The Unsorted BBS Collection/thegreatunsorted.tar/thegreatunsorted/texts/term_papers/mine-sp.txt

Text File | 1995-03-31 | 15KB | 240 lines

                                 Mining
                                   in
                                 Space
                                   --
                  AIAA and New York Academy of Sciences


          On December 10,  1986 the Greater New York Section  of  the
    American Institute of Aeronautics  and  Astronautics  (AIAA)  and
    the engineering section of  the  New  York  Academy  of  Sciences
    jointly presented a program on mining the planets.  Speakers were
    Greg Maryniak of the Space Studies Institute (SSI) and Dr.   Carl
    Peterson of the  Mining  and  Excavation  Research  Institute  of
    M.I.T.

          Maryniak spoke first  and  began  by  commenting  that  the
    quintessential predicament of space  flight  is  that  everything
    launched from Earth must  be  accelerated  to  orbital  velocity.
    Related to this is that the traditional way to create  things  in
    space has been to manufacture them on Earth and then launch  them
    into orbit  aboard  large  rockets.   The  difficulty  with  this
    approach is the huge cost-per-pound of boosting anything  out  of
    this planet's gravity well.  Furthermore,  Maryniak noted,  since
    (at least in the near to medium  term)  the  space  program  must
    depend upon the government for most of  its  funding,   for  this
    economic  drawback  necessarily  translates  into   a   political
    problem.

          Maryniak continued by noting that  the  early  settlers  in
    North America did not attempt to transport  across  the  Atlantic
    everything then needed to sustain them in the New World.   Rather
    they  brought  their  tools  with  them  and  constructed   their
    habitats from local materials.  Hence,   he  suggested  that  the
    solution to the dilemma to which  he  referred  required  not  so
    much a shift in technology as a shift in  thinking.   Space,   he
    argued,  should be considered not as a vacuum,  totally devoid of
    everything.  Rather, it should be regarded as an ocean,  that is,
    a hostile  environment  but  one  having  resources.   Among  the
    resources of space,  he suggested,  are readily  available  solar
    power and potential surface mines on the  Moon  and  later  other
    celestial bodies as well.

          The Moon, Maryniak stated,  contains many useful materials.
    Moreover,  it is twenty-two times easier to accelerate a  payload
    to lunar escape velocity than it is to accelerate  the  identical
    mass out of the EarthUs gravity well.  As a practical matter  the
    advantage in  terms  of  the  energy  required  is  even  greater
    because of the absence of a lunar atmosphere.  Among other things
    this  permits  the  use  of  devices  such   as   electromagnetic
    accelerators (mass drivers) to launch payloads  from  the  MoonUs
    surface.

          Even raw Lunar  soil  is  useful  as  shielding  for  space
    stations and  other  space  habitats.   At  present,   he  noted,
    exposure to radiation will prevent anyone for  spending  a  total
    of more than six months out of his or her entire lifetime on  the
    space station.  At the other end of the scale,  Lunar soil can be
    processed into its constituent materials.  In between  steps  are
    also of great interest.  For example,  the MoonUs soil is rich in
    oxygen,  which makes up most of the  mass  of  water  and  rocket
    propellant.  This oxygen could be RcookedS out of the Lunar soil.
    Since most of the mass of the equipment which would be  necessary
    to accomplish this would consist  of  relatively  low  technology
    hardware,  Maryniak suggested the possibility that  at  least  in
    the  longer  term  the   extraction   plant   itself   could   be
    manufactured largely on the Moon.  Another possibility  currently
    being examined is the manufacture of glass from  Lunar  soil  and
    using it as  construction  material.   The  techniques  involved,
    according to Maryniak,  are crude but effective.  (In answer to a
    question posed by a member  of  the  audience  after  the  formal
    presentation,  Maryniak  stated  that  he  believed  the  brittle
    properties of  glass  could  be  overcome  by  using  glass-glass
    composites.  He also suggested yet another possibility,  that  of
    using Lunar soil as a basis of concrete.)

