New Mars Forums

Considering the NSF has about 1/3 the budget as NHS, this shouldn't come as a surprised.  In general the American public is disenfranchised with sciences; seeing little return from their investment.  I swear, more people treat science as some sort of black magic rather than giving it the respect it deserves.  Within 15 years, engineers will probably have the same esteem as teachers in this country (*sarcasm* Related? Naa.)

Space tourism will be successful only until DeathTrapOne clips the front of "WhiteFright", killing all aboard.

There's a reason why SpaceX and TGV are shying away from the whole tourist angle:  the userbase is too dang small.  Space tourism is dependent not only upon those who can afford a $200k three minute thrill ride, but also that they would be interested.  Further, its more likely that the suborbital firms will exhaust their userbase long before they have the launch frequency to drive down the price.  I really hope SpaceX is able to pull it off; they have the best chance of making a dent in the current aerospace market.

Hehe, you won't be able to gut JPL, but you will be able to put them in check.  Force those fellows to come up with unified flight architecture that 80% of there future mission will be able to fly on.  I'm so sick and tired of JPL developing and entirely new vehicle each and every time they design a mission (and someone please teach them how to write a report while your in their "backside").  Other than that, good plan.

No, pressure is the force exerted on a unit surface and is a function of temperature, density and specific gas constant (represented by p = rho*R*T).  Isp is a measure of efficiency or the amount of energy within the reactive mass.

You really need to go back and balance your forces.  You cannot "press" against vacuum as there is nothing for you to transfer momentum to.  Simply put you have two pieces of information, mass and velocity.  Your propellant has a certain mass and velocity as does your spacecraft.  At the end of the day, the total momentum of the system is going to be zero, i.e. the sum of the momentum from the propellent is going to equal to the momentum imparted to the spacecraft.  There are a number of text you can get that will expand upon this for you; if you live near a college town you should be able to find an older edition of "Rocket Propulsion Elements - Sutton" for around $15 bucks.

To the topic at hand, what's particularly nice about this ion thruster is that it will play pretty nicely in a clustering configuration.  For a while, Glenn was simply increasing the diameter of there ion thrusters to gain performance, with little thought to the consequences.  This is not entirely a bad thing as they have been able to ratchet up performance without much of a hit to the lifetime of the acceleration grid.

Most in the area in electric propulsion acknowledge, however, the increased ion density in the thruster makes the ion thruster more susceptible to damage (especially for the long duration mission these large diameter thruster would be used for), nor do they have the necessary redundancy needed for a JIMO-type mission.  The more immediate issue is that the cathode emitters don't have the performance or lifetime to maintain the spacecraft's neutral charge.  If similar performance can be achieved with a cluster of ion thruster it's a definite win from a engineering and cost standpoint.

By the way, if anyone is interested in getting into electric propulsion now, the hot areas (for EP anyway) are grid optics and charge balancing.  Most of the other areas are loaded with experts in an already crowded niche of a niche market.  One of the joke we had in academia was "MPD produces more PhD than Isp."

WRT antimatter propulsion, 50-75 years off.  It takes more energy than we get out of it, reducing it to a glorified battery.  I think something along the lines of 50 mg of antimatter is produce annually (this may be wrong, but the triviality of the amount produced is not) which is not nearly enough to do anything worthwhile.  And as I said earlier it's just a battery, raw energy.  That energy needs to be imparted to some reactant mass for it to be useful (unless you plan on using some pusher-plate explosion thingy).  Point being, you will need some sort of space infrastructure to support this type of vehicle; unfortunately this is 40 years down the line.

Please remember folks, space is really, really, really hard.  It is both energy and time intensive and rarely yields something profitable.  At the end of the day, however, we do space to test the endurance of the human condition.  If we can sustain life in far away places such as the Moon, Mars and beyond; think about the things we can accomplish in those far away places right here on Earth.

This argument is getting silly, I'm having a difficult time seeing how it even relates to space flight.  Anyway, let's see if we can group this discussion back to Earth, shall we..

