Mars manned missions,Mars manned missions,Mars manned missions,Mars manned missions,Mars manned missions,Mars manned missions,Mars manned missions,
Manned mission to Mars
 
 
 
  

Mars is the fourth planet in the solar system and is at its closest approach 80 million km far away from Earth. Our moon is only about 385 000 km away from us, but is hard to reach anyway.  
But we cannot chose the shortest path because it takes far more energy to take that path rather than another. 
Because the distance is long, the travel time is long, too. 
A long time in space is very dangerous because of the solar winds, cosmic radiation and zero-gravity conditions. 
The trip is very long and such a project was never build before, so it seems the project must be very expensive, too. 
  

But reaching Mars is a bit easier thanks to Earth's rotation around the sun. As a rocket escapes Earth to reach another object in space, Earth gives it an extra speed because of its 30 km/sec orbital speed. When we try to reach Mars we profit from this effect, but when we reached the moon, we don't.  
We can also use our Moon to get a gravitational assist. For unmanned missions, it is more practical to use Venus for a gravitational assist because of its stronger gravity and higher speed. But if humans were to go to Mars on a Venus-Flyby route, they'd get fried because of strong solar radiation that is already dangerous enough between Earth and Mars. 

In 1989, scientists were asked to estimate the price of a manned Mars mission. They had 90 days to do so, and their report was called the 90-day report.  
They proposed and enormous spacecraft, that was supposed to be build in orbit, that should send a group of astronauts in orbit around Mars to let them land on Mars, and when they come back into the craft, it brings them back to earth. 
This spacecraft was supposed to run on liquid hydrogen ( H2 ) and liquid oxygen ( O2 ). All supplies were supposed to be brought from earth. 

Their result: catastrophic $400 billion. 

This was clearly too much for NASA. They abandoned the manned Mars mission, hoping to find a cheaper way to get there. 


  • Mars Direct
  • Exhaust-Modulated Plasma Rocket
  • Atomic-bomb rockets
  • Fusion engine rockets
  • Anti-matter rockets


    One now knows that it is not necessary to take all equipment from Earth to be able to go to Mars, stay there and to come back.  
    This is the idea of Mars Direct. 

    The Mars Direct Plan begins with the launch of an unmanned Earth Return Vehicle, or ERV, that will, on landing on Mars, manufacture its own propellant, thereby laying the groundwork for the arrival of astronauts. 
    Two years later a manned spacecraft and another unmanned ERV blast of for the Red Planet; the astronauts head for the previous landing site, while the unmanned craft prepares for the next manned mission, scheduled to arrive in another two years. 
    The project can continue for as long as desired, leaving behind a string of base camps across the Martian surface. 
    The astronauts get on Mars after half a year of travel, stay there for two years and get back to Earth in another half year of travel. 

    The goal is not beyond out reach. No giant spacecraft built with exotic equipment is required. Indeed, all the technologies needed for sending humans to Mars are available today. 
    We can reach the Red Planet with relatively small spacecraft launched directly to Mars by booster rockets embodying the same technology that carried astronauts to the moon more than 30 years ago. 

    (1) 3H2 + CO2   -->   CH4(to storage) + H2O 

    (2) 2H2O   -->    2H2 (back to (1)) + O2(to storage) 

    (3) CH4 + 2O2   -->   CO2 + 2H2O 

    (4) CO2   -->   C + O2 

    The 6 tons of hydrogen brought from Earth react with the Martian atmosphere ( 95% CO2 ) to produce water ( H2O ) and methane ( CH4 ). This process (1) is called methanation. Methane has the advantage that it is easier to store than hydrogen. The methane is liquefied and stored and the watermolecule is electrolyzed to get hydrogen and oxygen. The resulting oxygen gets stored and the hydrogen is used in process (1) again.  
    As a result, we get 48 tons of oxygen and 24 tons of methane ( compare that to the amount of hydrogen brought from earth! ).  
    But to ensure that the methane burns efficiently, further 36 tons of oxygen have to be produced (3).  
    This is done by braking apart the CO2 of the Martian atmosphere with the energy of the 100 kW reactor. 
    After 10 months, we have 108 tons of propellant. This is 18 times more than the original feedstock needed to produce it. 

    Much less mass has to be brought from Earth. This is the main reason why the Mars Direct mission is much less expensive than the 1990 version. 

    The return trip requires 96 tons of propellant, leaving 12 tons for the operation of the rovers. 

    Additional stockpiles of oxygen can also be produced; both for breathing and for conversion into water, by reacting the O2 with the H2 brought from Earth.  
    The ability of doing this also greatly reduces the amount of life-supporting supplies that must be hauled from Earth. 

    By reducing the amount of life-supporting supplies, the price of the mission gets greatly reduced. 
    It has been estimated that the entire mission would cost $20-30 billion. 
    This is not much more expensive than the $20 billion Apollo missions. 
    This might still seem to be a lot of money, but spent over 10 years, this amount would constitute an annual expenditure of about 20 percent of NASA's budget, or around 1 percent of the U.S. military's budget. 

    It is a small price to pay for a new world. (Robert Zubrin, astronautical engineer, president of the Mars Society and author of The Case for Mars 
     
     
      This is what the base on Mars would look like:  
     

    The rocket in the back is the ERV (Earth Return Vehicle), the tunafishcan-like looking thing is the habitat. In the front, you can see a greenhouse where food is produced. A greenhouse would be impossible on the Moon. In the far-back solar panels are visible which produce 5 kW of electricity. Close to the habitat is an antenna, used to keep up contact with Earth. Two rovers are also visible. One of the three astronauts is hooking up some instrumentation on a balloon that will float above the surface. On the top of the picture the two Martian Moons are visible. The bigger one is Phobos, the smaller one Deimos.  
       
