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Date: Sat, 31 Oct 92 05:02:40
From: Space Digest maintainer <digests@isu.isunet.edu>
Reply-To: Space-request@isu.isunet.edu
Subject: Space Digest V15 #361
To: Space Digest Readers
Precedence: bulk
Space Digest Sat, 31 Oct 92 Volume 15 : Issue 361
Today's Topics:
Automated space station construction
Comet Collision (3 msgs)
Comet collision?
Dyson spheres
Galileo Update - 10/30/92
GEORGE BUSH'S DRUG WAR: CLAIMING VICTORY, COVERING UP LOSSES
Gravity Assists (Was Re: Query Re: pluto direct)
HRMS for ETI
lunar phases
Moving comets
NBC Dateline 10/28/92
pocket satellite receivers
Surveyor landings (was Re: QUESTIONS: Apollo, Earth, Moon)
Welcome to the Space Digest!! Please send your messages to
"space@isu.isunet.edu", and (un)subscription requests of the form
"Subscribe Space <your name>" to one of these addresses: listserv@uga
(BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle
(THENET), or space-REQUEST@isu.isunet.edu (Internet).
----------------------------------------------------------------------
Date: Sat, 31 Oct 1992 02:31:29 GMT
From: "I am a terminator." <choy@skorpio.usask.ca>
Subject: Automated space station construction
Newsgroups: sci.space
Can robots be launched to build the space station? They can work overtime.
Henry Choy
choy@cs.usask.ca
------------------------------
Date: 30 Oct 1992 22:35:01 GMT
From: Carl J Lydick <carl@SOL1.GPS.CALTECH.EDU>
Subject: Comet Collision
Newsgroups: sci.space,alt.sci.planetary
In article <1992Oct30.164031.7633@ccu.umanitoba.ca>, youngs@ccu.umanitoba.ca (Scott D. Young) writes:
> When they say comets are made of "ices", they don't necessarily mean H2O.
> There's lots of methane, ammonia, etc. and the even detected Cynanide in
> Halley's in 1910. Not fit for easy consumtion.
Er, cyanogen, actually.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL
Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My
understanding of astronomy is purely at the amateur level (or below). So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it. If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.
------------------------------
Date: 30 Oct 1992 22:28:09 GMT
From: Carl J Lydick <carl@SOL1.GPS.CALTECH.EDU>
Subject: Comet Collision
Newsgroups: sci.space,alt.sci.planetary
In article <BwwKo2.6vt@breeze.rsre.mod.uk>, black@breeze.rsre.mod.uk (John Black) writes:
>Maybe a near comet approach could be a good thing. I did a rough calculation
>and estimated that there must be something of the order of 10 to the power 11
>metric tonnes of water. Maybe in 130 years time somewhere on the Earth could do
>with some water, eg the interior of large continents affected by drought. I
>know that one of the effects of the greenhouse effect is to make sea levels
>rise, but that is salt water, no good for crops, and still would be hundreds of
>miles from a continental desert region. The comet presumably is almost pure
>water and therefore would be ideal for crops, drinking etc.
>
>So if in 130 years technology is sufficiently advanced, it could be possible
>to alter the orbit of the comet so that it goes into a stable orbit around the
>Earth. The trick then would be to "chip" bits off the comet and "land' them
>in the appropriate region of the Earth. This would be the most difficult bit
>since viz the probable cause of the Tunguska event (see previous article on
>comet hitting Earth) you would end up doing the equivalent of nuking the region
>The comet could also be an almost infinite supply of water for lunar bases if
>there are any by then.
Well, if we've got the technology to drag a comet into orbit (that sucker is
BIG and moving at what, about 70,000 mph relative to earth?), then break it up
and ship fragments down to the surface, don't you think it's also likely we'd
have the technology to build a desalination plant and a pipeline? Cheaper?
And easier?
>Maybe this is all too much "pie in the sky" (no pun intended :-), 130 years is
>much too short to evolve technologies to do this sort of stuff, witness what
>could be viewed as comparativly slow progress in maned spaceflight in the last
>20 years (still that's probably a function of the spending). So this sort of
>stuff is more like 500 years off in the future.