While it is true that the rate of global consumption is on the rise, most reports indicate that the current sources will be able to *meet* global demand for around 40-50 years AFTER WHICH the currently reserves will no longer be able to meet global demand.  Petroleum will most likely not run dry for at least 100 years, coal probably not for 250 years if we continue our current trends unperturbed.  The fact being OPEC has no desire/need/want/whatever for cheap mid 90's gas prices, in fact they have been extremely accommodating all things considered.  The only thing they need to do is weather the "dependence on [Arab] Oil" neo-patriotism and ensure non of their markets adopt widespread nuclear alternatives.

Much of the "boom" we see in energy prices are due to the industrial miracle in China, which is already showing signs of cooling down.  Consumption rates for that region will become more "predicable" and the energy sector will be better able to deal with these ballooning supply/cost issues.  Honestly, the energy issue is no more serious an issue than it was a couple of years ago, it just that American consumers are finally being bit in the ass by the issue and the markets are acting like the adolescent uninformed pricks they are (but that's just my opinion )  There is a much large issue w.r.t. to the US energy and transportation infrastructure being in desperately need of rehabilitation (or being blown to hell); this is a important and serious matter, not dire.

Fuel cells.  Better batteries.  That's just about it.  The hydrogen economy is a bunch of hot air when taken outside the issue of the infrastructure rehabilitation here in the states.  Fuel cells on their own are utterly worthless considering there are no vast oceans of liquid hydrogen from which we can extract this miracle fuel.  We certainly have water, but the exercise of extracting hydrogen from water is so utterly inefficient its not worth the bother.  As an aside:  if consumers are overly concerned with purchasing the latest hybrid SUV (though I did drive one two years ago and it was pretty slick) I don't think they really "get it."

The "wars over resources" argument is something of a farce considering:
          a) the global nature of the economy.  Energy needs are tied to
              the respective countries involvement in the global markets.  If
              your not engaging in commerce with your neighbors, you
              probably don't need too much energy;

          b) There are many alternatives to oil.  Consider China.  sure they
              are going to need massive amounts of energy in the coming
              decades, but who is to say they can't get a large amount of
              their power from nuclear sources.  If China has anything it
              large expanses of useless, barren land; perfect locals for
              nuclear waste :-D

The easiest way to put the brakes on the Chinese economy would be to simply stop buying their crap, but wars are much more fun to talk about, right?!?

<homer simpson>The two greatest words in the english language.  De fault!  De fault!  De fault!<homer simpson>

Coincidentally, this was the episode were homer was selected to go into space .

LM has definitely got some problems.  As good as the RD-180 is for lifting payload, it has a nasty habit of generating 3g lateral kicks during staging; as far as I know this problem still persist.  I honestly don't think they will be able to man rate the AtlasV for manned missions, some of the LM folks I talked to didn't take the prospect of man-rating the AV too seriously (though this was before Challenger).

The x-33 concept doesn't have a chance of making it to orbit for the forseeable future.  The required structural efficiency is nearly an order of magnitude too low to be accomplished by today's technology.

The Air Force currectly owns all of the x-33s hardware.  IMO the most valuable portion of this design was the aerospike engine.  I could see this being used as a kick stage for future scramjet technology.

Hey guys, good to see we still have a health discussion here .

With respect to the small launcher issue, if you plan on going that route (which is not all bad, IMO) you first need to develop in-orbit construction methods.  As assembly time grows longer, mission cost begin to explode *cough* ISS/Shuttle.  Further, this method is useful ONLY if you leverage existing launch technologies.

My personal belief is that the first manned mission should be solely focused on building a base of operations in preparation of future manned missions.  All of the experiments should be focused on testing technologies and keeping the crew alive; this is much more important as it will lay the groundwork for sending larger crews.

I think a cryogenic tankage would be unneccisary when you could just go with gelled MMH/iRFNA loaded with Al; I'm not so much worried about the safety as I am the complexity of cryogenic propellant (KISS).  I know a lot of folks would like to just go with in-situ off the bat, but in a foreign environment its better to go with those things you are familiar with.

I don't know about the DC-X, but the VentureStar/X-33 didn't have a chance in hell of making it to orbit.  Truth be told, the calculations to disproved the concept could be done on the back of a napkin.  The purpose of the x-33 program was to develop technologies that NASA - at the time - felt would be necessary for developing a next generation crew transfer vehicle (non-cylindrical composite tanks, honeycomb structure, aerospike engine).  Unfortunately, NASA did a horrible job of letting the public know this, thus expectations of the program were unreasonable high.  If I recall, the x-33 required a structural efficiency of .05, which is nearly an order of magnitude greater than an existing launch technology...very unlikely to happen.  I'll try to verify this number later.

