72 thoughts on “The Inner Solar System”

  1. How do you expect anybody to get anything done with only a few billion dollar a year?

    Insanity! [ducking.]

    1. How’d you get a model of the first segment of the so-called high-speed rail they want to build in California?

  3. IIRC, it takes more than one SLS launch to perform the planned missions. I am not sure how SLS + in-orbit assembly is better than current launchers + in-orbit assembly. While there certainly are benefits for a SHLV, supporters have to ignore how many payloads and launches that can be purchased for the same amount of money. Also, time is a factor. We are waiting longer to spend more money and get less done.

    The Space Show is supposed to have to SLS people as guests, it should be interesting to hear what they have to say.

  4. Crippen (76): “…the new Space Launch System (SLS) — the most powerful rocket ever built.”

    Dear Mr. Crippen, it hasn’t been built.

  5. Back in the 1950’s they said that any rocket that could fly was already obsolete, because new designs were coming out of the pipeline so quickly. How a rocket whose critical hardware was designed back in the 1970’s can’t be obsolete is a question which points the lack of engine developments since then.

    1. The merlin engine doesn’t appear much different from c. 1970 tech performance wise, though the thrust/weight figure is getting better with each major revision. In terms of cost I’m seeing a massive improvement.

      1. The new F1b seems an impressive engine. The Raptor would be less than half the thrust. However, we can be sure the Raptor will be revised at a faster pace.

  6. I don’t understand how anyone can believe these things about SLS. It’s a rocket that will fly once a year, if we’re lucky. Are people imagining that SLS is actually going to receive massive budget increases and will end up flying more often? Are they just living in a fantasy world?

  8. Rick Boozer mentions landing humans on the polar regions of Mercury. Mercury requires severe delta-V *and* landing requires dealing with almost exactly the same gravity as Mars but with no aerobreaking whatsoever. Seems odd to mention this quite difficult mission at all. Even odder when not mentioning the somewhat human-friendly clouds of Venus (see Landis). After all, humans have put balloons in the clouds of Venus but have never landed anything on Mercury and no landers are in the pipeline.

    1. The delta V for Mercury is actually very large, but the planet would be one of my primary targets for development because of the intense sunlight, rapid transit, and very frequent launch windows. The intense sunlight would let you deep stack crops and feed them with just a small collector (about twenty times more so than Mars), and that advantage would be even greater in refining metals and processing ores because simple solar concentrators with very little gain could melt steel. A solar powered Prius on Mercury could do highway speeds.

    2. Once in orbit Mercury would be easier to land on than Mars, 3km/s to get up into low orbit compared to Mars 3.5km/s, the challenge would be the larger delta V to match orbits with the planet, Solar electric propulsion would be required for the transit.

      Putting people into Venuses atmosphere? How the heck would you get them out of that gravity well?

      1. I think that for early missions you wouldn’t drop them into the gravity well at all. Just put them in orbit low enough that the round trip time for radio signals to Venus from the crew module would be short enough to permit telepresence and real-time operation of robot explorers.

        1. Hang on, are we talking about space exploration or colonization? If the former, Mercury sounds easier than Venusian rotovators, if the latter, what’s the economic base on Venus going to be? The only way I see settlement happening is if we freeze the CO2 out and settle the surface.

          1. I was imagining the earliest phase of the human exploration of Venus: perhaps a small crewed astrobiology balloon base in the clouds — see Grinspoon for wild speculation on Venusian cloud life (or, less wildly, life precursors, or perhaps the mysterious UV absorbers at that altitude have some other property worth studying up close. )

            Admittedly without using any numbers, my thinking was that a rotovator could be much less massive than the equivalent of a Falcon 9 factory(!), and even less massive than what it would take to supply a cloud-to-Venusian-orbit return vehicle. Liftport, and Tethers Unlimited as well, published ideas on how various kinds of space elevators could be much less massive than typically imagined.

    3. The upper atmosphere of Venus is the nicest environment in the solar system outside of Hawaii, so who would want to leave? If they did, the rocket would be fueled with carbon, oxygen, hydrogen, and nitrogen taken from the Venus atmosphere. I’d free drop the launch stage from the permanent airship (which uses air as a lifting gas) and then light the engines after the drop, like an X-15. Another option would be to sacrifice a dedicated rockoon that lifts the rocket clear of the permanent airship prior to ignition.

      1. So all you need is something the size of a Falcon 9 floating under a balloon, and the plant required to manufacture the propellent required, and the energy system the generate that propellent.
        Hmmm, 5000 tonnes in Venuses atmosphere should do it, maybe start with 20,000 tonnes in LEO.

      2. Oh, not by any means. You’d also have the floating factory that builds the rockets, mining operations that exploit the density of Venus’s atmosphere near the surface to provide tremendous lift for excavating, plus all the floating crop lands, and of course floating sports arenas. Venus is very doable, but only on a large scale. The greatest thing about floating a city high in the atmosphere of Venus, with a surface underneath that’s hot enough to melt lead and dense enough to crush a submarine, is that it would be so easy to dispose of the bodies. A crime lord would do well there.

    4. I really mentioned Mercury as a far flung goal after other easier targets have been reached. It would not be done in the near future. Spreading out into the inner solar system will be a stepping stone type process.

