Mars: A Future Home for Humanity chapter two

 MARS DIRECT
                                       (c) Robert Zubrin & Chris McKay

         Here's  how  the  Mars Direct plan works.  At an early launch
         opportunity -  1999,  for  example  -  a  single  heavy  lift
         booster  with  a  capacity equal to that of the Saturn 5 used
         during the Apollo program is launched off Cape Canaveral.  It
         uses  an  upper  stage  to throw a 40 tonne automated payload
         onto a trajectory to Mars.  Arriving  at  Mars  eight  months
         later, the payload vehicle aerobrakes into orbit around Mars,
         and then lands with the help of a parachute.  This payload is
         the Earth Return Vehicle (ERV).  It flies out to Mars with its
         two  methane/oxygen propulsion stages unfueled.  In addition,
         it carries  six  tonnes  of  liquid  hydrogen  cargo,  a  100
         kilowatt   nuclear-reactor   mounted   in   the   back  of  a
         methane/oxygen-driven light truck, a small set of compressors
         along with an automated chemical processing unit, and  a  few
         small scientific rovers.

         On  landing the truck is telerobotically driven a few hundred
         meters away from the site, and the  reactor  is  deployed  to
         provide  power  to  the  compressors  and chemical processing
         unit.  The hydrogen brought from Earth can be quickly reacted
         with the Martian  atmosphere,  which  is  95  percent  carbon
         dioxide  (CO2)  gas,  to  produce  methane  and  water.  This
         eliminates the  need  for  long  term  storage  of  cryogenic
         hydrogen  on the planet's surface. The methane so produced is
         liquefied and stored, while  the  water  is  electrolysed  to
         produce  oxygen,  which  is  stored,  and  hydrogen, which is
         recycled  through  the  methanator.   Ultimately  these   two
         reactions  (methanation  and  water  electrolysis) produce 24
         tonnes of methane and 48 tonnes of oxygen.

         Since this is not enough oxygen to burn the  methane  at  its
         optimal  mixture  ratio, an additional 36 tonnes of oxygen is
         produced via direct disassociation of Martian carbon dioxide.
         The entire process takes ten months,  at  the  conclusion  of
         which  a  total  of 108 tonnes of methane/oxygen bipropellant
         will have been generated.  This represents a leverage  of  18
         to  1 of Martian propellant produced compared to the hydrogen
         brought from Earth needed to create it.  The ERV requires  96
         tonnes  of  the  bipropellant  for fueling, leaving 12 tonnes
         available to support  the  use  of  high  powered  chemically
         fueled,   long   range  ground  vehicles.   Large  additional
         stockpiles of oxygen can also be produced, both for breathing
         and for turning  into  water  by  combination  with  hydrogen
         brought  from  Earth.  Since water is 89% oxygen (by weight),
         and since the larger part of most foodstuffs is  water,  this
         greatly  reduces  the amount of life support consumables that
         need to be hauled from Earth.

         In 2001, following the successful  completion  of  the  vital
         propellant  production  on  Mars,  two more boosters lift off
         the Cape and throw their 40 tonne payloads towards Mars.  One
         of the payloads is a  fuel-factory/ERV,  just  like  the  one
         launched   in   1999.   The  other  is  a  habitation  module
         containing a crew of  four,  a  mixture  of  whole  food  and
         dehydrated  provisions  sufficient  for  three  years  and  a
         pressurized methane/oxygen ground rover. On the  way  out  to
         Mars,  artificial  gravity  can  be  provided  to the crew by
         extending  a  tether  from  the  habitat  to  the   burnt-out
         booster's upper stage, and spinning the assembly.

         Upon  arrival,  the crew's craft drops the tether, areobrakes
         and lands at the 1999 landing site where a fully  fueled  ERV
         and  fully  characterized and beaconed landing site await it.
         With the help of such navigation aids,  the  crew  should  be
         able  to  land right on the spot. But, even if the landing is
         off course by tens or even hundreds of kilometers,  the  crew
         can  still  achieve the surface rendezvous by driving over in
         their rover.  If they are off by thousands of kilometers, the
         second ERV provides a backup. However  assuming  the  landing
         and  rendezvous  at site number one is successful, the second
         ERV will land several hundred kilometers away to start making
         propellant for a 2003 mission, which in turn,  will  fly  out
         with  the  additional ERV to open up Mars landing site number
         three.

         Thus, every other year two heavy lift boosters are  launched,
         one  to  land a crew, and the other to prepare a site for the
         next mission. WITH AN AVERAGE LAUNCH RATE OF JUST ONE BOOSTER
         PER  YEAR,  WE  CAN  PURSUE  A  CONTINUING  PROGRAM  OF  MARS
         EXPLORATION. This is only about 10 percent of the U.S. launch
         capability,  and  is  clearly affordable.  In effect, the dog
         sled approach removes this dogsled approach removes the human
         Mars mission from the realm of mega-fantasy and reduces it to
         practice as a task of comparable difficulty to that faced  in
         launching Apollo missions to the Moon.

         The crew will stay on the surface for one-and-one-half years.
         Unlike  conventional  Mars  mission plans based upon orbiting
         motherships with small landing parties, no-one has been  left
         in  orbit,  vulnerable  to  the  hazards  of  cosmic rays and
         zero-gravity living.  Instead,  the  entire  crew  will  have
         available  to them the natural gravity and protection against
         cosmic  and  solar  radiation   afforded   by   the   Martian
         environment,  so  there  is  no  strong  motive  for  a quick
         departure.  The mobility afforded by the ground vehicles will
         allow  the  crew  to  accomplish  a  great  deal  of  surface
         exploration.  With  a  12  tonne surface fuel stockpile, they
         have the capability for more than 25,500 kilometers  traverse
         before  they leave. At the conclusion of their stay, the crew
         return to Earth in a direct flight from the  Martian  surface
         in the ERV. As the series of missions progresses, a string of
         small bases is left behind on the Martian surface, opening up
         broad stretches of territory for human exploration.

         Such  is  the  basic Mars Direct plan. By taking advantage of
         the most obvious local  resource  available  on  Mars  -  its
         atmosphere  -  the  plan allows us to accomplish a human Mars
         mission with what amounts to  a  Lunar  class  transportation
         system.  By  eliminating  any  requirement to introduce a new
         order of technology and complexity of operations beyond those
         needed for Lunar transportation to  accomplish  piloted  Mars
         missions,   the  plan  can  reduce  the  cost  of  the  Space
         Exploration Initiative by an order of magnitude  and  advance
         the   schedule  for  the  human  exploration  of  Mars  by  a
         generation.

         Purists may object that Mars  Direct  doesn't  go  completely
         native.  After all, the plan brings the reactor's energy, the
         ERV's hydrogen and part of the crew's food  from  Earth.   On
         the  other hand, while Amundsen may have lived of caribou and
         travelled by dogsled, he did his hunting with  modern  rifles
         and  brought  skies  (a  uniquely Norwegian innovation) along
         too.  Its necessary to be practical.  Utilization of  Martian
         resources   beyond   the   freely  available  carbon  dioxide
         "caribou" will come in the course of larger scale  bases  and
         settlements.