RED threshold late notice conjunction threat to ISS - Crew may evac into Soyuz

[Chris Bergin]

Still turning around several memos, so this will be updated:

http://www.nasaspaceflight.com/2009/03/threat-to-iss-crew-soyuz/

[Chris Bergin]

Updated the article. We'll see what happens over the next hour or so.

[bodge]

If anyone's following, there's audio d/link available right now from NASA TV online on the "Live Space Station Video" channel.

[Lee Jay]

If anyone's following, there's audio d/link available right now from NASA TV online on the "Live Space Station Video" channel.

http://www.nasa.gov/178952main_Mission_Audio_UP.asx

Sound's like they're going into the Soyuz.

[Captain Scarlet]

Wow, closing hatches now.

"We're with you every step of the way on this."

[bodge]

Also, if I got the right PAM debris, then this might be the tracking of it and the ISS on one map...
http://www.n2yo.com/?s=25090|25544

[Chris Bergin]

Yep, closing hatches, looks like they are going to be moved to Soyuz.

(Remember, this is a contingency).

[Stowbridge]

None of the other news sites are reporting this.

[shuttlefan]

Are they getting into their entry suits as well?

[Colds7ream]

Sounds like they're busy sealing off Harmony...

[marsavian]

None of the other news sites are reporting this.

Don't worry they will be there like vultures at the post-event conference ready to write their doom and gloom stories.

[Chris Bergin]

Last forward hatch is closed.

None of the other news sites are reporting this.

We aren't making it up. The memos are official and the loops pretty much says it all.

[Colds7ream]

Closing Destiny now?

[NavySpaceFan]

Heard COL Finke say they are closing the starboard hatch on Unity as well.

[Colds7ream]

So in the event that a module does get holed, will they reattach any modules connecting to it to a different CBM?

[NavySpaceFan]

US segment isolated according to COL Finke.

[Chris Bergin]

All three members of the crew needs to be in Soyuz in 20 minutes.

[Colds7ream]

Out of interest, how come there hasn't been a DAM performed for this?

[Lee Jay]

Out of interest, how come there hasn't been a DAM performed for this?

Conjunction's close distance discovered too late.

[Jorge]

Out of interest, how come there hasn't been a DAM performed for this?

Conjunction close distance discovered too late.

Right - it's even in the subject line of the thread...

[bodge]

Anyone have the guidelines for what make a conjunction 'Red' vs medium or low?

[bodge]

Also, looking at the tracking map, it looks like the conjunction will occur somewhere over the west coast of Africa, if not slightly inland.

[Chris Bergin]

Less than 10 minutes to the requirement for crew to be in Soyuz.

[mmeijeri]

If like me you are struggling to get multi-tracking to work, here's a link:

http://www.n2yo.com/?s=25090|25544

If you click 'draw lines', it makes it easier to find both the ISS and the debris. You will have to copy the URL, since the |25544 bit gets left off by the forum software.

[NavySpaceFan]

Finke and Magnus now on board Soyuz.

[Chris Bergin]

Col. Finke: "We are ready to depart" (in the case they need to).

[Chris Bergin]

Now just minutes away from the conjunction threat.

[Chris Bergin]

This is hardly to scale, obviously...

[Edgecrusher]

Looking at the real-time satellite tracker is really unnerving....

[Chris Bergin]

Ok, so now we wait on instrumentation, such as pressure checks I assume.

[simonbp]

If it's hit, it's already happened...

Simon

[Colds7ream]

Awaiting a signal with held breath...

[bodge]

Anyone speak Russian? All I got from the downlink was 'Good'.

[Chris Bergin]

Staying in Soyuz for five more minutes - MCC-M.

[psloss]

Sorry if I missed this post earlier, but nasa.gov notes the conjuction, also notes the :35 to :45 period in the Soyuz:
http://www.nasa.gov/station/

Station Crew Takes Precautionary Measures Due to Space Debris

International Space Station Expedition 18 crew members are taking precautionary measures due to space debris that has been determined to be within the range where a collision is possible. News of the close approach came too late for flight controllers to coordinate an avoidance maneuver. A portion of a spent satellite motor is within the distance of the station's debris avoidance maneuver requirement "box."

Crew members are entering their Soyuz TMA-13 capsule and soft-locking the hatches, in case the debris should affect the space station and they are required to undock. The closure of the hatches ensures the safety of the crew and the ability to quickly depart the station in the unlikely event the debris collided with the station causing a depressurization.

The time of closest approach of the debris to the station is 12:39 p.m. EDT. Once the object is clear of the station, the crew will exit the Soyuz and reopen the hatches.

The crew will be in the Soyuz from 12:35-12:45 p.m. EDT. They will remain in the Soyuz until the debris risk has passed. Moving the crew into the Soyuz is a precaution, as the probability of impact is low. The crew is currently putting space station into an unmanned configuration, including several interior station hatches.

