DISCUSSION:Cheap Manned Moon Missions?
Marcus Lindroos INF
comparatively cheap manned Moon mission proposals... Which of these three
projects do you think should be chosen?
1.SATURN V + EARTH ORBIT RENDEZVOUS:
-----------------------------------
A relatively low-budget alternative to the now-defunct National Launch System
HLLV, first proposed by Tom Frieling. To save money, the 1st and 2nd stages
of the "classic" Saturn V moon rocket should be revived instead of
redesigning a HLLV from scratch. No major modifications, except minor engine
upgrades+use of lightweight composite materials to slightly enhance
performance. No S-IVB stage would be necessary, instead a S-II second stage/
Manned Lander vehicle will be refuelled in Earth orbit by 2-3 Saturn V
"tankers". This permits a payload of at least 275 metric metric tons, 360t
using a fully fuelled second stage. A simple fuel depot in orbit (The Node)
will also be required.
---
This proposal has a lot in common with NASA's own 1st Lunar Outpost studies. An
ambitious program that would permit long stays on the surface (several months).
Unfortunately, the price tag would be in the $40 billion range, including
perhaps $10 billion spent on reviving a HLLV NASA has little use for. Even back
in 1972, an Apollo launch cost taxpayers $500 million - four times as much at
1994 rates! Will happen only if Congress decides to spend more money
on the space program, and if manned Mars missions are approved.
2.GENERAL DYNAMICS SHUTTLE/CENTAUR/APOLLO:
-----------------------------------------
GD claim the total cost of their project would be just $10 billion because
no HLLV will be required. Instead, their engineers have designed an ultra-light
20t LOX/LH2 lander that will land two astronauts and an Apollo Command Module
on the lunar surface. The vehicle will be launched into orbit by the Space
Shuttle, and dock with an upgraded Centaur upper stage, placed into orbit by a
Titan IV or ESA's Ariane 5 (the latter option [European cooperation] would save
another $4 billion). The "Apollo mk.II"/Centaur combination then launches from
LEO into translunar trajectory, after which the spent Centaur stage is
discarded.
---
Pros:relatively inexpensive, uses existing technology to save costs and time,
no new HLLV required. Cons: limited payload capacity. Overall, an attractive
proposal that would make an ideal expendable "Moon shuttle" since only about 5t
of propellant would be needed for the return trip to Earth. If this could be
manufactured from lunar soil (=oxygen, mostly), more supplies could be landed
on the Moon as well.
3."LUNAR MILLENNIUM"/RUSSIAN TECHNOLOGY (Soyuz/Energia/Proton)
---------------------------------------
A major drawback with all American/European space projects is they are very
expensive and therefore not very attractive to governments and taxpayers.
However, vast sums of money could be saved if Russian technology is used. For
example, the Energia HLLV only costs $200-$300 million per launch compared with
at least $500-$1000 million for the Shuttle or Saturn. George Herbert has
developed a mission based on hardware left over from the failed Soviet manned
Moon project of the 1960s, Energia and Soyuz. The latter (and Proton hardware)
would be suitable almost right away, a new ascent/descent stage and translunar
injection stage being the only new hardware required. The West and/or Japan
would fund part of the project and perhaps design a surface habitat
module/mobile laboratory as well.
---
Pros: far less expensive than the American projects, based on simple, existing
, proven hardware. Cons: the uncertain political situation means large-scale
Western/Japanese funding of long term projects would be something of a gamble.
Energia -currently the world's only HLLV- is still an unproven vehicle that
won't fly until 1996 because the economic troubles in Russia. Overall, I still
think it is worthwhile - NASA is confident Russian cooperation will save
billions of $s off Space Station Alpha.
CONCLUSION: Project #3 should be approved, landing men on the Moon before AD
2000. At the same time, NASA & ESA fund project#2. The General Dynamics lander
would be used to land the Western habitat module/surface rover on the Moon,
then astronauts later on. If cost effective, project #1 could be introduced to
support large scale projects on the Moon and Mars once the initial exploration
stage is over.
FACT: Dream on...Congress won't pay a single $ to outrageous projects like
these. This is 1994, after all - not 1961.
