Date: Wed, 25 Nov 92 05:04:40
From: Space Digest maintainer <digests@isu.isunet.edu>
Reply-To: Space-request@isu.isunet.edu
Subject: Space Digest V15 #454
To: Space Digest Readers
Precedence: bulk
Space Digest Wed, 25 Nov 92 Volume 15 : Issue 454
Today's Topics:
Computer synchronisation by GPS (2 msgs)
GAS
GPS handheld receivers (3 msgs)
Pumpless Liquid Rocket?
Russian Photon capsule lands in Pacific & comes to Seattle
Safe, cheap hypergolics (was Re: Pumpless Liquid Rocket?)
Scientific method
shuttle payload limits
Shuttle replacement (8 msgs)
Spaceborne Artificial Intelligence, Anyone?
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----------------------------------------------------------------------
Date: 24 Nov 92 16:09:53 GMT
From: Dave Hopkins <dhopkins@gpsemi.lincoln.com>
Subject: Computer synchronisation by GPS
Newsgroups: sci.space
As I understand it GPS has a number of accurate (atomic) clocks which are
fundamental to determining ones position. One of the quoted applications
for GPS is for synchronising computer systems across the world using this
time information.
How would such a system work and what advantages would this offer over
conventional handshaking techniques?
Dave Hopkins
------------------------------
Date: Tue, 24 Nov 1992 21:21:54 GMT
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Computer synchronisation by GPS
Newsgroups: sci.space
In article <By8A8I.JtL@bailgate.gpsemi.com> dhopkins@gpsemi.lincoln.com (Dave Hopkins) writes:
>As I understand it GPS has a number of accurate (atomic) clocks which are
>fundamental to determining ones position. One of the quoted applications
>for GPS is for synchronising computer systems across the world using this
>time information.
>
>How would such a system work and what advantages would this offer over
>conventional handshaking techniques?
GPS position-finding works by determining how far you are from several of
the satellites, and then finding the intersection of the spheres defined
by those distances. The distances, in turn, are found by measuring
speed-of-light lag of the signals from the satellites.
The satellites just basically broadcast extremely accurate time signals
("the time is now 12:45:23.6465346533") plus current orbital positions.
Of course, what you can observe is not absolute lag, but relative lag --
how long the signal from one satellite took relative to another -- but
with an extra satellite or two, and accurate knowledge of the orbits,
you can solve for the satellites' idea of the time and for your position.
Since this scheme demands very accurate clocks on the satellites, and
getting a position involves figuring out what absolute time they think
it is, a GPS receiver quite incidentally knows the time down to a
fraction of a microsecond. (In the spiffy military models, a fraction
of a nanosecond.)
The usual sorts of synchronization protocols go to great lengths to deal
with the problem of *not* having a common absolute time reference. With
GPS, you *have* a common absolute time reference. All GPS receivers,
anywhere in the world, agree on the exact instant when the GPS system
clock reads 1:45:67.8727634 (with several more decimal places if the
receiver is a spiffy one). If your computer has a GPS receiver, and you
tell it to start processing at 11:17:05.8368461 sharp, it will start
processing in exact synchronization with any other similarly-equipped
computer that got the same instructions.
--
MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology
-Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry
------------------------------
Date: Tue, 24 Nov 92 17:57:35 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: GAS
-From: aws@iti.org (Allen W. Sherzer)
-Subject: Re: Shuttle replacement
-Date: 24 Nov 92 21:31:30 GMT
-In article <vento-241192142942@elwood.lerc.nasa.gov> vento@mars.lerc.nasa.gov (Dan Vento) writes:
->Remember the Shuttle type small Space Experiments world (except for life
->sciences) has really only been around since the late 70's
-I hope you aren't referring to 'get away specials' since NASA doesn't fly
-them anymore.
As of when? There have been plenty flown this year - in fact, I believe
*Dennis* has flown at least one this year.