[Lee Jay]

GO to egress.

[Chris Bergin]

Object missed Go to egress Soyuz.

[Colds7ream]

Seems all is well! :-D

[shuttlefan]

GO to egress.

You mean the soyuz I hope...

[Lee Jay]

GO to egress.

You mean the soyuz I hope...

 

[generic_handle_42]

I believe it was Leroy Cain who said after the STS-93 ascent, "We don't need any more of these!"

[stockman]

phew!!  I guess they will have to break out the emergency Vodka once they are back inside... - quite an exciting issue...

[shuttlefan]

Object missed Go to egress Soyuz.

When will we know by how far?

[DaveS]

I believe it was Leroy Cain who said after the STS-93 ascent, "We don't need any more of these!"

It was John Shannon. He was the Ascent FD for that flight.

[generic_handle_42]

I believe it was Leroy Cain who said after the STS-93 ascent, "We don't need any more of these!"

It was John Shannon. He was the Ascent FD for that flight.

Thank you sir!  I stand corrected!

[KEdward5]

I believe it was Leroy Cain who said after the STS-93 ascent, "We don't need any more of these!"

It was John Shannon. He was the Ascent FD for that flight.

Thank you sir!  I stand corrected!

The "Yikes, you bet, concur, we don't need any more of these" video clip is the third attachment on this post,
http://forum.nasaspaceflight.com/index.php?topic=9944.msg189521#msg189521

"STS-93L2VideoECOs.wmv"

[generic_handle_42]

Yep, seen the video, just misplaced the voice!

Fincke just got done asking the ground for "details" later.  He didn't sound impressed!

[ChrisGebhardt]

I believe it was Leroy Cain who said after the STS-93 ascent, "We don't need any more of these!"

So say we all!


Man... I didn't need this excitment today.

[NavySpaceFan]

Anyone know the actual distance at Closest Point of Approach?  I'd log this down as a drill, a very realistic drill.

[Citabria]

Anyone know the actual distance at Closest Point of Approach?

And the relative velocity?

Is velocity a factor in determining the RED condition?

[ChrisGebhardt]

Anyone know the actual distance at Closest Point of Approach?

Is velocity a factor in determining the RED condition?

I would very much assume yes. This is how I'm thinking about this. An object travelling at 17,500mph in a southwest to northeast orbital trajectory collides with another object travelling 17,500mph in a northwest to southeast orbit. Those two objects would hit at a 90-degree angle.

An object travelling at 17,500mph in a southwest to northeast orbit colildes with another object travelling at 17,550mph that is also in a southwest to northeast orbit.

In these case, while any direct hit of any kind would not be good, I would say that it's much different being hit side-on by an object travelling at full-force 17,500mph than being hit by an object at 50mph.

(Basically, it's like being t-boned by a semi-truck travelling much faster than you are and travelling in a different direction v. having a fender-bender when someone hits the back of your car.)

Also, based on my line of reason (which someone please correct if it's wrong) is that orbital trajectories also play a factor.

[blazotron]

Just saw this amusing text on CNN:

"The debris was too close for the space station to move out of the way, so the station's 18 crew members were temporarily evacuated to a the station's Soyuz TMA-13 capsule, NASA said. From there, the crew could have undocked from the space station if the situation had become dangerous."

http://www.cnn.com/2009/TECH/03/12/space.station.evacuation/

That's one hell of a soyuz.

(edited to add link)

[ugordan]

Is velocity a factor in determining the RED condition?

I don't think so, even very small angles between their geocentric velocity vectors (assuming both objects are travelling at say 7.5 km/s) give dangerously large relative velocities.

Say a 2 degree difference in their orbital planes would give about 260 m/s impact speed if my math is correct.

[Jorge]

Anyone have the guidelines for what make a conjunction 'Red' vs medium or low?

The RED threshold is defined solely as probability of collision (Pc) > 10^-4. (Flight Rule B4-101 paragraph A.4).

[Ben the Space Brit]

Y'know, I remember waaayyy back in pre-ISS days, during the countdown to the launch of the FCB, I heard someone (I think it was on BBC news) seriously suggesting that a permanently-manned orbital outpost would need a laser turret fitted to it to disintegrate possibly dangerous debris. 

I'm not laughing so hard right now, I don't mind saying.

Just out of curiosity, how many of these near-evacs have been needed during the ISS's entire lifetime? I can't remember any others off-hand but, as has just been abundantly proven, these things seem to go under the Mainstream Media's radar unnoticed.

[Colds7ream]

Just saw this amusing text on CNN:

"The debris was too close for the space station to move out of the way, so the station's 18 crew members were temporarily evacuated to a the station's Soyuz TMA-13 capsule, NASA said. From there, the crew could have undocked from the space station if the situation had become dangerous."

http://www.cnn.com/2009/TECH/03/12/space.station.evacuation/

That's one hell of a soyuz.

