I don’t understand this “safe haven” concept.

[radarredux]

> <i><font color="yellow">So far the flight data shows a fatal foam strike is about 1 in 100 flights.</font>/i><br /><br />That was the same number I was using. To have a fatal foam strike on two consecutive launches would be (1 in 100) x (1 in 100) = 1 in 10,000.<br /><br />Presumably the changes NASA has made to the foam would reduce that number even further than 1 in 100. For example, the number and size of foam pieces shed on the last flight was apparently much lower than those of of previous launches. So, if the chances of a fatal foam strike was cut in half by these changes, then the odds of two consecutive fatal foam strikes would be 1 in 40,000.</i>

 

[nacnud]

<font color="yellow">That was the same number I was using. To have a fatal foam strike on two consecutive launches would be (1 in 100) x (1 in 100) = 1 in 10,000. <br /><br /><font color="white">Probablity doesn't work like that. The risk to each flight would be 1 in 100.</font></font>

 

[radarredux]

> <i><font color="yellow">Probablity doesn't work like that. The risk to each flight would be 1 in 100.</font>/i><br /><br />The scenario was that the next flight would have a fatal foam strike, and then the next flight after that would have a fatal foam strike. It is true that if there was a fatal foam strike on the first flight, then the second flight would also have a 1/100 chance of a fatal foam strike.<br /><br />However, if the statistical event is "two consecutive fatal foam strikes" before any first flight, then the 1/10,000 number is correct.</i>

 

[nacnud]

Sorry thought you were saying someting else.

 

[scottb50]

If a male prostitute can be a certified press person at the Whitehouse I would think just about anyone would do. <div class="Discussion_UserSignature"> </div>

 

[radarredux]

> <i><font color="yellow">Sorry thought you were saying someting else.</font>/i><br /><br />No problem.<br /><br />As a side note: I am really looking forward to the Shuttle resuming regular launches. I am not a big fan of the Shuttle, but for years to come she is and will be the only option for US manned flight. I think getting 2-3 successful launches complete, increasing the crew size (to even 3), and getting the Columbia module up there will really change attitudes.</i>

 

[racer7]

Two consecutive foam strikes may indeed be 1 in 10000. It doesn't work that way for your example though. At the point of a rescue flight being needed, the first strike has already happened. The chance of the next flight having a foam strike is 1 in 100. <br /><br />Actually, adjusting for the second strike it would be more like 1 in 50. You could also use the data set of the last three tanks flown which would be 2 out of 3. Numbers are fun!<br /><br />(Btw, I'm firmly on the side of flying, just pointing out the statistical problem.) <br /><br />edit: Sorry, I see that you pointed this out.

 

[nacnud]

Same trap I fell in, but still the risk to any individual flight is 1 in 100. The hard part is continuing the program after even just one bad, non fatal strike. How ever much I like the CLV I just wish the CEV was being designed in a way that makes it as launcher independent as possible. <br /><br />For example how much extra could have been delivered to the ISS by now if the payloads could have been taken by other launchers ie, Ariane 5, Delta 4H, Proton etc. This isn't necessarily a flaw with the ISS but is a lesson to be noted for future. For example SpaceHabs Apex seems a good possible way forward for ISS cargo.<br />

 

[askold]

From today's new conference:<br /><br /><b>But the "safe haven" option, in which the crew of a damaged space shuttle moved into the space station to await rescue is not without considerable risk itself. A major question mark has been how NASA would justify launching a rescue shuttle - a mission designated as STS-300 - that could fall victim to the same problem. O'Connor agreed it would be a tough call.</b><br /><br />http://spaceflightnow.com/shuttle/sts121/060621nogovotes/<br /><br />That's exactly the question I brought up 3 days ago. I feel vindicated.

 

[gawin]

actualy if the first flight has a fatal stike your odds on the second one are more like 1 in 50 because you now have 2 fatals in 100 flights.

 

[nacnud]

True.

 

[SpaceKiwi]

Math was never my thing, but doesn't the statistical probability change with every successive flight? For example, if they were to fly another hundred Shuttle missions without a LOV foam strike, wouldn't the probability then become 1 in 200? <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[nacnud]

It depends on whether you are useing the theoreticaly calculated statistics or ones bassed on actual flights.

