Why Christer and not Suni for EVA-4?

in article , Brian Gaff at
wrote on 12/18/06 9:04 AM:

"Craig Fink" wrote in message
news
On Mon, 18 Dec 2006 15:33:20 +0000, Jim Oberg wrote:

... EMU management issues that had pre-determined that Christer and not Suni
would make this 4th EVA? I want to make clear to my clients that Suni's not
going outside today had nothing to do with any performance issues on
Saturday -- which, there weren't any.

Who Lost the Camera? Looks like NASA is going to be going a bit Overboard to
make sure it doesn't happen again. Glued, Screwed and tethered. After making
such a big deal about a tiny light weight golf ball, NASA must be much more
worried about a much heavier camera with almost zero initial delta V and most
likely has a lower drag coefficient than the Space Station.

Fixed top posting

But what about the tool lost on an earlier eva this trip. I'm sure I did not
dream that. I understood that the camera issue was a broken catch of some kind
that meant only a light tug loosened it.

I was quite impressed by how she tackled that mess of cables. Goodness knows
how you figure out what goes where, and having to re route some deal with a
jammed cover and some cables joined when they should not have been etc. I know
they all train for this sort of stuff, but it sounded like a nightmare. I
have trouble disentangling my mains leads, so I can relate to the tether
confusion. This is why you have two people out there. I'd be more worried
with all this tethering that goes on pulling something vital off of the
outside of the station a at some future date.

Indeed, I think it was the tangle that unnerved her to the extent that, in
attempting to struggle, she broke the camera mount. I noticed a private
medical interview with Williams yesterday, so I would say she was either ill
not having to do with her EVA, or she was still recovering from the scare.

OTOH, I don't see the camera being a collision issue. It can't build up
enough relative velocity.

George Evans

"Danny Deger" wrote
Does anyone know if the ground radars have a track on the camera?

Yes, I do.
grin



























From today's on-orbit status report:

Lost EVA Camera Update: The Kodak DCS 760 still camera lost overboard
during EVA-3 is tracking below and in front of the station. After tomorrow's
(FD11) Shuttle undocking, it will be approximately 100 nmi in front of
Discovery, opening with 50 nmi per revolution.

The camera may or may not be a collision issue for the Space
Station depending on which way the camera fell relative to the space
station. If the camera has less drag, it fell up and may be a collision
issue in the future when the Space Station does a reboost. If the camera
fell down, more drag, then it's not an issue as I doubt the Space Station
is going to deliberately lower it's orbit below the camera.

If the camera fell up, then when the Station does a reboost it will have
to cross the altitude of the camera. Any future collision problem really
has to to with the angle between the velocity vectors. The difference in
the velocity vectors will most likely be very small, but the angle between
them will most likely be significant. The relative velocity will be huge.

Up or down, the camera gets a new number in the database. Worst yet,
nobody get to see the pictures.

--
Craig Fink
Courtesy E-Mail Welcome @
--

On Tue, 19 Dec 2006 02:43:20+0000, George Evans wrote:

OTOH, I don't see the camera being a collision issue. It can't build up
enough relative velocity.

didn't anybody read the report, below?

"Jim Oberg" wrote "Danny Deger"
wrote
Does anyone know if the ground radars have a track on the camera?

Yes, I do.
grin



























From today's on-orbit status report:

Lost EVA Camera Update: The Kodak DCS 760 still camera lost overboard
during EVA-3 is tracking below and in front of the station. After
tomorrow's (FD11) Shuttle undocking, it will be approximately 100 nmi in
front of Discovery, opening with 50 nmi per revolution.

Starting, undocking, rendezvous would be another level of redundancy. But
how many levels of redundancy are required. Failure one, the tether
breaking. The SAFER looks like it has two nozzles for each
direction, dual systems? That's two more failures to strand one astronaut.
Spacewalking is usally done with the buddy system, that add another three
failures to strand two astronauts. Six failures deep before "starting" a
Soyuz or Shuttle to go get stranded astronauts. Four without the tethers.

And that's not the only way to get a part or astronaut that is slowly
drifting away. Boating, nets are handy. Throw lines are specifically
designed for that purpose of getting someone back on board.

I would think NASA might actually have more of a problem with astronauts
accidently on purpose dropping something so they can take a little
tethered SAFER cruise. Like someone standing during entry when NASA had
no reasonable way of punishing the guy, it was his last mission. Using up
a little SAFER propellent at the end of the last spacewalk might even be
considered a nice reward for a sucessful mission. Plus, it would make
SAFER-2 even safer than SAFER. Use would show faults which leads to better
design.

--
Craig Fink
Courtesy E-Mail Welcome @
--

On Tue, 19 Dec 2006 01:57:57+0000, Danny Deger wrote:

How long would it take to "start" the Soyuz or the shuttle? My guess is too
long

in article , Craig Fink at
wrote on 12/19/06 3:31 AM:

The camera may or may not be a collision issue for the Space Station depending
on which way the camera fell relative to the space station. If the camera has
less drag, it fell up and may be a collision issue in the future when the
Space Station does a reboost. If the camera fell down, more drag, then it's
not an issue as I doubt the Space Station is going to deliberately lower it's
orbit below the camera.