    5. I mentioned Mercury only as an example of the most far flung of possible missions and not one that would be done in the near future. Remember, spreading into the inner solar system will be a stepping stone process.

      But there is some compelling evidence of extensive water ice on Mercury in the shadows of polar craters as there is on the moon. That would be an important resource for a base, should we ever decide to have one there. Such areas would also be permanently shielded from the Sun’s nearby fury and the extreme cold there is much easier to deal with than 800 degree F surface temperature that exists over the entirety of Venus’ surface (that’s even hotter than the sunlit side of Mercury).

      Even at high altitudes where a balloon would travel, the atmosphere is still highly corrosive (a significant constituent is sulfuric acid). Of course, people reaching Venus’ surface is out of the question. The atmospheric pressure of Venus at its surface is enormous and adding the corrosiveness makes it much worse. At least that problem would not have to be contended with on Mercury.

      2. One of the reasons I favor Mercury is the ice in the polar craters, and the advantages you get from having such intense sunlight. Every pound of solar cells shipped to or built on Mercury, the power return is about 20 times greater than on Mars, and for a polar installation (which would be very difficult on Mars due to the caps) the power would be available continuously by simply rotating the cells very slowly, upping the Mercury advantage over Mars to about 40 to 1.

        With the intense sunlight and water availability, the cheapest way to add power would be a small mylar collector heating a boiler running a small steam turbine, such as those you can buy for your home, while radiating the waste heat directly to space from the shadowed crater. The same advantages apply to growing plants, since for every square meter of pressure window or solar collector, about 20 times more crops can be grown on Mercury than on Mars. Likewise, refining metal ores should be vastly easier on Mercury, where cheap solar concentrators could provide the required temperatures.

        This makes me think that for a given amount of mass delivered or effort applied by a colonist, the productive return on investment (in new housing, power and food) on Mercury would be ten or so times higher than on Mars, which should allow a much faster rate of natural expansion. A Mercury colony should thrive in a situation where a Mars colony would be struggling with resources, having to use twenty times as much solar collector area or window area to gain the same level of output as the Mercury colony.

        1. A Mercury colony should thrive in a situation where a Mars colony would be struggling with resources, having to use twenty times as much solar collector area or window area to gain the same level of output as the Mercury colony.

          Agree entirely, they may even have enough surplus production to go and rescue Elon and friends from Mars.

        2. Before you can take advantage of mercury’s sunlight you have to get there.

          Mars: 5.7 km/s.
          Mercury 13.0

          It costs over twice as much and doesn’t have an atmosphere which thin as it is on mars comes with quite a few advantages. Including lowering the cost to land assuming (and it’s not really that big of an assumption) we can use it.

          You have to put your site in the right place on mercury. Anywhere on mars is fine although the equator is probably best.

          I like mercury. I think when martians feel the need for elbow room mercury will be like New Yorkers going to Florida.

          But the real killer. 8 months to mars. Multiple years to mercury (a lookup rather than a calculation… would somebody check me on this?)

          1. “Before you can take advantage of mercury’s sunlight you have to get there.

            Mars: 5.7 km/s.
            Mercury 13.0 km/s”

            At 13 km/sec you get to Mercury in 105 days [3 months].
            So a direct hohmann transfer one has the difference of
            5.7 km/s and 13.0 km/s. But also with this goes the difference
            of 3 months {Mercury} and 8 months {Mars}
            With gravity assist and longer trips times one can much lower
            delta-v requirements to Mercury.

            One could also be “unfair” and compare a trip time of 105 or
            less. What is delta-v requirement to get to Mars in 105 days
            or less.
            And consider there actually is such requirement to reduce
            radiation and effect of microgravity which a 105 trio would
            accomplish for a manned mission, it’s not really “unfair”.
            In addition to radiation and effects of zero gees, shorter trip
            times can allow less need for “life support” over longer trip
            durations.
            But to make it more objective, suppose mission trip had to be less than 4 months. What the delta-v to Mars?
            Or suppose 4 or 3 months is not fast enough. Let’s the requirement
            was 2 months or less?

            So with cargo [rather than living creatures] and not having a time requirement [though 6 1/2 years for Mercury Messenger, even for cargo
            may be too long] there is not a not difference between Mars and Mercury.

            Now another part is the trip back. And I think the trip back is more favorable for crew and cargo of Mercury mission.

            Let’s you had two different races or requirements on returning to Earth.
            One was fastest one could return. Other being at any random time you had to return.
            So, it’s 2021 May 3rd, or in June 24 2021, or etc. At some random times, one realize you need to get payload [say a crew] to Earth. How long [assuming spacecraft is ready] does take to get this payload to earth.

            So first one is you get to pick the time. So “planets are aligned” and requirement less than 16 delta-v chemical rocket power, what shortest time to get to Earth? Hit earth atmosphere with capsule that has is reentry that is reasonable [whatever that is- assume it can be at least Apollo lunar return reentry].

      3. “I mentioned Mercury only as an example of the most far flung of possible missions and not one that would be done in the near future. Remember, spreading into the inner solar system will be a stepping stone process.

