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8.0 The polar lunar base

       Several writers such as James Burke have discussed the
   "Merits of a Lunar Polar Base Location" [LB1, p.77-84].  He also
   cites a half dozen other writers of papers on lunar polar bases and
   related subjects.  From [LB1, p.84] some are:
   1. J.R. Arnold, "Ice in the lunar polar regions", J. Geophysics
      Res., 84, 5659-5668, 1979.
   2. J.D. Burke, "Where do we locate the Moon base?", Spaceflight,
      19, 363-366, 1977.
   3. J. Green, "The polar lunar base", in "The Future of the United
      States Space Program", AAS paper 78-191, Univelt, San diego, 1978.
      In "Thoughts on a Lunar Base" [LB1, p.25-30], Edward Teller
   also favors a polar lunar base.
       Among the attractions mentioned are: (1) possible deposits of
   ice, (2) areas where the sun may never fully set, and (3) frequent
   access to polar orbiting satellites or space stations.  While it
   would be helpful to find ice somewhere near the poles, we should
   certainly not count on it, and the hope of finding some seems to be
   a poor justification for vast expenditures of money.
       The availability of permanent
   sunlight would be much more useful, but this too seems unlikely.
   The inclination of the rotational axis of the moon to the ecliptic
   plane is 1.5424 degrees [41, p.68].  This means that if the moon
   were a perfect sphere 1738 kilometers in radius, then when the pole
   was furthest from the sun, it would be 1.5424 degrees or 46.79
   kilometers from the pole to the nearest point where the sun was
   visible.  If we were to build a ring of solar panels 46.79 kilometers
   from the pole, then we could expect to have most of the panels in
   sunlight most of the time and thus we would have permanent solar
   power.  Conversely, if one built a tower 630 meters or 2066 feet
   tall at the pole, then sunlight would just strike the top of the
   tower in the worst case.  Clearly the actual geometry of the poles
   will likely determine the final configuration of any polar solar
   power arrays which we build.
       It is true that a low lunar polar orbitting satellite would
   pass over the pole about every two hours, but access from a polar
   base would mean rising nearly straight up which probably implies
   the use of rocket boosters.  That we cannot tolerate because it will
   spoil the nearly perfect vacuum present on the moon.
       Notwithstanding the previously mentioned reservations, we too
   favor a polar lunar base.  However, our justification is that the
   north pole is the optimal location for the electromagnetic projectile
   launcher which will constitute the lunar portion of our momentum
   transfer system which will propel spaceships to Mars and elsewhere
   (see section 6.4).
   8.1  Site selection
       There is only one north pole of the moon, but it seems to be
   right on the northwest shoulder of the 80 km wide Peary crater.
   This could make construction very difficult.  Perhaps the floor of the
   Peary crater would be the best location.  Another possibility is
   the 80 km wide Byrd crater which is just south of the Peary crater.
       The crater floor appears wide and flat, but our projectiles must
   clear the surrounding crater rim.  From the center of the crater,
   the curvature of the moon's surface should give us about 450 meters
   (plus the height of the EMPL) of clearance 40 kilometers away, i.e.
   at the crater rim.  We could knock down part of the crater rim if
   necessary, but if nuclear explosives are used, care must be taken to
   avoid generating thousands of tons of oxygen which would create an
   unwanted artificial atmosphere.
   8.2  The lunar polar railroad
       The following table shows the distance to the pole from various
   lunar latitudes at which the first lunar base might be located.
*  Table 8.2-1
   Latitude         Distance to pole
      (deg)          (km)        (mi)
       55            1062        660
       57.5           986        613
       60             910        566
       62.5           834        518
       65             758        471
       From a previous discussion it is clear that we will have copious
   amounts of iron available for construction of anything we need.  Thus
   building a railroad, which is a major user of iron should not be a
       We advocate building an electrified railroad from the first lunar
   base north to the north pole.  This line will be double track so that
   traffic can travel in both directions at the same time and further,
   that if necessary, oversized cars stretching between the first and
   third or fourth rails could be used.  With so much iron available
   there is no reason to be chintzy.  We will use 100 pound rail (that
   means 100 pounds per foot for those not familiar with the business).
   The amount of iron required for each kilometer of double track will
   be the product of the following factors:
*      100 pounds per foot
   x  3.28 feet per meter
   x  1000 meters per kilometer
   x     4 rails
       This is 1,312,000 pounds per kilometer.  Converted to metric
   tons, it is 596.4 MT per kilometer - just for the rails. Counting
   the towers needed to suspend the power lines and the contact bars,
   it will require roughly 750 MT per kilometer.  What about ties?
   Ties may not be necessary because the compressive strength of the
   lunar surface is much higher than that of the earth.  Thus we have
   not included any allowance for ties.  In any case it matters little
   because we will have an infinite supply of iron.  Our little railroad
   will be 900 to 1000 kilometers long.
       The power to run this electrified railroad will come from solar
   panels mounted overhead on the cross beams which support the contact
   8.3  Construction of the main electromagnetic launcher
       The main electromagnetic projectile launcher will be built on
   tracks so that it can be rotated between each launch.  This is
   necessary because of the orbital and rotational motions of the
   earth and moon.  The earth's orbital velocity around the sun is
   about 29.8 kilometers per second, while the moon's orbital velocity
   around the earth is about 1.02 kilometers per second.  The rotational
   period of the moon is 27.322 days.  This corresponds to 13.176
   degrees per day or 0.0001525 degrees per second.   This means that
   in the two minutes between the launching of two projectiles, the
   moon will move around the earth by about 122.4 kilometers and the
   angle that the EMPL is pointing will change by about 0.0183 degrees
   if no compensation is made.  This will cause an error in the
   direction in which the projectiles are going.  Of course the
   projectiles will carry propellant to allow them to change course,
   but we must try to minimize the course corrections they must make.
   The pointing error due to the motion around the sun is much smaller,
   amounting to 0.9856 degrees per day or about 0.00137 degrees between
   shots two minutes apart.  Perhaps the most obvious problem is the
   fact that it will take days to launch all the projectiles.  During
   that time the moon will orbit through as much as 90 degrees of its
   path around the earth.  If the EMPL could not be rotated, then we
   couldn't keep it pointed in the direction of its target way out
   in the plane of the ecliptic.
       There are some precedents for the building of large structures
   which are movable.  The ones which come immediately to mind are
   some types of bridges and in the field of astronomy, some radio
   telescopes called "very large arrays" which are mounted on tracks to
   permit their accurate movement and placement.
       The EMPL will be designed here on earth.  The components will be
   fabricated on the moon, primarily from iron, titanium, silicon, and
   aluminum.  The components will be transported via the lunar polar
   railroad to the north pole where they will be assembled by a crew
   of androids.
     8.4 The cost of the primary EMPL

