space news from 22 Sept AW&ST
Henry Spencer
will issue a public request for proposals for launch services in October.
Bidding will be open to all; interest from the Chinese is expected, also
possibly other new suppliers.
NASA is preparing to release new transcripts of prelaunch conversations
among the Challenger crew. The tape is about an hour long, starting at
the time the crew entered the orbiter. There are some references to cold
weather, but nothing relevant to the launch decision. The recording was
not transcribed and released before because it provided no accident-relevant
information, and such conversations are normally confidential in deference
to crew privacy.
NASA space-station management recommends a redesigned station for launch
starting in 1993, focussing initially on a single crossbeam with manned
modules at the center and solar panels on the ends. Many systems planned
for external mounting on the "dual keel" station will now be inside enlarged
"resource nodes" connecting the manned modules, to reduce EVA requirements.
Extensive external structure resembling that of the "dual keel" station
might eventually evolve out of the initial configuration.
The redesign will probably delay attachment of the ESA lab module, and
possibly the Japanese module. The Canadian servicing facility might also
be affected. There are few assembly sequences that *don't* delay arrival
of the international components. The international partners might get
increased privileges in the US module group in compensation, although
doing this could make US users unhappy. Europe and Japan are pushing to get
their modules up as early as possible.
The redesign endorsed a crew escape module as desirable, but didn't make
it a formal part of the configuration. The intent here is probably an
attempt to separate the expensive escape module from the already-tight
budget.
The redesign will have a useful man-tended capability by the fifth assembly
flight (early 1994?) and will be permanently manned by the seventh or eighth
(mid 1994?). Full assembly of the previous configuration could have taken
31 launches over eight years.
The key changes that Fletcher might adopt are:
- Revision of assembly sequence to defer EVA until later missions.
- Change from the dual-keel configuration to the single-boom configuration,
at least for the first three years of operations. Automatic deployment of
the trusswork by robots is suggested as preferable to astronaut assembly.
The transverse boom may have disadvantages, such as pointing constraints
for instruments.
- Shortening of the pressurized modules to fit them better to reduced
shuttle lift limits.
- Emphasis on deployed rather than assembled utilities, again to reduce EVA.
- Use of expendables during assembly. This would probably require an
automated rendezvous and docking system, such as the Soviets have. The
polar platform may also need redesign to fly on the Titan 4, if there
won't be any polar Shuttle launches for a while.
- Basing the Orbital Maneuvering Vehicle in space during assembly, to give
more payload on shuttle flights. The OMV could also provide stationkeeping
and reboost during early assembly, before the station can do these for itself.
The review group found that shuttle launch rates will be a problem, given
that there will still be a backlog of missions from the launch hiatus. A
four-orbiter fleet is considered marginal in the circumstances.
Atlas E successfully launches NOAA weather satellite from Vandenberg Sept 17,
first successful US civilian satellite launch since shuttle 61C on Jan 12.
The satellite, NOAA-10, replaces the aging NOAA-6, which was called back into
service after NOAA-8 failed in orbit late last year. It also restores
Sarsat capability that was lost when NOAA-8 failed; NOAA-6 was too old to
have the search-and-rescue package. Launch was trouble-free when it finally
went off. It had been delayed a total of about a year due to scheduling
conflicts and problems with both satellite and booster. 12 Atlas E's remain
in inventory, assigned to military and civilian weather satellites through
about 1990. NOAA is concerned, however, that the USAF may stop using the
Atlas E, putting all the overhead costs in NOAA's lap. NOAA is studying
the cost of launching its satellites on Titan 2, just in case.
New report on problems of radioactive space debris calls it a serious
problem. There are about 50 reactors and isotope generators now in orbit,
mostly from the Soviet military radar satellites. The Teledyne Brown
report also says there is cause to worry about the possibility of one of
those satellites being fragmented by a debris collision; most of them are
in high-traffic orbital regions. The Soviets did speculate that the Cosmos
954 incident might have involved a debris collision. Another ominous item
is that the only US reactor in orbit, the experimental SNAP-10A launched
in 1965, has spawned pieces of debris on at least six occasions in the last
seven years; nobody knows what the debris is or why it's being released.
Launch failures are also a concern. The US has had two isotope generators
go into the ocean after launch failures, one later recovered intact and the
other believed to have survived intact. The Soviets have dropped two radar-
satellite reactors into the Pacific from launch failures, also a Lunokhod
with an isotope heat source.
NASA delays rollout of Atlantis for weather-protection tests two weeks to
Oct 7. This will be the first time a shuttle has been rolled out since
51L, and probably the last until launches resume. The main purpose is to
check new weather-protection shields on Pad 39B. NASA also is taking
advantage of the only time it will have a shuttle on the pad any time
soon to run assorted other tests of pad procedures and facilities. The
delay is because a jammed payload-changeout-room door must be repaired if
some of the auxiliary tests are to be run, and because wind instrumentation
for a hydrogen-trapping test must be in place before Atlantis returns to
the VAB if that test is to be run. The door repair is taking longer than
expected, and the wind-measuring gear won't be ready until mid-November.
Among the auxiliary tests are a crew-escape simulation, to evaluate the
escape procedures and train support crews on them.
Doubts are being expressed that the shuttle will be ready to go in the
first quarter of 1988. Testing and verification of the booster redesign
is a problem area, although Truly says that the worst part of clearing
the shuttle to fly again is the huge task of reviewing all the flight-
critical items from scratch. One thing that would necessarily involve
a major delay would be a vertical test firing of a full SRB. At the
moment all full tests are to be horizontal, although there has been a
strong recommendation for a new test stand at Morton Thiokol to permit
testing under dynamic loads that the current stand can't provide.
[Editorial for the week: I support the recommendation in "America: A
Spacefaring Nation Again" that military shuttle launches using volunteer
military crews should resume *immediately*, to meet immediate needs and
keep the launch crews in practice. -- HS]
House adopted and sent to the Senate an Administration-backed bill which
extends US patent law to cover space activities about US space vehicles;
essentially it makes a US space vehicle part of the US for patent purposes.
Senate action this year is unlikely due to lack of time.
Intelsat buys another Ariane for the third Intelsat 6, formerly contracted
for the Shuttle. The first and second Intelsat 6's have already made the
switch.
Intelsat plans to self-insure launch of the first two Intelsat 6 comsats,
and has cancelled partial launch insurance already obtained. Full coverage
for $200M satellites was unobtainable, and the premiums for partial coverage
were approaching the value of the coverage itself.
--
Henry Spencer @ U of Toronto Zoology
{allegra,ihnp4,decvax,pyramid}!utzoo!henry
Alex B Laney
>[Editorial for the week: I support the recommendation in "America: A
>Spacefaring Nation Again" that military shuttle launches using volunteer
>military crews should resume *immediately*, to meet immediate needs and
>keep the launch crews in practice. -- HS]
... I volunteer Henry.
--
- + - + -
Alex Laney, Xios Systems Corp, 105-1600 Carling Av, Ottawa (613)725-5411x402
utzoo -
> !dciem
allegra!ihnp4!utcsri -- > nrcaer!xios!lib!alex
ucbvax!hplabs -- /
> !seismo!hadron!netex!prcrs/
decvax --
Henry Spencer
> >military crews should resume *immediately*...
>
> ... I volunteer Henry.
I volunteer me, too!
Given some care -- warm weather, careful booster stacking, avoiding high
pressures in leak tests -- there is no real doubt that unmodified Shuttles
could be launched with little chance of disastrous failure. There wouldn't
be the slightest problem finding qualified volunteer crews.
lucius
> Given some care -- warm weather, careful booster stacking, avoiding high
> pressures in leak tests -- there is no real doubt that unmodified Shuttles
> could be launched with little chance of disastrous failure.
How can you be sure that the chance of disastrous failure is little?
