Why must space flight be safe?

[dwightlooi]

I have been pondering this issue recently. It has been the stated goals of successive man rated launch systems to strive for very low failure rates, especially loss of crew failure rates. The thing is is it really necessary?<br /><br />I am pretty sure that mercury astronauts flew with much higher risks than 1%. And I am pretty sure that you can easily recruit and retain astronauts if the risk is 1% rather than 0.1% which is 10 times safer and a hell lot more difficult to achieve.<br /><br /><b>Has anyone ever considered the fact that being an astronaut is a risky profession. Why not just declare it as such and sign on candidates able and willing to assume that risk? I am sure there will be no shortage of qualfied applicants.</b><br /><br /><b>Why not forget about the manrated thing altogether? Just take a reasonable rocket platform, put a capsule on it and launch it anyway. Put a capsule on the Atlas V or Delta IV and launch it without any man rating. Just live with the risks and die by it.</b> get the costs down to $50 to $80 million per launch. If someone dies every 100 shots, well we just accept that and keep doing it anyway. I doubt it'll be that bad even if you use EELVs without any manrating modifications since a gas generator cycle hydrogen engine and an inline design is inherently quite safe.<br /><br />So why not? Why not just accept the risk, lower the cost and just do it? Put a man on an EELV and launch it. Put a man on a SRB and launch it.

 

[ehs40]

i agree that nasa should have to be soooo strict on manned launch risks and if the risk was 10% i would still do it but some people wont just die if they dont have 2 i mean i dont know about u but i dont want to die b4 my time i still have a long time to go but risks of 10%or lower i would fly on

 

[SpaceKiwi]

Spaceflight has to be 'safe' because, in this PC world we live in, nobody is ever allowed to take a risk or die in any way other than peacefully in their sleep.<br /><br />The Shuttle nay-sayers bleet on endlessly about it being a 'death-trap'. Some believe that such is our 'technical know-how' these days that spacecraft should be as safe as, say, flying.<br /><br />Of course, this doesn't accurately acknowledge the situation with flying. Flying isn't safe, it's simply relatively reliable. If something goes wrong with that aircraft, you can bet dollars to doughnuts that the Grim Reaper is about to punch your ticket for you. I think I'd settle for the multiple redundency of most of Shuttle's systems any day.<br /><br /> <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>

 

[phaze]

$$$$$ -- both in the value of the hardware that can be lost and the expertise of the astronauts.<br /><br />If shuttles were humvees and astronauts were soldiers, it would be acceptable.<br /><br />I don't think it really has anything to do with PC world this or that.

 

[dwightlooi]

IMHO, a 1% failure rate is acceptable. In fact 5% is acceptble.<br /><br />As far as payload is concerned, most of the cost comes from the R&D and engineering that goes into it. It may only cost 5 or 10% more to build two probes instead of one, or two space station modules instead of one. Infact, this is routinely done so engineers have an accurate replica of whats up there if they need to figure some bug out.<br /><br />As far as astronauts are concerned, I think we should hire a breed of individuals who are able and willing to assume the risk of 5%. Trust me, there will be no shortage of over qualified candidates. Call me inhumane or call me whatever you want, but I think we should assign a dollar value to the life of an astronaut when making flight decisions. Let's make the number $100 million per astronaut. This should cover their earning potential over their life time plus account for some fo the negative PR fall out associated with their loss. It is a reasonable number. If you are flying $400 million worth of stuff, I think a 5% loss rate is acceptable.<br /><br />In the end, the success of a space program will be measured by the great things -- the monumental things -- it manages to accomplish. Moon and Mars landings, space telescope images, far flying probes, etc. It is not measured by the few lives lost along the way. I think we are being too stingy on life. Life is not sacred, it is a commodity. The reason we are so ineffective in many things -- such as our war in Iraq for instance -- is that we care too much about life.<br /><br />Life is a terminal disease, every single one out there dies from it. If you look at astronauts as the terminally ill and you recruit those who are willing to put it all on the line to fly, I think we will get a lot more done for a lot less money. And, I think, that is how we should do it.

