New Mars Forums

Sounds like a good way to launch a space probe of some kind - one way trip. 

One oddity - they don't mention payload mass, but are very specific about the sail size and beam size and energy required.

If Phobos turns out to have ice as a high fraction of it's composition, might it be beneficial to use an automated ice-mining/fuel production system there to fill a tank for Mars return?

Probably quoted elsewhere here, but related to the discussion of liquid CO2 for propulsion - Zubrins]http://www.universetoday.com/am/publish/mars_gashopper.html]Zubrin's Grasshopper

The hitch-on pressurized trailer is smart - allowing using the tractor for other purposes around base or out exploring.  With all the power systems in the "tractor", the trailer can be relatively light - a multi-layer inflatable structure perhaps.  That keeps it compact for transport but fast to set up.

A hybrid engine might be a good solution to the heat issue - you're going to need a heat source anyhow, so carry a modest amount of carbon and the O2 to burn it.  Use that to heat the CO2 above it's (very low) evaporation point, and the CO2 to run the engine.  (Using a hydrocarbon based fuel seems wasteful of hydrogen, which will probably be in somewhat short supply.)

There would need to be small but strong boilers for warming CO2 - but the dry ice can be kept in relatively light tanks - or even just a well insulated cupboard, with the explorers manually moving bricks over to an expansion tank when it runs out of gas.

Heh - I'm getting an image of a future Martian railroad, with the fireman tossing logs of CO2 into the boiler and logs of charcoal into the firebox.

There are two possible types of objections:  objections from physics, and objections from engineering.  These are mostly engineering issues - they may prove difficult (or easy) to overcome, but the only way to tell is to try to design a specific system and analyze/test it.

Objections from physics would, if properly done, kill the concept outright - e.g. if the scheme tried to produce more thrust than a given amount of reaction mass and energy allowed.  I'd say that it's more useful at this point to look at possible physics objections - but:

- big enough - ion engines also produce relatively tiny thrust - the point is to produce as much thrust with as little mass as possible, for maximum delta V on long flights.
- extreme temperatures - I've done no study of this - but one reason to use diamond is to be able to rapidly conduct away waste heat.
- reloading LH2 - really detailed technical issue.  You might as well say that pumping fuel and oxidizer into the high pressure chamber of a rocket poses a problem - of course it does, but there are technical solutions.  One simple approach - the rear of the notch, when it is fully expanded, opens onto a high pressure source of LH2, admitting a small droplet, and then closes off before the larger end of the notch, trapping the droplet.
- Diamond withstanding LH2 - I would expect diamond to react with LH2 at the surface, creating a hydrated (correct term?) boundary layer.  If pressure rips some hydrogens away from that surface, the next cycle will probably replace them.  On the other hand, if the hydrogen does NOT react with the diamond, that's probably almost as good, as it means there'd be no chemical modification of the notch surface, leaving the issue of potential mechanical ablation of the carbon.

I'm more concerned with a physics issue - can the notch possibly be made to close suddenly rapidly enough?  Having a high speed of sound doesn't help if the sound is 1hz (no matter how powerful) and takes a full second to close and open the notch.  Some sort of instantaneous impulse - like that of hitting it with a hammer - is more likely to create the desired effect - but that would likely waste most of the input energy as heat.

Piezo-electrics?  Someone suggested Surface Acoustic Wave devices - but I'm not familiar enough with the benefits of those to comment.  To me it looks like SAW technology just looks like it is supposed do signal filtering / conversion - perhaps the idea is to convert a powerful high frequency signal into an acoustic square wave pulse?

"Would you please tell us, as clearly as you can, and considering how long we will have waited for the answer, what you think is most important for us to know?"

No matter how they answer - with a joke, or a sermon or a scientific treatise, it'll tell us a lot about them.

Personal preference - we've been to the moon in my lifetime.  I'd settle for a flags/footprints/exploration/sample-return mission to Mars at this point.  Mars Direct provides that.  But I don't trust NASA to do it.

Based on past NASA performance, what will happen if we go with GWB's "vision" is this: 

NASA will spend a decade planning the moonbase and restoring our manned launch capabilities to where it was in 1970 (but nowhere near as safe or sensible as it could be done).  Then we'll spend a decade or more building the moonbase and futzing around doing "science experiments" and "exploration" that give the impression that the moonbase is useful for something.   And then we'll wake up after 25-30 years and realize that it's gotten us no closer to having infrastructure or technologies useful for getting us to Mars cheaper or faster or safer.

NASA has wasted 30 years of my life on the shuttle and ISS, in the sense that those were 30 years in which I COULD have see a moonbase established or men on Mars.  I certainly don't trust that they'll make it to Mars in what remains of my lifespan.   Given that politics drives their budget, maybe not even the moonbase.

I say - reward competence and punish incompetence.  Shut down the shuttle.  Give our share of the ISS to anyone who wants it, provided only that they'll keep it from crashing to Earth.  Pay NASA to keep doing research and developing and operating space probes like the Mars rovers, at about the same rate as today.  Pay for commercial launch of whatever NASA has to put into space. 