No, the problem is that you're ignoring the fact that if the technology for
what you suggest existed, then we'd be capable of dealing with that sort of
problem in much simpler ways.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL
Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My
understanding of astronomy is purely at the amateur level (or below). So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it. If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.
------------------------------
Date: 30 Oct 1992 22:39:06 GMT
From: Carl J Lydick <carl@SOL1.GPS.CALTECH.EDU>
Subject: Comet Collision
Newsgroups: sci.space,alt.sci.planetary
In article <1992Oct30.153103.29953@pixel.kodak.com>, dj@ekcolor.ssd.kodak.com (Dave Jones) writes:
>One day, I'm going to sit down and work out if Asimov's Martian Way really
>would have worked....soft land a chunk of Saturns Rings on Mars, when just
>getting into Earth orbit takes 90% of your starting mass? Hmmm.......
Ah, but if you aerobrake to get into a nearly circular orbit and use your
spacefaring iceberg for reaction mass in your descent, then you don't CARE if
you use up 100% of it in soft-landing it. After all, you've now got it in the
Martion atmosphere, where it would've ended up had you soft-landed 100% of the
mass (unless, of course, you increase the Martian atmospheric pressure
considerably).
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL
Disclaimer: Hey, I understand VAXen and VMS. That's what I get paid for. My
understanding of astronomy is purely at the amateur level (or below). So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it. If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.
------------------------------
Date: Fri, 30 Oct 92 22:19:52 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: Comet collision?
-From: morlan@afit.af.mil (Bruce W. Morlan)
-Subject: Re: Comet Collision
-Date: 28 Oct 92 18:17:45 GMT
-Organization: Air Force Institute of Technology
-rsb@mcc.com (Richard S. Brice) writes:
->Would anyone care to comment on how probability plays a role in the
->future interactions of earth and comet P/S-T and how much of the
->script is already written into the clock?
-Sure. The script is nearly totally written. The Heisenberg uncertainty
-associated with the objects in question (Earth, comet, Sun, other
-planets, etc.) is practically 0 over the time frame in question. On the
-other hand, the _uncertainty_ in the measurements leave much room for
-surprises. I cannot comment on the measurement errors.
-Bruce W. Morlan, Major, USAF Air Force Institute of Technology
-Dept. Department Head AFIT/ENC
-Department of Mathematics WPAFB OH 45433
Chaos is the measure of the degree to which errors in the initial measurement
of a system will affect the accuracy of predictions of the future condition
of the system. I don't really know how chaos is quantified or used in
calculations. The degree of chaos varies widely from system to system, and
in some systems it varies widely over time. For instance, the orbits of
the inner planets are slightly chaotic, Pluto perhaps more so, and the
degree of chaos in weather systems varies considerably over time (sometimes
very good predictions can be made several days ahead of time, and sometimes
the predictions for the next day are very uncertain). The net effect of
chaos is that the future state of a system is not a known quantity, but
a range of possible states, with a distribution of calculated probabilities.
(If some future event is considered a "sure thing" that means that almost all
of the probability distribution is within the range where the stated event
takes place.)
The long-term motion of Swift-Tuttle would have to be considered very
chaotic, due to the velocity changes brought about by outgassing. As the
comet moves further from the sun, the amount of outgassing decreases, to
its trajectory becomes less chaotic. (That's why there's so much interest
in getting precise measurement some years from now, though accuracy is still
not guaranteed - I believe Halley's Comet had a major outgassing event several
months ago, though it was several years from the perigee (perihelion, for
the politically correct :-) of its orbit. Gravitational influences of the
bodies of the outer solar system will also affect the comet, and uncertainties
in those will affect the accuracy of the calculations.)
As the comet comes by on its next approach, solar heating and outgassing
will resume and affect the comet's path somewhat, but since those changes
will have much less time to affect the comet before Earth flyby, they are
of much less concern than the changes during this pass.
