> Welll, Allen, I'm just a lowly mechanical engineer (hate those
>li'l electrons!!), but I would propose that there are some qualitative
>differences in forging a large, mechanical assembly out of steel,
>aluminum, and composites, compared to primarily software
>constructions. The laws of physics tend to thwart many of my best
>ideas! :-) Natural laws, particularly with respect to materials'
>behaviours, are far from perfectly understood, especially outside
>research labs. I can well understand how difficulties ("design error"
>assumes a goof...sometimes there's no predicting somethings) may
>appear in a new project far into the construction. Software, while
>vastly more complicated now than ever, is still a construct of the
>mind of man. The mind of God (nature, whatever) is vastly more
>complex, and it is sheer hubris to assume full knowledge of the
>physical world, much less that the knowledge will be fully and
>perfectly applied to a physical construction.
Whoa.. If I understand this, your saying that because physics is a
natural science it is very complex, but because software is man-made it
is perfectly understandable. Nothing could be farther from the truth.
As any software programmer can tell you, any program over a dozen lines
quickly assumes a life of it's own. Programs the size of operating
systems actually have a kind of "personality". With large programs
interactions frequently occur that you would have never of thought
possible.
In fact, materials engineering seems to be a better understood science
that software engineering, if only because materials engineering has been
around longer.
As an example, you can design bridges that will be guaranteed to last for
50 years. A software programmer will never guarantee that a program he's
written will last more than 5 minutes without a bugfix.
Now for my comment on Freedom. It seems we're getting a major redesign of
the space station, now that Clinton's slashed the budget. This seems to
be having the effect of pushing the completion date back even further
that it already has been.
Isn't it time for NASA to take the research it has and make an absolute
commitment to design a space station that can be built and launched
before the next presidential election? I think that they should
concentrate on getting something up there before somebody changes their
mind and cuts the budget is cut to zero.
--------------------------------------
John Andrusiak - umandru1@umanitoba.ca
------------------------------
Date: 22 Feb 93 08:31:04 GMT
From: "Frederick A. Ringwald" <Frederick.A.Ringwald@dartmouth.edu>
Subject: Price for meteorites
Newsgroups: sci.space,sci.astro
In article <1lnlgvINNq1s@morrow.stanford.edu>
joe@oas.stanford.edu (Joe Dellinger) writes:
> And is there any reason for major interstate highways to pass SO
> close to meteor craters?
Something to do with magnetic fields, no doubt. ;-)
Seriously, there is a market for meteorites: check the ads in Sky &
Telescope and Astronomy magazines for ideas of how much you can get.
But generally, unless you have something rare and wonderful - or very
large - if you have to travel cross-country to sell your meteorite, the
money you'll get for it won't pay the cost of the trip. Keep in mind,
too, that about 90% of the time, what appears to be a meteorite is just
a piece of industrial slag, from steelmaking. What makes you think it
is a meteorite, anyway?
------------------------------
Date: Mon, 22 Feb 1993 03:49:04 GMT
From: "Milo S. Medin" <medin@cincsac.arc.nasa.gov>
Subject: Regularly updated Weather images online and avilable for ftp
Newsgroups: sci.space,sci.geo.meteorology
Folks, we're now announcing for public access a set of files available
for anonymous ftp, containing scientific quality weather satellite images.
Initially, we have regular collection of Japanese GMS images, both in IR
and visible light. These images are received at a ground station at
Hickam AFB, HI, and processed at the University of Hawaii, then moved
to an archive site at NASA Ames Research Center, Moffett Field CA. From
there, they are copied to shadow archives sites. Each archive site
contains the last 4 days worth of images transmitted by the GMS satellite
on a revolving basis.
The GMS satellite transmits 28 sets of images per 24-hour cycle. Of those, 24
are hourly observations and the other 4 are half-hourly observations made for
the purpose of getting accurate wind-speed readings. Each set of images
consists of two images: one IR and one VIS image. The IR images have a
resolution of 5km while the VIS images have a resolution of 1.25km. Because of
the large size of the VIS images, we have been subsampling them down to a
resolution of 5km; i.e., we have made the resolution match the native IR
resolution. We will eventually provide full-resolution VIS imagery as well,
but it will probably be a while.