John Roberts
roberts@cmr.ncsl.nist.gov
------------------------------
Date: 24 Nov 92 16:00:44 GMT
From: Dave Hopkins <dhopkins@gpsemi.lincoln.com>
Subject: GPS handheld receivers
Newsgroups: sci.space
Is the market for GPS handheld receivers is really as big as we've been
lead to believe? What use will long, lat and alt be to anyone unless it
it is fully integrated into a navigation system?
------------------------------
Date: Tue, 24 Nov 1992 18:56:56 GMT
From: "Michael K. Heney" <mheney@access.digex.com>
Subject: GPS handheld receivers
Newsgroups: sci.space
In article <By89t9.Js5@bailgate.gpsemi.com> dhopkins@gpsemi.lincoln.com (Dave Hopkins) writes:
>Is the market for GPS handheld receivers is really as big as we've been
>lead to believe? What use will long, lat and alt be to anyone unless it
>it is fully integrated into a navigation system?
I'm a contractor to the Environmental Protection Agency (EPA), and there
are a number of applictions of hand-held GPS that we're kicking around here.
There's a lot of inspection and sampling work done by EPA, and two immediate
uses of lat/long come to mind: 1) for various programs, there are
"regional stndards" set for some measured quantity. Gasoline volatility
is one. Lat/Long can give a more accurate indication of what the applicable
standard is t the site, which is then used for enforcement purposes.
2) Modelling based on measurements made in the field. Accurate position
info can be fed into a geographic data base system along with sample data
providing better information for the models.
--
Mike Heney | Senior Systems Analyst and | Reach for the
mheney@access.digex.com | Space Activist / Entrepreneur | Stars, eh?
Kensington, MD (near DC) | * Will Work for Money * |
------------------------------
Date: 24 Nov 92 19:16:21 GMT
From: Dave Jones <dj@ekcolor.ssd.kodak.com>
Subject: GPS handheld receivers
Newsgroups: sci.space
Dave Hopkins (dhopkins@gpsemi.lincoln.com) wrote:
> Is the market for GPS handheld receivers is really as big as we've been
> lead to believe? What use will long, lat and alt be to anyone unless it
> it is fully integrated into a navigation system?
Integrated nav. systems have been around for plenty of time. GPS will
just be another (more accurate) source of information. And the system
doesn't have to be a gods-eye-view you-are-here display. How about
"sound alarm if we drag our anchor for more than 100ft from our current
position" - this is built into marine Loran systems already.
--
||------------------------------------------------------------------------
||Dave Jones (dj@ekcolor.ssd.kodak.com)|Eastman Kodak Co. Rochester, NY |
------------------------------
Date: 24 Nov 92 16:41:30 GMT
From: Thomas Clarke <clarke@acme.ucf.edu>
Subject: Pumpless Liquid Rocket?
Newsgroups: sci.space
In article <1eth9sINNmi@transfer.stratus.com> det@phlan.sw.stratus.com (David
Toland) writes:
> In article <schlegel.722562761@cwis> schlegel@cwis.unomaha.edu (Mark
Schlegel) writes:
> >henry@zoo.toronto.edu (Henry Spencer) writes:
> >
> >>The hydrostatic head in the plumbing, while useful -- it figures into the
> >>design calculations for both pump-fed and pressure-fed rockets -- is not
> >>enough to run a pressure-fed engine particularly well. Even
low-performance
> >>pressure-fed engines need 5-10 atmospheres of pressure. (One atmosphere is
> >>a 10m column of water, and most fuels and oxidizers are substantially less
> >>dense than water.)
> >
> I'm surprised no one has posted what occurred to me (and I replied to
> the original author via email). The reaction chamber has a pressure
> that's approximately equal to the thrust of the engine divided by the
> area of the nozzle orifice (actually a bit higher due to turbulence
> losses in the nozzle), so you have this chamber pressure working against
> the hydrostatic pressure. I haven't set up a mathematical model of
> this, but I find it hard to believe that a practical rocket motor
> could be built with a high enough hydrostatic pressure to feed the
> reaction chamber.
