tech: CCNet DIGEST, 20 August 1999

[Larry Klaes <lklaes@bbn.com>]

>From: Benny J Peiser <b.j.peiser@livjm.ac.uk>
>Sender: humbpeis@livjm.ac.uk
>To: cambridge-conference@livjm.ac.uk
>Subject: CCNet DIGEST, 20 August 1999
>Date: Fri, 20 Aug 1999 11:34:32 -0400 (EDT)
>Priority: NORMAL
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>CCNet DIGEST, 20 August 1999
>----------------------------
>
>     POEM OF THE DAY (suggested by Rolf Sinclair)
> 
>     I would rather be ashes than dust! 
>     I would rather that my spark should burn out 
>     in a brilliant blaze than it should be stifled by dry-rot. 
>     I would rather be a superb meteor, every atom 
>     of me in magnificent glow, than a sleepy and permanent planet. 
>     The function of man is to live, not to exist. 
>     I shall not waste my days trying to prolong them. 
>     I shall use my time.
> 
>     Attributed to Jack London (1876-1916).
>     [See <http://sunsite.berkeley..edu/London/credo.html>.]
>
>
>(1) AUGUST 15 BOLIDE IN SOUTHWEST US
>    Mark Boslough <mbboslo@sandia.gov> 
>
>(2) NEW RADAR IMAGES OF ASTEROID 1999 JM8
>    Ron Baalke <baalke@ssd.jpl.nasa.gov> 
>
>(3) RICHES IN THE RUBBLE OF THE SOLAR SYSTEM
>    Michael Paine <mpaine@tpgi.com.au>
>
>(4) RUSSIA SAYS U.S. IS PLANNING A NUCLEAR RACE IN SPACE
>    SPACE.COM <thoughts@SPACE.COM> 
>
>=============
>(1) AUGUST 15 BOLIDE IN SOUTHWEST US
>
>>From Mark Boslough <mbboslo@sandia.gov> 
>
>We captured a bright fireball on videotape Sunday evening August 15 
>at 11:18 PM local time in Albuquerque, NM (05:18 UT). Our radiometer 
>showed a peak magnitude of about -16.5. The object was due west of 
>Albuquerque. We estimate the range to be about 300 km based on our 
>elevation angle and eyewitness reports from El Paso, TX. The absolute 
>(100 km) magnitude is therefore about -19. The worldwide mean 
>frequency of bolides of this brightness is 10 to 20 per year.  
>Comparison to Ceplecha's data suggest a pre-atmospheric mass on the 
>order of one ton. There were intense thunderstorms over NW New Mexico 
>and NE Arizona at that time, so it is unlikely that a precise 
>trajectory will be determined. Our video is avaliable on the web
>at http://www.cs.sandia.gov/SEL/apps/energy/meteor.htm
> 
>Mark Boslough
>Richard Spalding
>
>==================
>(2) NEW RADAR IMAGES OF ASTEROID 1999 JM8
>
>>From Ron Baalke <baalke@ssd.jpl.nasa.gov> 
> 
>Recently discovered asteroid 1999 JM8 passed within 0.06 AU from the
>Earth on July 30, 1999.  Using the Goldstone Deep Space Network antenna 
>and the Arecibo Observatory, a team led by Steve Ostro from JPL were 
>able to bounce radar off of this asteroid.  The radar images obtained 
>from August 1-9 are available here:
> 
>http://neo.jpl.nasa.gov/images/1999jm8.html
> 
>Ron Baalke
>
>================
>(3) RICHES IN THE RUBBLE OF THE SOLAR SYSTEM
>
>>From Michael Paine <mpaine@tpgi.com.au>
>
>Hi Benny, welcome back.
>
>Here is the text on the latest article in my new column at 
>Explorezone. I wrote it after reading "Mining the Sky" by John Lewis. 
>http://explorezone.com/columns/space/1999/august_neo_mining.htm
> 
>Riches in the rubble of the solar system
> 
>By Michael Paine for explorezone.com 
> 
>Thirty years ago, when the Apollo astronauts brought rocks back from 
>the Moon, nobody rushed to stake a mining claim. Only traces of 
>useful materials were found. The surface of the Moon turned out to be
>barren and unattractive for commercial development. 
> 
>Asteroids, however, are another matter. Nearly all the raw materials 
>needed to build a self-sufficient space colony are available on the 
>most common type of asteroid. NASA plans to land a small robotic
>spacecraft on an asteroid within a few years, just one example of the
>belief that asteroids are both accessible and worth exploring.
> 
>Recipe for a solar system
> 
>Most asteroids are made from the raw ingredients of the solar system, 
>researchers believe. Those ingredients came from supernova -- 
>exploding overweight stars. The solidified debris from these 
>explosions contains mainly dust, rocks, water ice and iron (actually 
>an alloy of iron, nickel and cobalt -- a natural stainless steel).
> 
>Nearly 5 billion years ago, under the tug of gravity, debris from 
>supernovas gathered into a spinning disk. Most of this material fell
>into the center of the disk and formed our Sun. Further out the 
>material formed many planets. As these planets circled the Sun they
>collided with each other and grew larger, until just nine planets 
>were left. The debris from these collisions, together with other 
>leftover rubble, was either swallowed up in further collisions or was 
>mostly herded into planet-free zones like the asteroid belt between 
>Mars and Jupiter.