Our track record only suggests that the chance of a disaster isn't greatly
over 1 in 25, which seems to me to be unacceptable without taking precautions
to reduce it. Considering NASA's internal track record, I think those things
should stay grounded until they are checked over by people who are not being
pushed to gloss things over, and a full technical report of the checkout comes
out. Otherwise, we might have as many as 25 more flights, and then another
disaster, which would even further cripple our space capability.
Also, you propose getting launches going for military missions. Why
so much interest in running military missions in such haste? Further
militarization of space is one of the things we _ l_ e_ a_ s_ t need. Why should the
military get priority in recovery efforts after something goes wrong? It is
_ c_ r_ i_ m_ i_ n_ a_ l that, after the shuttle has been presented to the taxpayers as a
commercially viable venture, the commercial ventures and all but a handful of
scientific missions have been kicked off it in favor of the military.
--
-- Lucius Chiaraviglio
luc...@tardis.harvard.edu
{insert your favorite brave system here}!seismo!tardis!lucius
Please do not mail replies to me on husc2 (disk quota problems, and broken
mail system won't let me send mail out). Please send only to the address
given above.
Phil Karn
> pressures in leak tests -- there is no real doubt that unmodified Shuttles
> could be launched with little chance of disastrous failure. There wouldn't
> be the slightest problem finding qualified volunteer crews.
According to the Rogers commission, "O-ring thermal distress" has occurred
during launches in temperatures as high as 75 deg F (STS-61A, two different
joints). Anomalies also occurred on STS-41D and STS-2, which were both
launched at 70 F, despite a lower leak check pressure (100 psi on the nozzle
joint on 41D, 50 psi on STS-2). It would be mad to launch an unfixed SRB
with that kind of track record.
Perhaps I'd approve of a military flight of an unmodified shuttle if the DoD
FIRST turned over its SDI funding for a year and built another orbiter (and
possibly another launch pad) to cover NASA in the event of another disaster.
Unfortunately, though, it's always NASA who gets to eat the risks.
Phil
Henry Spencer
> Our track record only suggests that the chance of a disaster isn't greatly
> over 1 in 25, which seems to me to be unacceptable without taking precautions
Have you read the Rogers Commission report? The problems generally show a
strong correlation -- not a perfect one, but pretty strong -- with cold
temperatures and high-pressure leak tests. (The incidence of O-ring trouble
jumped *spectacularly* when NASA increased leak-test pressure; the Rogers
people were appalled that nobody had noticed.) Admittedly I should probably
have said "little doubt" rather than "no real doubt", but it seems like a
good bet to me. At the very least, given the correlations, it's safe to say
that SRB reliability with warm joints and low-pressure leak tests should be
rather better than the overall current record.
> ... stay grounded until they are checked over by people who are not being
> pushed to gloss things over...
If the basis for this is that it's unacceptable to risk crews, all I can say
is that qualified volunteers should not be hard to find. If the basis is
excessive risk to payloads, see comments below. If the basis is risk of
losing another orbiter, I *do* agree that it is not realistic to fly more
Shuttle missions without a commitment to prompt replacement of orbiters
lost due to accident. (You will note that the previous sentence does *not*
limit itself to missions prior to the safety overhaul.)
> Also, you propose getting launches going for military missions. Why
> so much interest in running military missions in such haste? ...
When it comes to keeping the launch crews in practice, the nature of the
payload is pretty irrelevant. And I personally think that a lot of other
payloads are more important. However, flying the Shuttle before the safety
changes are complete must be considered slightly risky. Not risky enough
not to do it, but risky enough to think twice about launching one-of-a-kind
payloads like the Space Telescope. The loss of a single military payload
wouldn't be a tenth of the disaster that losing the HST would be. Other
reasons are that the public is more willing to accept risks on military
missions flown by military crews -- look at the death rate in military
flying if you doubt this -- and that the current climate in Washington is
more favorable to strong backing of risky undertakings when there are
military motives. (This may not be pleasant, but we have to live in the
real world, folks.)
> Further militarization of space is one of the things we least need.
It is going to happen whether we like it or not; have you seen the current
notions of what the Shuttle cargo manifest will look like when launches
resume? Given that those payloads *will* fly, let them take the risks
and keep the system going while its problems are fixed.
> Why should the
> military get priority in recovery efforts after something goes wrong?
They aren't getting priority in recovery efforts, they are being asked to
assume the responsibility and risks of keeping a flawed system going
*before* the recovery effort is complete. They are, after all, sworn to
give their lives for their country if needed.
> It is criminal that, after the shuttle has been presented to the taxpayers
> as a commercially viable venture, the commercial ventures and all but a
> handful of scientific missions have been kicked off it...
Yup. But the taxpayers, or rather their elected representatives, didn't
feel like funding a commercially viable venture. The Shuttle program
survived by appealing to the military for help; we are now paying the piper.
(And the tune he played wasn't even all that good, dammit! Not even a
fifth orbiter, much less a fifteenth.)
Henry Spencer
Agreed that I overstated the case a bit, but only a bit. Being careful with
the O-rings will not reduce risk to zero, but it will improve the odds a lot.
Yes, there were O-ring problems in favorable conditions, but the points on
the graphs cluster awfully heavily on the "unfavorable" side.
> ... It would be mad to launch an unfixed SRB with that kind of track record.
Not mad, just a little daring in a good cause. There is no such thing as
a zero-risk mission. Remember "if we die, we want the program to continue;
the conquest of space is worth the risk of life"? The continuation of the
shuttle program is receding steadily farther into the future.
> Perhaps I'd approve of a military flight of an unmodified shuttle if the DoD
> FIRST turned over its SDI funding for a year and built another orbiter (and
> possibly another launch pad) to cover NASA in the event of another disaster.
Sounds like a fine idea to me; pity it won't happen.
> Unfortunately, though, it's always NASA who gets to eat the risks.
I do agree that flying the shuttle again immediately is unacceptable without
a firm commitment to replacing further losses. That's the biggest reason
why, unfortunately, it's not going to happen.
David desJardins
>about launching one-of-a-kind payloads like the Space Telescope. The
>loss of a single military payload wouldn't be a tenth of the disaster
>that losing the HST would be.
As much as I agree with your sentiment (that shuttle launches should
resume ASAP), the above makes no real sense, except perhaps politically.
The $1G HST doesn't add significantly to the risk of losing the $2.5G
orbiter (certainly not "ten times"!).
-- David desJardins
Brooks Gelfand
I agree, finding crews would probably not be a problem. The problem is
we cannot aford to loose any more shuttles. These things are not mass
produced; the lead time to replace one is several years.
They are very expensive. Loose another one and our glorious congress
may not appropriate the money needed to replace it.
Brooks Gelfand
Usenet netnews
Keywords:
From: j...@oddhack.Caltech.Edu (Jon Leech)
Path: oddhack!jon
The only qualified people (the current members of the Astronaut Corps)
say they will be happy to fly it - as soon as the SRBs are understood,
fixed, and tested (at least, this is what Sally Ride said in a talk she
gave at Caltech last night). Since these are the people who have been putting
their lives on the line all along, I tend to trust their judgement. By the
time any of the well-meaning volunteers could be trained, the joint redesign
and testing program will hopefully be completed anyway.
-- Jon Leech (j...@csvax.caltech.edu || ...seismo!cit-vax!jon)
Caltech Computer Science Graphics Group
__@/
David desJardins
> The only qualified people (the current members of the Astronaut Corps)
>say they will be happy to fly it - as soon as the SRBs are understood,
>fixed, and tested (at least, this is what Sally Ride said in a talk she
>gave at Caltech last night).
I find this very hard to believe. Certainly there was no problem with
finding people to fly on the first shuttle flight, with a *much* greater
risk than the 26th -- why would they suddenly not want to fly?
From what I read in the media (admittedly a very poor source of such
information) Sally Ride in particular is the most outspoken and insistent
of the astronauts on the safety issue. I wouldn't take her views as
representative without further evidence.
Finally, if the astronauts we have aren't willing to fly, then we
should be training some who are (whether or not shuttle flights are to
be resumed).