        But there is some compelling evidence of extensive water ice on Mercury in the shadows of polar craters as there is on the moon. That would be an important resource for a base, should we ever decide to have one there. Such areas would also be permanently shielded from the Sun’s nearby fury and the extreme cold there is much easier to deal with than 800 degree F surface temperature that exists over the entirety of Venus’ surface (that’s even hotter than the sunlit side of Mercury).”
        It takes less delta-v to go to Mars, but takes a longer time to get to Mars as compared to Mercury.
        Doing a direct Hohmann Transfer to Mercury is 105 day [just over 3 months] going to Mercury directly is costly mainly mostly because Mercury has different inclination and doing gravity assists one lower this delta-v cost, but it adds a lot time getting to Mercury.

        So with Mercury it seems you have two ways to get there, use a lot of delta-v and do simple Hohmann Transfer directly Mercury, and get crew to Mercury in 105 days. Second way is take longer duration trip time and use far less delta-v [though probably longer and more delta-v as compared to simple Hohmann Transfer to Mars.

        It seems if your requirement is to send crew to planet and get them there in less 4 months. It seems me that Mercury requires less delta-v than Mars. And getting to Earth from Mars or Mercury in less than 4 months could require less delta-v than from Earth to Mercury, due possible gravity assist with Venus and aerobraking with Earth. You you a more direct bounce off Venus, because you make up velocity differences using Earth’s gravity well and it’s atmosphere.
        And there less GCR closer to Sun than further from it, though solar flares would be more intense.
        Going to Mercury would depend upon the amount available ice at it’s poles. Polar ice at Mercury was discovered before lunar polar ice. And generally considered to have more polar ice than the Moon, but there seems no confirmation at this time of this assumption.

        In terms of temperatures, lunar polar regions have moderate surface temperature due to low angle of the sun. The sun at less than 30 degree angle has the solar energy spread over
        larger area if the surface in level. So one have area where a square meter of surface is receiving a 1/10th of solar radiation, thereby have surface cooler than the Moon at equator
        at noon. But anything facing the sun, gets all the solar energy. So a wall/hill or a solar panel
        can all the solar energy from Mercury distance.
        Another aspect is determining whether mercury has similar “peaks of ethereal light” as the Moon does. So that from fixed position one can receive more “half the day” [maybe 80-90% like the moon] where can collect solar energy.

        1. So here analysis of Mercury Messenger mission.
          http://ccar.colorado.edu/asen5050/projects/projects_2004/park/
          Comparing direct hohmann transfer vs multiple gravity assist that
          required “more than six and a half years”
          And also talk about bi-elliptic transfer which by going beyond Mars orbit:
          “assumed to be at 300,000,000 km from the Sun”.
          [Mars average distance from the Sun is 227.9 million km- and Perihelion
          being 206.6 with Aphelion being 249,200,000 km from Sun]

          Anyhow, to focusing on the 105 day direct hohmann transfer to
          the + 6 1/2 years:
          “Messenger was launched from Earth with a fuel capacity of 592.3 kg of fuel that allows a total delta-V of 2.25 km/sec for the life of the mission. We can make a rough assumption, to calculate the amount of fuel that is required for a given delta-V.

          We can use that calculation to calculate how much fuel is required to reach Mercury orbit, from the Earth using a single Hohmann transfer.”
          And this is:
          “Since we calculated that a single Hohmann transfer to reach Mercury would require an extra 2856 kg of fuel, this would lead to an additional $25,705,134 just for launch!”

          So not using single Hohmann transfer [arrives in 105 days] they used 592.3 kg of fuel requiring +6 1/2 years. And need additional 2856 kg of rocket fuel.
          Or if gave them about 50 million or more, they might have got it there in just over 3 months.
          But they couldn’t use the Delta II rocket which only lift 5000 kg to LEO.
          [Of course, now, Falcon 9 can twice lift as much as Delta II, so could same mission using Falcon 9 and send Messenger B in 105 days. Delta II was 45 mil, Falcon 9 say 55 million- not that you would actually want to fly a twin of Messenger.]
          Wiki, MESSENGER:
          “The 485-kilogram (1,069 lb) spacecraft was launched aboard a Delta II rocket in August 2004 to study Mercury’s chemical composition, geology, and magnetic field.”
          Of course with sending crew to Mercury, you would probably need more then 2 Falcon Heavies or something like that- so just crew and just Mercury orbit. And send lander, etc, etc.
          Maybe more expensive than single Manned Mars.
          But probably around the same cost as manned Mars that got the crew to Mars
          as quickly as one could get them to Mercury.
          via or or slower more efficient Messenger like trajectory

        2. -“The neutron data indicate that Mercury’s radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 20 centimeters thick that is less rich in hydrogen,” writes David Lawrence, a MESSENGER Participating Scientist based at The Johns Hopkins University Applied Physics Laboratory and the lead author of one of the papers. “The buried layer has a hydrogen content consistent with nearly pure water ice.”
          …
          “For more than 20 years the jury has been deliberating on whether the planet closest to the Sun hosts abundant water ice in its permanently shadowed polar regions. MESSENGER has now supplied a unanimous affirmative verdict.” –
          http://www.nasa.gov/mission_pages/messenger/media/PressConf20121129.html#.UnqCPFPU3zY

          But like Moon, there is not exploration to determine whether Mercury has minable
          water. There has been far more exploration of the Moon as compared to Mercury,
          but the Moon is still inadequately explored.
          It seemed like Mercury would have considerably water than the Moon, but it remains speculative.
          It seems if we explore moon to determine if and where there is minable water, we could have better means of understanding Mercury polar region.
          And from this point be better able design Mercury mission which provide more definitive clues.

