn't think we have electronics hardened enough to withstand a
slow transit across the Van Allen belts for an un-crewed automated
journey, which is the true shame.

Another shame is that breathing air is made on the ISS by using the
electrolysis of water to break it down into hydrogen and oxygen gasses,
with the hydrogen gas being dumped overboard... that could have been
used as mass for the ion engine to accelerate to provide thrust.

Pat