MARCU$
////
(o o)
------------------------------oOO--(_)--OOo-----------------------------------
Computer Science Department
University of Abo Akademi, Finland
Email: MLIN...@FINABO.ABO.FI
MLIN...@ATON.ABO.FI
MAIL: Marcus Lindroos, PL 402 A, 07880 Liljendal, FINLAND
Nick Janow
> CONCLUSION: Project #3 should be approved, landing men on the Moon before
> AD 2000.
Why men on the moon now? Remote sensing and automated rovers and processors
(producing oxygen) could "pave the way" for future manned missions, someday.
Why spend the extra money for manned missions now?
--
Marcus Lindroos INF
Because, astronauts are far better and more flexible than automated systems. I
imagine the first Moon missions would be a combination of both approaches.
Astronauts might explore the lunar surface using a mobile laboratory that would
be controlled from Earth while unmanned.
> --
>
> Nick_...@mindlink.bc.ca
MARCU$
Sheldon Simms
>In <38...@mindlink.bc.ca> Nick_...@mindlink.bc.ca writes:
>
>> Why men on the moon now? Remote sensing and automated rovers and processors
>> (producing oxygen) could "pave the way" for future manned missions, someday.
>> Why spend the extra money for manned missions now?
>
>Because, astronauts are far better and more flexible than automated systems. I
>imagine the first Moon missions would be a combination of both approaches.
>Astronauts might explore the lunar surface using a mobile laboratory that would
>be controlled from Earth while unmanned.
This seems to be the usual response given to someone asking why manned
missions are needed. I have another response: Because people want
to get the hell off this rock! To me manned missions are important
commitments to the manned colonization of space. It astounds me that there
are so many people dead set against manned missions "because of the danger"
or whatever. No one forces astronauts to go up. They want to go. I welcome
every attempt to move us towards putting people in space permanently.
-Sheldon
--
W. Sheldon Simms | Newt's Friend / Jack Kemp for President
she...@netcom.com | Freedom implies responsibility
-------------------------+--------------------------------------------
Henry Spencer
>>> Why men on the moon now? Remote sensing and automated rovers and processors
>>Because, astronauts are far better and more flexible than automated systems.
>
>missions are needed. I have another response: Because people want
>to get the hell off this rock! To me manned missions are important
Nobody (with any brains or vision) questions that there will be manned
missions eventually. The questions are "when?" and "is it worth doing
something else meanwhile?". (The two questions obviously interact, with
the answer to the second growing as the first's delay lengthens.)
One should bear carefully in mind that the two are not mutually exclusive.
Remote sensing and teleoperated rovers are useful precursors to manned
missions, but they are also useful *complements* to them. If you plan
the manned missions for some degree of flexibility -- which will be
necessary anyway, because surprises are inevitable -- then the amount
of precursor activity that is *really* helpful is limited. Cooperative
exploration using *both* approaches will work much better than a long
period of one before the other gets started. People saying otherwise are
looking for an excuse to stall manned missions.
Note that I haven't mentioned oxygen production and such so far. That's
because I think it vanishingly unlikely that such processes can be debugged
effectively without humans on the spot. A look at the history of in-flight
debugging of Spacelab experiments is instructive: *lots* of things don't
work as intended, even with meticulous preparation for a rare flight
opportunity, but can be fixed easily enough by humans on hand. Oxygen
production (etc.) experiments should be high-priority activities for the
first manned missions, and are probably not worth flying until then.
--
Belief is no substitute | Henry Spencer @ U of Toronto Zoology
for arithmetic. | he...@zoo.toronto.edu utzoo!henry
Nick Janow
stop it when it started to go that way because I approved a posting
too fast... please try and stay on-charter, and "tech" in tech -gwh]
MLIN...@FINABO.ABO.FI (Marcus Lindroos) writes:
>+ Why men on the moon now? Remote sensing and automated rovers and
>+ processors (producing oxygen) could "pave the way" for future manned
>+ missions, someday. Why spend the extra money for manned missions now?
>
> Because, astronauts are far better and more flexible than automated
> systems.
More flexible, yes. However, I wouldn't generalize by saying that either was
better. What's "better" for sifting tons of lunar dust for iron particles, a
man or an automated system? What's better for mapping the surface, a manned
orbiter or an remote controlled platform? Before you answer the latter,
assume equal amounts of money spent on the task.
> I imagine the first Moon missions would be a combination of both
> approaches. Astronauts might explore the lunar surface using a mobile
> laboratory that would be controlled from Earth while unmanned.