 

[drwayne]

"As far as astronauts are concerned, I think we should hire a breed of individuals who are able and willing to assume the risk of 5%."<br /><br />In my experience, the astronauts we have are already in that category. Quite a few I have known in the past would probably have gone if you told them it was 50/50.<br /><br />Any excessive risk aversion, if present, is present in political management. You can also say the same thing about any excessive risks (read that as Challenger, IMHO).<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[centsworth_II]

<font color="yellow">"If shuttles were humvees and astronauts were soldiers, it would be acceptable. <br /><br />I don't think it really has anything to do with PC world this or that."</font><br /><br />When dealing with a matter of national pride or "patriotism" it is very easy to get into PC trouble.<br /><br />That said, in human terms, the life of a astronaut is no more valuable than that of a soldier. In terms of dollars, it also costs to delay programs and missions in the pursuit of unrealistic safety goals. At this point in the shuttle program another shuttle can be lost and the economic loss will not be too great since they are being phased out anyway. <br /><br />I'm not anticipating a loss. The shuttle has flown 100 plus times, with foam flying off the fuel tank probably every time and there has been one lost. The loss risk has worked out to less than one percent even before improvements were made. I say fly the shuttle 10 to 20 more times as is and check for damage. No stopping flights to go back to the drawing board because of the foam. <div class="Discussion_UserSignature"> </div>

 

[tomnackid]

Its a matter of perception. The Mercury program was seen as a matter of national security therefore risks comparable to combat or espionage were acceptable. When the shuttle was first designed it was intended to be used as much for defense as it was for civilian tasks--probably a bad decision from the get got, but Nixon wouldn't allocate enough money for separate civilian and military launch vehicle development. (I have heard rumors, possibly from Stephen Baxter I'm not sure, that the shuttle was actually designed with bombing runs over the USSR as one possible mission. Can anyone confirm or deny this? This seems plausible since that was one of the missions proposed for DynaSoar and the shuttle is basically DynaSoar on steriods.)<br /><br />The Shuttle is a relic of the cold war when the risks and costs could still be justified as a matter of national security and prestige (ie. make capitalism look cooler than communism). After the Air force abandoned the shuttle (after driving most of the bad design decisions) it no longer seemed justifiable to risk lives at a rate comparable if not greater than that of combat just to launch a satellite.

 

[the_ten]

Going into space is a hazardous business. It's impossible to reduce it down to 0% risk/100% safety so at some point you have to find the middle ground on what's acceptable. To me, that middle ground is NOT where every time something bad happens, the entire space program comes to a grinding halt for years at a time.<br /><br />Don't take what I'm saying the wrong way. If disaster can be prevented then it should be... But let's not forget all the success the shuttle missions have had and only remember the times things went bad. The shuttle has a superb success rate and that should be considered as well as all those 'things that might happen under certain circumstances if the planets are in alignment, during an eclipse on leap year'... If you catch my drift...

 

[spacefire]

because spaceflight is an essential tool for our species survival. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[thermionic]

I don't think 1% is acceptable, certainly not 5%. Loss of life and property aside, we'd not be able to get anything complicated and significant done if we were loosing 5% of our manned launches. The shuttle is running at 2% right now, and look how it has affected the construction and operation of the ISS.

 

[cyrostir]

there is a different thing between taking a risk, and taking a stupid, avoidable risk......

 

[dwightlooi]