John Roberts
roberts@cmr.ncsl.nist.gov
------------------------------
Date: Fri, 30 Oct 92 21:49:06 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: Dyson spheres
-From: marc@r-node.gts.org (Marc Fournier - Admin)
-Subject: Re: Dyson's Spheres
-Date: 28 Oct 92 22:16:02 GMT
-In article <1992Oct26.202658.154145@zeus.calpoly.edu> jgreen@zeus.calpoly.edu (James Thomas Green) writes:
->Why not make the radius of the DS larger than 1 AU to avoid heating
->up the inside too much?
- I'm not a scientist, but how would that help?? The energy would still
-be trapped, wouldn't it? Supposing a solid sphere, that is.
-Marc G. Fournier | R-node Public Access Unix running UnixBBS 1.10
-Etobicoke, Ontario | 416-249-5366 24hrs 7 days/week network email
If the energy is really trapped, your sphere will melt or explode. A long-term
stable sphere must radiate over its entire surface at a rate equal to the
heat production of the central star. For a uniform radiating surface, the
radiation per square meter must equal the intensity of incident sunlight
at that distance from the sun. Therefore, the greater the radius of the
sphere, the fewer watts per square meter have to be radiated from the outer
surface.
For a given radius, you can get the most effective radiation (and thus the
lowest outer temperature) if the outer surface of your sphere approximates
a "black body" (completely nonreflective at all wavelengths). The formula
for blackbody radiation is: power radiated = k * (Ts^4 - Ta^4), where
k is the Stephan-Boltzmann constant (which is listed in the faq list as
5.6697E-8 W / (m^2 * k) (should be k^4)), Ts is the temperature of the radiating
surface (absolute temperature, measured in kelvins), and Ta is the ambient
temperature. The background radiation of space is about 3K, but light from
stars, etc. heats it up a little more. I think Henry posted the effective
temperature of the sky a few months ago, and I seem to recall it as being
about 15K. In any event, the Ta term is negligible when we want Ts to be
comfortable for humans.
As I posted before, a sphere around the sun of 1AU radius would be much too
hot for humans to live on (except maybe in refrigerated compartments).
I calculated the temperature at 1AU radius (given 1370 W/m^2 at 1AU) as
394K = 121 C = 250 F (very uncomfortable!). If you want the outer surface
of the sphere to be a comfortable 25 C, the power radiated from the outer
surface must be ~447 W/m^2, so the radius of the sphere must be increased
to 1.75 AU.
There's a further complicating factor - a true black body surface is
unobtainable. Given a flat spectral response (again unrealistic), efficiency
of radiation is directly proportional to the emissivity(?), which is
equal to one minus the reflectivity. For instance, a 90% reflective
surface will only radiate 10% as much energy at a given temperature
as a black body would, so for a given amount of power radiated, the
temperature of the surface is greater by the fourth root of the
inverse of the emissivity. So a 1AU Dyson sphere with a 90% reflective
outer surface would have an outer temperature of
394 * 10^.25 = 701K = 428 C = 802 F. To get back down to 25 C, you'd have to
move the radius out to 5.5 AU. Fortunately, I believe most metals have
pretty low reflectivity at thermal infrared wavelengths, and black paint
has emissivity of over 90%.
John Roberts
roberts@cmr.ncsl.nist.gov
------------------------------
Date: Sat, 31 Oct 1992 05:26:54 GMT
From: Ron Baalke <baalke@kelvin.jpl.nasa.gov>
Subject: Galileo Update - 10/30/92
Newsgroups: sci.space,sci.astro,alt.sci.planetary
Fowarded from Neal Ausman, Galileo Mission Director
GALILEO
MISSION DIRECTOR STATUS REPORT
POST-LAUNCH
October 23 - 29, 1992
SPACECRAFT
1. On October 23, a routine sun vector update was performed. This sun vector
is valid through November 13.