And the 2B dollar estimate for the HL-20/OSP were never going to happen.  Remember how much the SSME turbopump redesign ended up costing?  It's nothing unique to NASA, but development cost end up running *much* higher than the original proposal.  Part of this is because everyone underbids with the cost will be and know NASA/military will give them more money to complete the project.  Just the nature of the industry, but it's one of the first things that have to change if we are to accomplish a Mars mission.

On a side note, I didn't mean to imply I was working for NASA when I did work on the HL-20.  It was a research project while I was in school looking at some of the entry dynamics.  This, of course, is not to say that I won't be working for NASA in the next month, but that a matter for another time.

GCNR,
Sorry, I meant plasma based propulsion systems for exploration of the outer solar system.  Winged vehicles only make sense if you are making an entry from Earth orbit.  One possibility I've been thinking about are "desposable" heat shields that could be mounted on a winged vehicle and jettisoned once the vehicle is subsonic.  I haven't done any work on this, so please take it with a gigantic grain of salt.

My 3-4B dollar figure comes from the fact that NASA is already seeding millions of dollars to many universities and institutions across the country for the design on a new spaceflight architecture.  If NASA can properly manage these energies (a.k.a. don't let the researchers squander the money on pipe-dream or misc. side projects) then it could possibly be done.  If the aerospace industry is to pull off a mission of this scale, it really needs to display the ability to tighten the purse strings when required.  I'm just not seeing the contributing factors that would inflate the cost to the 5-6B dollar range; prototyping, simulation, live-testing seem as though they would be the same whether you go with a winged vehicle or capsule.  The only place where cost will be distinguishable is at the production stage where a winged vehicle would probably have a higher intial cost, but will deminish due to it's reusability.  Definitely a topic that needs more discussion.

The size of the crew is going to depend more on psychology rather than mission requirements.  For instance, you probably going to want an even numbered crew for an interplanetary mission.  When people are placed in confined spaces for long periods of time, you don't want critical mission decisions to come down to one person/vote.  There is similar support as to why you would want a 6 person crew as oppose to a 4 person crew (isolation of the minority view), which is certainly relevant for long duration missions.

Hell, the x-38 CRV was a $2 billion dollar program and that was a dead stick - parasailing contraption that had no reusability requirement.  An HL-20/42 type program would be twice the cost w/o a doubt.

With respect to In-Situ production, absolutely NO manned flight equipment can rely upon it until FULL SCALE production capabilities can be proven, preferably on the martian surface.  You can send humans people on a mission of this scale with unproven hardware,... that's unacceptable.

With respect to engine in general... they will be American-made, end of story.  What we should push for is an efficient production methodology by whom every is slated to build the engine(s).  We need clear, honest communication from those involved in the project (rather than the abomination that nasa.gov is).  If that mean Mars Society provides funding for Russian rocket scientist to conduct an independent review of component development, so be it.

The crew needs to come down w/ some sort of pressurized shelter.  If there is a problem with the HAB or conditions at the MAV site begin to deteriorate for some reason (unstable surface, sinkholes); the crew needs to be able to get to the MAV site immediately and launch ASAP.

The question of SSTO or staged for the MAV is an important one.  In my view, your better off going SSTO and dealing w/ the weight penalty.  Flight engineers have a hard time with staging equipment sitting on the launch pad one-hundred feet away; image the issues you would need to account for with equipment 35M mi away (on a good day).  At the end of the day, you have to eat some of these weight penalties for the sake of safety.

Your disregarding testing and simulation that must be done both on Earth and on Mars.  Heck, the x-38 program was expensive and that was just dropping a tiny craft from a b-52.

These things are easy on Earth because we've been doing them for 30-40 years; the margin for mistakes is much more narrow on Mars (no AAA, no ER).

A steerable parachute would be a waste of resources, the astronauts could probably walk the distance that would be gained from "steerability".  Especially if the crew is coming down on a sled with the rover, "fogetaboutit."

As has been pointed out earlier, your going to want to make course corrections as high in the atmosphere as possible to shrink your landing elipse.  It's a matter of energy conservation; why dilly-dally around hovering over the surface when you can just drive to your destination.