For a given cost, I expect that automated and remote controlled orbiters and
crawlers could map/explore more area with more instruments, providing much
more useful information. If a microprobe detects an interesting mineral
deposit, send a cheap penetrator probe, or redirect one of the thousands of
crawlers with appropriate instruments. In this scenario, automated rovers
offer much more flexibility than a manned roving lab.
she...@netcom.com (Sheldon Simms) responds to Marcus:
> This seems to be the usual response given to someone asking why manned
> missions are needed. I have another response: Because people want to get
> the hell off this rock! To me manned missions are important commitments to
> the manned colonization of space. It astounds me that there
> are so many people dead set against manned missions "because of the danger"
> or whatever. ... I welcome every attempt to move us towards putting
> people in space permanently.
I welcome every attempt towards a permanent manned presence in space too.
However, the key word is "permanent". The Apollo program put men in space,
but didn't do much for permanency. Skylab was no better. It provides some
very useful data, but it was designed for a transient manned presence, for
political goals.
I wonder how often those two examples are used as arguments against space
funding. "We spent billions putting men on the moon, and all we got was a
couple of rocks. You want use to spend hundreds of billions now for some
more rocks?" That may be simplistic, but so are politicians and
taxpayers/voters.
The Soviet space program has provided a more or less permanent manned
presence, but its results are mainly pure science and engineering, which
passes right over the head of the typical voter. :)
NASA couldn't get funding for the same type of project. No flash, no cash.
There are many paths to the goal of a permanent manned space presence. One
way is to spend hundreds of billions of dollars to put a few astronauts on
the moon, or on Mars, or in an orbiting can. While that may be glamourous,
it's politically infeasible. The money just isn't available for it.
Another path is less glamourous. It involves small projects, such as
single-purpose microsats, automated rover projects here on Earth, careful
compilation of data on near Earth asteroids, etc. There's no flash. Few
people are going to wish they were one of the people involved in the project
(though there are some), poring over star photographs night after night,
looking for faint trails, or debugging part of the program for an autonomous
vehicle. It won't get much funding either, just dribs and drabs here and
there.
However, that path can lead to the discovery of valuable resources in space,
such as water on the moon or in near-Earth asteroids. That can greatly
reduce the cost for further automated exploration and resource extraction.
After a few successful production systems deliver loads of water to NEO, the
cost for a manned presence will drop to reasonable levels, and possibly low
enough to justify commercial enterprises. Pretty soon, you'll have thousands
of people living and working in space.
A lot better than another Apollo mission, isn't it? :)
--
Nick Janow
> Note that I haven't mentioned oxygen production and such so far. That's
> because I think it vanishingly unlikely that such processes can be debugged
> effectively without humans on the spot.
You're probably right, for a lunar resource extraction system. However,
plunking a unit down with the assumption that the astronauts landing with it
can "give it a kick" and get it working sounds risky too. Some of the
assumptions that the system was built on could be incorrect, meaning that
some major redesign is needed.
A series of small, cheap, unmanned systems could prove--or disprove--some
assumptions without risking billions of dollars. Drop a fairly dumb rover
with four different wheel designs, several scooper designs, and that gadget
that should sift out titanium dioxide--if the assumptions are correct. Drop
a small solar furnace on the rover chassis/scooper design that worked last
time. Use that to measure how much hydrogen can be released from lunar soil
by simple heating. If the reflector doesn't deploy, well, it only cost a
tiny fraction of what a manned mission would, and you learned something
useful for the next attempt.
The first resource extraction systems can save money by sacrificing
efficiency for simplicity. There's no need for a fancy unit that can process
a small asteroid; send a bunch of microsat style units out to Earth's L5 zone
to try to capture a small chunk in a baggie, then warm it enough to steam its
way home. Send out tiny "mosquitos" with proboscises made of hollow heat
pipes. They thunk into what is hopefully a comet fragment, send some solar
heat into the interior, and capture the vapours for reaction mass and payload
mass. Simpler yet: send a little rocket (or a bunch of them) out looking for
small chunks. They grab the chunks and push them home using minimal reaction
mass, where a more complex processor can munch on the chunk, while an
astronaut gives it an occasional kick. :)
You can probably do quite a lot of micro-missions before reaching anywhere
near the cost of a single manned mission, and a few failures won't kill the
entire program.