          Estimating  the  cost  of  this  EMPL is complicated by three
     factors  which  we  are not accustomed to here on earth: (1) lunar
     resources,  including  unlimited electric power, will be free, (2)
     the  exact ratio of human labor hours to lunar android labor hours
     is  not  known,  and  (3)  the  cumulative  effects  of artificial
     intelligence may, and hopefully will, greatly reduce the number of
     human labor hours needed.
          Since the resources are free, the cost of each component will
     be  in direct proportion to the number of human labor hours needed
     to manufacture it. The more intelligent our androids are, the less
     everything will cost.
          Suppose that we decide to build an EMPL that is 10 kilometers
     long.  Then  we  can make a preliminary estimate based on Sandia's
     cost estimates [107, p.168-9].

     Table 8.4-1  Primary EMPL Costs
                                     Sandia               Proposed
     Item                          Cost ($ M)   Times    Cost ($ M)
     Project office                   115         1         115
     Research & development           410         0           0
     Facilities                       129         1         129
     Launcher system                  170        10        1700
     Energy storage system            327.8      10        3278
     Launch package                   413.2       1         413.2
     Launcher support systems           5.4      10?         54
     Control & monitoring systems      84         1?         84
     Installation and testing          12.4      10         124
     Operating costs for 7 years      350         1         350
                                     ----                  ----
                          Total      2016.8                6247.2

         If you check the previous cost estimate (section 4.4) you will
     see  that  we  have  deleted  nearly $400 million from the Project
     office  budget  and  have  given it a multiplier of only one. Why?
     Because  the  primary  EMPL  will  just  be  a  larger copy of the
     earth-to-moon  EMPL which has (we hope) by now already been built.
     Therefore,  they  will  need  no  more  "incremental  engineering"
     (budgeted  at  $386  million)  [107,  p.168] and by this time they
     should know how to run the project.
          The  value  of  the  facility here on earth would be about $6
     billion but its construction cost on the moon is unclear.
     8.5 Power for the launcher
         In order to launch one metric ton projectiles at 20 kilometers
     per  second  every  two  minutes,  we need about 2500 megawatts of
     power  (see  section  6.4). That is a lot a power! Fortunately, we
     will  have  about  10  years to provide this power. Nuclear power,
     solar  photovoltaic  power,  and solar thermal power are the three
     best options available.

          Ten  years  should  be  sufficient time to build enough solar
     panels to run it entirely from sunlight. Normal solar radiation is
     1400  watts  per  square  meter.  So, the power available from one
     square  kilometer  of  photovoltaic solar arrays at 10% efficiency
     would be:

     140 * 1000 * 1000  =  140 megawatts per square kilometer

         So, 17.86 square kilometers would provide 2500 megawatts. This
     corresponds to about 6.9 square miles. Remember that all along the
     electrified  railroad  from  the initial base to the polar base we
     will  have mounted photovoltaic arrays overhead on the cross beams
     which  carry  the electric power. How many kilometers of panels 20
     meters wide would be required to produce 2500 megawatts?