I think it works.
Say the rocket has a 100 meter hydrostatic pipe, so the
chamber pressure is 10 atm (147 psi){excuse mixed units}.
If the nozzle orifice is 100 square inches, then the
thrust is 14,700 punds. {Actually I think thrust
chamber area times pressure is a better approximation to
thrust when allowance is made for the expansion nozzle,
but that does not change the argument}
So if the fuel+structure weights less than 14,700 pounds
the rocket begins to accelerate. The acceleration increase
the pressure, increases the thrust, and away we go. As
one poster pointed out it would be wise to have a valve
at the bottom of the pipe to regulate flow and thrust.
An aluminum pipe capable of resisting 14.7K of thrust would
have a minimum cross section of .2 square inches (depending on
alloy etc.) Give it 1/2 square inch for safety and to allow
larger thrust under acceleration. This is 2000 cubic inches of
aluminum which weighs about 220 pounds - not a lot of overhead
on a system with 14.7K pounds of thrust. {A long slender pipe
would be subject to buckling failure, so something like the
guys on a sailboat mast would have to be used, of course}
The area of the motor is likely to be 1000 square inches (34 inches
diameter) if the throat is 100. If the tank has this same diameter
(seems natural and somewhat aerodynamic), then it must be 407 inches long,
about 10 meters, to hold 14.7K pounds of fuel as dense as water.
A bizarre looking craft but it should fly!!
I may have to build a small one. Anyone know of safe
(& cheap) hypergolic propellants?
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu
------------------------------
Date: 24 Nov 92 17:11:20 GMT
From: Glenn Chapman <glennc@cs.sfu.ca>
Subject: Russian Photon capsule lands in Pacific & comes to Seattle
Newsgroups: sci.space
Radio Moscow on Nov. 22 announced the successful splashdown of the
Europe-American 500 sample capsule, which was launched on Nov. 16th (see Nov.
16th posting for launch details). This was a 5 day special flight of the
Photon space processing style sample return probe. In this case the capsule
is filled with items to send "good will messages" in celebration the voyage
of Columbus. The capsule with landed about 300 Km (190 mi) off the
Washington state Pacific coast and was recovered by a Russian satellite
tracking ship. The ship will be docking in the Seattle area today (Nov. 24)
and apparently will be open for visitors. A Tacomo TV stationed showed news
clips this morning of the Photon capsule being lifted out of the sea onto the
ship. Photon is a spherical capsule which is derived from the first Vostok
capsules, not the more modern Soyuz bell shaped return system. The capsule
will be on display in Seattle.
In other activity on board the Commonwealth of Independent States Mir
space station cosmonauts Anatoli Solovyov and Sergei Avdeyev Anatoli
Artsebarski and Sergei Krikalev (up for 120 days now) ejected a small
satellite from the air lock on Nov. 23. Meanwhile the CIS has been holding
discussions with the European Space Agency concerning cooperative space
programs. According to a Radio Moscow report agreement has been reached
which will see 3 ESA cosmonauts visit the Mir space station in the next few
years. Also $50 million in contracts will go to Russian space companies.
Glenn Chapman
School Eng. Science
Simon Fraser U.
Burnaby, B.C., Canada
------------------------------
Date: 24 Nov 92 10:23:20 GMT
From: Bill Higgins-- Beam Jockey <higgins@fnalf.fnal.gov>
Subject: Safe, cheap hypergolics (was Re: Pumpless Liquid Rocket?)
Newsgroups: sci.space
In article <1992Nov24.164130.21385@cs.ucf.edu>, clarke@acme.ucf.edu (Thomas Clarke) writes:
[description of spaghetti-strand hydrostatic-pressurized rocket deleted]
>A bizarre looking craft but it should fly!!