        1. The entire solar system is the goal. Depots should be on every leg to everywhere. The priority being to places that are easiest to get to or the fastest growing colonies then progressively moving outward.

  9. “The combination of SLS and Orion will effectively establish a highway to the entire solar system.”
    Less of highway as compared to Saturn V.
    What’s changed since Saturn V?
    So NASA takes longer to attempt to build SLS than it did build Saturn V.
    Isn’t this the most significant change since Saturn V?

    If limited to cost to less than 10 billion [so SLS or even just Orion is excluded- as is JWST]
    What is the most effective way establish a highway to the entire solar system?
    We have not spent nor likely to spend in total 10 billion dollar on COT.
    So that’s a candidate.
    And this gets us from surface to LEO. As they say 1/2 way.
    And that road which can be used by more than government cars.
    And of the millions of miles of road, very few miles are just for government vehicles.
    Should we build more roads just for government vehicles? Is some national priory
    for doing this? We may spend hundreds of billions on highways, but not tens of billions
    on highways solely for government vehicles.
    One might have a somewhat silly rule, for every 1 billion spend on government highways
    we spend at least 10 billion of public highways. Instead NASA doing the opposite.

    So anyhow what could be done which costs less than 10 billion which would do something
    in regards to a highway to the entire solar system?
    It seems that fuel depots *could* costs less than 10 billion- assuming some effort was made
    doing it for less than 10 billion rather than effort at spending more than 10 billion.
    One we should not confuse highway cost with gasoline costs.
    “United States consumed about 134 billion gallons”- http://www.eia.gov/tools/faqs/faq.cfm?id=23&t=10 So say 3 times 134 billion.
    Which involves hundreds of thousands of gas stations.
    Nor confuse it with the costs of all the vehicles which use the roads.

    Now is possible to explore the Moon so as to determine where best locations
    within say 4 -10 kilometers, to mine lunar water, would be and for this to cost
    less than 10 billion dollars.
    We start by limited it to lunar polar region. The lunar polar region [both north and south]
    is fairly small region. In addition it’s possible to limit it areas with dark craters- craters
    which don’t get “seasonal” times of sunlight.
    So the 10 billion solar worth challenge is to find small area within not a large possible area where there is rather might be enough lunar water. Starting might be best, and determining whether
    “might” becomes what can reasonable declare, is.
    If you determined where there was minable lunar water, does this “establish a highway to the entire solar system”? It seems it could said to equal to doing survey of part of establishing highway.
    And survey generally cost less than making a highway, but are always needed for a highway.

    Actual “highway to the entire solar system” is a rather grand thing and is not done by making the right vehicle. But one were loosely say a vehicle ever started highways, it would be vehicles which were mass produced, rather than custom made vehicle made by a government.

      1. Except you’re missing something Rick. Putting a ship in LEO creates a market now that leads to lower costs. It’s not like people aren’t working to lower costs but the fastest way to do that is to have somebody competing with you at lower costs. It lights a fire under ya that doesn’t exist otherwise.

        We aren’t going to save anything by waiting to put that ship in orbit. It’s a one time cost. If everybody waits for the price to be right the price is never right. We need those people telling their stories about how “if only they’d waited.” It’s been fifty years now. We’ve waited long enough.

        1. “It’s been fifty years now. We’ve waited long enough.”

          A large part of the reason why we’ve been waiting 50 years is because of the exorbitant expense of the first leg of the trip to LEO. You’re just another one of those people who don’t realize two facts: 1) things are finally fundamentally changing now and 2) what kept us from having significant progress for those fifty years will no longer apply soon. Like a child with too much unreasoning petulance to put off instant gratification to wait even just a few years longer and throwing a tantrum because of his lack of patience, “I want my spaceship and I want it now!”

          You can say what else you want. I can tell you are too intransigent to consider any position than the one you currently have. Bye.

          1. Intransigent profoundly does not describe an INTJ which requires a fact based rather than authoritarian argument to persuade. I used to believe in intrinsic value (a proposition pounded into us by commercial entities that aught to know better) but completely reversed my position in a moment when Rand and Titus pointed out simple facts. I’m easy to convince. You just need facts.

        2. There is already a few ships in orbit. I assume that you mean another vessel designed with profit in mind. For that, you’re going to have to wait until there are at least two companies capable of sending people to LEO and back, after which Bigelow will launch his first station.

          2. I assume that you mean another vessel designed with profit in mind.

            Yes, you assume correctly. I agree that Bigelow isn’t sitting on a production facility in NV for no reason. He’s waiting for the right moment. I’d even like to see others get there first, but most don’t have the deep pockets he has.

            I’m a bit disappointed that nobody has made the obvious argument against mine that now is the time but I’m ready when they do.

    2. I believe the Nautilus X fits that bill. Sprial design them for LEO2GEO and space platforms, LEO2EM1-2, Lunar orbit , LEO2ES Lagrange point … vehicles create traffic to destinations and the gas stations to service them.