<i>there is a different thing between taking a risk, and taking a stupid, avoidable risk...... </i><br /><br /><b>No, I think a risk should be avoided only if it doesn't cost too much to avoid and avoiding it will not cost the mission.</b><br /><br />Let's take the shuttle for instance. <b>I agree with the fact that the Shuttle is fundamentally not the right design for the future needs of NASA -- not in terms of fundamentals related to safety, not in terms of cost and not in terms of payload rating. Hence, I agree with the decision to retire it. However, after the Columbia disaster, I would not have halted flight for two years. I'll take a month or two to figure out what happened. And then, I'll say, yes the shuttle is not as safe as we would like. But, no, we will not chicken out of the current missionat hand -- which is to finish the ISS and retire the shuttle fleet. Here is what we do... we fly the shuttle anyway.</b> We make 20 more flights, we do so KNOWING that there is roughly a 20% chance that we will lose another shuttle and its crew over the course of the 20 remaining flights. Though, because the foam debris damage issue is a re-entry issue, we probably will not lose an ISS payload. If that happens, well, then it happens. One thing I will do though is reduce the crewing per flight to the minimum required -- say four astronauts instead of seven, if necessary I'll increase in orbit time to compensate of reduced manpower. I'll tell the astronauts the truth, those who do not want to fly will not be forced to do so.<br /><br /><b>As far as the next generation of launch vehicles I will not strive for unrealistic safety goals either. I think 1% is fully acceptable. Infact I think a 5% to 10% risk for the first few "new" vehicle flights is acceptable. Think about it, 4 launches a year for 25 years and you get one fatal accident? That is OK. In fact I doubt space flight will get much safer than that!</b> Hence, I will not restrict myself from EELVs or new designs or shut

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>there is a different thing between taking a risk, and taking a stupid, avoidable risk...... <br /><br />No, I think a risk should be avoided only if it doesn't cost too much to avoid and avoiding it will not cost the mission. <p><hr /></p></p></blockquote><br /><br />I think the U.S. general publics as well as your payload customer will disagree with you. If it can be proved that the mistake can be avoided in retrospect, someone's head(s) will roll, especially when it comes to human lives. <br /><br />If it's just cargo, one will have a more tolerable risk factor. But even at that, the current 'national security asset' cargo does not tolerate your 5% or 10% failure rate, let alone 7 astronauts lives.<br /><br />Also, the 2 trageic accidents on the Shuttle can not be quanitified by realiability analysis as they both were, IMO; management decision failures not technical failures.<br /><br />The 'man-rating' of EELV maybe an exercise in waste of money. Both EELVs were designed for maximum payload performance and therefore cut safety margin where they could. We all know that, at the end of this analysis, the new 'man-rated' EELV would be a brand new vehicles with thicker structural walls, more redundant avionics and IVHMS, requalifying many components including the engines, and may require a new computer system. Another word --- practically a brand new vehicle for each EELVs. The analysis may cost millions, but building and requalifying the vehicle will cost billions.<br /><br />These astronauts, just like test pilots, are brave men & women. Let's not (continue to) subject them to stupid mistakes.<br /> <div class="Discussion_UserSignature"> </div>

 

[dwightlooi]

I am not saying, and I have never said, that we would tolerate 5% risks or 1% risks. I am saying that we should!<br /><br />As far as EELVs are concerned, I am not advocating manrating them as opposed to shuttle derivatives. I am say fly them as is, unmanrated and simply eat the risks. Yes, we can make it safer, but we'll rather spend the billions flying missions and reaching the goals we laid out than striving for impossibly high safety standards.<br /><br />As far as Iraq and our wars is concerned. I think we need to develop a stomach for deaths. If you cannot tolerate 1800 deaths in a war involving 250,000 troops and spaning almost 2.5 years now, you might as well disband the military. War is a game of trading lives for objectives. It is a terrible thing. But we must accpet it and wage it if necessary. That is a fact of life.

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>As far as EELVs are concerned, I am not advocating manrating them as opposed to shuttle derivatives. I am say fly them as is, unmanrated and simply eat the risks. Yes, we can make it safer, but we'll rather spend the billions flying missions and reaching the goals we laid out than striving for impossibly high safety standards. <p><hr /></p></p></blockquote><br /><br />The EELVs maybe good for launching cargo if it costs less than the SDLV, but without the LES launching crew would be very difficult to justify.<br /><br />But why would NASA go back to the EELVs if they spent all that money for SDLV? They would want a high launch rate so justify the expenditures on SDLVs. <div class="Discussion_UserSignature"> </div>

 

[cyrostir]

<blockquote><font class="small">In reply to:</font><hr /><p>As far as Iraq and our wars is concerned. I think we need to develop a stomach for deaths. If you cannot tolerate 1800 deaths in a war involving 250,000 troops and spaning almost 2.5 years now, you might as well disband the military. War is a game of trading lives for objectives. It is a terrible thing. But we must accpet it and wage it if necessary. That is a fact of life.<p><hr /></p></p></blockquote><br /><br />Seriously - THINK OF WWII - No one complaind the hundreds of thousands of civillians bombed during the war, also think of all the soldiers who died.........