-- David desJardins
Usenet netnews
Keywords:
From: j...@oddhack.Caltech.Edu (Jon Leech)
Path: oddhack!jon
In article <2...@cartan.Berkeley.EDU> desj@brahms (David desJardins) writes:
>In article <11...@cit-vax.Caltech.Edu> j...@cit-vax.UUCP (Jon Leech) writes:
>> The only qualified people (the current members of the Astronaut Corps)
>>say they will be happy to fly it - as soon as the SRBs are understood,
>>fixed, and tested (at least, this is what Sally Ride said in a talk she
>>gave at Caltech last night).
>
> I find this very hard to believe. Certainly there was no problem with
>finding people to fly on the first shuttle flight, with a *much* greater
>risk than the 26th -- why would they suddenly not want to fly?
I find it very easy to believe. The first flights of the shuttle
were flown by experienced test pilots who knew and accepted high risks.
The Mission Specialists and Payload Specialists are there to do a different
job, one which should not require undue risk of life. Without these people,
perhaps shuttles can be flown, but they won't be doing nearly as much.
>
> From what I read in the media (admittedly a very poor source of such
>information) Sally Ride in particular is the most outspoken and insistent
>of the astronauts on the safety issue. I wouldn't take her views as
>representative without further evidence.
If so, perhaps it is because her membership on the Rogers Commission
gave her a better understanding of the many flaws in NASA and the shuttle
program. Her views are certainly representative of Sally Ride, at least.
>
> Finally, if the astronauts we have aren't willing to fly, then we
>should be training some who are (whether or not shuttle flights are to
>be resumed).
>
> -- David desJardins
This is ridiculous. We certainly don't need astronauts if the
shuttle is not going to fly again. Since it is, we need the current
astronauts, who have the most experience and familiarity with the system.
Offering their - or any - lives to a system with at least one demonstrated
fatal failure mode is very generous for people who are NOT that familiar
and who won't fly themselves.
Waiting until 1988 for another shuttle flight is unpleasant,
but we'll be waiting a hell of a lot longer if we start flying them
again and lose another one.
Henry Spencer
> resume ASAP), the above makes no real sense, except perhaps politically.
> The $1G HST doesn't add significantly to the risk of losing the $2.5G
> orbiter (certainly not "ten times"!).
I was comparing payloads, not orbiters. Any immediate resumption of
launches clearly demands a commitment to replace any further orbiter losses.
But replacing the HST would be difficult and very expensive; remember that
a new one would probably cost a good deal more than the existing one.
Replacing an orbiter could be justified in terms of strongly-supported
(well, relatively strongly-supported) things like military space activity
and the Space Station. Replacing the HST would be harder. Better we
should launch something we can afford to lose.
Henry Spencer
> say they will be happy to fly it - as soon as the SRBs are understood,
> fixed, and tested (at least, this is what Sally Ride said in a talk she
> their lives on the line all along, I tend to trust their judgement. By the
> time any of the well-meaning volunteers could be trained, the joint redesign
> and testing program will hopefully be completed anyway.
When I said "qualified volunteers", I meant from the current astronauts.
Sally Ride is not the whole astronaut corps. The astronauts have an obvious
vested interest in pushing the safety issue as hard as they can; this should
be seen as what it is, a political maneuver to encourage badly-needed changes.
If there was a top-level decision to the effect that there *will* be launches
at once but that the safety cleanup will continue, I don't think there would
be any problem getting astronauts for the flights. Also, as I have observed
before, a good fraction of the astronauts are military officers, who are
sworn to risk their lives for their country on request anyway.
Henry Spencer
> were flown by experienced test pilots who knew and accepted high risks.
> The Mission Specialists and Payload Specialists are there to do a different
> job, one which should not require undue risk of life. Without these people,
> perhaps shuttles can be flown, but they won't be doing nearly as much.
It is a verifiable fact that there are Payload Specialists who would fly on
the Shuttle tomorrow if they could; the "Spacefaring Nation" report identified
some. And if you look at the record, I think you'll find that Mission
Specialists flew pretty early in the program. I'm sure that not all of the
Mission/Payload Specialists would volunteer; I'm equally sure that enough
of them would.
David desJardins
>> I find this very hard to believe. Certainly there was no problem with
>>finding people to fly on the first shuttle flight, with a *much* greater
>>risk than the 26th -- why would they suddenly not want to fly?
>
>were flown by experienced test pilots who knew and accepted high risks.
>The Mission Specialists and Payload Specialists are there to do a different
>job, one which should not require undue risk of life. Without these people,
>perhaps shuttles can be flown, but they won't be doing nearly as much.
The original proposal was a resumption of flights with military crews.
In any case, those who are willing to fly should fly, and those who are
not should not. I still believe (Ms. Ride's statements notwithstanding)
that there will be plenty of volunteers.
> If so, perhaps it is because her membership on the Rogers Commission
>gave her a better understanding of the many flaws in NASA and the shuttle
>program.
Certainly possible. The converse is also possible -- that she was chosen
for the commission because of her views on safety.
The Rogers Commission "discovered" very little, and what they did every-
one else now knows from their report. Mostly what the Rogers Commission
did is publish their opinions about how NASA should be run (or, if you
prefer, "the many flaws in NASA and the shuttle program"). I seriously
doubt that it would cause any serious change in the opinions of any person
who was already knowledgeable about the program.
The basic question should be, "What is an acceptable level of risk?"
Not, "How can we completely minimize risk?" We do the latter simply by
never flying at all.
>> Finally, if the astronauts we have aren't willing to fly, then we
>>should be training some who are (whether or not shuttle flights are to
>>be resumed).
>
> This is ridiculous. We certainly don't need astronauts if the
>shuttle is not going to fly again.
If at some time in the future (say, after another accident) we need
to fly the shuttle despite known safety problems, it would certainly be
desirable to have trained crews who are willing to fly.
>Since it is, we need the current astronauts, who have the most experience
>and familiarity with the system.
But mostly we need people who are willing to do their jobs when the
need arises. At any rate, I really doubt that this is seriously a problem,
since I still find it impossible to imagine that any substantial number
of the current astronauts would refuse to fly.
>Offering their - or any - lives to a system with at least one demonstrated
>fatal failure mode is very generous for people who are NOT that familiar
>and who won't fly themselves.
Why is it different than the 25th flight, where we DID offer the crew's
lives to a system with at least one (undemonstrated) fatal failure mode?
Or the 27th flight, on which we WILL offer their lives to a system with
at least one still undemonstrated fatal failure mode? You are just as
dead if you are killed by an undemonstrated failure mode as you are if
you are killed by a demonstrated mode.
If you are saying that we should never fly the shuttle unless and until
we are certain that there are NO fatal failure modes, then we are never
going to fly it at all, and one is left to wonder why we built them in
the first place.
> Waiting until 1988 for another shuttle flight is unpleasant,
>but we'll be waiting a hell of a lot longer if we start flying them
>again and lose another one.
We definitely need a commitment to replace any shuttles that are
lost. Self-insurance is hardly a complicated notion. Let us make the
pessimistic assumption that there is a 1% additional chance of joint
failure for each launch before the problem is fixed, and the optimistic
assumption that we can conduct 5 launches in this time. At $2.5G per
shuttle, this comes to $125M expected additional cost for these flights.
Can we really not afford this?
-- David desJardins
Usenet netnews
Keywords:
From: j...@oddhack.Caltech.Edu (Jon Leech)
Path: oddhack!jon
In article <2...@cartan.Berkeley.EDU> desj@brahms (David desJardins) writes:
> The Rogers Commission "discovered" very little, and what they did every-
>one else now knows from their report. Mostly what the Rogers Commission
>did is publish their opinions about how NASA should be run (or, if you
>prefer, "the many flaws in NASA and the shuttle program"). I seriously
>doubt that it would cause any serious change in the opinions of any person
>who was already knowledgeable about the program.
What exactly does `knowledgeable about the program' mean?