The initial velocity relative to the station is more important than drag. If
the camera's initial velocity was generally forward and that it's relative
speed was a tenth of a foot per second, then, during the first orbit, will
loop up and back about 300 feet above the station, and end about a quarter
mile roughly behind the station. Each orbit would take it another quarter
mile behind. By the end of just the first day the camera would be six miles
back.

From the perspective of the station, if the camera has less drag, this
pattern will be exaggerated, placing the camera even farther back and
somewhat higher each day. In this case, when reboost occurs, it will take
the station forward and up above the orbit of the camera. If the camera has
more drag that component will eventually cause the camera to cross the
station orbit far behind and then safely under the orbit.

The only way the camera could even conceivably end up in the vicinity of the
station is initially going generally backward with less drag. In this case
the camera would loop forward six miles a day but then cross and begin drift
back and up. Reboost could conceivably cause the station to converge with
the camera.

Another interesting possibility is an initial direction perpendicular to the
station orbit. In this case the camera will make a close pass ever 45
minutes until differential drag removes it from the area. Of course each
pass will be at a tenth of a foot per second.

If the camera fell up, then when the Station does a reboost it will have to
cross the altitude of the camera. Any future collision problem really has to
to with the angle between the velocity vectors. The difference in the velocity
vectors will most likely be very small, but the angle between them will most
likely be significant. The relative velocity will be huge.

There is no way the relative velocity will ever be huge. At the very worst
I'm guessing there may be enough to take out an antenna, but nothing life
threatening.

Up or down, the camera gets a new number in the database. Worst yet, nobody
get to see the pictures.

This is the worst part of losing the camera.

George Evans

I agree with you about the short term, and the low velocity impacts on the
order of it's initial departing velocity.

I was talking about longer term. If the two are at different altitudes for
any length of time, precession become the main problem that gives the
relative velocity of the two a huge magnitude. Drag is the determining
factor, not initial velocity. If the object fell down (more drag) it's
gone forever as far as the Space Station is concerned. If it fell up (less
drag), then the Space Station has to cross it's altitude again at some
point in the future, depending on the reboost magnitudes and time
intervals, it may cross multiple times after spending a large amount of
time at different altitudes.

One on an ascending pass, the other descending would give a maximum of 114
degrees closing angle for an impact at equator. Faster than the orbital
speed of either, and the amount of damage would be tremendous. Luckily it
can be tracked.

Something smaller, like a nut or a bolt, it's just random luck when they
pass though each other's altitude.

Remember last flight, after the Shuttle left the Station and before the
deorbit burn. I wonder if the debris they saw was just a normal part of
the debris field leaving the Space Station, they just happened to be
parked in it for a while.

--
Craig Fink
Courtesy E-Mail Welcome @
--


On Wed, 20 Dec 2006 05:35:17 +0000, George Evans wrote:

in article , Craig Fink at
wrote on 12/19/06 3:31 AM:

The camera may or may not be a collision issue for the Space Station depending
on which way the camera fell relative to the space station. If the camera has
less drag, it fell up and may be a collision issue in the future when the
Space Station does a reboost. If the camera fell down, more drag, then it's
not an issue as I doubt the Space Station is going to deliberately lower it's
orbit below the camera.

The initial velocity relative to the station is more important than drag. If
the camera's initial velocity was generally forward and that it's relative
speed was a tenth of a foot per second, then, during the first orbit, will
loop up and back about 300 feet above the station, and end about a quarter
mile roughly behind the station. Each orbit would take it another quarter
mile behind. By the end of just the first day the camera would be six miles
back.

From the perspective of the station, if the camera has less drag, this
pattern will be exaggerated, placing the camera even farther back and
somewhat higher each day. In this case, when reboost occurs, it will take
the station forward and up above the orbit of the camera. If the camera has
more drag that component will eventually cause the camera to cross the
station orbit far behind and then safely under the orbit.

The only way the camera could even conceivably end up in the vicinity of the
station is initially going generally backward with less drag. In this case
the camera would loop forward six miles a day but then cross and begin drift
back and up. Reboost could conceivably cause the station to converge with
the camera.

Another interesting possibility is an initial direction perpendicular to the
station orbit. In this case the camera will make a close pass ever 45
minutes until differential drag removes it from the area. Of course each
pass will be at a tenth of a foot per second.

If the camera fell up, then when the Station does a reboost it will have to
cross the altitude of the camera. Any future collision problem really has to
to with the angle between the velocity vectors. The difference in the velocity
vectors will most likely be very small, but the angle between them will most
likely be significant. The relative velocity will be huge.

There is no way the relative velocity will ever be huge. At the very worst
I'm guessing there may be enough to take out an antenna, but nothing life
threatening.

Up or down, the camera gets a new number in the database. Worst yet, nobody
get to see the pictures.

This is the worst part of losing the camera.

George Evans

I agree with you about the short term, and the low velocity impacts on the
order of it's initial departing velocity.

