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12.0 The Jupiter Mission

          Jupiter  is  the  largest  (discovered)  planet  in the solar
     system.  Although  more than five times as distant from the sun as
     is  the  Earth,  it is visible to the unaided eye on a clear night
     due  to  its  tremendous  size. Jupiter is more than 1300 times as
     large  as  the  earth and masses about 318 times as much as earth.
     Around  it orbit at least 16 satellites, the four largest of which
     were  discovered  by  Galileo  Galilei  in  1610.  Contrary to the
     teaching  this  author  received when a child, Jupiter does indeed
     have  rings,  although they are not nearly as spectacular as those
     of Saturn.

     Jupiter - the giant planet
     Datum                         Value      units       Source
     Mass                          1.900e+27  kg          [3, p.289]
     Equatorial radius             7.1492e+4  km           "
     Equatorial inclination        3.12       deg          "
     Equ. surface gravity          22.88      m/sec/sec    "
     Equ. escape velocity          59.6       km/sec       "
     Mean density                  1.33       g/cu.cm.     "
     Sidereal rotation period      9.841      hours        "
     Mean distance from Sun        7.7833e+8  km           "
     Mean orbital velocity         13.06      km/sec       "
     Sidereal period               4332.71    Earth days   "
     Inclination to ecliptic       1.308      degrees      "
     Orbital eccentricity          0.0483                  "

          The  US has sent five spacecraft to investigate Jupiter. They
     were Pioneer 10 and 11, Voyager 1 and 2, and, finally, the current
     mission,  Galileo.  For  an  outstanding  report  on  the  Jupiter
     missions,  the  reader  is  referred  to "Voyage to Jupiter", NASA
     publication number SP-439 [96].

     Table 12.0-1      Spacecraft Visits to Jupiter
     Spacecraft        Launch Date           Arrival Date
     Pioneer 10        March 3,1972          December 4,1973
     Pioneer 11        April 6,1973          December 3,1974
     Voyager 2         August 20,1977        July 9,1979
     Voyager 1         September 5,1977      March 5,1979
     Galileo           October 18,1989       December 7,1995

     Source: [96] "Voyage to Jupiter", p.31.

          The  Galileo mission is in deep trouble due to the failure of
     its  main  antenna  to  open  properly. But, true to form, NASA is
     unwilling  to  ask  for  help.  They  would  rather lose the whole
     mission  than  turn  to  the  Russians for help. The Russians have
     informally  offered  to send a communications satellite to Jupiter
     to relay data back to earth from the crippled Galileo  spacecraft.
     12.1 The Galilean satellites
          The  four  major  satellites  of  Jupiter  are:  Io,  Europa,
     Ganymede,  and  Callisto. These are the four satellites which were
     discovered by Galileo Galilei and which are now referred to as the
     Galilean  satellites.  The Voyager spacecraft provided us with the
     wonderful  closeup  pictures  of these satellites. Analysis of the
     photos  and instrument measurements greatly improved our knowledge
     of the Galilean satellites. Active volcanoes were discovered on Io
     with  fountains  of "lava" rising not just kilometers but hundreds
     of  kilometers  above  the  surface.  The cover photo, courtesy of
     NASA,  is  a  picture of Io, perhaps the most exciting body in the
     solar system (except for Earth of course).
         According to William Hartmann, et al, in  "Out of the Cradle",
     the wide range of colors on Io are due to  various forms of sulfur
     and  sulfur  oxide  which  is  white  and falls like snow from the
     plumes of the volcanoes. The colors give us a thermal map of Io.

     Table 12.1-1  Sulfur Color vs Temperature
         Temperature(C)         Color
             > 600              Black
               300              Brown
               125              Orange
                20              Yellow
             - 200              White

     Source: [38] "Out of the Cradle", p.149,152.

          The  following  data  on  the  Galilean  satellites  has been
     assembled from various sources as shown.

     Io - innermost Galilean satellite
     Datum                         Value      units       Source
     Mass                          8.94e+22   kg          [3, p.290]
     Equatorial radius             1.815e+3   km           "
     Orbital inclination           0.04       deg          "
     Equ. surface gravity (.185g)  1.81       m/sec/sec   author
     Equ. escape velocity          2.56       km/sec      author
     Mean density                  3.57       g/cu.cm.    [3, p.290]
     Sidereal rotation period      1.7698605  Earth days  [19, p.370]
     Mean distance from Jupiter    4.216e+5   km          [3, p.290]
     Mean orbital velocity         17.3       km/sec      author
     Sidereal period               1.7698605  Earth days  [19, p.370]
     Inclination to ecliptic       1.308      degrees     [3, p.289]
     Orbital eccentricity          0.0                    [3, p.290]