>
>I may have to build a small one. Anyone know of safe
>(& cheap) hypergolic propellants?
Yes. Vinegar and baking soda.
O~~* /_) ' / / /_/ ' , , ' ,_ _ \|/
- ~ -~~~~~~~~~~~/_) / / / / / / (_) (_) / / / _\~~~~~~~~~~~zap!
/ \ (_) (_) / | \
| | Bill Higgins Fermi National Accelerator Laboratory
\ / Bitnet: HIGGINS@FNAL.BITNET
- - Internet: HIGGINS@FNAL.FNAL.GOV
~ SPAN/Hepnet: 43011::HIGGINS
------------------------------
Date: 24 Nov 92 19:21:31 GMT
From: Sam Warden <samw@bucket.rain.com>
Subject: Scientific method
Newsgroups: sci.space
It's been my very strong impression that very little working
science is done according to this formal theory of hypothesis
verifying, but rather the opposite: theories are in fact
constructed to match the known facts. But they have to stand
internal scrutiny for empirical `fudging'. You try to
derive the known facts from your fundamental assumptions in
a way that is both rigorous and elegant, and what is tested
by your (collective) success or failure is those assumtions
themselves. It seems to me. ;-)
--
samw@bucket.rain.com (Sam Warden) -- and not a mere Device.
------------------------------
Date: 24 Nov 92 22:04:47 GMT
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: shuttle payload limits
Newsgroups: sci.space
In article <23NOV199223205010@judy.uh.edu> wingo%cspara.decnet@Fedex.Msfc.Nasa.Gov writes:
>>That "rated capacity" is obsolete; the shuttle has never been capable of
>>lifting that much without violating one operating rule or another. (Yes,
>>this means that the original specs were never met.)
>
>No this means that after the development was nearly complete NASA added abort
>modes to the launch phase that put severe strains on the orbiter frame. This
>LATE requirement caused NASA to derate the lift capability of the orbiter...
Say I'm a customer. I don't care *why* it doesn't meet the specs. All I
know is that it was supposed to be capable of (safely) launching my 65000lb
payload, but in fact it has never been cleared to do so. I call that not
meeting the specs.
(Who am I? Hint: I wear a blue uniform, and I *wrote* that 65000lb
requirement. It was a firm spec, not just a vague guideline.)
>... It is my understanding that some space station
>element flights will be as high as 44,000 to 47,000 lbs. They will of course
>waive some of the constraints on the abort modes for these flights.
>... There are no payloads heavier than SS Freedom elements.
Not any more, because nobody's going to build something that they'd never
be allowed to fly. If memory serves, those SSF elements have had radical
surgery at least once to keep them within shuttle weight limits. There
would be bigger payloads -- a few -- if the shuttle was allowed to go up
with more.
--
MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology
-Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry
------------------------------
Date: 24 Nov 92 18:31:35 GMT
From: Pat <prb@access.digex.com>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <1992Nov24.062745.4287@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
>
>Spacelab and Astro are two payloads that we want very much to return
>from orbit on a regular basis. That allows them to be easily refitted
>with new experiment racks and reflown. *That's* more cost effective
>than throwing them away each time or refitting them in space. Neither
>spam in a can nor a space station can handle the needs of those missions
>as effectively or as cheaply as Shuttle. Not that they are all that
>cheap mind you, but the experimental community thinks them worthwhile.
>
I think astro only returns because the shuttle returns. Most astro
program objectives could be flown on expendable sattellites rather
like IUE. i am certain IUE, COBE, IRAS have performed as ably as ASTRO
without the launch delays or costs. Notice NASA is funding the 4 great
observatories. if ASTRO was so great, they'd fly it more.
Space lab is useful, certainly, but you could automate it and fly most of
the experiments on disposables with return capacity if you really wanted.
certainly the shuttle has certain unique capacities but judging how often
LDEF, ASTRO and SPacelab have flown over the last 12 years, i dont think
people are dying for those missiions.