 

[lampblack]

Gee whiz. Saying that we shouldn't be risk-averse (on the one hand) and saying safety be damned and full torpedoes ahead (on the other) are very different things. One is reasonable and courageous; the other is foolhardy and thoroughly dismissive of the actual (and very real) value of human life.<br /><br />Reasonable people take reasonable risks. But that is not to say that we shouldn't put due emphasis on preserving the best (and yes, reusable) part of any spaceflight system -- the astronauts. <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>

 

[tomnackid]

"Seriously - THINK OF WWII - No one complaind the hundreds of thousands of civillians bombed during the war, also think of all the soldiers who died......... "<br /><br /><br />One of the reasons the allies won WWII is that we did not resort to suicide troops like the Germans and Japanese did. Also, we would have been more than happy to accept Gemany and Japans surrender without dropping a single bomb on any of their cites, it was their choice to keep fighting in the face of overwhelming odds. In addition US bombers used daylight raids precision bombing techniques (at much greater risk to themselves) to reduce damage as much as possible given the technology of the day. All in all history shows that societies that value life are more successful in the long run than those with a cannon fodder mentality. Ultimately most "cannon fodder" governments end up being torn down by their own disillusioned and angry soldiers!

 

[shishka]

Political climate aside, I see no reason our current space program won't take the same level of risk with their flights as they did during the Mercury, Gemini and Apollo programs.

 

[the_ten]

<font color="yellow">"I don't think 1% is acceptable, certainly not 5%."</font><br />----------<br />You saying you don't think a 99% success rate is acceptable. To expect 100% success is simply unreasonable and unrealistic, especially when we're talking about something that can be defined as extremely hazardous.<br /><br /><font color="yellow">"Loss of life and property aside, we'd not be able to get anything complicated and significant done if we were loosing 5% of our manned launches."</font><br />----------<br />So you don't consider a 95% success rate, successful? You don't think anything can be accomplished with a 95% success rate? Again, unreasonable and unrealistic.<br /><br /><font color="yellow">"The shuttle is running at 2% right now, and look how it has affected the construction and operation of the ISS.</font><br />----------<br />The only reason ISS construction has been so severely affected is because NASA stops all operations for years at a time whenever there's a problem, usually not resulting in a complete resolution.<br /><br />Considering STS-114 still experienced the falling foam, what was accomplished by the 2 1/2 years worth of downtime? The less-likelihood of a certainly uncommon problem? Based on the shuttles *actual history of success*, STS-114 is no safer now than it would have been 2 1/2 years ago.<br /><br />In my opinion, the end result doesn't justify the 2 1/2 years delay. NASA's upper management is in more need of an overhaul than the shuttle fleet.

 

[tomnackid]

"You saying you don't think a 99% success rate is acceptable. To expect 100% success is simply unreasonable and unrealistic, especially when we're talking about something that can be defined as extremely hazardous. "<br />--------------------------------------------------------<br />I think that a big problem with this discussion is that people in general don't have a good understanding of statistics (as the popularity of state lotteries and casinos abundantly makes clear!)<br /><br />Would you drive in an automobile that has a 99% success rate? At first glance you might say "sure, 99% seems pretty good odds!" But think about what it means really. If you take 100 trips in a car (maybe 2 months driving at most for the average person) one of those trips will be certain to be fatal. Now putting it that way would you drive a car that is certain to kill a person every month?<br /><br />Here is another example. We usually use the term "million to one shot" as meaning "just about impossible". Well, there are 200 million people in the US right now, if the odds of someone being say a serial killer are "a million to one" then there are right now 200 serial killers running around the US--an average of 4 per state! (On the bright side if the odds of being a genius are "a million to one" then we also have an average of 4 Einstiens per state!)<br /><br />I agree that testing new techniques and pushing the envelope inherently requires a greater acceptance of risk. But there is no reason for people to die just to launch a communications satellite or deliver groceries to the space station. The fact is that no matter how much NASA, congress and the general public wanted the shuttle to be the route to cheap and safe space travel it never was that. It is still an experimental craft pushing the envelope and its safety record shows that. <br /><br />PS: I don't think Rutan and Branson will get many customers if their marketing campaign is "Only one fatality per every hundred flights!"