Seriously, would it be possible, just once, for these people to check their facts before publishing? :-(

[ugordan]

Just saw this amusing text on CNN:

Seriously, would it be possible, just once, for these people to check their facts before publishing? :-(

There's something about CNN and the number 18 when reporting space - remember the "Columbia broke up while going 18 times the speed of light" text...?

[mmeijeri]

Seriously, would it be possible, just once, for these people to check their facts before publishing? :-(

Here's another gem from the BBC:

"Nasa spokesman Josh Byerly said the debris was was 2.54cm (about one-third of an inch) in width. "
http://news.bbc.co.uk/2/hi/science/nature/7940431.stm

[Ben the Space Brit]

Here's another gem from the BBC:

"Nasa spokesman Josh Byerly said the debris was was 2.54cm (about one-third of an inch) in width. "
http://news.bbc.co.uk/2/hi/science/nature/7940431.stm

Please, God, let this be a symptom of the BBC's recently-acquired inability to use imperial units of measurements, not the actual words of the NASA spokesman.

That aside, one inch width at the sort of relative velocities we're talking about here would be like shooting the ISS with an anti-aircraft round at close range.  It would have blown a fist-sized hole through the hull and made a mess of the interior of any module it hit.  A close shave indeed.

[astrobrian]

Fox news had it at a 7 member crew, I never knew the station was such a busy place with comers and goers  3, 7, 18 , who knew 

[Colds7ream]

I see CNN have corrected themselves... :-)

[david1971]

Just saw this amusing text on CNN:

"The debris was too close for the space station to move out of the way, so the station's 18 crew members were temporarily evacuated to a the station's Soyuz TMA-13 capsule, NASA said. From there, the crew could have undocked from the space station if the situation had become dangerous."

Looks like Bruce Willis dodged a close one...

[erioladastra]

- The difference between red and yellow is how large the probability of collision is.  It is a statistical number based on error of the solution.  This was red which meant a higher probability of collision but it was never a “valid” Pc which means there was not enough data to get a sure fit.
- We will never know how close it came – since we didn’t have radar on it at the time, more data would mean you have to project back, which would be just as accurate as we had projected forward.
- Due to late notices a Debris avoidance maneuver could not be planned in time.
- The radar cross section was 0.009M^2 – could be big but recall this is what the radar sees.  Could have been much bigger.  Or smaller.
- No, you can just move a module and rebolt it on to another CBM.  All the data, fluid lines and ventilation are all plumbed one way.  Physically, it wouldn’t be doable anyway.

[JLicklider]

Here's gloom and doom for ya;
Drudge Report top headline: DEBRIS SCARE FORCES ASTRONAUTS TO EVACUATE SPACE STATION
The link takes you to this article which is not as hyped up:
http://www.breitbart.com/article.php?id=D96SK9083&show_article=1

It does say the debris was less than an inch, but that a small piece can cause huge damage. 

<flame suit on>
I personally would like to defend the media for a moment.  They see their job as a responsibility to get information out as fast as possible.  Unfortunately too many times that speed comes at the expense of errors and outright incorrect information.  More than likely they do not have access to L-2 here at NSF, or even browse the free forums.  But that is no excuse for reporting incorrect information.  CNN did get something wrong, but corrected themselves.  "The stations 18 crew members" could easily have been meant to be written as " the stations Expedition 18 crew members."  Simple mistake. 
We have to understand the news agencies have to report about everything, and are not as 'into' space information as those of us lurking, and better yet contributing to, these forums. 
<flame suit off>

Joey

[ShuttleDiscovery]

Wow sounded like a bit of a scare up there. I'm glad everything is ok.

[bodge]

Anyone have the guidelines for what make a conjunction 'Red' vs medium or low?

The RED threshold is defined solely as probability of collision (Pc) > 10^-4. (Flight Rule B4-101 paragraph A.4).

Interesting. This makes me wonder at what probability of collision you just decide to leave station altogether, then re-dock after the event is over. Given a large enough impact energy I'd personally think it'd be better to get away from ISS sooner than later..when there might be a debris cloud that you now have to evac through instead of away from. Not to mention...couldn't the debris just as likely whack into the Soyuz itself while waiting docked? Is there anything worse than a condition red?

[Herb Schaltegger]

Here's another gem from the BBC:

"Nasa spokesman Josh Byerly said the debris was was 2.54cm (about one-third of an inch) in width. "
http://news.bbc.co.uk/2/hi/science/nature/7940431.stm

Please, God, let this be a symptom of the BBC's recently-acquired inability to use imperial units of measurements, not the actual words of the NASA spokesman.

That aside, one inch width at the sort of relative velocities we're talking about here would be like shooting the ISS with an anti-aircraft round at close range.  It would have blown a fist-sized hole through the hull and made a mess of the interior of any module it hit.  A close shave indeed.