--
Philip Young
|>
|> Why men on the moon now? Remote sensing and automated rovers and processors
|> (producing oxygen) could "pave the way" for future manned missions, someday.
|> Why spend the extra money for manned missions now?
Because manned missions are far more newsworthy. I've met many
people over the years who watched (with admiration, I might add)
the Apollo Moon-landings, and the 1st shuttle launch. High-level,
non-negative exposure translates into greater political support
for the whole business (and pleasure) of space.
Seen any interviews with Clementine?
Followups to sci.space.policy, please.
--
Philip R. Young yo...@bunyip.oz.dg.com
It won't happen overnight, but it will happen.
- Rachel Hunter
Henry Spencer
>> ... I think it vanishingly unlikely that such processes can be debugged
>> effectively without humans on the spot.
>
>You're probably right, for a lunar resource extraction system. However,
>plunking a unit down with the assumption that the astronauts landing with it
>can "give it a kick" and get it working sounds risky too. Some of the
>assumptions that the system was built on could be incorrect, meaning that
>some major redesign is needed.
It's possible. Indeed, a test mission should probably have several designs
along (on a suitably small scale) so as to have backups. (If more than
one works, great -- then you can start comparing efficiency etc.)
However, it is equally likely that the things that would prevent successful
operation would be trivial details, rather than major design flaws. There
was nothing fundamental wrong with the tethered-satellite cable reel, or
Compton's antenna, or the Intelsat grappling hardware. It was the details
that weren't quite right. Same story for most of the Spacelab experiments
that have been debugged in space. You can't find the big flaws until the
trivia are out of the way. First you have to make the thing work the way
you intended; *then* you get to find out if that approach is the right one.
>A series of small, cheap, unmanned systems could prove--or disprove--some
>assumptions without risking billions of dollars...
At one mission per trivial bug, that could get pretty costly.
Of course you don't make a major mission *dependent* on the success of
such things until you've tested them "for real". (This is a lesson that
NASA has been gradually forgetting in the last twenty years.) But a
manned mission is just the right time to *test* such things, because you
get a lot more test mileage out of a system when you can fix the minor
bugs without having to build and fly a whole replacement mission each time.
>... There's no need for a fancy unit that can process
>a small asteroid; send a bunch of microsat style units out to Earth's L5 zone
>to try to capture a small chunk in a baggie...
Um, except that we have no idea whether there's anything in Earth's L5 zone
to be captured. If you're talking about the Earth-Moon L5 point, last I
heard there has never been a solid confirmation that there are even dust
clouds there, and it's fairly definitely established that there is nothing
even a meter across. If you're talking about the Earth-Sun L5 point, all
searches of that area have come up dry, and the gravity well there is
feeble enough that any "Earth Trojan" object probably wanders back and
forth a long, long way along Earth's orbit (as the only known Mars Trojan
does in Mars's orbit).
>You can probably do quite a lot of micro-missions before reaching anywhere
>near the cost of a single manned mission, and a few failures won't kill the
>entire program.
Ask JPL what happened when they lost six Rangers in a row. (And it wasn't
even a fair test -- some of those were launcher failures.) That was back
in the tolerant early days. You can bet your booties that a few failures
would be very bad news for any program today.
Nick Janow
> However, it is equally likely that the things that would prevent successful
> operation would be trivial details, rather than major design flaws.
Micro-missions sound like a reasonable way to test at least some trivial
details, such as moving joints in a vacuum, pointing a laser at a target,
etc. If the mission is cheap enough, you can treat the equipment roughly,
hoping to show up some bugs that might happen by accident. You wouldn't
shake the extremely expensive Mars Orbiter "just to see if the antenna ribs
might stick", but you would do it on a piece of equipment designed to test
antenna ribs, along with other things.
> At one mission per trivial bug, that could get pretty costly.
Less costly than one major manned mission failed due to a trivial bug that
can't be dealt with by on-board personnel (ie. the lubricant chosen for most
moving parts reacts with the Martian superoxidized soil particles, destroying
the bearings).
> Um, except that we have no idea whether there's anything in Earth's L5 zone
> to be captured. If you're talking about the Earth-Moon L5 point, last I
> heard there has never been a solid confirmation that there are even dust
> clouds there, and it's fairly definitely established that there is nothing
> even a meter across. If you're talking about the Earth-Sun L5 point, all
> searches of that area have come up dry...