 

[j05h]

And we can argue different statistics forever. One truth is this: the Shuttle is an inherently dangerous design. Payloads and fragile heatshields should on top of the rocket, away from falling debris. <br /><br />The Safe Haven makes sense, but it'd make much more sense if there was another Soyuz or two waiting on the ground. I'd like to point out that if we'd continued with X38, OSP, etc, and had the gumption to build it against the Shuttle Forever crowd's wishes, these kind of situations would be much more managable. The idea of a second pilotted US spacecraft was to radical for 20 years, now we are in a situation where we don't have functional US access to LEO. <br /><br />josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[brandbll]

Just have Sir Richard Branson swoop up the stranded people in SpaceShipOne. <div class="Discussion_UserSignature"> <p><font size="3">You wanna talk some jive? I'll talk some jive. I'll talk some jive like you've never heard!</font></p> </div>

 

[radarredux]

> <i><font color="yellow">And we can argue different statistics forever. One truth is this: the Shuttle is an inherently dangerous design. Payloads and fragile heatshields should on top of the rocket, away from falling debris.</font>/i><br /><br />I agree on both points.</i>

 

[frodo1008]

Actually as a person that supports the shuttle I also support the ISS, and any improvements to it. Which would have definitely included the ACRV or X38. If our infinitely wise (cough, cough) congress had continued the relatively minor costs of such a vehicle, there would now be a vehicle on board the ISS that was ideal for this mission! To say nothing of having the capability to have a full crew of six on board the ISS itself. <br /><br />Then people wonder why the approval rating of congress is even lower than that of President Bush!!<br /><br />Then the following:<br /><br />(1) As has been pointed out by a number of posters here, spaceflight (even the robotic kind) is always going to be fraught with danger! Astronauts are in the same insurance class as our soldiers in Iraq, they are uninsurable! They accept the danger, and so do we who support the manned space entry into the solar system of human beings! As I say, even the robotic missions fail.<br /><br />(2) As we have flown over one hundred shuttle flights without the foam destroying or damaging a shuttle (with the one tragic exception of the Columbia). Then it is somewhat reasonable to believe that this isn't something that happens on every flight!<br /><br />(3) I don't need statistical math to reasonably and logically tell me that the chances of two shuttles in a row being disabled by the very same thing are indeed remote! So that makes the ISS under these circumstances to indeed be a reasonable safe haven.<br /><br />(4) We have to fly sometime reasonably soon or just abandon the shuttle and at least our interest in the ISS.<br /><br />and finally:<br /><br />(5) For some on these boards there is absolutely nothing that would satisfy these requirements short of canceling the shuttle and the ISS and placing all the money for the manned portion of NASA into the unmanned science programs! (which will not happen, as the money would not even go back to NASA anyway). This would quite probably result in the canceling of

 

[frodo1008]

I thought this was a realitively serious discussion, so why make jokes?

 

[frodo1008]

I thought this was a realitively serious discussion, so why make jokes?

 

[askold]

"(3) I don't need statistical math to reasonably and logically tell me that the chances of two shuttles in a row being disabled by the very same thing are indeed remote!"<br /><br />But, this isn't a question of statistics. It's "gaming out the situation".<br /><br />The 2 no-go votes are justifying their decison to go along with the launch contending that the ISS is a safe haven in case of a "vehicle loss" but not a "crew loss". Yet O'Conner himself admits it would be a tough call to send up Atlantis on a rescue mission since it has the same design flaw.<br /><br />It's not a matter of statistics, it's logic - you can't claim that it's OK to fly with a no-go because of a safe-haven then say it's a tough call to send Atlantis to the "safe haven". It doesn't make an sense.

 

[radarredux]

> <i><font color="yellow">That's exactly the question I brought up 3 days ago. I feel vindicated.</font>/i><br /><br />There are a lot of risks involved in building out ISS. At this point, there are probably only two choices: (1) fly now or (2) shutdown the Shuttle program and abandon ISS.<br /><br />My frustration with the effort is that NASA is flying with a full compliment of crew. I would be more comfortable with flying a minimal crew for this "test flight". This would reduce the number of lives at risk and allow for a longer period of time at the "safe haven". With just two more astronauts living on ISS, perhaps ISS could be a safe haven long enough for a soyuz rescue, especially if this test flight had as it major cargo extra supplies for just such an emergency.<br /><br />But coming back to a theme I have mentioned before -- I think the greatest risk is to the Shuttle program itself and ultimately the ISS. Any significant foam loss, <b><i><font color="yellow">even if it doesn't touch the orbiter</font>/i></i></b>, over the next 2-3 flights would probably result in another year or more grounding ("suspension of flight" to be politically correct). That may very well be the kiss of death for STS/ISS.</i>

 

[radarredux]

> <i><font color="yellow">It's not a matter of statistics, it's logic - you can't claim that it's OK to fly with a no-go because of a safe-haven then say it's a tough call to send Atlantis to the "safe haven". It doesn't make an sense.</font>/i><br /><br />Part of the problem, and part of why the statistics are of minimal value, is that there have been a number of changes to the ET and procedures since Columbia. If a piece of foam falls off this next flight, there will be a question of whether the loss was strictly a probabilistic failure (the unlucky 1 in 100), or does it reflect something fundamentally wrong with the tank (i.e., the real probability is 1 in 2).<br /><br />It's not like NASA is going to fly 100-1000 unmanned shuttle launches (and with no changes to the tank design) to determine the actual probability before the next scheduled manned launch.<br /><br />Unfortunately, the <b><i>real answer</i></b> is that NASA doesn't really know what the risks are. Wind tunnel tests and computer modelling can only get you so far. At some point they have to go fly. That is the only way they can begin to gain some confidence in what the real risks/probabilities are.<br /><br />Once again, my beef is that they are flying with a full crew instead of a minimal crew reflecting a true "test flight".</i>