 

[dwightlooi]

<b>IMHO, an effective policy for NASA will be to demand an 80% success rate for any NEW space launch vehicle, manned or otherwise, with a catastrophic failure rate that will result in the loss of crew or launch escape system use being 5%. This relaxed standard applies to the first five launches of a NEW vehicle. After that, it is to 5% failure and 1% catastrophic failure.</b> If and when an accident happens, the standard goes back up to 80% and 5% for the next 5 launches. As long as it is honestly believed that a launch can be made with no more than 5% chance of the loss of crew or utilization launch escape, the launch will proceed. Safety will be continually improved after launches resumed.<br /><br />Hence, by this strategy, we would have spent a month or two identifying the cause of the Columbia loss and come to the conclusion that (1) There is a problem with foam shedding and the layout of the shuttle system in general. (2) We cannot really fix it, though extra care can and should be taken when applying foam in certain areas. (3) The risk of a fatal accident, both projected and statistically indicated, is less than 5%. Hence, we will continue flying anyway and finish the ISS. If any astronaut do not wish to fly on the mission, they will be substituted. Now lets get on with it.<br /><br />I think this is a reasonable and realistic policy. In fact, I do not think that, regardless of how many billions we spend and how much time we waste, we can do significantly better. We cannot live in a Timid New World!

 

[thermionic]

I don't have anything profound to add, but since I was quoted I shall respond...<br /><br />I don't think 99% success rate (informally defined as the craft, astronauts, and cargo survive) is acceptable. Think of the space program as a big machine, and each launch as a piece of it. If the machine requires 100 pieces (e.g. 100 flights to complete VSE), then it is busted - />not working<- if each piece has 1% failure rate. That's what I was trying to get at.<br /><br />Now I'm not saying I expect 100% success, but if the physics, dynamics, materials, procedures of space flight are well understood, I don't see why it has to be dangerous. Solve the problem, build it right, do it right, so it will work very close to every time.<br /><br /> />>So you don't consider a 95% success rate successful?<br /><br />Well, it depends on what the goal is. I think the STS is very successful in the context of being the world's first reusable space plane, and all the other things that it is. It's so early in humanity's space efforts that a program as ambitious as the STS is bound to have some problems that we haven't sorted out. I think that it will be viewed as exceding expectations, considering our knowledge and skill level at this point in history.<br /><br />But STS has failed to have the reliability needed to build the ISS. At 98%, we stand a 'reasonable' chance of finishing the ISS with the 15-30 flights the various plans call for. At 95%, we're likely to loose one, possibly 2 more shuttles in the effort. And if we'd been running at 95% through the program so far, we'd only have one or 2 left. So the ISS could not be completed.<br /><br /> />>The only reason ISS construction has been so severely affected is because NASA stops all operations ... whenever there's a problem...<br /><br />Yes, that's true. But I think it has to be done that way. If a problem is brought to light, we have to make an effort to fix it. That's how progress occurs.<br /><br /> />>STS-114 is

 

[centsworth_II]

<font color="yellow">"Would you drive in an automobile that has a 99% success rate?"</font><br /><br />Maybe a better analogy would be climbing Mount Everest. According to one report, http://www.americanalpineclub.org/docs/HueyEverestAAJ_03.pdf, the climber death rate is close to 2%. And I see no lack of climbers willing to give it a try. <div class="Discussion_UserSignature"> </div>