However, to put things in perspective . . . during the SSF design process (for the Lab, Hab, nodes, etc.) I was once tasked with estimating the time for loss of pressure for an arbitrary-sized hole on the pressure shell of the station.  Granted, some of the starting assumptions no longer hold (such as we don't have a Hab module and the third and fourth nodes, but of course we now add on Russian segments . . . etc.), but even for a one-inch diameter hole it would take a surprisingly long time for the pressure to drop to vacuum inside the station, even assuming no hatches were closed and the ACS didn't attempt to maintain pressure.  The flow goes sonic and chokes at the hole, limiting flow rate.

Of course, the hole might be substantially bigger than one inch.  More worrisome to me is if the debris struck an outlying element and broke up into many smaller objects all big enough to penetrate the MDS in several modules.  THAT makes all predictions null and void, no refunds, no returns.

[mmeijeri]

Of course, the hole might be substantially bigger than one inch.  More worrisome to me is if the debris struck an outlying element and broke up into many smaller objects all big enough to penetrate the MDS in several modules.  THAT makes all predictions null and void, no refunds, no returns.

I vaguely remember reading about "self-healing" hull panels with some kind of embedded foam capsules. Whatever happened to that?

[Jorge]

Anyone have the guidelines for what make a conjunction 'Red' vs medium or low?

The RED threshold is defined solely as probability of collision (Pc) > 10^-4. (Flight Rule B4-101 paragraph A.4).

Interesting. This makes me wonder at what probability of collision you just decide to leave station altogether, then re-dock after the event is over. Given a large enough impact energy I'd personally think it'd be better to get away from ISS sooner than later..when there might be a debris cloud that you now have to evac through instead of away from. Not to mention...couldn't the debris just as likely whack into the Soyuz itself while waiting docked? Is there anything worse than a condition red?

No, not under the current rules.

[elmarko]

I'm sure Chris, seen as he's in the business, will backup my point that the media is not always misinformed, they just don't have the time or the resources to actually fact check due to the pressure they are under.

I guarantee you that any incorrect detail in a story, if brought to the attention of the writer, will make that writer feel slightly dismayed. People do actually take pride in their work, but they can't always give it 100% for lots of reasons.

Also, I don't mind admitting that I was quite scared this afternoon. Waiting for them to speak after TCA reminded me of that big in Apollo 13 when everyone is waiting for them to come out of blackout :/

[JimO]

All the discussion about how big a hole the impact might make and then how long it might take for the air to leak out may be irrelevant. As I recall, hypervelocity impacts of this type don't drill holes, they create explosions in the hull -- tiny, small, medium, and hideous. The bigger explosions rupture into the cabin interior and ignite a shock front of flame across the pressurized cabin. And not a singe-your-eyebrows-and-jump-back-wincing kind of flame either; crispy critter kinda flame. Worrying about breathing after such an event might be extraneous.

Am I thinking of only pure oxygen cabins, or does this effect also rule in 80/20 N2?O2 mixes too?

[rdale]

Conjunction:    At 12:39pm EDT, the ISS had a conjunction with a small piece of orbital debris (Object #25090, PAM-D debris) which passed by the station inside the Red Threshold.  Due to late notification, which was well beyond the timeline for maneuvering, a DAM (Debris Avoidance Maneuver) could not be performed.  As a precaution, the three crewmembers withdrew to the Soyuz 17S capsule at 12:35pm, leaving the spacecraft’s hatch open (in case the Soyuz itself was struck).  The crew returned to the ISS at ~12:45pm.     [The late notification was due to the high uncertainty of the object’s location on its low-perigee (154 km), high eccentricity orbit, which resulted in an error in solar radiation pressure prediction.  Subsequent correction of this value brought the object into the Red box.]

[joncz]

As I recall, hypervelocity impacts of this type don't drill holes, they create explosions in the hull -- tiny, small, medium, and hideous. The bigger explosions rupture into the cabin interior and ignite a shock front of flame across the pressurized cabin. And not a singe-your-eyebrows-and-jump-back-wincing kind of flame either; crispy critter kinda flame. Worrying about breathing after such an event might be extraneous.

Am I thinking of only pure oxygen cabins, or does this effect also rule in 80/20 N2?O2 mixes too?

You're describing any typical kinetic energy weapon, such as Lockheed's CKEM / LOSAT:



There is no warhead, just a tungsten penetrator.

[yinzer]

All the discussion about how big a hole the impact might make and then how long it might take for the air to leak out may be irrelevant. As I recall, hypervelocity impacts of this type don't drill holes, they create explosions in the hull -- tiny, small, medium, and hideous. The bigger explosions rupture into the cabin interior and ignite a shock front of flame across the pressurized cabin. And not a singe-your-eyebrows-and-jump-back-wincing kind of flame either; crispy critter kinda flame. Worrying about breathing after such an event might be extraneous.

Am I thinking of only pure oxygen cabins, or does this effect also rule in 80/20 N2?O2 mixes too?

