New Mars Forums

Mars is the only place we have found where a colony can be established with current technology that is completely independent from Earth.  As such, it takes priority over any other options.

The problem with extrasolar planets is that they are so hard to get to.  There is no reason to wait for 2600s technology when there is somewhere that we can colonize now.

The cheapest way of getting into space right now is Russia's Soyuz spacecraft, cost $20 million per ticket.  As his website says, the cheapest that anyone has ever been able to send people to the moon for is $10 billion per ticket.  If you use the moon as a stop on the way to Mars, then the cost of getting to Mars will have to be more expensive than going to the moon.  So he will probably need to raise the price by around 4 orders of magnitude in order to pay for the trip.

Solar power is somewhat expensive on the Earth.  It would be many times more expensive on the moon, not free.

Hmm...  the more I read about the plan, the more impracticle it looks.  Even assuming that he has all the technology to implamant his plan (which he certainly does not), the infostructure that he wants to build would cost at least $1 trillion.

World's ten largest economies (GDP, PPP basis, from wikipedia):

1. European Union 10.84 trillion
2. United States 10.40 trillion
3. China (mainland) 5.70 trillion
4. Japan 3.55 trillion
5. India 2.66 trillion
6. Russia 1.35 trillion
7. Brazil 1.34 trillion
8. South Korea 931 billion
9. Canada 923 billion
10. Mexico 900 billion

The US spends about $15 billion on NASA per year, which is about 0.15% of GDP.  Other countries are spending less on space, both absolutely and proportionately.  Compared to what many countries spend on the military and other government programs, .15% is not really that much.  Any of the top countries should be able to fund an agressive space program if they really wanted to.

Of course the reason that I posted the Boeing goals is that I could not find any NASA goals for the ISS.  The same is not true for many of the international partners.  The ESA has clear goals in terms of science, tech development, and gaining astronaut experience.  Japans space agency also has clear science and technology goals for the station.  Russia seems to think that it would make a great space hotel.  Also, while the American Space Shuttle is needed to build the station, Russia, the ESA, and Japan are all working on efficient ways to resupply the station or transport people to it.  So it is starting to look like the ISS will be mainly built and paid for by the US, but most of the benefits will go to the non-US partners.

According to [http://www.boeing.com/defense-space/spa … goals.html]Boeing, the ISS goals are:

1. Find solutions to crucial problems in medicine, ecology and other areas of science.
    This is subdivided into:
    *Microgravity Science
             +Materials Science
             +Fluid Physics
             +Combustion Science
             +Biotechnology
             +Fundamental Physics.
         ;This category makes sense.;
     *Life Science
         ;no more explanation, but probably the affect of 0-g on life.;
      *Space Science
             +Structure and evolution of the universe
             +Exploration of the solar system
             +The Sun-Earth connection
             +The astronomical search for origins and planetary systems.
          ;This category is reasonable, though I think that satellites or ground-based observatories could do much of it better.;
      *Earth Science
           ;Taking pictures of the Earth.  I think that this is partly to blame for the annoying 51.6-degree orbit of the ISS.  Satellites can do this better.;
       *Engineering Research and Technology
              +Commercial space communication systems
              +Energy use efficiencies and air/water quality
              +Automated maintenance functions and construction techniques.
           ;In the explanation, they make it clear that testing out life support and other systems for use on Mars missions is a part of this, so this is a good category.;
        *Space Product Development
               +A new category of plant-based pharmaceuticals
               +Hardier, disease- and drought-resistant crops
               +Improvements in catalysts used for extracting oil and improving petroleum yields
               +A new generation of highly pure and accurate semiconductors
               +Commercial space power.
               +Bioterrorism defense
             ;I am mystified by the relationship many of these have to microgravity.  If the space station really can help do these things, then I agree that this is a reasonable category.;

2.Lay the foundation for developing space-based commerce and enterprise.
             ;No more explanation.  I guess this is related to the last "science" objective.;

3.Create greater worldwide demand for space-related education at all levels by cultivating the excitement, wonder and discovery that the ISS symbolizes.
             ;Huh?;

4.Foster world peace through high-profile, long-term international cooperation in space.
             ;Making sure that the Russian engineers are not building missiles for third world countries.;

Actually, the more things that break on ISS, the more I think that the space station is worth having.  It is hard to be sure how reliably a piece of equipment will work after prolonged operation in 0 gravity, and the only way to be sure is by testing it.  It is better to have things breaking on ISS than breaking on a Mars mission.

The ISS is not very focused on any one purpose.  Different people think the ISS should do different things.  So it ends up doing many things a little bit but not doing any of them very well.

Momentum is proportional to velocity.  Kinetic energy is proportional to the square of the velocity.  Therefore it is possible to get more momentum with the same amount of energy if the exhaust velocity is lower.

I think SBird is right.  It is just that the change in mass for chemical reactions is so tiny that it would be hard to detect even with sensitive detectors.

Actually, it is not the most efficient use of energy.  In this case the spacecraft is energy limited rather than propellant limited.  Methods of propulsion with lower exhaust velocities create more impulse with the same amount of energy.  The most efficient engine would maximize the ratio of impulse/(propellant mass + fission fuel mass).  This is maximized when propellant is equal to fission fuel mass.  Really, the best thing to do is to use the fission fuel as propellant.  This principle is used in Orion, which is why it is one of the few fission technologies that might be practical for interstellar travel.

I am not sure exactly how much heat you could get out of the solar wind, but I dont think that it would be enough to make a significant impact on Mars' climate.  I do know that the solar wind has a force of only about 1% of solar light pressure.  Since the solar wind is much slower than light the energy ratio between wind and light would be even worse, probably around .001-.01% as much energy as the light has.

Putting mirrors closer to the sun is an interesting idea.  The problem is getting the reflected light to be concentrated on Mars.

A dusty m2p2 may be workable as a first stage, but I have my doubts about the salt water reactor and the photonic drive.  The sources that I found all listed the salt water reactor's isp at 10,000, which is completely insufficient for interstellar purposes.  A rocket that was 90% fuel would need an isp of 1.3 million to reach .1c.   I also don’t think that a nuclear photonic drive achieve the thrust or even the impulse required by relying on fission and photons alone.  Light just takes too much energy to produce for the impulse it provides.

Beamed energy/momentum is actually one of the better options available to us in the near future.  Rather than using lasers, current plans would use either microwaves or a particle momentum beam.  Microwaves could be produced much more efficiently than laser light.  The momentum beam would accelerate ions to high velocities where they would push against a mini-magnetosphere, providing thrust.  The using particles produces thrust more efficiently than light, but the particle beam would disperse at a shorter range.  I have read a proposal for accelerating a small probe to .1c that needed "only" 100 GW to power the microwave/particle beam.  Of course 100 GW is still more than the total power consumption of most states.