New Mars Forums

My opinion is that science has it's limitations, especially where it comes to theorizing about long times ago. Beside that, prevailing cosmoligical and evolutionary explanations are subject to changes and are confronted with facts that are difficult to take with. Also yet are other theories that explain certain facts, but have less interest.

However, Mars fascinates me. When it comes to hypothesizing about what has been there, I just think it's mostly speculation.

Calculating on these space-cycles I think it will not be a very fruitfull idea. For a given number of cyclers, the gain in frequence when going via Venus is slight, but there is a increase in average travel-time. It's about 1.9 years when 5 Earth-Venus cycles and 2 Venus-Mars cycles are used. Then 7 Earth-Mars cycles are preferable.

About comparison of space-flight: I think it's not only a fact of economic and/or technical capabilities but also a matter of choice. I have the strong idea that the ambitions of ESA are more related to commercial outweighing things and by NASA more related to military input (keep in mind that a substantial part of satelites is military). This is also the case for the former Sowjet-Union.

About the asians: I really ask myself how ambitious they are. Has Japan really the ambitions to do something 'big' in space? Also China I ask myself. I think their time will come. Three times the inhabitants of Europe and America, 3 times the number of engineers.....

Keep also in mind that ESA and Japan with human spaceflight liked it most to take a ride with Americans or Russians. For them, there no really need to build something to drive.

Russians to Mars?

In the book 'Race to Mars' (Frank Miles ao 1988) a drawing is presented with a Sowjet-Sprint-mission, using only 4 Energia's, 2 Proton rockets, a Soyuz to mann the vehicle, a Mir-like habitat and a Mars-excursion-moodule. I think, if they would they had been landed some years ago. But the Berlin wall broke down.

NASA and ESA are worrying about HLLV, cheap transport of astronauts and also more or less about space-stations. Russia has it all.

Maybe something is an little optimistic, but the Energia is really nice!

Yes, Kirk is my man. Also the original crew I like the most, because it has something predicible. All that nasty space-women, trying to seduce Kirk, while Spock lifts up his eyebrow and McCoy looks like  :angry:

The films, I like First Contact (the Borg fascinates me) and also the Nexus (or is this not the right title?).

Reserved about terraforming? I also a little. But the challenge to me, and maybe to most of the people on this forum, is just to brainstorm what are the possibilities. For me personally it's the technological issue that fascinates.

My personal feeling is that at least some planets/moons should never be terraformed, te keep them as 'cosmic parks'. And of course, cautiousnes is very important.

I think Mars will never be terraformed, neither colonized, because it is to uninteresting to do there something. There is nothing to mine we cannot find on earth. There are only 2 real reasons for continuous human precense on Mars, each have very limited importance, that are:
1. Tourism
2. Areography

I read in any comment on this forum about production of fluorocarbons to make a greenhouse-effect. Somebody said it would ask millions of tons. Is this much? I don't think so. When you make, say, ten factory's that produce 10 million kg a year, which are rather big factory's but not extremely, it must be possible to put enough in the martian atmosphere in some decades.

I think the most important question is the availability in the martian ores. Maybe the fluorocarbons can directly synthesized from a proces with certain conditions (pressure and temperature with a catalyst) so that CO2 reacts with MFx to CF4 and MOy, where M is some metal.

Antoher question is then the energy that is required, meaybe fusion?

And also a question: Do we want to put this toxic stuff in the martian atmosphere? :bars:

The main reason to use Kerosene on the first stagge of the  S aturn V, and essentielly the main reason to  use the rather low-ISP propellant for the shuttles SRB´s, is the low kost per kg. For the first stage the prize is rather important. For upper stages one has to realize that all fuel has to be lift up one or morre, so ISP is more important. A  first stage with LO2/LH2 is also yet not rational (you can consider the SSME as second stage by considering the SRB´s as the first).

As I thought, depending on different factors, the cargo for LEO inclation max. 30° the ratio is 1.5 to nearly 6 percent.

I thinkk it´s reasonable to point some planets and moons as kind of ´cosmic parks´and  not inhavbit them.  I don´t know which would be best candidates, but some planets or sateellites that have a brother/sister that is very like antoher aree good candidates.  eg  Callisto or Ganymede should be left as it is.

The position of Venus in relation to Mars and Earth for this mission is easily determined, because of the resonance of the synodic periods of Mars and Venus. So, taking going to  via Venus, this will be possible 1 in 3 launch-windows.  Every next opportunity to take  this  scenario is roughly the same, but turned about 140° in prograde direction. This can easily be calculated.

The situation is then:
The Earth-Venus trajectory  is a lengthened Hohmann-trajectory with perihelion about 0,65 AU, which has to be passed. With  big amounts of fuel, shielding for the sun is rather easy, so this is not  a topic. Solar cells are very  efficient. The Aerth-Venus will take about 5 months. Then the Venus-Mars trajectory will last about 7 months, a shorteened Hohmann-trajectory.  Further shorteningg of this trajectory is possible, paying it by dramatically  increase of delta-v for deceleration at Mars. But when aerobraaking is used, this doesn´t need to be a point.

Then follows the journey back, taking a shorthened or lenthened Hohmanntrajectory, because the pure  Hohmann-launch-window has passed when the mission arrives at Mars. By adding a little delta-v this is rather easy to obtain.

In all, this mission  is much moree  complex to calculate, but I think  still for the crew-considerations (total length and abort-possibilities) preferable.

SBird, do you know a site where I can find the locations, the energy and the kind of the cosmic radiation? I thought that more than 70% of dangerous radiation was from the sun, but this is really disappointing. The rather 'çheap' solution of using the fuel as shield doesn't really work, Im afraid.
I have searched internet for the cosmic radiation, but I can't find very clear information. Maybe you can help.

Last time I'm calculating a mission trajectory using on route to Mars a Venus-fly-by, often called a mission of the opposition-category. This results in general in a total mission duration of less then 2 years. The possibility of such a mission comes every 3 Mars-launchwindows, ti every 6.4 years.

However, calculating this is a thorough job. Maybe sombody has some work done on it and has some tips. I use formulas of orbital mechanics, including Lamberts Theorem. I want to correct for deviations from circular-coplanar, because I think these can't be neglected to get a realistic result.

The way I do it yet:

I guess some scenario, ti a depart date from earth, a Venus-fly-by date and a Mars-arrival date. I calculate with a program written by myself from orbital elements the three position-vectors and also velocity-vectors of the planets.

Then putting to vectors (FROM and TO) in a second program and giving a desired travel time a calculate, using Lamberts tehorem, ao the velocity-vectors of to and from. New calculations have to be made using new guesses to get the situation that v-hyperbolic for Venus is the some, both for coming from earth and going to Mars. Then I calculate the delta-v-fly-by and caluclate the r-periathenum (?, is this right terminology). If this is lower than 6330 kilometers, the spacecraft will fall into the paralyzing warmth of Venus and I have to do the whole mess again. This doesn't really proceed.

To it, I have to optimalize for delta-v both for departure from Earth and arrival at Mars.

I think the result will be 20 to 30 march 2018 as arrival at Mars and departure beginning april 2017, total delta-v about 9 km/s (taken is here hyperbolic excess speed). But a slight delta-v at periathenum could alter the situation and then a more optimal trajectory is maybe possible.

Can anyone help?

BTW: Ever noticed that the synodic periods of Venus and Mars have a nearly perfect 3 to 4 resonance?