 

[frodo1008]

I asked this once before and got no answer from you, which is just one more reason to think that your agenda of just shutting down both the shuttle and the ISS is what you really want here. <br /><br />The point is, are you then perfectly willing to wait until NASA is 100% sure of no foam damage at all? Even if this takes us well into the next year?<br /><br />In another post on another thread I stated that I thought that if the shuttle had to go over another year that it was quite possible, and perhaps even reasonable that the shuttle and the ISS would be both shut down for good. You then agreed with me!<br /><br />So NOW you are so worried about the shuttle (a position that you have never exhibited before), does this mean that you are no longer concerned about the time or money this would cause the current shuttle and ISS? <br /><br />However, I would be quite willing to admit that this entire thread is just a theoretical exercise in futility anyway. NASA is going to launch in July, based on prior history and the relative (OK by you if I use the word relative here?) safety of going up to the ISS!<br />And that is simply that!!<br /><br />In the final analysis, in the very unlikely event that both shuttle crews were to be stranded on the ISS, I am certain that both NASA and the RSA, along with the entire aerospace industry of the world would move heaven and hell to get supplies out to the ISS (for while having that many people, some lucky 13, would be very uncomfortable, the ISS would be capable of having such a crew for as long as it took, providing enough supplies could be gotten up to it), and eventually bring those people home!<br /><br />Heck, it might even have some good to it in taking the world's collective imaginations off of terrorism for awhile!<br /><br />However, I really don't think that I have anything to worry about, and if you ARE sincere here, then neither do you!<br />

 

[frodo1008]

I will readily admit that I don't understand it either, and like yourself am not totally happy about it. Perhaps it is because there are a whole lot of things that need to be done to check out the surveillance and possible repair activities of returning the shuttles to flight. I did notice that if a rescue is needed that the rescue shuttle will only be going up with 4, and will be capable of bringing back 10 or 11 per a Shuttle_guy post. But like I said to askold, NASA has decided to do this anyway, even if legitimate concerns like yours are brought up (and I can't believe that they haven't already been brought up).<br /><br />However, even with quite a bit of aerospace experience and education, I don't feel qualified to tell NASA what to do even if others here feel they are. Despite the Challenger and Columbia, the over all record of NASA and the other manned programs has been great if you know anything at all of the difficulties of trying to do what they are trying to do here!<br /><br />What some who have made nothing but complaints about the shuttle and ISS and how much they cost have no realization of is the following:<br /><br />ALL OF THESE ACTIIVITIES ARE UNIQUE, AND HAVE NEVER BEEN EVEN ATTEMPTED BEFORE!! Yet some on these boards, seem to think that we are turning out bottle caps here! What an extreme arrogance that is!!<br /><br />The better of the pure private enterprise types such as Rutan KNOW how difficult the task before them is! <br /><br />At this particular point in time, and for quite some time to come, the greatest expertise in getting people into orbit and accomplishing useful work with them is going to continue to be with NSA and its partners on the ISS!<br /><br />And that IS the way it IS!!!<br />

 

[unseent]

Assuming the Discovery make it to ISS, it actually could be a safe for the. It seems like people don't haven't look up all the information about the Soyuz. Have look at these 2 links:<br /><br />http://www.nasa.gov/mission_pages/station/structure/elements/soyuz/index.html<br />http://www.nasa.gov/mission_pages/station/expeditions/expedition14/index.html<br /><br /><br /> Seems like it actually is pretty feasible for 2 Soyuzs to bring down at least 5 people from the ISS if the Discovery crew does get stranded there. According to the first link, there is always a Soyuz docked in the ISS that could be used bail out 3 people immediately off ISS. The 2nd link shows that the next Soyuz launch is in September, about 60 days from the space shuttle launch. I think it could be feasible for the that Soyuz to launch with 1 crew member at least 30 days earlier and at the latest 60 days after Discovery first launched.<br /><br />This means within 60 days, there would be only 4 people left on ISS. And I am pretty sure the 2nd Soyuz mission could bring more supplies for those 4 to last in the ISS for long time. It should be more than enough time for another Space Shuttle or Soyuz to go up and get the rest of the stranded crew. Seems like this could be feasible solution if the shuttle actually get damaged badly.<br /><br />As other people said, they need to launch the shuttle now otherwise you might as well retire them. According to NASA, shuttle will be retired in 2010 or so. It might take till 2010 or longer to get the foam problem fully fixed. Now is good enough time to try and see if shuttle can still work till 2010 or not.