The directory structure in each place looks like the following:
gms
/ \
ir vis
/ \ / \
hdf gif hdf gif
Each of the directories labelled hdf contains images in HDF format and each of
the directories labelled gif contain images in GIF format.
The intent is for the HDF files to contain true research quality data while
the GIF files are meant to contain visually appealing data. Thus you should
not expect the GIF files to contain research quality data. We *will* be
enhancing - and thus adulterating - these files. But the HDF files are
guaranteed to be unenhanced.
A problem with the HDF files so far is that no navigational data has been
included. We apologize for this; it's the result of us just not having gotten
it done yet. We have concentrated on building the software to create reliable
revolving archives and we have not put all the effort into extracting the
navigation information until very recently. However, we are now working on
doing this and within 1-2 weeks, each of the HDF files will have a header
containing all of the satellite parameters and then you will be able to do the
navigation. Also, we are considering providing pre-navigated data as well for
those who do not wish to do the navigation themselves. Again, sorry this is
not in yet. It's coming though.
Right now, the following archive sites are available for access by anonymous
FTP.
explorer.arc.nasa.gov ~ftp/pub/Weather
plaza.aarnet.edu.au ~ftp/Weather
Only Australian sites should use the archive at plaza.aarnet.edu.au.
Explorer is located at NASA Ames, and is a LAN away from FIX-West, which
should be closest to most folks, as it has close access to NSI, NSFNET, ESNET,
Milnet, etc... Explorer is also running with a modified FTP server that supports large socket buffer sizes which allows TCP windows to expand up to the limit, so if you are on the other end of a high delay Internet path, and have
a good ftp client that also uses bigger windows, you should get good performance
during transfers.
Note that these images are quite large. The GIF images alone run about 2-3 MB
each, so if you aren't connected via a T1 based infrastructure, please don't
try and download everything in sight.
We are also working on setting up a site on the east coast at the NASA Goddard
Space Flight Center, and for European access at UCL in London. The GSFC
site will be the primary archive for NOAA GOES images, and the London
site will be the primary archive for European METSAT data, though these
files will also be migrated to the other archive sites so that all archives
contain the same information. We also may be able to provide South polar
images from a downlink site at McMurdo base via another Internet link to
them. As new archives come online, messages updating this information will be
sent out.
This work is a combination of efforts by the University of Hawaii, the NASA
Office of Space Science and Applications, and the NASA NREN Project Office
(which sponsors access as part of it's educational outreach program), with help
from a number of other organizations worldwide.
Also, the explorer.arc.nasa.gov host also has 84 CD-ROM drives online, with
the full CD-ROM sets of Viking, Magellan, and Voyager data online and ftpable.
These data sets are located in the ~ftp/cdrom directory, and are mounted
in 14 Pioneer CD changer drives.
For more information, feel free to contact myself or Torben Nielsen
(torben@hawaii.edu).
Thanks,
Milo
------------------------------
Date: 18 Feb 93 19:29:29 GMT
From: George Foutrakis <georgef@hpux3.neuronet.pitt.edu>
Subject: SSF Dead
Newsgroups: sci.space
Your "reliable source" inside NASA must have watched the Presidential
Address just like everyone else.
------------------------------
Date: 21 Feb 93 23:35:38 GMT
From: Brian Stuart Thorn <BrianT@cup.portal.com>
Subject: Titan or Bust! (Saturn Moon)...
Newsgroups: sci.space
>Even using chemical rockets, a transfer orbit to Saturn shouldn't
>take more than five years. (The outer solar system is big,
>but not quite that big.) I think Cassini is using another series of
>Earth and Venus flybys like Galileo (I have no idea why: I'd think
>a direct launch on a Titan IV would be possible...) If more advanced
>propulsion (nuclear thermal or nuclear electric) were available,
>I'd expect the transfer time to drop below three years (or the payload
>to increase dramatically, which ever you prefer...)
>
> Frank Crary
> CU Boulder
Getting to Saturn has been done in 4 1/2 years (Voyager 1), but
Voyager wasn't stopping at Saturn. Cassini can't be going so
fast that it cannot enter Saturnian orbit. Hence a more leisurely
flighttime.
Cassini is indeed beyond Titan IV/Centaur direct ascent launch
capability, so we get Venus/Venus/Earth/Jupiter instead. If the
uprated Solids for Titan IV are not available (they aren't yet)