People who were supposedly `knowedgeable' about the SRBs either were
never informed about the O-ring erosion problem, or chose to ignore it
repeatedly. Without changes in `how NASA should be run', I see no reason to
believe exactly the same thing will not happen with some other
potentially fatal problem, enough times that potential turns into reality.
Perhaps the Commission recommendations are not the best way to fix
NASA management problems, but SOMETHING should be done if we are to
avoid another Challenger (ideally an infusion of money big enough
to restore the quality-control procedures and `can do' attitude of the
Apollo days).
>
>>Offering their - or any - lives to a system with at least one demonstrated
>>fatal failure mode is very generous for people who are NOT that familiar
>>and who won't fly themselves.
>
> Why is it different than the 25th flight, where we DID offer the crew's
>lives to a system with at least one (undemonstrated) fatal failure mode?
>Or the 27th flight, on which we WILL offer their lives to a system with
>at least one still undemonstrated fatal failure mode? You are just as
>dead if you are killed by an undemonstrated failure mode as you are if
>you are killed by a demonstrated mode.
> If you are saying that we should never fly the shuttle unless and until
>we are certain that there are NO fatal failure modes, then we are never
>going to fly it at all, and one is left to wonder why we built them in
>the first place.
No, that's not what I'm saying. Consider an analogy to automobiles
or airplanes: when something seriously wrong happens (engines falling
off, say, or doors flying open at 30,000 feet), the vehicle is grounded
until the fundamental problem is fixed. Then it continues flying - with
the knowledge that there are unquantifiable further risks. This happens
even with military aircraft on occasion.
In an ideal world we could afford to take the (probably low)
risks of flying shuttles immediately. In the real world, where another
shuttle loss would almost certainly not be replaced and might even
spell the end of civilian manned space flight, it behooves NASA to
be careful. This does not mean being `certain that there are NO fatal
failure modes'; it DOES mean being confident that the joint erosion
problem will not occur again, and fixing all the other problems
possible while the joint fix is going on.
As long as I'm saying things people disagree with, how about
this: the Challenger disaster is in certain respects the BEST possible
thing to happen to the American space effort recently; by shoving
commerical payloads off the Shuttle, we may finally get a healthy
private ELV industry.
Henry Spencer
> or airplanes: when something seriously wrong happens (engines falling
> off, say, or doors flying open at 30,000 feet), the vehicle is grounded
Not always. It will probably be grounded until something is understood
about the causes of the problem. Often it will then resume flying, under
restrictions (e.g. the door flies off at 30,000 feet so max altitude is
25,000 for the moment), while the definitive fix is devised. The suggestion
I and others are making is that applying the same standard to the Shuttle
would be reasonable.
David desJardins
>Because there is a *known* problem which poses a serious hazard to flying
>the shuttle. A problem of this magnitude cannot go ignored.... The most
>rational philosophy is to seek out and identify all the problems and
>potential problems we can find. Once those problems are known, solutions
>can be devised for them, within the limits of practicality (time, money,
>available technology, so forth).
Exactly. In this particular case the limit is not one of money -- the
cost of SRB redesign is amply justified by the resulting increase in launch
reliability -- but one of time.
>Once this is done what remains are problems for which perfect solutions have
>not been found and unknown problems.
The SRB problem falls into the former category. There is no perfect
solution (i.e., one which would be ready to fly tomorrow).
>[...] there's always going to be some risk, but at some point we have to
>decide if we're going to assume that risk. Only one who is foolhardy would
>choose to ignore a known problem such as with the SRBs right now and say,
>"Sounds like an acceptable risk to me."
This is where you are wrong. What is foolish is to refuse to fly until
all known problems are fixed, regardless of the cost (in time and money).
It is also hypocritical, in that other equally serious problems are being
neglected while others get the publicity. I think that any person who is
knowledgeable about the shuttle would agree that if the shuttle were to be
launched immediately, with simple precautions (e.g., not launching in arctic
weather!), that the risk of loss due to SSME malfunction would be substan-
tially than the risk of SRB failure. The main engines are extremely com-
plicated, and an internal failure which would be minor in a more ordinary
piece of hardware could easily prove fatal inside of the SSME. But we
accept this (known) risk of flying the shuttle; why are the SRB risks any
different? In each case the only rational approach is to analyze the
risks and benefits of a launch and determine if it is desirable.
>Young and Crippen (and all the other astronauts who could have been chosen
>as the first two shuttle crew) believed they understood what could go wrong
>and what could be done about such problems. Certainly they knew that some
>problems were unsolvable and would result in loss of orbiter and crew.
>Those problems were undoubtedly given most careful consideration and the
>conclusion was such problems were unlikely in the extreme.
Nonsense. I don't have access to internal NASA documents, but I'm sure
that the estimated probability of mission failure was at least 10-20%. And
if it was at the low end of this range they were being unrealistic.
The risk now, after 25 flights, is *much* less.
>The risk was deemed to be acceptable. Had they known about this SRB mis-
>feature I would hope that they would have said the risk is unacceptable;
>let's do something about this problem first, then we'll fly.
Why would you hope this?
>And that's what the astronauts seem to be saying now.
As I have said, I find this impossible to believe. Henry has quoted
sources which say otherwise.
>> Finally, if the astronauts we have aren't willing to fly, then we
>> should be training some who are (whether or not shuttle flights are to
>> be resumed).
>
>Seriously, there is a big difference between bravery and stupidity.
>I think the astronauts who say they want to continue flying after the
>SRBs are fixed display a great deal of courage.
Are you joking? Why would anyone become an astronaut who is not willing
to accept the risks?
The point is that the astronauts were willing to accept much greater
risks on the early flights, so why are lesser risks suddenly too much to
accept?
>I wouldn't want to fly with anyone so reckless as to propose resuming launch
>of shuttles without attempting to understand and fix the SRB problem.
The problem *is* understood, and a large part of the fix is not flying in
certain conditions and taking certain precautions.
*I* wouldn't want to fly with someone so irrational as to demand that
certain risks be reduced while other, larger risks remain. Nor with someone
so irrational as to be willing to fly with a 10% unknown risk but not with
a 1% known risk.
>It's not that I don't think the goal is worth risking lives. Quite the
>contrary, I do think the risk is worthwhile and I'm willing to take that
>risk personally. But flying the shuttle now, without fixing the SRBs (at
>least!) first, is unconscionable. Should the tragedy repeat itself, the
>result would be a waste of human life. I cannot condone such a waste....
I have this feeling that we are never going to understand each other.
I can't understand how you can worry so much about a few lives while millions
die every year whom you could have saved by giving them some food. Or while
thousands are killed with weapons paid for by your tax dollars. Or while
thousands of accident victims could be saved by an investment in trauma
centers. If your desire is to save lives, it makes a lot more sense to
invest your dollars and time in those things than to worry about making the
shuttle safe.
It seems instead that your interest is in saving a few *particular* lives.
And if you value the possible preservation of those particular lives more
than the benefits of resuming shuttle launches, then I can note that you are
being irrational, but I don't see how I can change your mind.
-- David desJardins
Patrick McGehearty
to fly is based on a misapprehension about why they raised the issue.
I am basing my opinions on books such as The Right Stuff, and general
knowledge of risk-takers and organization politics.
The astronauts are not afraid to fly when a reasonable risk/cost/feasiblity
tradeoff has been and the best available (in terms of time/cost/etc)
fixes have been implemented. However, the crash and following
investigation gives strong evidence that they disagree with
previous policy on what are the reasonable tradeoffs.
Therefore, they are trying to change the organization structure
so that the "astronauts" as a group have significant input in
making these tradeoff decisions.
Statements like "We won't fly until its fixed" are made for reasons
of political positioning. While legally it is feasible to order
flights over astronaut objections, it is politically shakey.
Imagine what would happen to NASA if some number of astronauts were
saying the shuttle was unsafe, and another one blew up!!?