      1. Yes they do. It seems quite obvious, doesn’t it? Nautilus-X may cost too much fuel compared to some other options but it is a move in the right direction IMHO… or at least getting thought moving in the right direction.

  11. Rick, that was too funny. You’re two points are a mainstay of my arguments. That first leg is always going to limit participation. The reason we will overcome it is not because we will get the cost down to some magic point, but because their will be a profit at whatever point it is.

    I’ve pointed out that profit is available now for putting a ship in LEO. But that realization is not enough. It does cost money which I do not have. If I did, I’d spend it on that because opportunity is not a still target.

    Oh, and how is being dismissive winning you any points? I agree with most of what you’re saying. Is any minor nit too much for you to tolerate? I think you’ve made some great points.

  12. BTW, SpaceX is doing a great job of lighting that fire. Imagine where we would be without them. But I’d like to see SpaceX and other get more competition. Yes, the market limits that, but greatness comes from climbing to become king of the hill regardless of the size of the hill (which tends to grow because of competition.)

  13. “The reason we will overcome it is not because we will get the cost down to some magic point, but because their will be a profit at whatever point it is.”

    “BTW, SpaceX is doing a great job of lighting that fire. Imagine where we would be without them. But I’d like to see SpaceX and other get more competition. “

    And you misunderstand me if you think that I think otherwise. I made those very points in my book. I’m just saying that pressing for an in orbit spaceship immediately is premature. The lower lift costs will help make it come within whatever budget exists. Building it immediately without regard to the current cost in the market place might restrict the size and capabilities of such a vehicle because of trying to wheedle down the costs of the spacecraft to compensate for the cost of getting it to orbit.

    My point is and was, we are talking at cross purposes.

  14. I think it’s quite possible that ‘immediate’ is not a difference between us.

    My immediate is in the next five years but possibly next year. We have no idea how fast costs will come down except that Elon has promised $20m/seat rather than the Soyez $65m. We are waiting for Superdracos to be integrated and tested in Dragon which is in progress today but are not an actually physical requirement. Dragon could take seven to orbit and back today. Falcon Heavy has been delayed but I’m feeling confident it will fly before the end of 2014.

    I believe that $20m per seat could be reduced to $2m to $4m rather quickly, but it may not happen for decades. For payloads beyond just passengers the time frame may be even longer.

    My contention is that profits are possible today at today’s cost. Tomorrows cost will increase those profits. Under those circumstances, to which we both seem to agree, is it logical to wait?

    No. Why? Because giving up today’s profits doesn’t make you more profitable tomorrow. It actually makes you less because you’ve lost today’s profits with which you could invest tomorrow.

    I think this is pretty simple. I respectfully look forward to you or anybody else correcting me.

  15. restrict the size and capabilities of such a vehicle

    This is absolutely true, but notice it does not affect my argument.

    1. Rick, this discussion has given me a new thought, for which I thank you.

      Is there a possible benefit of losing the payload fairing? Bigelow makes habitats that use inflatable material around a hard central core. But think about trailer pop outs. They are more like an accordion than a balloon. Would there be a benefit to making a habitat that has it’s own integrated fairing and later inflates like an accordion rather than as a balloon?

  16. gbaikie,

    I’m having a bit of difficulty parsing what you’re saying.

    Obviously you can get there faster by using more fuel. Because of the cost of sending crew I think we should restrict ourselves to minimum cost transfers. That’s about 8 to 9 months for mars AFAIK. I don’t know how to calculate the equivalent for mercury although I’m sure I could eventually work it out. I did see that messenger mission being 6.5 yrs.

    Doing a direct Hohmann Transfer to Mercury is 105 day [just over 3 months] going to Mercury directly is costly mainly mostly because Mercury has different inclination and doing gravity assists one lower this delta-v cost, but it adds a lot time getting to Mercury.

    So 3 mo. vs. 8 mo. is not apples to apples. What is?

  17. Let me restrict that a bit. Assume you use the exact same amount of fuel for each. Then how long would it take to get to each? Will the fuel that gets you to mars in 8 months get you to mercury. If so, how long?

    That would be the apples I’m interested in.

    1. “Let me restrict that a bit. Assume you use the exact same amount of fuel for each. Then how long would it take to get to each? Will the fuel that gets you to mars in 8 months get you to mercury. If so, how long?
      That would be the apples I’m interested in.”

      Well, that is would be the 6 1/2 years to the 8 month sort of comparison.
      Or that’s what Mercury Messenger planners were also interested in.

      I am under the impression that the biggest obstacle in term of delta-v is the need to change to Mercury’s different inclination of it’s orbit:
      “Orbit inclination (deg) 7.00 [Mercury} 0.00 [Earth]”
      http://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html

      So as I understand it, it’s analogous to changing inclination as if you were in LEO- which is costly.
      Or similar getting to GEO from 28 latitude. If launch from Earth’s equator you don’t pay this penalty
      to change to 0 inclination geostationary orbit
      Also the difference of inclination of most space rock is reason it’s hard to get to large number of them and part of reason impactor hit earth at average around 20 km/sec- a significant portion of velocity difference can be due to a rock having a different orbital inclination than Earth.