The rest of what was NASA's budget should accumulate every year in a prize fund with USEFUL goals - especially goals that will have commercial value once the R&D are paid for, if only to help companies win other prizes. 

That'll get us to the moon and Mars and beyond much sooner than giving the job to NASA, and it'll end up establishing technologies and infrastructure to make access to space far less costly.

BTW - if you want something with a REALLY high giggle factor (i.e., FAR less analysis than the space elevator) :

http://www.halfbakery.com/idea/polar_5f … r_5fbeanie   

This would be a good complement to using space elevators to launch cargo to orbit, as it is more suitable for launching human beings (shorter time to orbit, less time spent in the van Allen radiation belts, no need for laser power to the out-going vehicles).

I used to have a link to a more serious site by someone else, but now I can't find it.

Look at that paper again.  The real costs are in the development of the stuff you'd take into space or to the moon or Mars.  That's the real reason why you prefer one launch - to cut out the massive added costs entailed in designing ten things that launch separately and have to be put together in space.

But why not take that logic further?  The important question isn't "how do we get stuff into space cheaper?" (if it's worth sending something into space, the launch costs aren't an impossible obstacle).  The important question is "how do we get development costs down?"   

It is true that if we did have a really cheap way into space, development costs would fall radically.  But why?  Because we could build something, take it into space, test it, see how it fails, fix it, and launch again.   That's the approach being used by Armadillo Aerospace, BTW.

Since we do NOT have a cheap way into space, the next best alternative plan would be to get into space and stay there building and testing things. 

Oh hey - like a space station!   We have woefully failed to make proper use of the space station - frittering away that massive investment on "science experiments".  (Heard of any big breakthroughs as a result of all that 'valuable' science?   I haven't.  Heck, NASA scientists are even still complaining that they don't know enough about the effects of long-term zero-G on astronauts for a trip to Mars.  You'd think they'd have THAT figured out by now, if anything.)

The ISS should have been a machine shop for assembling and building and testing experimental space systems.  I say we give John Carmack NASA (with budget), the ISS and shuttles, and see if he can get to the Moon or Mars.

The same logic applies to a Mars mission.  Instead of trying to research all the factors that will affect a Mars exploration rover and design a rover that will not fail, design a plausible first cut at it that can be easily modified, send it to Mars, and send along skilled engineer/machinists who can "fix it til it works", with the support of scientists and engineers back on earth as needed.  Let the planetary exploration scientists follow a few years later, after some infrastructure has been built for them.

Of course, there IS this little problem:

http://www.gambling-law-us.com/Federal- … law.htm]US gambling laws

Interesting to note that it isn't the lottery itself that appears to be illegal - it's any form of promotion or supporting communication other than word of mouth that appears to be illegal.  I believe it's worded so that even if you ran the lottery from another country, participants would technically be breaking the law if they used the mail or internet even to find out about it. 

There is a loop-hole for states.  So maybe one could get a license to run such a lottery for a state. 

But IANAL so don't take my word for it! 

If I were dictator - I'd:

0) Write a constitution preventing all levels of government from interfering with a few fundamental rights and a few contingent rights, and tightly specifying the powers of national government - especially limiting exercise of military power other than in defense.

1) Create a national military loyal to the Constitution, rather than to me.   Shoot any officers who violate this.

2) Break the nation up into a reasonable number of regions that - so long as they sustain some honest form of democracy and respect the constitutional rights of their people - would have minimal interference from me.  Interfere instantly and severely with any that don't.  Encourage the people of these regions to allow even more freedom than the Constitution requires.

Space doesn't come into it until AFTER I retire in favor of the newly elected President and council of regional leaders, none of which could be me, as required by my Constitution. 

As my final act as El Presidente, I would order myself frozen for 30 years, during which time my small nation would become one of the richest places on earth and I would become known as the Beloved Founder.  Upon thawing out, I'd suggest that my grateful nation use their wealth and the much advanced technology of the day to send me and 10000 eager volunteers out to the space frontier.

I thought that the most on-point comment in the article was that we have excess launch capacity that would work just fine for launching cargo, and we should use it.

If we're going to design and build any new vehicle - especially on the tight budget Bush has planned - let's put the effort into making a safe but reasonably inexpensive human launch/return system. 

For safety, it should have a single high reliability engine per stage.  Ideally it should be a single stage, so if it can launch, it'll probably make it to orbit.  Inefficient, but safer - less to inspect, less to go wrong, and some of the things that can go wrong won't be as disastrous (e.g. if the one engine doesn't fire).

There should be safe abort options throughout 100% of the flight - from boarding through landing.   Launch little more than crew and plenty of air in a capsule designed to handle re-entry.   It needs an emergency rocket eject system, and perhaps that can double as a back-up de-orbiting system - just enough to bring them down into thicker atmosphere where their orbit will eventually decay, if they have no other options.

Fly everything else ahead of time and check it out on orbit before the humans lift off - even the rocket needed to do a normal de-orbit.  Have a spare de-orbit rocket standing by to launch if needed.