I was thinking of the Earth-Sun trojan point (or zone, since the stuff
wanders). I was under the impression that present equipment wasn't capable
of searching for small stuff (under a few meters dia.) that far out. I
thought there might be a higher probability of finding chunks there, and the
missions would have lower delta-v requirements than chasing near-Earth
asteroids.
A microsat, with a simple IR sensor and very low data rate xmtr, might be
small enough to be tucked onto some existing launch, yet effective enough to
provide a basic yes/no search of Earth's orbit. No maneuvering ability, no
fancy imaging equipment; just a single IR photodiode (okay, maybe several for
reliability) mounted on the rim of the thing, scanning by rotation for a
signal that indicates "Chunk of material found. Beep beep!". :)
> That was back in the tolerant early days. You can bet your booties that a
> few failures would be very bad news for any program today.
Yah, the political climate is a lot less tolerant these days. However, a few
failed micro-missions might be tolerable if there are enough missions that
they are too routine to hold media attention, and if there are enough
successful missions to be able to say that the _program_ is proceeding well.
--
Nick Szabo
>operation would be trivial details, rather than major design flaws. There
>was nothing fundamental wrong with the tethered-satellite cable reel...
Which astronauts were not able to fix. Astronauts are not able
fix the vast majority of problems. Putting astronauts on the moon
would require equipment orders of magnitude more complex
and expensive than automated LOX plant. This life support
an safety equipment would also have an orders of magnitude more
unfixable problems.
Several Shuttle flights have come back early due to problems
astronauts couldn't fix. The Shuttle can come back within
an hour; it would take several days from the moon (assuming
it wasn't the return craft that was busted).
This is one of the reasons that each Shuttle flight costs over $1
billion and a bare-bones lunar base is projected by NASA to cost over
$100 billion. An automated LOX plant would cost two orders of
magnitude less -- but that's still far too expensive to be
economical, alas. Requiring astronauts makes the project
nearly 1,000 times too expensive for the LOX market. Of
course, this might be just fine if the goal is to politically
lobby for a moonbase rather than start a private-sector
business or develop space.
--
Nick Szabo sz...@netcom.com
Nick Szabo
>If you're talking about the Earth-Sun L5 point, all
>searches of that area have come up dry...
Nevertheless, several small (c. 10m diameter) asteroids have
been found wandering very close to Earth's orbit. Mission
deta-v's would not be significantly different from missions
to hypotechnical E-S Trojan asteroids. These mini-asteroids
are probably useless little rockpiles, but they could be used to
test or even train automated machines for use farther out.
LOX extraction from slightly larger, regolith-covered Earth-crossers
might be relatively more economical than LOX extraction from the Moon,
due to lower delta-v, orders of magnitude lower thrust, and
uninterrupted sunlight. Drawback is that the mean RTLT goes
from 3 seconds, with a modicum of manual teleoperation,
to tens of minutes, which allows only teleprogramming. Of
course, this decision will be made wrt tech that will have
been driven by other markets which are larger and easier to tackle
than LOX.
--
Nick Szabo sz...@netcom.com
Henry Spencer
>>operation would be trivial details, rather than major design flaws. There
>>was nothing fundamental wrong with the tethered-satellite cable reel...
>
>Which astronauts were not able to fix. Astronauts are not able
Numbers, Nick? I can think of more, offhand, that were fixable than
that weren't. The tethered-satellite problem wouldn't have been fixable
even if the astronauts had been allowed to try -- which they weren't --
but a lot of other mechanical problems have been sorted out, e.g. the
Eureca antenna-stowing episode.
There will always be some things that are deep design flaws or just too
damned awkward to fix in the field. But quite a few Spacelab experiments,
for example, have been saved by a bit of manual intervention. Often the
little things *can* be solved by hands and brains on-site, especially if
they have adequate tools, parts, and documentation.
>This is one of the reasons that each Shuttle flight costs over $1
>billion and a bare-bones lunar base is projected by NASA to cost over
>$100 billion. An automated LOX plant would cost two orders of
>magnitude less...
Ah yes, once again we have NASA estimates for the projects Nick doesn't
like and Nick's own estimates for the ones he does. I know people who
could do a bare-bones lunar base for a lot less than $100G, and I doubt
that business-as-usual NASA could do a lunar LOX plant for $1G. I won't
comment further on the merits of the estimates -- it's not really in
the scope of this newsgroup -- but honest man-vs-machine comparisons
must start with agreement on the underlying assumptions.