          One possible application of such Moon-made glass  would  be
    in glass-glass composite beams.  Among other things,  these could
    be employed as structural elements in  a  solar  power  satellite
    (SPS).  While interest in the SPS has waned in this country,   at
    least temporarily,  it is a  major  focus  of  attention  in  the
    U.S.S. R. , Western Europe and Japan.  In particular, the Soviets
    have stated that  they  will  build  an  SPS  by  the  year  2000
    (although they plan on using Earth launched materials.  Similarly
    the Japanese are conducting SPS related  sounding  rocket  tests.
    SSI studies have suggested that more than 90%,   and  perhaps  as
    much as 99% of the mass of an  SPS  can  be  constructed  out  of
    Lunar materials.

          According to Maryniak,  a fair amount of work  has  already
    been performed on the layout of Lunar mines and how  to  separate
    materials on the Moon.  Different techniques from those  employed
    on Earth must be used because of the  absence  of  water  on  the
    Moon.  On the other hand,  Lunar materials processing can involve
    the use of self-replicating factories.  Such a procedure  may  be
    able to produce a so-called Rmass payback ratioS  of  500  to  1.
    That is,  the mass of the manufactories which can be  established
    by this method will equal 500 times  the  mass  of  the  original
    RseedS plant emplaced on the Moon.

          Maryniak also  discussed  the  mining  of  asteroids  using
    mass-driver engines,  a technique which SSI has  long  advocated.
    Essentially this would entail a  spacecraft  capturing  either  a
    sizable fragment of a large  asteroid  or  preferably  an  entire
    small asteroid.  The spacecraft would be equipped with  machinery
    to  extract  minerals  and  other  useful  materials   from   the
    asteroidal mass.  The slag or other waste products  generated  in
    this process would be  reduced  to  finely  pulverized  form  and
    accelerated by a mass driver in  order  to  propel  the  captured
    asteroid into an orbit around Earth.  If the Earth has  so-called
    Trojan asteroids,  as does Jupiter,  the energy required to bring
    materials from them to low Earth orbit (LEO) would be only 1%  as
    great as that required to launch the same  amount  of  mass  from
    Earth.  (Once again,  moreover,  the fact  that  more  economical
    means of propulsion can be used for orbital  transfers  than  for
    accelerating material to orbital velocity would likely  make  the
    practical advantages even greater. ) However, Maryniak noted that
    observations already performed have ruled  out  any  Earth-Trojan
    bodies larger than one mile in diameter.

          In addition  to  the  previously  mentioned  SPS,   another
    possible use for materials mined from planets  would  be  in  the
    construction of space  colonies.   In  this  connection  Maryniak
    noted that a so-called biosphere was presently being  constructed
    outside of Tucson,  Arizona.  When it is completed  eight  people
    will inhabit it for  two  years  entirely  sealed  off  from  the
    outside world.  One of the objectives of this experiment will  be
    to prove the concept of long-duration closed cycle  life  support
    systems.

          As the foregoing illustrates,  MaryniakUs primary focus was
    upon mining the planets as a  source  for  materials  to  use  in
    space. Dr.  PetersonUs principal interest, on the other hand, was
    the potential application of techniques and  equipment  developed
    for use on the Moon and the  asteroids  to  the  mining  industry
    here on Earth.  Dr Peterson began his presentation by noting that
    the U. S.  mining  industry  was  in  very  poor  condition.   In
    particular,  it has been  criticized  for  using  what  has  been
    described as Rneanderthal technology.  S  Dr.   Peterson  clearly
    implied that such criticism is justified,  noting that the sooner
    or later the philosophy of not doing what you  canUt  make  money
    on today will come back to haunt people.  A possible solution  to
    this problem,  Dr.  Peterson,  suggested,  is a marriage  between
    mining and aerospace.

          (As an aside, Dr.  PetersonUs admonition would appear to be
    as applicable to the  space  program  as  it  is  to  the  mining
    industry,   and  especially  to  the  reluctance  of   both   the
    government and the private sector to fund  long-lead  time  space
    projects.  The current problems NASA is  having  getting  funding
    for the space station approved by Congress and the failure  begin
    now to implement the recommendations of the  National  Commission
    on Space particularly come to mind.)