(as an organization, and to the decision makers, never mind
the national tragedy aspects) Witch hunts instead of white washes
would be the order of the day.
I suspect that the astronauts will knowing accept considerable risks
if they feel in control of the risk assessment process.
I also believe that they are more concerned with the success of
the space program as a whole than their individual risk, but that
like the rest of the above is just my opinion.
- Patrick McGehearty (A Space Advocate like (most of) the rest of you)
Ronald O. Christian
>But flying the shuttle now, without fixing the SRBs (at least!) first, is
>unconscionable. Should the tragedy repeat itself, the result would be a
>stake is mine or not. I hope there are not too many people who disagree.
> Roger Noe ihnp4!uniq!rjnoe
Well, at first I did. I got the impression that we understood the
SRB failure well enough not to launch when conditions are right for
a second failure. Right? I mean, I had a car once that wouldn't run
when it rained. Just stalled out. I simply didn't try to drive it
when it rained...
Furthermore, although one can't deny the value of human life, (at least
that's the way I feel about *mine*) there *are* things that are more
important. What constitutes an acceptable risk varies widely from
one individual to another. Not suicidal. Just placing a higher value
on the goal of the mission.
Then I got to thinking. (Exit knee-jerk mode :-)) What happens if
*another* shuttle does the old skyrocket trick? Does Congress shut
down NASA until the year 3000? The point is, there is more at stake
here than a few lives. Also, what happens when the weather's cold and
the President just has to be on television with the astronauts again? :-)
Let's fix the SRB's first.
Ron
--
--
Ronald O. Christian (Fujitsu America Inc., San Jose, Calif.)
seismo!amdahl!fai!ronc -or- ihnp4!pesnta!fai!ronc
Oliver's law of assumed responsibility:
"If you are seen fixing it, you will be blamed for breaking it."
Frank Caggiano
>I think that any person who is
>knowledgeable about the shuttle would agree that if the shuttle were to be
>launched immediately, with simple precautions (e.g., not launching in arctic
>weather!), that the risk of loss due to SSME malfunction would be substan-
>tially than the risk of SRB failure.
I never relized that the weather in Florida during January was considered
arctic. I always wondered why so many people went there on vacation :-)
Frank Caggiano
Eugene Miya N.
be considered policy or a sign of how NASA (my employer) thinks
about policy. This is strictly my opinion. Enough disclaimer.
Shortly, after the Challenger accident it amazed me the attention
given the the crew as Heros. Roger Noe and I discussed this a bit
because we saw them more as victims. Shortly there after, I signed
off due to the volume of trash in the space and shuttle groups.
[I've only returned because of the reorganization of the net groups,
and will leave when it gets bad again.] No discussion about sending
crews up can take place with adequately considering some other
major accidents. We typically think of an accident as a single
focused event: Chernobyl is a good counter to this way of thinking.
Consider, as I did several months ago, SUPPOSE there had existed a
different emergency situation on the Challenger. Let's say it made
it into orbit, but badily damaged, but the crew could live 10 days
(stretching it), and further SUPPOSE, we had the capability to launch
another shuttle during this time frame, but that since the weather
was basically the same, we had to risk a rescue/second accident.
(Assuming a potentially time wear-out problem.) Do we let the crew die
in orbit (or try and re-enter in a crippled craft)? Do we risk
a second crew to the potential of a similar accident under near
identical conditions (remember we did not know within 10 days the cause
of the accident) [give more thought to this condition, would you go up
knowing the odds to save another crew in orbit, or is it a futile
gesture]? These are the kinds of conditions which bring out
heroism (or more victims). The space program has had many close calls
in the Mercury, Gemini, and Apollo programs (as well as similar Soviet
problems).
Sure, we are all going to be careful the NEXT time. It's our history.
It's how mankind progresses. Sure, the next mission and subsequent ones
are going to have increased awareness, but don't focus on this one
problem. Don't forget there were other identified problems. Keep
general awareness.
--eugene miya
NASA Ames Research Center
eug...@ames-aurora.ARPA
"You trust the `reply' command with all those different mailers out there?"
{hplabs,hao,nike,ihnp4,decwrl,allegra,tektronix,menlo70}!ames!aurora!eugene
David desJardins
>But is the perceived shortness of time due to unbridled eagerness to resume
>launches, or is it because we've made a reasonable effort to discover pre-
>viously unknown problems and to implement corrections for known problems?
>Only the latter is (in my opinion) proper justification for saying that
>further delay is unwarranted. When the point is reached where we can
>honestly say (not just about the SRB joints, but about all the criticality-1
>problems) that we've made a reasonable attempt to rectify the problems we
>know about and that further delay would be all out of proportion to the
>expected gains in safety and functionality, then and only then will it be
>time to reconsider launching again. This is precisely what happened
>following the 204 fire and that's precisely what we should be doing now.
Great. I can honestly say that further delay would be all out of
proportion to a risk that I estimate at 1%. Let's go.
>> >.... Only one who is foolhardy would
>> >choose to ignore a known problem such as with the SRBs right now and say,
>> >"Sounds like an acceptable risk to me."
>>
>> This is where you are wrong. What is foolish is to refuse to fly until
>> all known problems are fixed, regardless of the cost (in time and money).
>
>Just *who* is proposing that? Not me. Because to fix all known problems
>either requires infinite time and money or the attitude of an ostrich.
>I have neither. What is important is that we not be reckless, that we
>not take *unreasonable* risks.
You said (the quote is immediately above!) that it would be foolhardy to
decide that a known problem constitutes an acceptable risk. The words are
right there in black and white. If you can never decide that a known problem
constitutes an acceptable risk then you can never launch. Period.
With regard to your restatement, what is your criterion for determining
whether a risk is reasonable or unreasonable? My criterion (and, I think,
the rational one) has already been presented -- the value of launching must
be weighed against the expected costs.
If you were to accept this criterion, I find it hard to understand how
you could argue against shuttle launches. Make the pessimistic assumption
that the probability of SRB failure is 1% for each launch (it should be
quite low, given that we know what conditions to avoid and can pay special
attention to SRB assembly). That comes out to an expected cost of around
$25M, based on an orbiter replacement cost of $2G+, plus the cost of other
items like the SRB casings and crew training. The mean cost to NASA of
each shuttle flight (not depreciation, just operational costs) is something
like $200M, so the additional cost of accepting the SRB risk seems to be
fairly small. But the real kicker is that, of that $200M, much of it is
expenses that NASA incurs even if there are no shuttle launches! Personnel
costs, maintenance of facilities and equipment, and so forth, cannot be
substantially reduced. And there is a hidden cost even in those expenses
that can be reduced -- the cost of losing trained personnel. Suppose that
NASA can reduce its costs by 75%, to only $50M per launch canceled -- a
very optimistic estimate.
Then, I claim, the additional cost of launching a shuttle immediately,
*even including the cost of assuming the SRB risk*, is only $150M + $25M,
or LESS than we have been willing to pay for previous shuttle launches,
and less than we will pay once launches are resumed. Not to mention other
benefits, such as improved morale and avoiding the cost of rescheduling or
canceling shuttle payloads, which can hardly be estimated.
So, if you accept the cost analysis criterion, it is impossible for me
to understand how you can oppose the resumption of shuttle flights.
>How can you say you're certain of the estimated probability of failure without
>consulting experts? Are you an aerospace risk assessment engineer? And how
>are you defining "mission failure" probability? If you refer to the chance of
>losing both orbiter and crew, you'd better check the figures. I've worked in
>aerospace, especially engineering on some very new designs, and I find it very
>hard to believe that any responsible organization would insist on testing an
>untried design if they calculated the probability of losing both pilot and
>aircraft at one in five. That's reckless. If you can't reduce the chance
>well below that, there's just no point in trying it, unless you were the one
>who invested *all* the time, money, and talent in the project and it's only
>your life at risk and therefore no one else at all has anything to lose if
>you choose to be reckless. (I am also ignoring here possibilities of risk
>to innocent bystanders and the public at large, which would of course enter
>into consideration in a real situation.)