2. On October 27 and 28, delta Differenced One-Way Range (DOR) passes were
performed over DSS-14/63 (Goldstone/Madrid) and DSS-14/43 (Goldstone/Canberra).
Initial results indicate that the delta DORs were successfully performed.
3. On October 27, a NO-OP command was sent to reset the command loss timer to
264 hours, its planned value for this mission phase.
4. On October 27, a periodic RPM (Retro-Propulsion Module) 10-Newton thruster
maintenance activity was performed; 10 of the 12 thrusters were "flushed"
during the activity. The P-thrusters were not flushed because they were used
to perform science turn (SITURN) activities on the same day. Spacecraft
performance throughout the activity was normal.
5. On October 27, the spacecraft performed a 17 degree SITURN. The purpose of
the SITURN was to maintain the spacecraft within plus or minus 13 degrees of
the sun while at the current solar distance.
6. On October 27, the Earth vector and Earth stars were updated to the
spacecraft's current attitude. This change implements the attitude maintenance
strategy required in the case of an AACS (Attitude and Articulation Control
Subsystem) POR (Power On Reset). If a fault occurs which terminates the
currently executing sequence, the spacecraft will maintain its current
attitude.
7. On October 28, Cruise Science Memory Readouts (MROs) were performed for
the Extreme Ultraviolet Spectrometer (EUV). Preliminary analysis indicates the
data was received properly. Subsequent to the MRO, the EUV was powered off,
as per plan. The HIC (Heavy Ion Counter) will be thus able to transmit data
when the Spacecraft is configured for the 7.68 kbps downlink on November 4.
8. On October 28, an Ultra Stable Oscillator (USO) test was performed to
verify the health status of the USO and collect gravitational red shift
experiment data; long term trend analysis is continuing.
9. On October 29, real-time commands were sent to perform a CDS (Command Data
Subsystem) memory verification test. Specifically, each memory location in
the standard and extended memory of the CDS A-string and B-string are being
readout. The purpose is to verify each memory location and identify any bad
memory locations. The test was in progress at the writing of this report.
10. The AC/DC bus imbalance measurements exhibited some change. The AC
measurement has ranged from 16DN to 17DN and now reads 17 DN (3.9 volts).
The DC measurement has ranged from 131 DN (15.3 volts) to 138 DN (16.2 volts)
and now reads 136 DN (16.0 volts). These measurement variations are
consistent with the model developed by the AC/DC special anomaly team.
11. The Spacecraft status as of October 29, 1992, is as follows:
a) System Power Margin - 82 watts
b) Spin Configuration - Dual-Spin
c) Spin Rate/Sensor - 3.15 rpm/Star Scanner
d) Spacecraft Attitude is approximately 11 degree
off-sun (leading) and 7 degrees off-earth (lagging)
e) Downlink telemetry rate/antenna-1200 bps (coded)/LGA-1
f) General Thermal Control - all temperatures within
acceptable range
g) RPM Tank Pressures - all within acceptable range
h) Orbiter Science- UVS, DDS, MAG, EPD, and HIC are
powered on
i) Probe/RRH - powered off, temperatures within
acceptable range
j) CMD Loss Timer Setting - 264 hours
Time To Initiation - 263 hours
UPLINK GENERATION/COMMAND REVIEW AND APPROVAL: None
GDS (Ground Data Systems):
1. A second Probe Mission Readiness Test/Ground Data System Test was
conducted Monday, October 26 with the DSN (Deep Space Network) SPC 60 (Signal
Processing Center in Madrid). Probe data were routed through the DSN station
processors to the Galileo MTS (MCCC Telemetry Subsystem) where it was
processed, displayed and routed to the Probe Flight Operations Equipment (PFOE)
in real-time. A compressed Probe tape was created for non-realtime processing
on the PFOE. Post test analysis of both the real-time data and the compressed
Probe tape is continuing. The first probe MRT (Mission Readiness Test) was
reported last week; analysis is complete and the test was successful.