> 
>Blast-furnace planets
> 
>The inner planets (Mercury, Venus, Earth and Mars) likely started off 
>as hot balls of molten metal and rock.. Like a blast furnace used for
>making iron, most of the metal sank to the center of each planet and 
>a thin, rocky crust formed on the surface. The crust material of 
>these planets generally has much less metal than the raw ingredients 
>of the solar system. Most crust is the equivalent of the slag, or 
>discard, from a blast furnace, and there are just a few places near 
>the Earth's surface where metal ores are concentrated enough to make 
>mining worthwhile.
> 
>The good stuff is deep within Earth's interior.
> 
>Riches in the rubble
> 
>Solar system rubble still collides with the Earth -- the smaller 
>rocks reach the ground as meteorites. Some meteorites are nearly pure
>stainless steel, born in ancient supernovas.
> 
>Most of the asteroids are made of the same stuff as meteorites. They 
>too are rich in useful metals and chemicals such as water and carbon,
>and hence their commercial potential.
> 
>An example of the possible riches amongst this rubble of the solar 
>system is the asteroid Amun. The orbit of this mile-wide object comes 
>close to the Earth's orbit and, over millions of years, it could be a
>threat to the Earth. Before then, however, it is likely that mankind
>will have visited the asteroid and mined it away to nothing, because
>research indicates Amun is made from that primordial stainless steel.
>Planetary Scientist John Lewis, from the University of Arizona,
>estimates that the iron, nickel and cobalt in this single asteroid is
>worth about $20,000 billion at market prices.
> 
>Amun is unusually rich in metals and is typical of perhaps only 5 
>percent of asteroids. Most asteroids contain more rock than metal, but
>at least half of the material in these so-called stony asteroids could
>also be put to human use.
> 
>Let the asteroids come to us
> 
>Some half a million asteroids 100 yards across or larger orbit the 
>Sun along paths that cross or come close to the orbit of the Earth. 
>In principle, it is easier to reach about 100,000 of these "Near 
>Earth Asteroids" and return a payload to the Earth than it is to 
>return the same payload from the Moon. 
> 
>The recent Deep Space 1 flyby of asteroid Braille showed that we have 
>the space technology to reach Near Earth Asteroids. By using material 
>mined in space, mission planners could avoid the very high cost of 
>launching materials from Earth. 
> 
>The biggest technical difficulty in mining solid metal asteroids such 
>as Amun might be the task of chopping chunks of metal from the main 
>block. On Earth we have never had the luxury of mining a giant lump 
>of pure stainless steel, so we don't even know how to do it. 
> 
>Still, there is plenty of iron in common asteroids that could be 
>mined using conventional techniques. These asteroids also contain 
>water, which is not only important for surviving and manufacturing in 
>space but also has potential as a rocket propellant.
> 
>A new steam-powered "Rocket"
> 
>In 1829 George Stephensen won the first ever railway competition with 
>a steam engine called the "Rocket." Although steam engines have now
>gone out of style on the surface of the Earth, there is great potential
>for steam-powered rockets in space. 
> 
>In the vacuum of space a craft produces thrust by shooting matter at 
>high speed out an exhaust portal. Conventional rockets burn exotic 
>chemicals and the combustion products are forced out of a rocket 
>nozzle to produce thrust.
> 
>An alternative to a chemical rocket is to heat a volatile material (a 
>material which readily forms a gas) and expel the resulting 
>superheated gas from the rocket chamber. The natural choice for this 
>expendable material is water. Possible sources of heat are nuclear or 
>solar power.
> 
>The main obstacle to steam powered rockets is the cost of launching 
>tons of water into space from the Earth's surface. At a current cost 
>of thousands of dollars per pound launched, we might as well send 
>exotic chemicals into space -- the cost of the material becomes 
>irrelevant.
> 
>But what if we could obtain water in space? The Moon's polar regions 
>are suspected of holding frozen water, but the lunar poles are 
>difficult to reach and launching payloads from the Moon is 
>technologically and economically difficult. The obvious source of 
>water is Near Earth Asteroids, because asteroids typically contain 10 
>to 20 percent water in the form of permafrost or saturated minerals. 
>Dormant comets also orbit the Sun near the Earth, and these "dirty 
>snowballs" likely contain more than 50 percent water.
> 
>There is another advantage to using water in space rockets. A thick 
>layer of water ice around a manned spacecraft makes an excellent 
>shield from radiation and small meteoroids. Water storage tanks could
>surround the habitable modules of spacecraft, like igloos in space.
> 
>The next giant leap for Mankind
> 
>Our Earth-based technology for mining and processing raw materials 
>needs to be adapted for use in space -- for mining the asteroids. If 
>the dreams of science fiction writers are to become a reality and 
>humans are to colonize space, then the next step is to tap into the 
>vast resources of the rubble of the solar system.
>
>Copyright 1999, Explorezone
>
>==============
>(4) RUSSIA SAYS U.S. IS PLANNING A NUCLEAR RACE IN SPACE
>
>>From SPACE.COM <thoughts@SPACE.COM> 
> 
>Rather than declaring renewed friendship with the United States, 
>Russia walked away from new arms control talks on Thursday, accusing 
>Washington of trying to start a new nuclear arms race in outer space.
>http://www.space.com/news/international/russia_warning_819.html
>
> 
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