"A wave of flame" sounds suspiciously like a oversimplification and dramatization rather than an accurate description, as does "explosion".

What you're talking about is how the energy from the projectile gets transferred to the inside of the ISS if its debris shielding fails.

This debris shielding is based on the Whipple bumper principle: disrupt the incoming projectile with an outer shield so that the inner shield gets hit with an easier-to-tolerate spray of superheated gas and debris rather than a solid object.  Whipple shield performance in terms of projectile size and velocity is not simple.  At low speeds, you can obviously stop a pretty big projectile, because there's just not that much energy to deal with.  As the projectile speed increases up to about 3 km/sec the projectile size you can stop decreases rapidly.  As speeds increase further, the Whipple bumper effect starts to come into play, and the projectile size you can tolerate goes up.  The ISS can stop a sphere weighing nearly ten times as much at 6 km/sec as it can at 3 km/sec.  As the speed increases further, even the fully disrupted projectile can penetrate the inner shield.

What happens inside the ISS is probably a question of how much energy can you transfer to the internal atmosphere, and will depend greatly on the type of the projectile.  Something heavy and comparatively slow-moving (think armor-piercing shell) could penetrate the debris shielding easily but could go right on through.  Something fully disrupted will dump more energy into the ISS atmosphere, which is going to create a shock with associated very high temperatures and pressures.  Of course, there might very well be two inches of air and then the back of a payload rack that gets thoroughly demolished; the shock might be very attenuated by the time it makes it to the center aisle where the people are.

Obviously if you get hit by something large enough you're screwed, but what else is new?

There are graphs of ISS debris shielding performance here.

[mmeijeri]

Obviously if you get hit by something large enough you're screwed, but what else is new?

And if it's big enough, you'll see it coming and you'll be able to avoid it. If it's small enough, you can survive a hit. Is there a gap between these two extremes and if so how big is it?

[Jorge]

Obviously if you get hit by something large enough you're screwed, but what else is new?

And if it's big enough, you'll see it coming and you'll be able to avoid it. If it's small enough, you can survive a hit. Is there a gap between these two extremes and if so how big is it?

Yes, there is a gap.

5-10 cm on the upper end (limit of what can be tracked)

0.1-1 cm on the lower end (depending on how well shielded the target is)

[nooneofconsequence]

Aspect ratio here matters - if you change your profile to minimize it, a target like the ISS reduces its cross sectional area for a strike considerably (4x-10x).

Given the volume of the threshold and the minimum cross section, still a very unlikely event - thankfully. Next refinement would be to model the boundary cross section, which is next most likely for a grazing hit (least damage), then onto the least likely, which is where the impact parameter is a substantial overlap of both objects - that's the dramatic one.

[erioladastra]

Anyone have the guidelines for what make a conjunction 'Red' vs medium or low?

The RED threshold is defined solely as probability of collision (Pc) > 10^-4. (Flight Rule B4-101 paragraph A.4).

Interesting. This makes me wonder at what probability of collision you just decide to leave station altogether, then re-dock after the event is over. Given a large enough impact energy I'd personally think it'd be better to get away from ISS sooner than later..when there might be a debris cloud that you now have to evac through instead of away from. Not to mention...couldn't the debris just as likely whack into the Soyuz itself while waiting docked? Is there anything worse than a condition red?

We woul dnever do that.  If far enough out, then you would do a reboost.  If too close to do a manuver, you would be even more vulnerable, potentially in the Soyuz seperated from ISS.  And unless you knew with very high probability - something you NEVER get with these numbers - you would never want to preemtively abandon ISS.

[Comga]

- The radar cross section was 0.009M^2 – could be big but recall this is what the radar sees.  Could have been much bigger.  Or smaller.

As a friend would say: DOH!

Fox News reported the debris as being one third of an inch.  Without intending criticism, they mistook 0.009 m^2 area for 0.009 m = 9 mm ~1/3 inch linear.

0.009 m^2 is equivalent to a sphere ~11 cm in diameter.  Think candlepin bowling bowling ball (particularly if you are from New England in the middle of the 20th century) at perhaps 10 km/sec (a bowling lane length in a millisecond.)  This size is way off the chart for ISS debris tolerance, which runs generally between 0.5 and 1.5 cm.  In fact it is a pretty big chunk, as one would suspect and in line with Jorge's estimate of the minimum trackable object size.

[Stowbridge]

Last forward hatch is closed.

None of the other news sites are reporting this.

We aren't making it up. The memos are official and the loops pretty much says it all.

Yes sorry, but you can understand that a story that has been on site for over 90 minutes and not on another news site is either a large jump on the other sites, or accuracy may be in question.

Especially so when there are "two line blog sites", and those that use the dumbing down to a 12 year old level "Twitter", which is the most hideous thing I've ever seen a 'journalist' use. They could easily beat you while you're collating a proper news article.

Obviously you had a large jump, and I continue to be impressed by your level of sources. I'm not even taking into account how long you might of been holding this back for your L2 members.