          Part of the mining industryUs difficulty,  according to Dr.
    Peterson is that is represents a rather small market.  This tends
    to discourage long range research.  The result is to  produce  on
    the  one  hand  brilliant  solutions  to  individual,   immediate
    problems,  but on the other hand overall  systems  of  incredible
    complexity. This complexity, which according to Dr.  Peterson has
    now reached intolerable  levels,   results  from  the  fact  that
    mining machinery evolves one step at a time and thus  is  subject
    to the restriction that each new subsystem has to  be  compatible
    with all of the other parts of the system that have not  changed.
    Using slides to illustrate his point,  Dr.  Peterson  noted  that
    so-called RcontinuousS coal mining machines can in  fact  operate
    only 50% of the time.  The machine must  stop  when  the  shuttle
    car,  which removes  the  coal,   is  full.   The  shuttle  cars,
    moreover, have to stay out of each others way.  Furthermore,  not
    only are Earthbound  mining  machines  too  heavy  to  take  into
    space,  they are rapidly becoming too heavy to take into mines on
    Earth.

          When humanity begins to colonize the Moon,   Dr.   Peterson
    asserted,  it will eventually prove necessary  to  go  below  the
    surface for the construction of habitats,  even if the extraction
    of  Lunar  materials  can  be  restricted   to   surface   mining
    operations.  As a result,  the same problems  currently  plaguing
    Earthbound mining will be encountered.  This is where  Earth  and
    Moon mining can converge.  Since  Moon  mining  will  start  from
    square one,  Dr.  Peterson implied,  systems can be designed as a
    whole rather than piecemeal.  By the same token,  for the reasons
    mentioned there is a  need  in  the  case  of  Earthbound  mining
    machinery to back up and look at systems as  a  whole.   What  is
    required,  therefore,  is a research program aimed at  developing
    technology  that  will  be  useful  on  the  Moon   but   pending
    development of Lunar mining operations  can  also  be  used  down
    here on Earth.

          In particular,  the mining industry on Earth  is  inhibited
    by overly complex equipment unsuited to todayUs opportunities  in
    remote control and automation.  It needs machines  simple  enough
    to take advantage of tele-operation  and  automation.   The  same
    needs exist with respect  to  the  Moon.   Therefore  the  mining
    institute hopes to raise enough funds for sustained  research  in
    mining techniques useful both on Earth  and  on  other  celestial
    bodies as well. In this last connection, Dr.  Peterson noted that
    the mining industry  is  subject  to  the  same  problem  as  the
    aerospace industry:  Congress is reluctant  to  fund  long  range
    research.  In addition,  the mining industry has a problem of its
    own in that because individual companies are  highly  competitive
    research results are generally not shared.

          Dr.   Peterson  acknowledged,   however,   that  there  are
    differences  between  mining  on  Earth  and  mining   on   other
    planetary  bodies.   The  most  important  is  the  one   already
    mentioned-heavy equipment cannot be used  in  space.   This  will
    mean additional problems for space miners.  Unlike space  vacuum,
    rock does not provide a  predictable  environment.   Furthermore,
    the constraint in mining is not energy requirements,   but  force
    requirements.  Rock requires heavy  forces  to  move.   In  other
    words,  one reason earthbound mining equipment is heavy  is  that
    it breaks.  This brute force method,  however,  cannot be used in
    space.  Entirely aside from  weight  limitations,   heavy  forces
    cannot be generated on the  Moon  and  especially  on  asteroids,
    because lower gravity means less traction.  NASA  has  done  some
    research on certain details of this problem,  but there is a need
    for fundamental thinking about how to avoid using big forces.

          One solution,  although it  would  be  limited  to  surface
    mining,  is the slusher-scoop.  This device scoops up material in
    a bucket dragged across the surface by cables and a  winch.   One
    obvious advantage of  this  method  is  that  it  by  passes  low
    gravity traction problems.  Slushers are already in use  here  on
    Earth.  According to Peterson,  the  device  was  invented  by  a
    person named Pat Farell.  Farell was,  Peterson stated,   a  very
    innovative mining engineer  partly  because  be  did  not  attend
    college and therefore did not learn what couldnUt be done.

          Some possible alternatives to the use of  big  forces  were
    discussed during the question period  that  followed  the  formal
    presentations.  One  was  the  so  called  laser  cutter.   This,
    Peterson indicated,  is a potential solution  if  power  problems
    can be overcome.   It  does  a  good  job  and  leaves  behind  a
    vitrified tube  in  the  rock.   Another  possibility  is  fusion
    pellets,  which create shock waves by impact.  On the other hand,
    nuclear charges are not  practical.   Aside  from  considerations
    generated by treaties banning the presence of nuclear weapons  in
    space,  they would throw  material  too  far  in  a  low  gravity
    environment.