Let's use some simple statistics. There were approximately two dozen
manned US space flights before the shuttle. Two of these resulted in what
I would call "mission failure," one in loss of vehicle and crew. Thus,
our a priori assumption would be that the chance of mission failure on manned
flights seems to be about 10%.
There are obviously many other factors to be considered. On the positive
side: much greater knowledge about rocket propulsion and space flight in
general and technological improvements since the 1960s and early 70s. On
the negative side: at the time of the first launch the shuttle was the
most complicated and least tested of US manned space vehicles; in particular,
neither the SSMEs nor the SRBs had been tested in flight, nor had the thermal
protection been tested on atmospheric reentry, nor had there ever been a
flying reentry from orbit (although there had been some testing of the
shuttle's landing capability, and of course extensive simulation).
In my opinion, the technological advancement about makes up for the
greatly increased complexity of the shuttle, and so the relative lack of
testing would put the first shuttle launch at greater risk than previous
space flights. A more optimistic assessment perhaps would estimate the
risks as equal.
No doubt you could produce some calculations which would have a much
smaller result. But, as you yourself say later in your article, it is
impossible to estimate unknown risks accurately. For example, the estimate
of the risk of catastrophic SRB burnthrough was obviously much too low
(although flying it outside its rated temperature range certainly didn't
help!). I am not saying that risk assessment has no value; quite the
contrary. It has great value for estimating relative risks and setting
priorities. But to pretend that the numbers produced by risk-assessment
engineers are accurate predictions of the probability of failure is just
fantasy.
I wish I had access to the data, say of risk assessments for all US
space flights, so that I could perform a statistical analysis of the
relationship between predicted and observed risks. I am very confident
that the results, when applied to shuttle risk assessment figures, would
justify my estimates of the probability of failure of the initial shuttle
mission.
>I disagree with your assessment that the first shuttle flights were
>riskier than is flying now with the problems the STS is known to have.
>The SRBs, in particular, were among the elements with what was perceived
>to be the lowest chance of failure. Taking this as true meant that the
>complete lack of a redundant system was acceptable. [...] The problem
>existed on STS-1, but it wasn't until 51-L that it was commonly known.
>And that makes all the difference.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is precisely the point. It makes no difference at all. The risk
is the same regardless of whether you know about it! The *only* difference
is that until a shuttle actually blows up you can hide your head in the
sand and pretend that it is perfectly safe. And then after the accident
you can pretend that it is completely unsafe. But the *fact* of the matter
is that the danger was always exactly the same.
It appears to have turned out that the risk of initial shuttle flights
was less than we might have expected -- certainly less than I expected --
it seems to have been on the order of 5%. But we must realize that we
have been very lucky! I'm sure that if you had told the shuttle designers
before the launch that we would have 24 perfect shuttle flights (i.e., no
mission failures) they would have been *extremely* pleased. For that matter,
I don't know of any informed analyst who failed to predict that we would
lose at least one shuttle during the life of the shuttle program. So why,
when that loss finally occurs, do we pretend that the risk of flying the
shuttle has increased? In fact the risk has *decreased* substantially,
because we have now identified one of the major unknown failure modes of
the shuttle and can take steps to mitigate it.
>Partially true. But it's premature to say we thoroughly understand what
>happened to 51-L, why it happened, what similar malfunctions could occur in
>future flights and how to lessen the chance that they will happen. It was
>only a few weeks ago, I think, that Morton Thiokol duplicated the joint
>rupture for the first time since the accident. You seem to agree that the
>shuttle should not fly (at least) until this problem is understood and fixed,
>to whatever extent is feasible. The difference of opinion is over whether
>or not the problem has yet been understood, fixed, and what the limits of
>feasibility are.
>> *I* wouldn't want to fly with someone so irrational as to demand that
>> certain risks be reduced while other, larger risks remain. Nor with someone
>> so irrational as to be willing to fly with a 10% unknown risk but not with
>> a 1% known risk.
>
>Where do you get these ideas, David? I'm in favor of reducing *all* major
>risks, when practical and clearly beneficial to do so. And how can you
>measure the amount of unknown risk? Rational behavior dictates doing what
>is practical to reduce known risks. You can't do much about unknown ones.
Here is the quote I referred to above, where you admit that risk assess-
ment cannot do much to measure unknown risks.
In any case, your reply is not responsive. Do you agree that the first
shuttle flight was much more hazardous than an immediate one would be now?
This seems impossible to deny, given that we can now substantially reduce
the chance of SRB failure by avoiding certain launch conditions, and further
given the fact that there seems not to have been a single serious design
flaw on the shuttle itself, which is amazing given its great complexity
(i.e., it would not have been all that surprising to lose one of the first
few shuttle flights to, say, a structural weakness, while it would be very
surprising now).
>> I can't understand how you can worry so much about a few lives while
>> millions die every year whom you could have saved by giving them some
>> food. Or while thousands are killed with weapons paid for by your tax
>> dollars. Or while thousands of accident victims could be saved by an
>> investment in trauma centers. If your desire is to save lives, it makes
>> a lot more sense to invest your dollars and time in those things than to
>> worry about making the shuttle safe.
>
>This reeks of the same thinking that some people have used over the last
>two decades in protest of spending money on space exploration. "Why spend
>billions on going to space when there are people starving in Berkeley,
>California?" The argument is specious and has been presented and refuted
>too many times already. I think we've got better things to do with
>sci.space.shuttle.
Then why the hell do you bring it up? I didn't make this argument; I
didn't even say anything that resembles it. *You* brought it up in order
to discredit what I was saying by associating it with this nonsensical
argument, while not having to respond to what I said.
Again, I will ask you specific questions. Do you deny that, if you
desire to save lives, you could save more lives by spending $100M on trauma
centers, or cancer research, or aid to Ethiopia, than you could by spending
that $100M on making the shuttle safer? The truth of this seems to be self-
evident, since you could save at most seven lives on the shuttle, while any
of the alternatives would save a hundred or more lives.
And then, if you accept the above, do you admit that your interest in
making the shuttle perfectly safe cannot be solely justified by an interest
in saving lives? This is the only point I was trying to make. You may
accept it, but the person to whom I was replying with the above lines did
not, and that is why I wrote them.
>>It seems instead that your interest is in saving a few *particular* lives.
>
>Yes! Have you figured out *why* I am so concerned with these few particular
>lives? Because when we lose them we stand a chance of losing our space
>program. As valuable as I consider individual human lives to be, I think
>the continued exploration of space is more important. If we proceed too
>quickly, if we aren't careful enough, if we WASTE human lives in an accident
>that should have been avoided, then the citizens of this country just may
>decide that people don't belong in space and that decision would be more of
>a tragedy than the death of seven remarkable people.
Aha! This I can agree with. It is certainly true that the American
people are too stupid to understand why lives should and must be risked,
and so for political reasons it may well be best to avoid risks that would
otherwise be acceptable. So if you believe that these political consider-
ations make it necessary to avoid risks that would otherwise be acceptable,
then I (and, I suspect, Henry as well) will admit that this might well be
correct -- while I may still disagree, I can at least understand this point
of view.
-- David desJardins
Charles Daffinger
Common, People... 260+ lines... three levels of followups quoted?
I know it's been said dozens of times, but once more..
P L E A S E, please trim the dead weight out!
-charles (sorry for the clutter)
--
... You raise the blade, you make the change, you re-arrange me til I'm sane...
Pink Floyd
Roger J. Noe
> In article <1...@uniq.UUCP> rj...@uniq.UUCP (Roger J. Noe) writes:
> >... [have we] made a reasonable effort to discover previously
> >unknown problems and to implement corrections for known problems?
> >further delay is unwarranted. When the point is reached where we can
> >attempt to rectify [these problems] and that further delay would
> >be all out of proportion to the expected gains in safety and functionality,
> >then and only then will it be time to reconsider launching again.