>wasteful. Might as well bring down a satellite or two at the marginal
>cost of a little maneuvering fuel. It's only useful for LEO satellites
>due to the lack of direct to GEO capability of the Shuttle, which is
>a shame, but it is a viable approach for those cases where Shuttle
>will be going to those orbital altitudes anyway. The problem is that
>
I think this is easier said then done. Henry, Alan????
>>Atlas is close. If it can't, we can go with Titan III for far far less.
>
>Splash.
>
>
>>
>>The new Titan SRMs will close most if not all of that gap.
>
>Boom, boom.
>
Easy slam. but an ad hominem attack doesnt make an argument.
I believe henry pointed out awhile ago that the shuttle has no greater
flight safety record then any expendable launcher. actually i think
he pointed out that the man rated versions of launchers were
not statiscally significantly improved over the non man rated versions.
fact is you could describe the shuttle with the same Boom Boom.
>
>>
>>In the last ten years or so almost all the boosters have been blown up
>>by range safety.
>
>Small confort to a crewed vehicle. Boom is boom.
>
Nonsense. a booster destroyed by the RSO is part of a planned process.
All previous manned missions had emergency escape provisions for the
crew during boost. I cant remember wether apollo used a escape rocket
or the SM engines, but the crew could get clear. certainly not fun,
but probably no worse then ejection seats. certainly any manned vehicle
would have this capacity. Henry, does the Soyuz have an escape rocket????
>>>the idea of a powered descent and vertical
>>>landing gives me the willies...
>>
>>Much safer than airplanes for most people. A DC crash will only affect the
>>Spaceport. When aircraft crash they tend to kill people on the ground.
>
>And a Shuttle crash landing is that of a glider, no boom, and perhaps
>survivable by the crew. Plus who says the SSTO will crash on the Spaceport
>grounds, few aircraft do. If they have a guidance failure, it might be
>downtown Disney World. All those kids, consumed in flaming rocket fuel,
>I can see the headlines now.
>
Actually, i think you are wrong there. i doubt a guidance failure would
be any worse for a DC-Y,1 then for a 747. remember it is a piloted
ppowered vehicle. if the ILS screws, the crew is still able to visualy
guide as well as get instructions from ground control. now a control
systems failure is possible, but with triple redundancy and smart pilots
even many severe control failures can be flown around. i know of
L-1011's flown in without elevator controls. United almost landed
a DC-10 minus an engine and all controls. Convertibles have been landed.
Besides, a DC flies on LOX/LH. coming in it should be low fuel and
LOX/LH does not really explode effficiently. you get steam and water
not a big boom. Several thousand pounds of JP-4 burns much better then
LOX/LH i would bet. the LOX should disperse rapidly and the LH burns
but not as persistently as a petroleum fire.
------------------------------
Date: 24 Nov 92 18:34:42 GMT
From: Pat <prb@access.digex.com>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <1992Nov24.151915.28177@iti.org> aws@iti.org (Allen W. Sherzer) writes:
>
>Would you consider a pickup truck which only worked one day a week and
>cost $200 per mile to operate 'working hardware'? I wouldn't which is
>why I don't consider Shuttle working hardware.
>
Sounds like a Jaguar XJ-12E circa 1977 :-)
------------------------------
Date: 24 Nov 92 18:39:38 GMT
From: Pat <prb@access.digex.com>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <By6K6I.4K6.1@cs.cmu.edu> amon@elegabalus.cs.qub.ac.uk writes:
>
>BTW... Did the pictures of the Isreali crash into an apartment block get shown
>on the air over in the US (and the rest of the world) as much as here? Anyone
>heard outcries to allow 747's to only take off and land over water?
>
YES, We get Cnn here:-) and usually we route aircraft over water,
but they call it noise abatement. The pilots hate it BTW.