In any case, I think it's pretty obvious that without truly revolutionary
changes in the situation, it's not cost-effective to send humans along
solely to serve as troubleshooters for an experimental LOX plant. If
the plant is truly an *experimental* one, rather than a misguided attempt
to go straight to a production plant, it's going to be smaller than any
reasonable manned spacecraft... and kilograms are a lot harder to argue
about than dollars.
To my mind, this means that it's doubtful, at best, to try experimental
LOX plants until humans are being sent for other reasons (such as the
resumption of in-depth lunar exploration). When even straightforward
things like microgravity crystal growth have turned up a steady sequence
of surprises and not-quite-working experiments, I don't think the odds of
a LOX plant working the first time are very good.
Nick Szabo
>I can think of more, offhand, that were fixable than
>that weren't.
Naturally -- NASA and its fans in media heavily publicize the handful of
things astronauts have fixed, at a cost of several billion dollars,
and put in fine print, at best, the the thousands things that
have gone wrong that astronauts can't fix. The only non-fixed
failures we get to read in NASA press releases are the really big
items like the tether experiment and the Shuttle failures that lead
to early return.
>But quite a few Spacelab experiments,
>for example, have been saved by a bit of manual intervention.
It's a _specification requirement_ for most Shuttle experiments that
they require manual intervention -- even when obviously could
be built without such dependence. There werent' very many of
these kind of "problems" with the LDEF experiments -- in
fact many worked right through the unplanned Shuttle delays,
lengthened by the never-ending quest to make the space travel
perfectly benign for our beloved astronauts.
>Ah yes, once again we have NASA estimates for the projects Nick doesn't
>like and Nick's own estimates for the ones he does.
NASA doesn't even bother to study a wide variety of potentially
lucrative space industries[*], so just what numbers am I supposed
to use? My numbers, unlike those of tradtional heavy-space-industry
advocates, are based on reasonable near-future extrapolation of
launch costs, eg the commercial Ariane 5 under development.
If you want to compare my number to some fantasy numbers, like
Criswell's, I'll adjust my assumptions accordingly and still
win out apples-to-apples -- though I wouldn't dare show the
resulting hallucination to an investor. Such extrapolation might be
fine for good ol' pork barrel lobbying, but I'd probably lose to
Criswell et. al. on that count, since unlike the lunar base
schemes my boring automated extraction and processing missions
don't even include anthropomorphic robots, much less heroic astronauts.
>Not that business-as-usual NASA could do a lunar LOX plant for $1G.
Business-as-usual NASA, and people affiliated with it or inspired
by it, are the only people who take lunar LOX seriously.
>In any case, I think it's pretty obvious that without truly revolutionary
>changes in the situation, it's not cost-effective to send humans along
>solely to serve as troubleshooters for an experimental LOX plant.
We agree!
This has diverged away from tech; followups to sci.space.policy.
[*]: a few examples among many: comet volatile extraction,
processing of asteroidal metals, prospecting for precious
metals on planetary bodies, large scale processing of native materials,
large scale plasma-phase processing, very low cost power generation
at Jupiter, native materials as thermal propellants, low-thrust rocket
engines with very long (>1 year) firing lifetimes, cellsats (prior to
the Iridium et. al. proposals), small launch vehicle with airplane
first stage (prior to Pegasus), SSTO (in detail), high-Isp engine
flight tests, evolutionary design for robotics & control, etc. If
I'm wrong on any of these counts, I'd love to see references.
--
Nick Szabo sz...@netcom.com
Josh Hopkins
>he...@zoo.toronto.edu (Henry Spencer) writes:
>>I can think of more, offhand, that were fixable than
>>that weren't.
>Naturally -- NASA and its fans in media heavily publicize the handful of
>things astronauts have fixed, at a cost of several billion dollars,
>and put in fine print, at best, the the thousands things that
>have gone wrong that astronauts can't fix.
Actually, I would have suggested exactly the opposite selection effect.
You never hear about it when an astronaut fidgets with a glovebox and makes
it work or adjusts the crystal growth solution and gets the crystals to grow,
because, frankly, it's boring. However, if the shuttle toilet leaks,
even if it get's fixed, you'll be hearing about it on the news. The little
fidgeting that all of us do to make our computers and machines work is never
going to get into the news, even if it's done by an astronaut.