> Great. I can honestly say that further delay would be all out of
> proportion to a risk that I estimate at 1%. Let's go.
That's your opinion. As you can see, not everyone agrees with that opinion.
[To avoid four levels of inclusions, the next few paragraphs are presented as
a dialogue.]
RJN: .... Only one who is foolhardy would choose to ignore a known problem
such as with the SRBs right now and say, [the risk is acceptable]
DdJ: This is where you are wrong. What is foolish is to refuse to fly until
all known problems are fixed, regardless of the cost (in time and money).
RJN: Just *who* is proposing that? Not me.... What is important is that we not
be reckless, that we not take *unreasonable* risks.
DdJ: You said (the quote is immediately above!) that it would be foolhardy to
decide that a known problem constitutes an acceptable risk. The words are
right there in black and white. If you can never decide that a known
problem constitutes an acceptable risk then you can never launch. Period.
Read it again, David. "... a known problem SUCH AS WITH THE SRBs RIGHT NOW"
(emphasis added). Not just any known problem, but a problem that has already
demonstrated its capacity to destroy STS and crew. A problem for which, the
experts have said, virtually nothing can be done to prevent "moby lossage"
even if it's detected in advance. The are a number of criticality-1R problems
which show potential for this much destruction and which are unavoidable after
they start. It makes good sense to take at least SOME steps to see that they
never get started.
> With regard to your restatement, what is your criterion for determining
> whether a risk is reasonable or unreasonable? My criterion (and, I think,
> the rational one) has already been presented -- the value of launching must
> be weighed against the expected costs.
We are in agreement that the value of launching must be weighed against the
expected costs. But I don't think that expected-case analysis is sufficient;
I think worst-case conditions need to be examined, too. In the end, it comes
down to a value judgment, which is going to be different for every person.
My standard is to leave it up to the experts, i.e. the NASA and contractor
personnel directly involved with the mission. If they are all in agreement
that the time is right, I'm comfortable with that. This, by the way, is
apparently not what happened just before the 51-L launch and demonstrates
the need for independent oversight. If and when I become immediately
involved in a space mission, I would hope that I have some participation in
the go/no-go decision.
> If you were to accept this criterion, I find it hard to understand how
> you could argue against shuttle launches. Make the pessimistic assumption
> that the probability of SRB failure is 1% for each launch ...
> .... That comes out to an expected cost of around
> $25M, based on an orbiter replacement cost of $2G+, plus the cost of other
> items like the SRB casings and crew training. The mean cost to NASA of
> each shuttle flight (not depreciation, just operational costs) is something
> like $200M, so the additional cost of accepting the SRB risk seems to be
> fairly small. But the real kicker is that, of that $200M, much of it is
> expenses that NASA incurs even if there are no shuttle launches!
It's not all dollars, David. If the same accident happens again, you can be
pretty sure that Congress (with the approval of most of the U.S. citizenship)
and the President will take the STS away from NASA, if not dissolve or
radically change the mission of NASA itself. Crewed space exploration would
(or very well could) completely cease in the United States for a couple of
generations, easily. Remember, most of the general public is still under
the impression that space launches are basically safe, that AS-204 and
STS-51L were just flukes. The truth is that it is very dangerous and
only with the utmost care (and a little luck) can we prevent total disasters.
If we can make plain just how dangerous this undertaking truly is, then
the public could be a little more tolerant of accidents. Then isolated
(i.e. non-systematic) incidents would have much less chance of causing the
cancellation of entire programs. But if NASA says, "Uh, we did lose one
orbiter and, coincidentally, its crew, but we're very confident that future
missions will show more nominal performance" then the people are going to
say they're fools and should be stopped.
> So, if you accept the cost analysis criterion, it is impossible for me
> to understand how you can oppose the resumption of shuttle flights.
Clearly, I reject out of hand the cost analysis criterion. If STS was meant
to be a for-profit venture, it would be in the hands of NASA, Inc. not NASA,
a U.S. government administration. It never should have been expected, much
less required, to live up to the profit making fantasy. Certainly not when
Congress (and its constituency) was unwilling to invest the necessary venture
capital to achieve the kind of operational efficiency they wanted.
> Let's use some simple statistics. There were approximately two dozen
> manned US space flights before the shuttle. Two of these resulted in what
> I would call "mission failure," one in loss of vehicle and crew. Thus,
> our a priori assumption would be that the chance of mission failure on manned
> flights seems to be about 10%.
> There are obviously many other factors to be considered.
One of which you are forgetting: that we show the same care in making mission
decisions that we used to. In any event, the number of space missions so far
is so small as to be statistically insignificant, from an actuarial point of
view.
> >I disagree with your assessment that the first shuttle flights were
> >riskier than is flying now ....
> >The SRBs, in particular, were among the elements with what was perceived
> >to be the lowest chance of failure. Taking this as true meant that the
> >complete lack of a redundant system was acceptable. [...] The problem
> >existed on STS-1, but it wasn't until 51-L that it was commonly known.
> >And that makes all the difference.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> This is precisely the point. It makes no difference at all. The risk
> is the same regardless of whether you know about it!
I insist this makes all the difference. You can't do anything about a problem
until you're aware of it. Accidents because of ignorance, in spite of making
a sound attempt to discover unknown risks, are understandable because they are
unavoidable in any human endeavor. But to say "why do anything about a problem
I just learned about if it was always there anyway?" is just self-deception.
As it turns out, several people *did* know of the SRB problem beforehand and
either didn't speak up or were silenced by others. This is inexcusable. Now
that a major disaster has occurred, we have the opportunity to actually reduce
the risk of shuttle flights, and not only in the area of SRBs. Up until the
25th shuttle mission, the risk was nearly the same as the first flight, not
significantly less since the engineering changes were limited. Mostly what
has changed is our confidence in various parts of STS, not the actual risks
associated with flying it.
> .... I'm sure that if you had told the shuttle designers
> before the launch that we would have 24 perfect shuttle flights (i.e., no
> mission failures) they would have been *extremely* pleased.
What do you call a "mission failure?" Just look at the launch aborts - a
redundant set (of computers) launch sequencer (RSLS) abort June 26, 1984
(41-D, Discovery), another one July 12, 1985 (51-F, Challenger) and then an
abort-to-orbit (ATO) on the same mission when it launched 17 days later
(remember, one SSME shut down and another one was about to had they not
overridden what turned out to be faulty sensors), and a final RSLS abort on
December 19, 1985 (61-C, Columbia), the last mission before 51-L. Not to
mention malfunctions in fuel cells, on-board computers, auxiliary power
units, remote manipulator system, etc. But that's four launch aborts in
24 missions. If you merely define "mission failure" to be loss of crew
and vehicle, that's something different. But I think many on the design
team would have been less than pleased to find out, before STS-1, that one
orbiter and crew would be obliterated in the first 25 missions.
> ... I don't know of any informed analyst who failed to predict that we would
> lose at least one shuttle during the life of the shuttle program. So why,
> when that loss finally occurs, do we pretend that the risk of flying the
> shuttle has increased? In fact the risk has *decreased* substantially,
> because we have now identified one of the major unknown failure modes of
> the shuttle and can take steps to mitigate it.
That "life of the shuttle program" was supposed to be like 100 flights for
each of the orbiters. One vehicle in 400 launches is 16 times less than one
vehicle in 25 launches. And it says nothing about losing a crew.
We aren't pretending that the risk has increased; just that we are now aware
of a risk of which we were formerly ignorant. The risk decreases only when
we *do* take some steps to prevent future occurrences of the problem. We've
just started on that.
> Do you agree that the first
> shuttle flight was much more hazardous than an immediate one would be now?
No, just about the same. The difference is that we know of a bug we can start
fixing, and that is what will make future shuttle missions less hazardous than
the first. We also know of things we didn't before STS-1, things that won't
cause problems. But that doesn't change either how risky STS-1 was or how
risky an immediate flight would be.