[Chris Bergin]

I'm not even taking into account how long you might of been holding this back for your L2 members.

30 minutes, which is how long it took for some fact/context checking and a quick write up of eight paras...expanded the article over the next 20 minutes. I publish in L2 as and when I get hold of content. We don't "hold back" breaking news such as this.

L2 is mainly about big unreleased presentations and video etc (that's why it's subscription as it's a huge - 90+ percent of the site - database), along with "raw copy" memos etc, and allows for the clarifications/explanations from the NASA etc guys we have in there - which in turn aids accuracy.

[Herb Schaltegger]

And if it's big enough, you'll see it coming and you'll be able to avoid it. If it's small enough, you can survive a hit. Is there a gap between these two extremes and if so how big is it?

I think that's one of those unknowns that keep Safety people up at night after an incident like this.

The fact remains that even though the U.S., European and Japanese modules have the best MDS that we (the aerospace engineering community, that is) knew how to devise in the 1990's (and I can't speak to the Russian segments or the Soyuz), there are just too damned many variables and too little hard data to be certain of much, even with those pressurized elements.  There are also small windows that don't have any MDS at all and rely on their own design philosophies and redundancies.

In addition, there are tons of vulnerable things externally, everything form PV arrays to radiators (a radiator leaking ammonia would be a Bad Thing, bordering on a Very Bad Thing depending on the severity and the timing) to electronics modules to even things as mundane as EVA handholds - remember the ding discovered recently (last year?) that was nicking up gloves in the vicinity of the Quest airlock?

Ugh.  Too many variables to be sure of much of anything except that NASA and the international partners are doing about the best they can to quantify and manage the risks.

[mmeijeri]

Ugh.  Too many variables to be sure of much of anything except that NASA and the international partners are doing about the best they can to quantify and manage the risks.

How much do you think adding more shielding might help? Would it be useful to designate one module as a safe haven and give it extra shielding? Would it help to give the modules triple whipple shields (I like the sound of that )? Or even armour plating? Or perhaps added inflatables surrounding an existing module?

I also read about plans for radar satellites. They would be dual purpose, because the Pentagon would like to use them for intelligence gathering as well. How much would having continuous global coverage help with the detection of pieces of debris and determination of their orbits? And would there be any point in having a powerful radar on the ISS itself? I would guess not, because whatever is within line of sight would hit you before you had the chance to evade it.

I understand getting enough power is a major problem for radar satellites, which I suppose could be solved with more mass. And mass is also a problem with shielding of course. I'll admit to looking for an excuse to build a heavier launcher

[Jim]

1.  I also read about plans for radar satellites. They would be dual purpose, because the Pentagon would like to use them for intelligence gathering as well.

2.  How much would having continuous global coverage help with the detection of pieces of debris and determination of their orbits?

3.  And would there be any point in having a powerful radar on the ISS itself? I would guess not, because whatever is within line of sight would hit you before you had the chance to evade it.

4. I'll admit to looking for an excuse to build a heavier launcher

1.  No because they look down at earth and not outward

2.  Define how this would be achieved.  The sensors need to look outward from earth and cover GSO

3.  Correct.  The debris needs to be detected a few orbits before conjunction

4.  You're not going to find it here

[Spacenick]

Would abandoning the ISS with the Soyuz for a short time really be as problematic as was said earlier?
I mean technically the ISS should be capable of sustained operation without humans on board for at least a day or two, and the Soyuz should be more than capable enough to get  away a fair distance and then return after an hour or so, I mean the Russians once used it to get from one space station to the other and back again.
I guess the main problem would be, that one can't start repairing whatever might be broken as fast as one can whens till docked.

[Jorge]

Would abandoning the ISS with the Soyuz for a short time really be as problematic as was said earlier?

Yes.

I mean technically the ISS should be capable of sustained operation without humans on board for at least a day or two,

That is not the issue here.

and the Soyuz should be more than capable enough to get  away a fair distance and then return after an hour or so, I mean the Russians once used it to get from one space station to the other and back again.
I guess the main problem would be, that one can't start repairing whatever might be broken as fast as one can whens till docked.

No, you're missing the point.

If you have enough notice to do a reboost burn to avoid the debris, that is ALWAYS what you will do.

If you don't have enough notice to do a reboost burn, then BY DEFINITION you are not confident enough in the debris trajectory to even know if you would be improving the situation by undocking. AT BEST, you are robbing the Soyuz of the partial shielding provided by the bulk of ISS around it. AT WORST you could be sending the Soyuz right into the debris.

[Spacenick]

Well I understood the not enough time to reboost problem in the sense that it would be to problematic to reboost the ISS.
My point is that one could know very well in which direction one moves away the debris whiel having not enough time to prepare a reboost of the entire ISS which will involve, switching control from the US Momentum attitude system to russian attitude thrusters, commanding a docked progress or ISS thrusters, maybe preparing the solar arrays in some way and so on.
This would need much more preperation time than hopping into a Soyuz, undock and full throttle prograde (or any other direction that is feasable for that matter)

[robertross]

Is there anything worse than a condition red?