      With 28 latitude to GEO, they can change inclination in suborbital trajectory [fly towards equatorial, and then go to orbit] or do GTO and change inclination at apogee. {Or also could use the moon}
      Or generally the slower one’s going the easier it’s to change inclination.

      Or if you in elliptical orbit around Earth of say 200 km and 20,000 km you don’t want to change inclination while at the 200 km distance.
      Which what you are essentially doing with a simple Hohmann transfer to Mercury and changing the inclination at Mercury. Though Mercury’s gravity well/sphere of influence is helpful- or I suppose it’s why it’s only 13 km/sec in total rather than it being more.

      But suppose you want to do faster the 6 1/2 year and longer than 3 months.
      So minimize the time of gravity assists needed and use more delta-v.

      So something like hohmann transfer Mercury, which returns to Venus distance [rather than Earth distance], which intersect Venus [giving energy and change inclination to Venus [taking velocity and changing inclination to spacecraft] and then returning to Mercury. Which takes bit longer than simple hohmann transfer to Mars [8 months].

      So one leaving Earth with hohmann transfer Mercury, it gets to Mercury in 105 days and would return back to Earth orbit in another 105 days [and Earth wouldn’t be there] but instead of going back to Earth, one leaves at time when Venus crossing the trajectory return path of Mercury to Earth. And one uses Venus gravity to slingshot back to Mercury. Or behaving as if it’s a hohmann transfer of Venus to Mercury.
      So a Earth to Mercury, Earth, Mercury is 105 +105 +105 trajectory time. A Earth to Mercury, Venus, Mercury is 105 + eighty something + eighty something , giving 265 days or Mercury orbit time of 88.0 day, so being around 3 Mercury years.
      So somewhere close. Or if first pass is Mercury June, the next return skip year and be somewhere around next summer. Though you probably Mercury’s “spring/fall” [when crossing zero solar plane’s inclination- on first pass]

  18. Thank you, gbaikie

    Well, that is would be the 6 1/2 years to the 8 month sort of comparison.

    And of course, if you have the fuel to reduce the 6.5 yrs. to mercury you could send a much bigger expedition faster or the same rate to mars. Adding billions of dollars to the cost.

    1. “Well, that is would be the 6 1/2 years to the 8 month sort of comparison.

      And of course, if you have the fuel to reduce the 6.5 yrs. to mercury you could send a much bigger expedition faster or the same rate to mars. Adding billions of dollars to the cost.”

      Perhaps it would be billions additional to a program of 100 billion or more- it’s not significant.

      So, first, I was addressing, : Rick Boozer, “I mentioned Mercury only as an example of the most far flung of possible missions and not one that would be done in the near future. ”
      Which I would agree with simply due to lack of political interest. But not due the technical challenge or matter of being too costly.
      I favor NASA developing fuel depots and I expect this will costs billions. The longer term purpose of
      fuel depot is to lower the cost of using more rocket fuel. It will allow more rocket fuel to be used at lower costs.
      And the development of the use of fuel depots is essentially a requirement for Manned Mars- it should regarded as on the critical path type stuff. Fuel depots are a good idea [not necessarily as critical for Manned Moon- we did Apollo without fuel depots and obviously something similar could be done again without fuel depots- not a good way to do it, but possible]. Likewise it seems fuel depots are perhaps if anything less needed for Manned Mercury vs Manned Mars.
      So without fuel depots and if doing Manned Mercury it may cost a few billion more, roughly speaking in terms of more rocket fuel needed. And with fuel depots it maybe around 1 billion in additional cost.
      Or somewhere around 1 percent more.
      But it seems the challenge of of getting crew to Mars will cost more the 1 billion dollars- in terms of NASA costs.
      Or say you want to send a crew Mars or Mercury. NASA had lots of money and funded bother operation at same time. So two teams- one Mercury and one Mars. With equal funding the Mercury team seems to have better chance of getting there quicker [therefore cheaper].
      One advantage for Mercury team is one could assume the choice of area is restricted, it seems obvious to me that you want to go to Mercury’s polar regions. It seems polar regions of Mars could a good selection, but there could be disagreement about this. The polar region on Mars is roughly about the size of Antarctic, and on Mercury it’s about Greenland or less.

      With Mercury as with the Moon, one “can get” more constant solar energy. I don’t agree with ” Every pound of solar cells shipped to or built on Mercury, the power return is about 20 times greater than on Mars” unless one is including the energy storage needs [batteries], and then possibly, it’s an underestimate.

      Though with Mercury it seems “everything” hinges on whether there minable water on Mercury, whereas with Mars access to water is requirement, there is water, particularly if you focus on Mars
      polar region.

      The trump card with Mercury is you send crew there in 3 month. I happen to believe that one can also send crew to Mars in 2 to 3 months. Strangely enough by using a similar trajectory leg of hohmann Mercury to Mars, but starting from Earth [requires more rocket fuel] but it seems to me, most people tend think that as this idea is crazy [or at least too expensive]. Otherwise, if one confines
      oneself to Earth to Mars hohmann transfer [with patched conic] one needs imagine things less nuclear propulsion getting to Mars quickly.

      1. [Oh but for edit button]]
        “Otherwise, if one confines oneself to Earth to Mars hohmann transfer [with patched conic] one needs imagine things less nuclear propulsion getting to Mars quickly.”
        Is:
        Otherwise, if one confines oneself to Earth to Mars hohmann transfer [with patched conic] one needs to imagine things like nuclear propulsion in order to get to Mars quickly.”