> This seems impossible to deny, given that we can now substantially reduce
> the chance of SRB failure by avoiding certain launch conditions, and further
> given the fact that there seems not to have been a single serious design
> flaw on the shuttle itself, which is amazing given its great complexity
I agree, it is amazing. Hats off to NASA, Rockwell International, and all the
other contractors with the possible exception of Morton Thiokol. :-)
But the final evidence is not yet in on what else might cause similar launch
accidents. It seems prudent to take the time to analyze the situation and
make what engineering and operational changes we can to make the occurrence
less likely in the future. While we're at it, why don't we fix a lot of the
other problems we've been warned about, rather than waiting until after a
disaster has happened?
> .... do you admit that your interest in
> making the shuttle perfectly safe cannot be solely justified by an interest
> in saving lives? This is the only point I was trying to make.
I am not interested in making the shuttle "perfectly safe" because I do not
pursue unattainable goals. In any event, I have pointed out that my goal is
not just to save lives (although that is something I do pursue in various ways)
but to save the crewed space exploration program. One way to accomplish this
is to take steps to help prevent further loss of shuttle orbiters and crews.
> .... It is certainly true that the American
> people are too stupid to understand why lives should and must be risked,
I would not call them stupid. Let's just say they don't share my goals.
> and so for political reasons it may well be best to avoid risks that would
> otherwise be acceptable. So if you believe that these political consider-
> ations make it necessary to avoid risks that would otherwise be acceptable,
> then I (and, I suspect, Henry as well) will admit that this might well be
> correct -- while I may still disagree, I can at least understand this point
> of view.
>
> -- David desJardins
I'm happy to see that you have come to understand my point of view, in spite
of your earlier doubts. I hope that others have found our exchange interesting
and, possibly, enlightening. Considering what is at stake, this mutual
understanding is very rewarding and all too rare over this medium. (There
are a couple puns in that sentence for those daring to look.) Now if we can
only get Congress to talk this much about space exploration ...
Roger Noe ihnp4!uniq!rjnoe
Uniq Digital Technologies (312) 879-1566
Batavia, Illinois 60510 41:51:10 N. 88:18:25 W.
--
"While chaotic and inane ramblings abound, [USENET] is quite popular."
Communications of the ACM, vol. 29, no. 10 (Oct. 1986), p. 958.
D. Starr
{ You should all be familiar with this argument by now... }
Some observations on the whole controversy:
1. Political considerations being what they are, *nothing* is going
to get shuttles flying before '88. A widespread lobbying effort would
be needed to change NASA's policy, and I really doubt that any such
effort could be effective before 1988 anyway. Still, lobbying for a
clear *policy* concerning flying/grounding the shuttle over known,
potentially-fatal bugs would be useful, because this situation will
occur again some day.
2. On the policy issue, perhaps what NASA needs to do is equip only the
replacement shuttle with an escape system. Then, when hazardous conditions
are discovered (for example, the O-ring erosion on flights beore 51-L),
there would still be one vehicle which could be flown for missions considered
essential. Note that this escape system need only be sufficient for a
skeleton crew.
3. On the escape issue, I wonder: would Young and Crippen (?) have survived
if the SRB failure had occurred on the first flight of Columbia? Consider,
somebody stayed conscious long enough to turn on two air packs, and the
official "cause of death" is now said to be impact with the Atlantic Ocean.
This seems to imply that there is at least some chance that ejection seats
could have been used before impact.
4. On the chance of failure of the first shuttle flight, it is worth noting
that NASA had taken precautions against the "most likely" failures. The
ejection seats were based around the idea that the most likely catastrophic
failure was SSME explosion during or shortly (<20 seconds) after ignition.
This was, at least, where they tended to blow up in tests.
5. Back to the subject of resuming flights immediately: where would the
payloads come from? Given that the government has decided to ban commercial
payloads in order to promote an expendable booster industry, and that even
the most enthusiastic supporters of the "launch now" point of view have
identified a lot of scientific payloads (indeed, nearly all of them) that
shouldn't be risked, what's left? Even spysats are doubtful--given the cost
and lead time for replacing a Big Bird (or equivalent), is the Air Force
really going to be that enthusiastic about launching before this known bug
is fixed? Probably not, unless the satellites we have in orbit now degrade
severely.
6. On a related topic: I see that Hughes has redesigned the "Jarvis"
proposal to use shuttle parts--ET, one SSME and two SRBs. I see a problem
here in that, because they use the same technology, a shuttle failure will
(at least temporarily) ground Jarvis, and vice versa. I thought that one
of the motivations for a new MLV was to provide launch capability when the
shuttle is grounded by technical problems; this proposal certainly doesn't
seem to do that. The shuttle-based Jarvis is a nice addition to the shuttle
family, but if it's built we'll still need an alternative vehicle.
Disclaimer: The opinions expressed do not represent those of my employer,
and may not represent my views by this time tomorrow.
Alex B Laney
> ... Often it will then resume flying, under
>restrictions (e.g. the door flies off at 30,000 feet so max altitude is
>25,000 for the moment), while the definitive fix is devised. The suggestion
>I and others are making is that applying the same standard to the Shuttle
>would be reasonable.
Ok -- but how much reasonable work can be done in under about 1 minute of flying
time and about 5 miles altitude limit per flight?
[ Announcing a new service -- Shuttle thrill rides! ]
--
- + - + -
Alex Laney, Xios Systems Corp, 105-1600 Carling Av, Ottawa (613)725-5411x402
utzoo -
> !dciem
allegra!ihnp4!utcsri -- > nrcaer!xios!lib!alex
ucbvax!hplabs -- /
> !seismo!hadron!netex!prcrs/
decvax --
Henry Spencer
> assume they are somewhat representative of the others...
We can probably rely on the public statements of some of the astronauts to
be representative... representative, that is, of the *public* *statements*
that other astronauts would make. This has little or nothing to do with
their private opinions. They are obviously in a position where their open
and public support for safety improvements is very important to both NASA
and themselves. Displays of such support tell us nothing about how they
would actually feel about flying a mission tomorrow.
Henry Spencer
> replacement shuttle with an escape system. Then, when hazardous conditions
Unfortunately, this assumes that escape systems suffice for safety. As I
recall it (my copy of the report isn't handy), the Rogers Commission found
that no escape system would have helped. They recommended investigating
an escape system for a different situation: an intact orbiter flying at
low altitude, more or less under control, but with no airstrip handy.
(The orbiter is too flimsy to ditch or belly-land safely. I've read the
STS-1 flight plan; all the sequences which involve descent into the ocean
end in "EJECT".) Not even an escape capsule would suffice to get the crew
out of something like an asymmetric SRB ignition.
> 3. On the escape issue, I wonder: would Young and Crippen (?) have survived
> if the SRB failure had occurred on the first flight of Columbia? Consider,
> somebody stayed conscious long enough to turn on two air packs, and the
> official "cause of death" is now said to be impact with the Atlantic Ocean.
> This seems to imply that there is at least some chance that ejection seats
> could have been used before impact.
Given that Young and Crippen were wearing spacesuits, and assuming that
damage to equipment or hatches didn't interfere, they could probably have
ejected if their suits had on-suit or on-seat emergency oxygen supplies
(I'm not sure whether they did or not). The suits are important: they
eliminate unconsciousness due to decompression (which almost certainly
knocked out the 51L crew within 10-20 seconds) and they provide enough
physical protection to make high-speed ejection practical. Even modern
ejection seats are normally red-lined at around 600 knots, as I recall,
because the pilot isn't well enough protected against the slipstream.
> 5. Back to the subject of resuming flights immediately: where would the
> payloads come from? ... Even spysats are doubtful--given the cost
> and lead time for replacing a Big Bird (or equivalent)...
The key point here is that the USAF is (a) well funded, and (b) in the
business of taking risks in the national interest. Undoubtedly the USAF
would prefer not to take risks with its satellites, and indeed the USAF is
getting more openly anti-Shuttle by the day, but they can simply be given
orders otherwise.