TRAJECTORY
As of noon Thursday, October 29, 1992, the Galileo Spacecraft trajectory
status was as follows:
Distance from Earth 34,380,800 km (.23 AU)
Distance from Sun 181,306,000 km (1.21 AU)
Heliocentric Speed 108,300 km per hour
Distance from Jupiter 958,755,200 km
Round Trip Light Time 3 minutes, 48 seconds
SPECIAL TOPIC
1. As of October 29, 1992, a total of 8584 real-time commands have been
transmitted to Galileo since Launch. Of these, 3613 were initiated in the
sequence design process and 4971 initiated in the real-time command process.
In the past week, 227 real time commands were transmitted: 227 were initiated
in the sequence design process and none initiated in the real time command
process. In addition, 5911 mini-sequence commands have been transmitted since
March 1991; 3753 were pre-planned and 2158 were not. In the past week, no
mini-sequence commands were transmitted. Major command activities this week
included commands to reset the command loss timer and perform a CDS memory
verification test.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | If God had wanted us to
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | have elections, he would
|_____|/ |_|/ |_____|/ | have given us candidates.
------------------------------
Date: Fri, 30 Oct 1992 22:01:46 GMT
From: "I am a terminator." <choy@skorpio.usask.ca>
Subject: GEORGE BUSH'S DRUG WAR: CLAIMING VICTORY, COVERING UP LOSSES
Newsgroups: sci.space
In article <29731@life.ai.mit.edu>, Clinton for President <75300.3115@compuserve.com> writes:
|>
|> FOR IMMEDIATE RELEASE
|> October 20, 1992
|>
|> GEORGE BUSH'S DRUG WAR: CLAIMING VICTORY, COVERING UP LOSSES
|> [Statement by Bob Boorstin, Deputy Communications Director]
|>
|> George Bush just doesn't get it. He's shown time and time again he
|> doesn't understand America's economic problems. Now he's showing
|> again he doesn't understand America's drug problem.
etc.
|> Bill Clinton will lead a national and international crusade against
|> drugs. He knows we have to tackle both demand for drugs and the
|> supply of drugs. He sees the drug problem from a personal
|> perspective, not a political one. And he knows we can do better than
|> George Bush's cynical, failed drug war and attempted coverup.
Let's beam George Bush into a wall.
------------------------------
Date: Sat, 31 Oct 1992 05:33:00 GMT
From: Ron Baalke <baalke@kelvin.jpl.nasa.gov>
Subject: Gravity Assists (Was Re: Query Re: pluto direct)
Newsgroups: sci.space
In article <1992Oct30.163302.15547@rcvie.co.at>, se_taylo@rcvie.co.at (Ian Taylor) writes...
>
>While I'm here, anyone know if a gravity assist trajectory can be used to
>*reduce* speed?
Sure. Mariner 10 used a gravity assist of Venus to help it decelerate towards
Mercury. Voyager 2 lost speed when it flew by Neptune on its way out of
the solar system. Ulysses utilized a gravity assist of Jupiter to leave
the ecliptic plane, which in turn cut the spacecraft's heliocentric velocity
in half. Galileo will be using a Io gravity assist help it slow down
enough to go into orbit around Jupiter.
___ _____ ___
/_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov
| | | | __ \ /| | | | Jet Propulsion Lab |
___| | | | |__) |/ | | |__ M/S 525-3684 Telos | If God had wanted us to
/___| | | | ___/ | |/__ /| Pasadena, CA 91109 | have elections, he would
|_____|/ |_|/ |_____|/ | have given us candidates.
------------------------------
Date: 31 Oct 92 01:44:26 GMT
From: Stanley Friesen <swf@teradata.com>
Subject: HRMS for ETI
Newsgroups: sci.space,sci.bio
In article <BwxxDo.66t.1@cs.cmu.edu> nickh@CS.CMU.EDU (Nick Haines) writes:
|In article <1346@tdat.teradata.COM> swf@teradata.com (Stanley Friesen) writes:
|
|But what we do know is that simply putting lots of organic chemicals,
|amino acids, what-have-you together, even in planetary quantities for
|billions of years, is not likely to `generate life forms'. ...