        {But with nuclear it still doesn’t seem to work- it’s seems more of a distraction rather than solution. Though I would say one advantage of nuclear propulsion is it “kind of” forces a non-hohmann trajectories- low thrust/higher efficient propulsion is not using hohmann trajectories {{yes I know nuclear can provide higher thrust, but it can also can provide more efficient low thrust}} }.

        1. If you consider one way then 8 mo. vs. 3 mo. is really no impediment. They will probably be living the remainder of their lives on mars.

          Nuclear power should be common. It is not because humans are superstitious idiots.

  19. billions additional to a program of 100 billion or more- it’s not significant.

    It’s not just 1% or 2%. I should ask what percent of additional cost would you consider significant? I have said, and I’m confident, that we could put a dozen colonists on mars for $2b ($3b if we are serious about survival after arrival) and that’s before economies of scale. Perhaps eventually down to $5m per colonist (Elon’s $500k is too far for me to imagine.)

    So that additional fuel cost would be over 100% which is significant and rules mercury out as a first destination. Put another way, mars will grow more than twice as fast for the same investment. Both would be worth doing. Mars is worth doing now. The only thing we are waiting for is a demonstration of a crewed mars lander. I use Elon’s numbers assuming they will be in the ballpark.

    the development of the use of fuel depots is essentially a requirement for Manned Mars

    Desirable, yes. Essential, no. Unless you consider a ship being refueled in orbit is essentially a depot? A depot is a time shift more than a cost shift. Having depots means a ship doesn’t have to wait months in orbit before it departs. Depots will allow fuel costs to come down but the cost will be what it is at any given time. The time shift is immediate.

    When you project hundreds of billions then depots seem essential. They will become essential in the same way that all modern conveniences are even though we did without before they existed. They would make sense now. But essential implies we can’t do without them which just isn’t true.

    If you can’t accept my lower cost of $2b than you will not agree. We will just have to wait until it’s done.

    Actually my thought is a compromise between two extremes. Direct and depots. Elon seems to be part of the direct crowd with MCT and the desire to build a 200mt payload launch vehicle. You, gbaikie, are obviously on the depot side. My position, refueling a ship in orbit before departure, is a middle ground.

    1. “billions additional to a program of 100 billion or more- it’s not significant.

      It’s not just 1% or 2%. I should ask what percent of additional cost would you consider significant? I have said, and I’m confident, that we could put a dozen colonists on mars for $2b ($3b if we are serious about survival after arrival) and that’s before economies of scale. Perhaps eventually down to $5m per colonist (Elon’s $500k is too far for me to imagine.)”

      I would favor a Mars prize. I think it should be larger you seem to suggest.
      But say it’s 5 billion to land dozen people. Payable upon safe landing. Up to dozen and so 416.6 million per surviving crew. And another 416.6 million per crew surviving after 5 years on the surface.
      Prize expires 2033. Total amount possible 10 billion dollars.

      But mainly talking about what NASA does with budget of somewhere around 17 billion per years.
      Don’t think we should want to do a prize for Mercury at this point in time .
      Maybe one for the Moon.
      But I think it would good for US government to offer the Mars prize which could as high as 10 billion dollars for 12 mars settlers.
      This wouldn’t change my view that NASA should develop fuel depots and then explore the Moon [unless lunar prize is offered related to exploration the moon to find minable lunar water- say 2 billion dollar for 10 tonnes of lunar rocket made [a hefty price amounting to $200,000 per kg]. Which should enough money for the needed exploration, and enough water mined to prove minable lunar water is indeed found. And perhaps actually start commercial lunar mining. So evidence provided that the water was mined from Moon and rocket fuel made from this water. Paid once 10 tonnes of rocket fuel is made. Prize expire 2023.]
      So if such lunar prize is offered, NASA could still do it’s Lunar exploration, but end the program if and when a party won the lunar prize. So those wanting to do prize could wait for results from NASA exploration or could jump in at any time do it themselves. It’s vaguely possible NASA could finish lunar exploration before prize expires.
      Same type rule could apply to NASA Mars exploration. So by time NASA finishes exploring the moon,
      and Musk is already sending people to Mars, then NASA could not explore Mars, and go to Mercury or where ever. But getting the Mars prize is still “a plan” then NASA could do a Manned Mars program until such time as colonists arrive.

      “So that additional fuel cost would be over 100% which is significant and rules mercury out as a first destination. Put another way, mars will grow more than twice as fast for the same investment. Both would be worth doing. Mars is worth doing now. The only thing we are waiting for is a demonstration of a crewed mars lander. I use Elon’s numbers assuming they will be in the ballpark.”

      As far as Mercury, we need further robotic exploration to clarify whether minable water is actually
      on Mercury.
      But at time of start of Manned Mercury, I will assume there are fuel depots at Lunar orbit and L-1.
      And assume I can buy any quantity of rocket fuel [either brought from the Moon or Earth and at $5000 per lb [$10 million per ton]. It could be more than this and unlikely much less than this.