     Datum                         Value      units       Source
     Mass                          4.80e+22   kg          [3, p.290]
     Equatorial radius             1.569e+3   km           "
     Orbital inclination           0.47       deg          "
     Equ. surface gravity (.133g)  1.30       m/sec/sec   author
     Equ. escape velocity          2.02       km/sec      author
     Mean density                  2.97       g/cu.cm.    [3, p.290]
     Sidereal rotation period      3.5540942  Earth days  [19, p.370]
     Mean distance from Jupiter    6.709e+5   km          [3, p.290]
     Mean orbital velocity         13.7       km/sec      author
     Sidereal period               3.5540942  Earth days  [19, p.370]
     Inclination to ecliptic       1.308      degrees     [3, p.289]
     Orbital eccentricity          0.01                   [3, p.290]

     Datum                         Value      units       Source
     Mass                          1.48e+23   kg          [3, p.290]
     Equatorial radius             2.631e+3   km           "
     Orbital inclination           0.19       deg          "
     Equ. surface gravity (.146g)  1.43       m/sec/sec   author
     Equ. escape velocity          2.74       km/sec      author
     Mean density                  1.94       g/cu.cm.    [3, p.290]
     Sidereal rotation period      7.1663872  Earth days  [19, p.370]
     Mean distance from Jupiter    1.070e+6   km          [3, p.290]
     Mean orbital velocity         10.9       km/sec      author
     Sidereal period               7.1663872  Earth days  [19, p.370]
     Inclination to ecliptic       1.308      degrees     [3, p.289]
     Orbital eccentricity          0.0                    [3, p.290]

     Callisto - outermost Galilean satellite
     Datum                         Value      units       Source
     Mass                          1.08e+23   kg          [3, p.290]
     Equatorial radius             2.400e+3   km           "
     Orbital inclination           0.28       deg          "
     Equ. surface gravity (.127g)  1.25       m/sec/sec   author
     Equ. escape velocity          2.45       km/sec      author
     Mean density                  1.86       g/cu.cm.    [3, p.290]
     Sidereal rotation period      16.753552  Earth days  [19, p.370]
     Mean distance from Jupiter    1.883e+6   km          [3, p.290]
     Mean orbital velocity         8.2        km/sec      author
     Sidereal period               16.753552  Earth days  [19, p.370]
     Inclination to ecliptic       1.308      degrees     [3, p.289]
     Orbital eccentricity          0.01                   [3, p.290]

          One  of  the  most  significant investigations made by the US
     spacecraft  was  the characterization of the Jovian magnetosphere.
     This  magnetosphere  is  a  plasma  whose  origin is primarily the
     volcanic  activity  of  Io  which is, in turn, due to the gravita-
     tional  stresses  on  Io from Jupiter. Each Pioneer spacecraft was
     subjected  to  in excess of 400,000 rads of radiation during their
     transit  of  the  Jovian  system [3, p.37]. This is 1000 times the
     dose  fatal  to  humans.  The  intensity  of  this field drops off
     rapidly  with  the  distance  from Jupiter. The field intensity is
     about  20%  of the peak at the orbit of Io and about 2% of peak at
     the  orbit  of  Europa.  Thus,  the  astronauts  in "2001: A Space
     Odyssey",  "2010",  and, especially, the miners in "Outland" would
     all  receive  fatal  doses  of radiation. By the orbit of Ganymede
     (about  15  Jovian  radii),  it  has dropped another two orders of
     magnitude.  Perhaps  by  the  orbit  of  Callisto (about 26 Jovian
     radii),  astronauts  can explore the surface without fear of fatal

         Since the vast majority of the particles which constitute this
     field  are  charged,  it  is  possible  to use magnetic shields to
     protect our astronauts from it. This concept has been addressed by
     various authors over the last thirty years. One of the most recent
     papers  entitled "Magnetic Radiation Shielding: An Idea Whose Time
     has Returned", written by Geoffrey Landis, describes a  "magnetic/
     electrostatic  plasma  shield  in  which  an  electrostatic  field
     shields  the  crew  from  positively  charged  particles  while  a
     magnetic field confines electrons from the space plasma to provide
     charge neutrality" [SM 47, p.383]. Such a shield might allow us to
     visit even Io.
          The  remaining 12 or so satellites of Jupiter are very likely
     all  captured asteroids. They are all very small and most orbit at
     great distances from Jupiter.

     12.2 Selecting a home in the Jovian system
          Large  amounts  of ice are believed to be present on Ganymede
     and Callisto. They both have densities which are less than 2 grams
     per  cubic  centimeter  and  both are estimated to consist of more
     than  60%  water-ice  by  John  Lewis  and  Mark  Lupo [3, p.172].
     Pictures  of  Callisto  show  how  recent impacts have exposed the
     underlying  ice. Evidently, the surface is covered by as little as
     a  few centimeters of dark dust and debris and below that lie many
     kilometers of ice.
          We  suggest  the north pole of Callisto as the tentative site
     for  the  first  Jovian  base.  This  site  would allow continuous
     observation  of  the  Jovian  system  from  a  site of comparative
     safety. It would also have direct access to the ice from which LOX
     and LH2 propellants would be made.
          From  Callisto,  the  planet  Jupiter would appear about 4.35
     degrees  wide  as  compared  to  about 0.5 degrees for the moon as
     viewed from earth. The amount of sunlight received at Callisto (or
     Jupiter)  is  only  about  3.7%  of what we get on earth. All life
     support  systems  must  be prepared for temperatures of about -173
     degrees Celsius [41, p.122].
     12.3 Outline of an unmanned mission to Callisto
          Once  again,  we  would  send  an unmanned mission to Jupiter
     before  sending a manned mission. This mission would be similar to
     the  previously described mission to Phobos; however, in this case
     the  spaceship  would  maneuver  into  an  equatorial orbit around
     Callisto  instead  of  landing  on it. From this orbit, it will be
     possible  to launch projectiles back toward earth to slow down the
     incoming  manned  spaceship.  If  the  projectiles  are  carefully
     launched,  their  effect  on  the  orbit  of the spaceship will be
     minimal  and can be compensated for, as required, using propellant
     from  Callisto. If we launched projectiles every 5 minutes from an
     equatorial  orbit,  we  would  expect  orbital  perturbations   on
     opposite  sides  of Callisto to nearly cancel each other out. Some
     projectiles  would  be  wasted  because  they  would  crash   into
     callisto, but so what?
         The mission outline might be something like the following:

         1. Maneuver  into  Callisto's orbit upon arrival at the Jovian
     system.  Callisto  is  moving  at  about 8.2 kilometers per second
     around Jupiter.
         2. Close on Callisto.
         3. Maneuver into an equatorial orbit around Callisto.
         4. Despin the spaceship.
         5. Detach all landing modules.  This would include  propellant
     production facilities, empty tanks, nuclear power units, androids,
     science  experiments, observation equipment, communications equip-
     ment, rocket engines, spare parts, and so on.
         6. Land the equipment at the north pole using  propellant from
     the  spaceship.  This operation could possibly be done in steps if
     the first unit landed was the propellant production facility. Then
     propellant from Callisto could be used to bring down the rest.
         7.  Propellant will be  lifted to the spaceship to be used for
     pointing the EMPL during the slowing-down of the manned spaceship.
     Due  to  the  problems of storing cryogenic propellants, it may be
     necessary  to lift water or ice and only convert it to LOX and LH2
     at the last moment, using on board electrolysis facilities.
         8. The spaceship will be  spun up again before the manned ship
     12.4 Recovering helium-3 from Jupiter
         One of the discoveries made by Voyager 1 was that about 11% by
     volume  of  the  atmosphere  of Jupiter is helium [96, p.87]. This
     closely matches the percent of helium found on the sun, indicating
     that Jupiter is a good sample of the  primordial nebula from which
     the solar system formed.
          Between  1973  and  1978  some members of the  British Inter-
     planetary Society  worked  on a project called Daedalus. It was an
     interstellar spacecraft which was intended to run on deuterium and
     helium-3  [66,  p.68].  Their intention was to "mine" the helium-3
     from the atmosphere of Jupiter.
          Even  assuming  a low concentration of helium-3, it is easily
     calculated  that  there  is more helium-3 on Jupiter than there is
     water  in  all  oceans of earth (roughly 100 times more). Although
     some  recent  papers  such  as "Helium-3 Mining of Uranus" by Dani
     Eder  which  appeared in volume 8 of "Space Manufacturing", prefer
     Uranus to Jupiter, we prefer Jupiter. After all, it is much closer
     and far more interesting than Uranus.
     12.5 The manned spaceship to Jupiter
         The manned spaceship which we send to Jupiter will be the same
     ship  that went to Mars. This will save much construction time and
     thus money  as well. No doubt there will be significant refurbish-
     ment  of  the  ship  before  its  departure for Jupiter.  The most
     significant  modification  will  be the quadrupling of the nuclear
     power  supplies.  The  purpose will be to enable the EMPL to throw
     projectiles twice as fast as the original EMPL - which will permit
     the  ship  to  travel twice as fast. Other changes will be made to
     include the latest "low" technology available.
         Recruitment of another crew may be considerably more difficult
     because of the much longer anticipated travel times (6 months each
     way)  and  the  lower interest in Jupiter. Surprisingly, the total
     expedition  time  will  be less than the Mars expedition (580 days
     vs. 824 days). This writer will certainly go if at all possible.
     12.6 Timeline
         If the Mars expedition leaves in the 22nd year of the project,
     then  it  will  return in the 24th year. Modifications to the ship
     will  probably  take  a  year  to complete. Therefore, we might be
     ready  to  leave  for  Jupiter in the 26th year. We must also wait
     until the Callisto ship has successfully accomplished its mission.
          By  quadrupling  the power of the primary EMPL and the ship's
     EMPL,  we can double the speed of the spaceship and thus halve the
     travel time to Jupiter. The ship's speed will be boosted to nearly
     40 kilometers per second - the  upgraded capability of the primary
     EMPL.  The  travel  time  to  Jupiter  will  be reduced to about 6
          Launch  windows  to Jupiter occur about every 399 days. Thus,
     when  we  arrive  at  Jupiter there will only be (399 - 180 =) 219
     days  until  the  return launch window. Counting the return travel
     time,  the  total  trip time will be about (399 + 180 =) 579 days.
     Notice that this is 245 days LESS than the Mars trip.