Yep, can't disagree here. But whatever the process, I think it likely
to be an ubiquitous one.
| The
|current idea is that one starts with a self-reproducing system that
|does not _need_ such a finely-controlled environment (such as a clay
|mineral), that such a system can, over time, select to control more of
|its environment (a `cell') and that this environment may be suitable
|for the development of nucleic acids (or something similar). But it's
|a very long and precarious chain to get from clays to algae (or even
|to viroids). And clay minerals aren't going to be sending us any radio
|signals.
Well, here you are talking about Cairns-Smith's hypothesis/model.
I would scarcely call this the principle 'current idea', most people
studying the problem are still approaching it from the RNA/DNA angle
[based on the realization that RNA can have catalytic properties, so
proteinaceous enzymes are unnecessary].
Actually, I personally do favor Cairns-Smith's approach, but only a small
handful of people are acutally working on it.
[I disagree with him a little on a couple of issues, such as the extent
to which the early 'hybrid' forms would have "fed" on pre-existing
oranic goo and the tining of the origin of photosynthesis, but those
are fairly trivial details].
|Lest you misunderstand me, I fully support spending money on SETI:
|it's not expensive, and it attempts to answer one of the really big
|questions about the universe. But none of us really expect to find
|high-tech civilizations everywhere (for the simple reason that we
|haven't seen them yet) and I think the reason lies in that term of the
|Drake equation. When we get out there, I don't expect to find
|universal dumb life, I expect to find no life at all.
Actually, I rather expect to find bacterial level life most places.
I suspect that Earth is rather typical of planets at this distance from
stars of this class. So the ratio of complex life forms to 'prokaryote'
type life forms is probably about the same as the *time* ratios on Earth.
It is the startling *speed* with which life appeared on Earth that convinces
me. Any process that was not nearly inevitable would not be expected to
happen in the time frame that it now appears to have happened in (unless
Hoyle is right, that is - but that would make life even *more* ubiquitous).
The *earliest* rocks that are sufficiently intact to retain traces of life
in fact have such traces, so life appeared within a few 10's of millions to
a few hundred million years of the termination of the massive bombardment
phase (with its liquid or near liquid surface).
--
sarima@teradata.com (formerly tdatirv!sarima)
or
Stanley.Friesen@ElSegundoCA.ncr.com
------------------------------
Date: Sat, 31 Oct 1992 00:25:29 GMT
From: Leigh Palmer <palmer@sfu.ca>
Subject: lunar phases
Newsgroups: sci.space
In article <spitz.720440629@irb.uni-hannover.de> spitz@irb.uni-hannover.de (Jan
Spitzkowsky) writes:
>Please help,
>
>I need an algorithm for calculating the lunar phases.
>I need it for computing the red letter days, most of them
>depend on the moon like Easter.
I'd really like to know what red letter days are. I've heard the phrase
but I've never known what it meant! Please let the rest of us know. The
computation of the date of Easter is done by numerological rather than
astronomical algorithm, and that may help answer your question.
See "Explanatory Supplement to the Astronomical Ephemeris and the American
Ephemeris and Nautical Almanac" in your library, the chapter on Calendars.
You will learn that the algorithm has nothing to do with the physical moon
for most Christians. Orthodox Christians are the only ones who calculate
the phase of the physical moon, and they reckon day of the week by the
longitude of Jerusalem. I don't know whether they use apparent solar time
or mean solar time.
Leigh
------------------------------
Date: Fri, 30 Oct 92 20:37:56 EST
From: John Roberts <roberts@cmr.ncsl.nist.gov>
Subject: Moving comets
-From: henry@zoo.toronto.edu (Henry Spencer)
-Subject: Re: Scenario of comet hitting Earth
-Date: 29 Oct 92 18:16:02 GMT
-Bombs are actually a relatively good way to move asteroids. Comets
-are a difficult case, because they are probably fragile and because they
-probably have a thin crust with concentrated volatiles underneath. A
-small nearby nuclear explosion would blow off the crust on one side, and
-the result would be a tremendous spill of gas from the comet itself.