------------------------------
Date: Tue, 24 Nov 1992 19:38:20 GMT
From: Dan Vento <vento@mars.lerc.nasa.gov>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <1992Nov24.151915.28177@iti.org>, aws@iti.org (Allen W. Sherzer)
wrote:
>
> In article <1992Nov24.062745.4287@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes:
>
> >Spacelab and Astro are two payloads that we want very much to return
> >from orbit on a regular basis.
>
> No, Spacelab and Astor are two payloads that we want very much to keep
> in orbit so they can be used. Building multi-billion $$ payloads and then
> flying them for a few days every two years isn't cost effective.
>
No, you definitely want to be able to bring these kinds of payloads back on
a regular basis at least until we have gained much more experience. Many,
if not most of the Spacelab type payloads are very new concepts, flying for
the first time, often built by organizations with little space hardware
experience. Rethinking and reflight are part of the learning curve.
Remember the Shuttle type small Space Experiments world (except for life
sciences) has really only been around since the late 70's and we are only
just learning to do many things that are taken for granted in ground-based
laboratories. Being able to retrieve and refly payloads before building
the space station version is the only way to prevent having a whole lot of
space junk inside your $30 Billion dollar space station.
Dan Vento
vento@mars.lerc.nasa.gov
------------------------------
Date: Tue, 24 Nov 92 18:49:49 GMT
From: Dave Jones <dj@ekcolor.ssd.kodak.com>
Subject: Shuttle replacement
Newsgroups: sci.space
Gary Coffman (gary@ke4zv.uucp) wrote:
>
> Deadheading is never cost effective. But that's a management problem,
> not a Shuttle problem per se. If you have to charge an entire Shuttle
> mission against a satellite return, then it is expensive, but if the
> return mission is piggybacked on a mission that carries things *to*
> orbit, or does other experimental work, then landing *empty* is also
> wasteful. Might as well bring down a satellite or two at the marginal
> cost of a little maneuvering fuel.
Folding two missions into one is not a trivial matter. Doing de-orbit with
x tons of satellite aboard is a whole different ball game from doing it
empty. You have to consider extra fuel to take up there for de-orbit,
extra to maneuver from deployment orbit to pickup orbit, more supplies
for extra time on orbit, more fuel to drive the extra supplies around,
launch windows, and so on. Trying to retrieve an object can make the
original payload objective impossible to achieve. NASA must love people
who say "While you're up there, why don't you......". It ain't exactly
climbing around on the roof of a house.
--
||------------------------------------------------------------------------
||Dave Jones (dj@ekcolor.ssd.kodak.com)|Eastman Kodak Co. Rochester, NY |
------------------------------
Date: 24 Nov 92 21:31:30 GMT
From: "Allen W. Sherzer" <aws@iti.org>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <vento-241192142942@elwood.lerc.nasa.gov> vento@mars.lerc.nasa.gov (Dan Vento) writes:
>> No, Spacelab and Astor are two payloads that we want very much to keep
>> in orbit so they can be used.
>No, you definitely want to be able to bring these kinds of payloads back on
>a regular basis at least until we have gained much more experience.
We want to bring back individual experiment racks. We don't want to bring
back the entire lab.
>if not most of the Spacelab type payloads are very new concepts, flying for
>the first time, often built by organizations with little space hardware
>experience. Rethinking and reflight are part of the learning curve.
Exactly. Those users are ill served by a Spacelab which flies one time
every couple of years. They WOULD be well served by something like
ISF which is up there all the time and so offers far more flight
opportunities.
>Remember the Shuttle type small Space Experiments world (except for life
>sciences) has really only been around since the late 70's
I hope you aren't referring to 'get away specials' since NASA doesn't fly
them anymore.