      Now, of course at this point assuming the is a “good” chance of minable Mercury water, one could also provide a prize which again essentially gets private exploration of Mercury. And likewise, NASA could proceed to explore Mercury until such time as Mercury has been adequately explored to determine where the best places of minable water could be on Mercury.
      Also since there already are fuel depots, NASA could see if anyone wants to sell them rocket fuel at
      Mercury orbit. So rocket fuel could made on the moon and shipped to Mercury. And stored at Mercury L-2. {not sure how far that is from Mercury}.
      So something like Mercury Messenger, could go to L-1, refuel, then go to Mercury.

      So:
      http://ccar.colorado.edu/asen5050/projects/projects_2004/park/
      Messenger was launched from Earth with a fuel capacity of 592.3 kg of fuel
      “Since we calculated that a single Hohmann transfer to reach Mercury would require an extra 2856 kg of fuel,”
      So not to direct transfer and from L-1, is addition 1000 lb or less. So 5 million worth of rocket fuel to get there in not 6 1/2 year but around 1 year. And if wanted there in 3 months, somewhere around 2 tons- 20 million in costs. And it had cost 45 million to launch from earth and spacecraft itself is 100 million or so.
      Similarly, humans launched from Earth would have the majority of their costs being the launch from
      Earth.

      1. “Mercury Distance to L-points {AU}
        L-1 0.38562,0
        L-2 0.38857,0
        L-3 -0.38710,0
        L-4 0.19355, 0.33524
        L-5 0.19355, -0.33524
        Table 1 – Lagrange Points in the Solar System (Distance in AU) – Planets Aligned”
        http://ccar.colorado.edu/asen5050/projects/projects_2003/cain/

        So Earth L-1 is according to chart: 0.98999,0
        So 1 AU = 149,597,870.700 kilometers
        0.98999,0 times 149,597,870.7 is 148,100,396
        So, 148,100,396 km from Sun and when Earth at
        1 AU from Sun, Earth/Sun is 1,497,474.7 km from Earth.

        If take L-2 0.38857,0 and subtract 0.38562,0
        The distance between Mercury L-1 and 2 is:
        0.00295 AU or 441,313.7 km
        Which about 1/6 of distance of earth/sun L-1 & L-2 .

        Anyways, to answer my question about 200,000 km from Mercury.
        Or closer to Mercury than Earth/Moon L-1
        And so you could have Mercury L-2 in Mercury’s shadow.
        I wonder if Mercury’s elliptical orbit affect things in there L-points-
        Earth orbits in near circle and is more distance.
        Mercury has Perihelion of 46 million km and Aphelion of 69.8 million km.
        http://nssdc.gsfc.nasa.gov/planetary/factsheet/
        http://en.wikipedia.org/wiki/Astronomical_unit

  21. Mars prize: 5 billion to land dozen people ($416m each) another $5b for living five years.

    That would be collected in ten years. I support ya. What do you need me to do?

    1. I think there is fair amount of agreement of the value of having prizes.
      It seems NASA has embraced them to some extent, it would nice if US government
      could incorporate them as ways cause more innovation.
      This also applies to other governments, as well as non-governmental organizations.

      It would nice if more politicians would mention such ideas. According Robert Zubrin and a discussion with Newt Gringrich:
      “I countered by saying that while Mars Direct might cost $30 to $50 billion if implemented by NASA, if done by a private outfit spending its own money, the out-of-pocket cost would probably be in the $5 billion range.” And:
      “Starting immediately, 10 percent of NASA’s budget would be put aside yearly to accumulate a prize fund. There would be at least two prizes: a $5 billion prize to develop and demonstrate a heavy-lift booster capable of lifting at least 100 tons to low Earth orbit, and a $10 billion prize for the first human mission to Mars.”
      http://www.nationalreview.com/articles/289775/mars-prize-robert-zubrin

      I think we can scratch idea reducing NASA budget. Nor does government need really store money, one have unfunded and direct future congress deal funding it within a year or so before anyone blasted off to Mars. Politicians love doing things that has no immediate costs, but the word of Congress [voting and passing on it is straight up bill] is sufficient.
      But starting an Office which managing all kinds of prizes, plus including a Mars prize as example of such prize, may be even more appealing to congress critters. So you would bureaucrats who decide
      on the details- who probably would screw it up, if not public feedback. Though I suppose one have some section of Treasury Department which charged with such a task.

      One could refine exactly what kind of prize it would be. Does one actually need a dozen people, or would need more or less.
      One could change it, so it’s not just private sector. You have prizes government projects. It seems a good thing find on Mars is caves. So as incentive to find caves,, one have a prize that adds some funding to project which is successful in terms of doing this. So some Discovery mission is going to do Mars exploration and has funding cap- so prize if it completes the task could effectively raise it’s cap on spending. And generally could encourage missions which relate to these “government prizes”.

      But anyways back to Mars prize, though don’t necessarily agree with value of it, one could have fly by of Mars as prize. What would agree with is getting something fast to Mars orbit or surface [if survive
      “landing”. So that doesn’t need to a large payload. Prizes can also be international competition. I think both both national and international has value. Generally I think we should have more national,
      but having some international ones seems like has good advantages to it. And X-prize was international. But you also have prize which meant to involve more than one nation, so not just some team from another but something has teams from different countries working together.
      So three classes, national, open to any national, and teams from different nations.

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