-If you knew what you were doing, and did it carefully, this could permit
-steering a comet with far less effort than the brute-force approach.
How far could a well-placed 10-magaton explosion divert the path of
Swift-Tuttle over the course of 120 years?
I've seen calculations of this type in the past, but I don't have access
to them now.
John Roberts
roberts@cmr.ncsl.nist.gov
------------------------------
Date: Sat, 31 Oct 1992 01:13:40 GMT
From: Rod Beckwith <rodb@slugo.corp.sgi.com>
Subject: NBC Dateline 10/28/92
Newsgroups: sci.space
I know how you guys hate posting this sort of thing over here & I normally
refrain, but I have not been able to get any information on this in A.A.V.
Please help me out if you are able.
Thanks in advance.....Rod
>pjweaver@ralvm29.vnet.ibm.com (Paul Weaver) writes:
> Did anyone else see Dateline NBC last night (10/28/92)? There was a story
on
> computer hackers near the end of the show, and they showed how these guys
get
> into the computers of the phone companies, banks, and the government. In
one
> brief glimpse, there was a shot of a computer screen after they had
logged >into Wright Patterson AFB, and the subject on the screen said
something to the >effect of "Catalogue of UFO parts list"!!
>
> Did anyone else catch this? They did not talk about UFOs on the show as
it >wasn't the subject of the report, so you would have had to have seen
the actual >computer screen.
> --
>>Yeah! I saw that too. They were some output from a defense computer and
>>something about 'UFO Parts List' scrolled through the screen...
>>-Garrett
>>> Well,well,
>>>I guess this thing is just going to slip through the cracks again.
Everyone
>>>is always bitching in this group that there is no serious discussions or
no
>>>evidence to research. A question was brought up about some hackers
video
>>>screen on NBC Dateline that had a UFO parts list on it. I find reference
to
>>>a project that an official at JPL posts, that appears to be a legit
Acronym
>>>for some program that nobody has heard of & NOBODY IS INTERESTED?
>>>I know it is not sensational, but it is something.
>>>I will ask again, has anyone heard about the UFO Atlas launch? See
Below:
=========================
SPACE CALENDAR
September 27, 1992
=========================
>>>* indicates change from last month's calendar
>>> October 1992
>>> ?? - Galaxy 7 Ariane Launch
>>> ?? - UFO Atlas Launch
>>> 04 - 35th Anniversary, Sputnik Launch (1st Satellite ever)
>>> 05 - Progress Launch (Soviet)
>>> 09 - Galileo, Trajectory Correction Maneuver 15 (TCM-15)
>>> 10 - Draconid Meteor Shower (Solar Longitude 197.0 degrees)
>>> *10 - Mars Observer, 1st Trajectory Correction Maneuver (TCM-1)
>>> 12 - SETI Scanning Begins
>>> 12 - 500th Anniversary, Columbus Discovers America
>>> *12-15 - Galileo, Dual Drive Actuator Test #4 (DDA-4)
>>> *12 - DFS-3/Kopernikus Delta 2 Launch
>>> 15 - STS-52, Columbia, Laser Geodynamics Satellite (LAGEOS-II)
>>> 15 - Freja Long March Launch (Sweden/China)
>>> 20 - AUSROC II Launch
>>> 21 - Orionid Meteor Shower (Solar Longitude 208.4 degrees)
>>>What do you think the acronym stands for?
>>>Uranium Freqeuncy Oscillator?
>>>Under Funded Orbitor?
>>>Unearthly Fungus Observer?
>>>OR WAIT, Mabye (now hold on to you hats) UNIDENTIFIED FLYING OBJECT!
>>>Probably something much more mundane, but I can't believe that nobody
has
>>>shown any curiosity in this.
>>>One reaps what one sows......nuff said.