No, not under the current rules.

Forgive the blunt question, but wouldn't a unknown strike be considered a worse condition than red? There may not be a 'condition' in the rules, just a fact of spaceflight: bad day.

[Jorge]

Is there anything worse than a condition red?

No, not under the current rules.

Forgive the blunt question, but wouldn't a unknown strike be considered a worse condition than red? There may not be a 'condition' in the rules, just a fact of spaceflight: bad day.

Of course. And the one thing that would be worse than a DEFCON 1 alert would be an actual nuclear strike. That was so obvious I didn't deem it worthy of response.

[Lee Jay]

What is the approximate annual probability of ISS suffering a leak due to MMOD?

[Jorge]

Well I understood the not enough time to reboost problem in the sense that it would be to problematic to reboost the ISS.
My point is that one could know very well in which direction one moves away the debris whiel having not enough time to prepare a reboost of the entire ISS which will involve, switching control from the US Momentum attitude system to russian attitude thrusters, commanding a docked progress or ISS thrusters, maybe preparing the solar arrays in some way and so on.
This would need much more preperation time than hopping into a Soyuz, undock and full throttle prograde (or any other direction that is feasable for that matter)

If you do not have enough confidence in the conjunctor's trajectory to perform a reboost burn in time, there is no way in hell you will have enough confidence to undock the Soyuz. Period.

[Patchouli]

I wonder if they could put some sort of defensive laser on ISS .
Maybe something like this weapon.
http://en.wikipedia.org/wiki/Advanced_tactical_laser

[Jorge]

I wonder if they could put some sort of defensive laser on ISS .
Maybe something like this weapon.
http://en.wikipedia.org/wiki/Advanced_tactical_laser

You sure could.

Would it do any good?

No. The ground wouldn't have sufficient confidence in the trajectory and without that there is no way to aim the laser.

Tracking capability is the bottleneck here.

[Jim]

I wonder if they could put some sort of defensive laser on ISS .
Maybe something like this weapon.
http://en.wikipedia.org/wiki/Advanced_tactical_laser

No, because it doesn't have the power to vaporize the object

[robertross]

Is there anything worse than a condition red?

No, not under the current rules.

Forgive the blunt question, but wouldn't a unknown strike be considered a worse condition than red? There may not be a 'condition' in the rules, just a fact of spaceflight: bad day.

Of course. And the one thing that would be worse than a DEFCON 1 alert would be an actual nuclear strike. That was so obvious I didn't deem it worthy of response.

I know, I guess it just warranted a statement to the obvious. There is a case worse than 'red', but we don't need to go there as the point is mute. Got it.

[mmeijeri]

I know, I guess it just warranted a statement to the obvious. There is a case worse than 'red', but we don't need to go there as the point is mute. Got it.

Well, there's an intermediate condition: BOM, or Beans On the Menu.

[robertross]

I know, I guess it just warranted a statement to the obvious. There is a case worse than 'red', but we don't need to go there as the point is mute. Got it.

Well, there's an intermediate condition: BOM, or Beans On the Menu.

I don't know if I dare ask the meaning of that term...

[erioladastra]

“ISS should be capable of sustained operation without humans on board for at least a day or two, and the Soyuz should be more than capable enough to get  away a fair distance and then return after an hour”

It is not that simple.  First, ISS can handle a few days without crew however, whenever the entire crew undocks you have to prepare for being unmanned long term if something goes wrong with redocking.  And we did not have time to prepare for that.  If not prepared and you can’t redock, there are several failures that would cause a loss of station (even in the proper config, the longer you are unmanned the more risk you are at losing ISS).

Soyuz does NOT have enough consumables to go for a short jaunt and return.  You want to protect for them being able to undock and then if something goes wrong, be able to loiter and then reenter.

And yes, you want to have the option for the crew to repair any hole.

“My point is that one could know very well in which direction one moves away the debris whiel having not enough time to prepare a reboost of the entire ISS which will involve, switching control from the US Momentum attitude system to russian attitude thrusters, commanding a docked progress or ISS thrusters, maybe preparing the solar arrays in some way and so on.
This would need much more preperation time than hopping into a Soyuz, undock and full throttle prograde (or any other direction that is feasable for that matter)”

It is not a matter of time in this case, it is a matter what is the best posture to respond to an emergency and return IF NECCCESARY.

“Forgive the blunt question, but wouldn't a unknown strike be considered a worse condition than red? There may not be a 'condition' in the rules, just a fact of spaceflight: bad day.”

Yes, that is then called a rapid depress and we have regular, well trained procedures for that.

[bodge]

Is there anything worse than a condition red?

No, not under the current rules.