     

     
     

    The habitats have the advantage of being able to be used on any celestial object mankind would like to land on. Here you can see a colony on the Moon, where the inhabitants have Mars-habitats. 
     
     
     
     
     
     
     

    Here is a short table of "facts" that previously made a manned Marsmission impossible and how it is now made possible with Mars Direct. 
      
     
     
     
     
    Launch cost to high  Launch cost cheaper through ability of producing propellant, oxygen and water on Mars, thereby reducing mass at launch. 
    Further reduction through new technological developments.
    Development takes to long ( 30 years ) The devolopment would now take 10 years with only 20% of NASA's annual budget a year. The reason for the longer development time of the "Mega-spacecraft" mission is due to its size. It would have to be build in orbit and would be enormous. So the construction would have taken longer and it would have taken longer to find the funds.
    0 gravity conditions during the flights back and forth are very harmful. With Mars Direct, there are no 0-g conditions. The manned craft is attached with a tether to the life-support systems that is sent at the same time. Both are sent into rotation around one another, so that the astronauts profit of the centrifugal force as artificial gravity. Gravitational conditions will be similar to those on Mars.
    Radiation to high. During the stay on Mars radiations are not too dangerous thanks to Mars' thin but never the less existing atmosphere. During the flight, cosmic and solar radiations come into account. Solar flare radiation gets completely shielded with 12 cm of water. The residual cosmic-ray dose, about 50 rem for the 2,5 year mission, represents a statistical cancer risk of ~1%, roughly the same as the risk from smoking for the same amount of time. 
    Contamination from Mars-bacteriae. -Mars almost certainly is now dead, at least on the surface, where astronauts intend to land. 
    -If there is a Mars-bacteria, it won't be harmful to humans, because it would be adapted to Martian conditions. 
    -If there is a Mars-bacteria, we're already infected: We keep getting bombarded with rock from Mars. This bacteria would easily have survived and infected humanity. 
    -There are guys at NASA who make sure the astronauts are not infected before they get free again.
    Global sandstorms It isn't a good idea to land during a sandstorm, so the rocket would have to stay in orbit until the storm stops. However, during the astronaut's stay on Mars, a 200 km/h storm wouldn't be dangerous; it would exert the same force as a 20 km/h breeze on Earth.
    Psychological problems Compared with the stresses dealt with by previous generations of explorers, the adversities that will be faced by the hand-picked crew of a Mars mission seem extremely modest.
      
     
    Details: 
     

    --  Consumable Requirements for Mars Direct Mission with Crew of Four 
     
     
    Daily Need per person (kilograms) Percent recycled Daily waste per person (kilograms) Payload for 200-day return flight (kilograms) Payload for 600-day stay on surface (kilograms)
    Oxygen 1,0 80 0,2 160 0
    Dry Food 0,5 0 0,5 400 1 200
    Whole Food 1,0 0 1,0 800 2 400
    Potable water 4,0 80 0 0 0
    Wash water 26 90 2,6 2 080 0
    Total 32,5 87 4,3 3 440 3 600
     
     
     

    -- Mass Allocation for Earth Return Vehicle  
     
     
    ERV Component Metric Tons
    ERV cabin structure 3,0
    Life-support system 1,0
    Consumables 3,4
    Solar array (5 kilowatts of electricity) 1,0
    Reaction control system 0,5
    Communications and information management 0,1
    Furniture and interior 0,5
    Space suits (4) 0,4
    Spares and margin (16 percent) 1,6
    Aeroshell 1,8
    Rover 0,5
    Hydrogen feedstock 6,3
    ERV propulsion stages 4,5
    Propellant production plant 0,5
    Nuclear reactor (100 kilowatts of electricity) 3,5
    ERV total mass 28,6
     
     
     

    Other manned missions: 
      

  • There are still other plans for manned missions to Mars like an Exhaust-Modulated Plasma Rocket that could bring people to Mars within 90 days. 
    This mission has the disadvantage of being far more expensive ( construction has to be made in orbit, new technology ) and the astronauts could only stay for a far shorter lapse of time than with the Mars Direct mission, probably insufficient for answering a few major questions about Mars, e.g: The existents of life or the abundance of water.   
    Anyway, here is how it works:

    The Exhaust-Modulated Plasma Rocket is well-suited for "split-sprint" missions allowing fast, one-way low-payload human transits of 90 to 104 days, as well as slower, 180-day, high-payload robotic precursor flights. 

    The idea of it is to ionize hydrogen and to push outwards with the help of a magnetic field. Note that hydrogen is much more difficult to store than methane, for example.
    Most propellant is used to escape Earth and at arrival close to Mars. The rocket is launched when Mars is closest to Earth, which allows a 90 day transit time, but only a 30 day stay on Mars.

    Although I know of no estimated price, the mission would probably be by far more expensive than the Mars Direct mission. 
      

  • Other missions would also be possible. Atom or hydrogen bomb-rockets would allow humans to get to Mars really quickly, but would also be extremely dangerous and even forbidden because of the space-nuclear ban treaty. 
  • Fusion engines would be another high-speed transportation method, but we don't have the technology yet.
     

  • Anti-matter rockets would probably work and be extremely powerful, but nobody knows how to produce and to store large quantities of Anti-matter and way of figuring that out is in site.
     

    But fortunately, we don't need such exotic technologies to reach Mars, since Mars Direct would work fine and be far less expensive.
      





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