     17.86 square kilometers / 20 meters  =  893 kilometers

          This  means  that  by simply covering the railroad with solar
     arrays,  we  can  generate  enough  power  to run the polar EMPL -
     provided  that  the transmission lines are superconducting so that
     there will be no transmission losses.
         An estimate of the solar panel manufacturing rate necessary to
     satisfy  this  demand can be calculated in a similar manner. There
     are about 31.5 million seconds in a year or 315 million seconds in
     10  years.  Therefore,  a single machine which produced one square
     meter  every 17.64 seconds (or faster) could do the job. We expect
     that  there  will  be many solar panel manufacturing machines, not
     just one, although we will begin with just one.
         Nuclear power is the other alternative available to us. As was
     mentioned  before,  Brookhaven National Laboratory has built a gas
     core  particle bed reactor that can produce 200Mw from a 300kg 1.0
     by  0.56  meter  package [72, p.302]. Presumably, this is thermal,
     not  electrical  power,  so  there  will  be  a  major loss during
     conversion. But clearly sufficient units could be built to satisfy
     this  requirement.  These  units  could  be built on the moon from
     lunar  materials  with the possible exception of the fuel pellets.
     The  pellets  would  be  thrown to the moon with the earth-to-moon
     EMPL.  They  would  land  on  the  lunar  slide lander with little
     danger,  almost  no propellant, and at low cost. Some studies have
     already  been done concerning the use of an EMPL to launch nuclear
     materials - see for example [SM 2, p.305].
     8.6 Perturbations of the orbit of the moon
         The launching of thousands of  projectiles from the north pole
     of  the  moon  will  have  a completely negligible effect upon the
     motion  of  the moon. According to Paul Spudis [3, p.49], the moon
     is  receding  from the earth at about 3 centimeters per year. That
     is about 0.00000000095 or 0.95e-9 meters per second.
          If  we  launched  3000 one metric ton projectiles, ALL IN THE
     SAME DIRECTION, then the momentum would be:

     Momentum = 3000 MT * 20 km/second = 6.0e+10 kg meters/second

         The velocity change of the moon would be:

     Velocity change = 6.0e+10 / 7.35e+22 = 0.816e-12 meters/second

         where 7.35e+22 kg is the mass of the moon.

          Clearly,  this  is  negligibly small. Furthermore, we will be
     launching the projectiles in thousands of different directions, so
     that the overall effect will nearly cancel out.
          Of  more  concern  are  the  perturbations  of  Phobos due to
     activities  there.  The  mass  of  Phobos  is  only about 1.08e+16
     kilograms or about 0.000000147 of the mass of the moon.

         The velocity change of Phobos would be:

     Velocity change = 6.0e+10 / 1.08e+16 = 5.555e-6  meters/second

          Here  too  however,  the projectiles will be launched in many
     different  directions  so that the overall effect will be signifi-
     cantly smaller.
     8.7 Timeline
          The  following  time  estimates  are  based  on  the  assumed
     existence of the earth-to-moon EMPL. It is badly needed to deliver
     materials to the moon cheaply.
          We estimate that by laying 500 meters of double track per day
     for  five  years,  we could build an electrified railroad from the
     first  lunar  base  north  to  the  north  pole  of the moon. This
     railroad would be constructed by two large automatic machines (one
     to prepare the roadbed and the other to lay the rails) and a small
     number  of  androids  controlled  from  earth.  It  will require a
     significant  but  "low  tech"  manufacturing facility at the first
     lunar base to make the rails and other components.
         The primary EMPL, as described in sections 6.4 and 8.3,  would
     be  constructed  at  or near the north pole over a period of about
     five  years  subsequent  to  the completion of the railroad to the
     site. This will require a significant crew of androids at the site
     and a significant manufacturing capability at the first lunar base
     because  the  components of the EMPL will be more complex than the
     components of the railroad.
     8.8 Political summary
          1.  The  polar  lunar base is needed for the placement of the
     primary EMPL because of its unique location. Only the poles of the
     moon  remain  fixed  relative  to  the  distant  stars  during the
     rotation  of  the moon around the earth. Therefore, only those two
     places  are suitable for the primary EMPL, the key to the momentum
     transfer propulsion system.
          2.  In order to build a polar lunar base it will be necessary
     to  build  an electrified railroad from the first lunar base north
     to  the  north  pole  of  the  moon.  There will be plenty of iron
     available  from  the  maria  (about  12%  of  which  is  iron)  to
     accomplish  this. This project is expected to take about 5 years -
     beginning  about a year after the establishment of the first lunar
          3.  The  primary  EMPL, as described in sections 6.4 and 8.3,
     will  be  constructed  at  or near the north pole over a period of
     about  five  years subsequent to the completion of the railroad to
     the  site. This facility will provide the momentum which will move
     our spaceships to Mars or Jupiter or elsewhere.