Forgive the blunt question, but wouldn't a unknown strike be considered a worse condition than red? There may not be a 'condition' in the rules, just a fact of spaceflight: bad day.

Of course. And the one thing that would be worse than a DEFCON 1 alert would be an actual nuclear strike. That was so obvious I didn't deem it worthy of response.

Actually, it wasn't all that obvious given that red left you as a sitting duck at ISS, compared to abandoning ship proactively and just coming home. Forgive me if the question valued crew survival more than ISS survival. If you were crossing a railroad track and your car suddenly stalled out with a train coming at you, would you sit and hope the impact wasn't too horrible (or the chance that maybe the train is going to switch tracks before getting to you) or would you hop out of your car and run? My opinion is that given an unavoidable, highly likely collision (some probability greater than those for 'red') if you had the time to get away before the object got into your 'box' then I'd hope you were doing so.

[Jorge]

Is there anything worse than a condition red?

No, not under the current rules.

Forgive the blunt question, but wouldn't a unknown strike be considered a worse condition than red? There may not be a 'condition' in the rules, just a fact of spaceflight: bad day.

Of course. And the one thing that would be worse than a DEFCON 1 alert would be an actual nuclear strike. That was so obvious I didn't deem it worthy of response.

Actually, it wasn't all that obvious given that red left you as a sitting duck at ISS, compared to abandoning ship proactively and just coming home. Forgive me if the question valued crew survival more than ISS survival. If you were crossing a railroad track and your car suddenly stalled out with a train coming at you, would you sit and hope the impact wasn't too horrible (or the chance that maybe the train is going to switch tracks before getting to you) or would you hop out of your car and run?

Inappropriate analogy. Trains are on tracks. You know where the train is going and you know whether or not you are on the track with the train. If you are on the track when the train goes through the probability of collision is 100%. If you are even a few feet off the track in either direction the probability of collision is zero. This is not the case with debris trajectories.

[vt_hokie]

Inappropriate analogy. Trains are on tracks. You know where the train is going and you know whether or not you are on the track with the train. If you are on the track when the train goes through the probability of collision is 100%. If you are even a few feet off the track in either direction the probability of collision is zero. This is not the case with debris trajectories.

It basically becomes an excercise in covariance analysis, right?

[Jorge]

Inappropriate analogy. Trains are on tracks. You know where the train is going and you know whether or not you are on the track with the train. If you are on the track when the train goes through the probability of collision is 100%. If you are even a few feet off the track in either direction the probability of collision is zero. This is not the case with debris trajectories.

It basically becomes an excercise in covariance analysis, right?

Pretty much. The state vector itself defines a "mean" trajectory and the covariance matrix essentially defines an ellipsoid in space about the mean, within which there is a given probability of finding the actual object.

If a train's trajectory were defined not by the track but by a diffuse "probability cloud" around the track, which way do you jump in order to avoid the train?

[Lee Jay]

Inappropriate analogy. Trains are on tracks. You know where the train is going and you know whether or not you are on the track with the train. If you are on the track when the train goes through the probability of collision is 100%. If you are even a few feet off the track in either direction the probability of collision is zero. This is not the case with debris trajectories.

It basically becomes an excercise in covariance analysis, right?

Pretty much. The state vector itself defines a "mean" trajectory and the covariance matrix essentially defines an ellipsoid in space about the mean, within which there is a given probability of finding the actual object.

If a train's trajectory were defined not by the track but by a diffuse "probability cloud" around the track, which way do you jump in order to avoid the train?

Doesn't matter, as long as you get several sigma out from the center of the elipse, before the train gets there!   

[vt_hokie]

Doesn't matter, as long as you get several sigma out from the center of the elipse, before the train gets there!   

LOL!

[rdale]

Radio comms from the event have been posted at http://www.nasa.gov/mission_pages/station/main/index.html

[Warren Platts]

Space station may have to duck orbiting debris

Again.

http://news.yahoo.com/s/ap/20090316/ap_on_sc/space_shuttle_28

[Comga]

The Baltimore Sun got it correct.  (Unlike Fox News, they know what that funny hat thing and the number two mean in m^2.  )
 
"The debris, part of a mechanism to put a satellite in proper orbit, measured about 5 inches, a size that "will wreck your whole day," said Mark Matney, an orbit debris scientist for NASA."
 
It was traveling 5.5 miles per second -- about 20,000 mph.

The debris is likely a small weight followed by a 39-inch string or strand that was used to stabilize a global positioning satellite placed in orbit in May 1993, said Harvard astrophysicist Jonathan McDowell, who tracks all objects in orbit.

One of the reasons NASA got such late warning on the debris is that it is an unusual orbit that keeps dipping into the atmosphere and changing, McDowell said. It was in the worst kind of orbit to track, Matney said.

[aquarius]

I read somewhere that the station crews had to take temporary refuge in escape ships 5 times previously due to orbital debris threats.

Does anybody know exactly when or during which expeditions these events happened?