I would still guess having astronauts around helps, but this dissagreement
shows even more clearly that we shouldn't be making assuptions without
collecting the data.
>It's a _specification requirement_ for most Shuttle experiments that
>they require manual intervention -- even when obviously could
>be built without such dependence.
In part because if they don't require intervention they don't need to be flown
on the middeck or in Spacelab. Plenty of experiments have flown in GAS cans.
It might be appropriate to compare their success rates to those of middeck
experiments, once you eliminate all the grade schools and so on.
>There werent' very many of
>these kind of "problems" with the LDEF experiments -- in
>fact many worked right through the unplanned Shuttle delays,
Nick, I'm not aware that any of the LDEF experiments had power or moving parts.
How, pray tell, could they have had fixable problems? When the sole purpose
of an experiment is to see what happens when you leave something in space,
it's hard to have an unsuccessful experiment by leaving it in space.
--
Josh Hopkins jbh5...@uxa.cso.uiuc.edu
Concern for man himself and his fate must always form the chief interest of
all technical endeavors...Never forget this in the midst of your diagrams and
equations. - Einstein
Kieran A. Carroll
>sz...@netcom.com (Nick Szabo) writes:
>>There werent' very many of
>>these kind of "problems" with the LDEF experiments -- in
>>fact many worked right through the unplanned Shuttle delays,
>
>Nick, I'm not aware that any of the LDEF experiments had power or moving parts.
>How, pray tell, could they have had fixable problems? When the sole purpose
>of an experiment is to see what happens when you leave something in space,
>it's hard to have an unsuccessful experiment by leaving it in space.
Josh;
While I agree with the main point that you're making regarding
the simplicity of LDEF experiments, I have knowledge of *one* such
experiment that had moving parts. Rod Tennyson of the University of
Toronto's Institute for Aerospace Studies flew a materials-science
payload on LDEF. It comprised several tubes of various materials,
including graphite-epoxy composites, instrumented with strain
gauges, and a tape recorder that sampled strain for each tube, plus
temperature, once every (something like 120 minutes). It had its
own internal power supply. The electronics and tape recorder worked
fine, lots of good data were obtained after LDEF was retrieved.
However, due to the unexpectedly long time on-orbit, the tape had
filled up completely, which invalidated some of the planned experimental
results---a complete record of start-to-finish behaviour on-orbit
was needed in order to calibrate drift in the strain gauges, or something
like that.
Fortunately, the UTIAS experiment was not on the ram-direction face
of LDEF. Some other truly simple experiments came back with *no*
materials samples left at all, the samples having eroded completely
away due to atomic oxygen exposure! (The ram-face was considered prime
real estate *before* launch, but five years later property values had
dropped considerably :-)
I believe that the restriction with LDEF was that there be no
telemetry. Experiments with their own power supplies were allowed,
as were moving parts (within reason). There were rumours that the
DoD had payloads on board that *may* have violated Rule #1, however...
--
Kieran A. Carroll @ U of Toronto Aerospace Institute
uunet!attcan!utzoo!kcarroll kcar...@zoo.toronto.edu
Pat
small missions don't get much scrutiny.
ALEXIS got pretty badly roughed over, and all i saw was
a little blurb in the filler articles.
Numerous GAS cans have failed, and never been noted.
if the mission is below $10Million, i don't think it's on the
media horizon. maybe rush limbaugh can flog it, but that's about
the level it would be at.
pat
--
-----------------------------------------------------------------------------
No matter how dire the situation, don't panic -- LLIB #280
David DeFelice, 3-6186
>
>small missions don't get much scrutiny.
>
>if the mission is below $10Million, i don't think it's on the
>media horizon.
That's the idea behind and the beauty of the GAS cans and other small
experiments...if they don't work, fly them again with little lost little
added cost. You always get the payload back and even failures tend to
provide valuable data points. Most cans fly on a "space available" type
manifest. The biggest penalty for failure is getting back in the queue
line for the next flight op.
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David M. DeFelice - NASA Lewis Research Center - Community Relations Office
(216) 433-6186 Cleveland, Ohio
___________________________________________________________________________
"Why can't life be menu driven or at least have an 'undo' feature?"
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