I was talking about longer term. If the two are at different altitudes for
any length of time, precession become the main problem that gives the
relative velocity of the two a huge magnitude. Drag is the determining
factor, not initial velocity. If the object fell down (more drag) it's
gone forever as far as the Space Station is concerned. If it fell up (less
drag), then the Space Station has to cross it's altitude again at some
point in the future, depending on the reboost magnitudes and time
intervals, it may cross multiple times after spending a large amount of
time at different altitudes.

One on an ascending pass, the other descending would give a maximum of 114
degrees closing angle for an impact at equator. Faster than the orbital
speed of either, and the amount of damage would be tremendous. Luckily it
can be tracked.

Something smaller, like a nut or a bolt, it's just random luck when they
pass though each other's altitude.

Remember last flight, after the Shuttle left the Station and before the
deorbit burn. I wonder if the debris they saw was just a normal part of
the debris field leaving the Space Station, they just happened to be
parked in it for a while.

--
Craig Fink
Courtesy E-Mail Welcome @
--


On Wed, 20 Dec 2006 05:35:17 +0000, George Evans wrote:

in article , Craig Fink at
wrote on 12/19/06 3:31 AM:

The camera may or may not be a collision issue for the Space Station depending
on which way the camera fell relative to the space station. If the camera has
less drag, it fell up and may be a collision issue in the future when the
Space Station does a reboost. If the camera fell down, more drag, then it's
not an issue as I doubt the Space Station is going to deliberately lower it's
orbit below the camera.

The initial velocity relative to the station is more important than drag. If
the camera's initial velocity was generally forward and that it's relative
speed was a tenth of a foot per second, then, during the first orbit, will
loop up and back about 300 feet above the station, and end about a quarter
mile roughly behind the station. Each orbit would take it another quarter
mile behind. By the end of just the first day the camera would be six miles
back.

From the perspective of the station, if the camera has less drag, this
pattern will be exaggerated, placing the camera even farther back and
somewhat higher each day. In this case, when reboost occurs, it will take
the station forward and up above the orbit of the camera. If the camera has
more drag that component will eventually cause the camera to cross the
station orbit far behind and then safely under the orbit.

The only way the camera could even conceivably end up in the vicinity of the
station is initially going generally backward with less drag. In this case
the camera would loop forward six miles a day but then cross and begin drift
back and up. Reboost could conceivably cause the station to converge with
the camera.

Another interesting possibility is an initial direction perpendicular to the
station orbit. In this case the camera will make a close pass ever 45
minutes until differential drag removes it from the area. Of course each
pass will be at a tenth of a foot per second.

If the camera fell up, then when the Station does a reboost it will have to
cross the altitude of the camera. Any future collision problem really has to
to with the angle between the velocity vectors. The difference in the velocity
vectors will most likely be very small, but the angle between them will most
likely be significant. The relative velocity will be huge.

There is no way the relative velocity will ever be huge. At the very worst
I'm guessing there may be enough to take out an antenna, but nothing life
threatening.

Up or down, the camera gets a new number in the database. Worst yet, nobody
get to see the pictures.

This is the worst part of losing the camera.

George Evans


--
Craig Fink
Courtesy E-Mail Welcome @

Starting, undocking, rendezvous would be another level of redundancy. But
how many levels of redundancy are required. Failure one, the tether
breaking. The SAFER looks like it has two nozzles for each
direction, dual systems? That's two more failures to strand one astronaut.
Spacewalking is usally done with the buddy system, that add another three
failures to strand two astronauts. Six failures deep before "starting" a
Soyuz or Shuttle to go get stranded astronauts. Four without the tethers.

And that's not the only way to get a part or astronaut that is slowly
drifting away. Boating, nets are handy. Throw lines are specifically
designed for that purpose of getting someone back on board.

I would think NASA might actually have more of a problem with astronauts
accidently on purpose dropping something so they can take a little
tethered SAFER cruise. Like someone standing during entry when NASA had
no reasonable way of punishing the guy, it was his last mission. Using up
a little SAFER propellent at the end of the last spacewalk might even be
considered a nice reward for a sucessful mission. Plus, it would make
SAFER-2 even safer than SAFER. Use would show faults which leads to better
design.

--
Craig Fink
Courtesy E-Mail Welcome @
--
Craig Fink
Courtesy E-Mail Welcome @

The camera may or may not be a collision issue for the Space
Station depending on which way the camera fell relative to the space
station. If the camera has less drag, it fell up and may be a collision
issue in the future when the Space Station does a reboost. If the camera
fell down, more drag, then it's not an issue as I doubt the Space Station
is going to deliberately lower it's orbit below the camera.

If the camera fell up, then when the Station does a reboost it will have
to cross the altitude of the camera. Any future collision problem really
has to to with the angle between the velocity vectors. The difference in
the velocity vectors will most likely be very small, but the angle between
them will most likely be significant. The relative velocity will be huge.

Up or down, the camera gets a new number in the database. Worst yet,
nobody get to see the pictures.

--
Craig Fink
Courtesy E-Mail Welcome @
--
Craig Fink
Courtesy E-Mail Welcome @