Allen
--
+---------------------------------------------------------------------------+
| Allen W. Sherzer | "A great man is one who does nothing but leaves |
| aws@iti.org | nothing undone" |
+----------------------151 DAYS TO FIRST FLIGHT OF DCX----------------------+
------------------------------
Date: 24 Nov 92 16:08:20 EST
From: Chris Jones <clj@ksr.com>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <By8Gsp.I9q@access.digex.com>, prb@access (Pat) writes:
>Nonsense. a booster destroyed by the RSO is part of a planned process.
>All previous manned missions had emergency escape provisions for the
>crew during boost.
All US missions up through the fourth shuttle launch had crew escape
provisions. After the loss of Challenger, the escape pole was added to the
shuttle, so there were 21 missions flown with no escape provisions after
launch, and I'd say that the shuttle currently has no escape provision during
boost.
> I cant remember wether apollo used a escape rocket
>or the SM engines,
It had an escape rocket.
> but the crew could get clear. certainly not fun,
>but probably no worse then ejection seats. certainly any manned vehicle
>would have this capacity. Henry, does the Soyuz have an escape rocket????
Yes, all Soyuz flights have had an escape rocket. There have been two launch
aborts of Soyuz flights: one just before liftoff in which the escape rocket
pulled the spacecraft and its occupants to safety, and one during the third
stage burn, which was again non-fatal, although a gruelling reentry featuring G
forces around the 15 level.
The two Soviet Voskhod flights (first multi-man crew and first EVA,
respectively) had neither ejection seats (as flown on Vostok) or an escape
rocket.
--
Chris Jones clj@ksr.com
------------------------------
Date: Tue, 24 Nov 1992 21:27:05 GMT
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Shuttle replacement
Newsgroups: sci.space
In article <vento-241192142942@elwood.lerc.nasa.gov> vento@mars.lerc.nasa.gov (Dan Vento) writes:
>> No, Spacelab and Astor are two payloads that we want very much to keep
>> in orbit so they can be used...
>
>No, you definitely want to be able to bring these kinds of payloads back on
>a regular basis at least until we have gained much more experience...
We want to bring back *individual items* from Spacelab, at varying times.
But returning *small* payloads has never been a problem. The issue here
is whether we want to be able to return *big* payloads in one piece. I
see no major requirement to return a payload larger than one Spacelab
experiment rack. Taking the infrastructure -- pressure hull, services,
etc. -- up and down all the time is crazy. As is limiting the mission
length to a week or two for the sake of hauling it up and down.
--
MS-DOS is the OS/360 of the 1980s. | Henry Spencer @ U of Toronto Zoology
-Hal W. Hardenbergh (1985)| henry@zoo.toronto.edu utzoo!henry
------------------------------
Date: 24 Nov 92 18:22:27 GMT
From: "R. S. Statsinger" <robert@aero.org>
Subject: Spaceborne Artificial Intelligence, Anyone?
Newsgroups: comp.ai,sci.space
Greetings!
We've been funded this FY for a research project in spaceborne
AI applications. This is an exciting topic, because we are just
now entering the first generation of spaceborne computer technology
with sufficient CPU bandwidth and address space to allow for
reasonably sophisticated space software. Although much of the improved
bandwidth and addressability in onboard computers is in support of
improved sensors, the opportunity clearly exists to enhance the
types of spaceborne software applications we deploy.
Please note that this endeavor is every bit as exciting for
commercial, non-military space applications as it is for the
military. If we're ever going to explore the cosmos in galaxy-class
warp-driven starships, then long before that we're going to need
sophisticated, fault-tolerant, realtime, space-qualified software -
and AI (along with generic operating systems for the coming
generations of spaceborne computer architectures) is certain
to be a part of this.
Anyway, I've been wondering if this has ever been kicked around
here in the Wonderful World of Usenet, and these two groups seemed
like a good place to start. I'll try to follow these two groups
for a while, but if anyone has anything to say on the subject
PLEASE don't hesitate to send me email.
Thanks much in advance.
Bob Statsinger
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End of Space Digest Volume 15 : Issue 454
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