>>>Rod
--
Rod Beckwith |$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Datacom I/S |"The great obstacle of progress is not ignorance,
rodb@corp.sgi.com|but the illusion of knowledge."
|$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
------------------------------
Date: Sat, 31 Oct 1992 00:37:15 GMT
From: Leigh Palmer <palmer@sfu.ca>
Subject: pocket satellite receivers
Newsgroups: sci.space
There is now a yuppie tempter for sale by Sony. It's called a "Pyxis" and
it is in a really slick package, advertised by the Manufacturer for C$1199
here in Canada, so it must be well under US$1000 real price. They tout it
as a marvelous Christmas gift for the outdoorsman, sailor, etc. It comes in
two parts, the antenna being connected to the computer by a two meter cord.
Incidentally, I have heard that full available (to the US military)
precision can be deduced from data collected by these civilian devices if
one integrates over long time periods. The numbers do seem to jump *around*
the correct value, as I've observed in my backyard with one of these units,
owned by a friend. I've never done the integration. Can anyone provide
information about this rumor?
Leigh
------------------------------
Date: Fri, 30 Oct 1992 23:27:56 GMT
From: Ed McCreary <mccreary@sword.eng.hou.compaq.com>
Subject: Surveyor landings (was Re: QUESTIONS: Apollo, Earth, Moon)
Newsgroups: sci.astro,sci.space
In article <1992Oct30.033908.1@fnalf.fnal.gov> higgins@fnalf.fnal.gov (Bill Higgins-- Beam Jockey) writes:
>I've played Lunar Lander (being a relic of the compter dark ages
>beforre Flight Simulator and Sim City), so I can appreciate the
>usefulness of a throttlable engine. So how did Surveyor manage to
>land? I recall a big solid-fuel motor and small liquid-fuel "vernier"
>engines. Was there a computer playing Lunar Lander on board? Was
>there a radar altimeter? Or did they just get the probe to
>*approximately* zero velocity with the big motor, and build it
>extra-sturdy to survive a drop? How does this compare with the scheme
>Luna 9 used to land, which I understand was rougher?
from "Solar System Log" by Andrew Wilson, a fine book I picked up for
$2.00 new at a used bookstore...
At an altitude of about 96km, a marking radar mounted inside the retromotor
nozzle signalled that braking should begin. the 94cm in diameter,
35.6-44.5 KN Thiokol motor was ignited 7 sec later at about 76km altitude
to cut the 9600km/hr approach speed to about 400km/hr in a 42sec burn. On
Surveyor 1 this motor accounted for 655kg of the 995kg launch weight. The
three liquid engines were commanded by the autopilot to provide stability
during this phase.
A radar altimeter Doppler velocity-sensing (RADVS) system provided the
data for vehicle control once the solid motor had been ejected about
40km above the surface to clear the legs for landing. At this height
radar returns from the groud were excellent and the RADVS fed the
information into the computers for closed-loop control. Surveyor was
an important step in provin this concept for the ApolloLunar Module.
The three liquid thrusters continued to fire to chop the descent speed
to5 km/hr some 4.3 m above the surface. To avoid disturbing the
landing area with plume impringement, the thrusters were shut off
and Surveyor free-fell to an 11 km/hr landing.
>(I recall that one of the Surveyors was moved after landing with the
>verniers.)
from same...
On November 17, 1967, 177hr after landing, Surveyor 6 became the first
spacecraft to be launched from the lunar surface when a 2.5 sec burn of
its three thrusters, comsuming 0.7kg of propellant, lifted it
3m high and a 7 degrees tilt moved it 2.5 meters to the west.
It's a wonderful book covering all of the unmanned missions in
detail up to Giotto and Suisei. I recommend it to anyone who
can find it.
--
In the midst of the word he was trying to say,|McCreary@sword.eng.hou.compaq.com
In the midst of his laughter and glee, |Me, speak for Compaq?
He had softly and suddenly vanished away--- |Yeah, right.
For the Snark *was* a Boojum, you see. |#include <stddisclaimer.h>
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End of Space Digest Volume 15 : Issue 361
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