Design of Manned Mission to Mars

Lauge said:
Pellegrino also claims that the tractor design reduces structural mass, since the spacecraft structure is in tension rather than in compression during boost. It sounds reasonable to me, but I'm no rocket scientist ( ;)), so I can't say whether this is a valid argument or just a marketing gimmick.

It's reasonable enough. The antimatter "reaction chamber" is where the radioactive nastiness happens. Numerous particles are created, one being high energy gamma rays. Being essentially light that can penetrate lead (and thus cannot be reflected), the gamma ray flux is not a beam, but an omnidirectional glow. The gamma rays cannot be readily used for anything since they pass through most shielding (of reasonable mass) and are unaffected by magnetic fields. Thus the best way to deal with gamma rays is simple distance. In the case of Valkyrie, that distance is measured in kilometers... easy to do with a tug configuration and a tether, a nightmare with a pusher configuration and a "tower." The exhaust which will blow past the crew and whatnot is largely composed of mesons, which *are* readily affected by magnetic fields, and thus relatively easily shielded against.
 
prolific1 said:
I think I'll revert this design back to a low thrust NEP setup like the STCAEM NEP study that had a similar engine layout.

Note that in this case the engine modules on each are are equipped with *many* individual ion engines. One craps out, the easiest thing to do is shut down an opposing member to balance out the thrust. Easy to do when you have a lot of engines.
 
Note that in this case the engine modules on each are are equipped with *many* individual ion engines. One craps out, the easiest thing to do is shut down an opposing member to balance out the thrust. Easy to do when you have a lot of engines.

Duly noted ;D
 
New NEP tractor design. I have yet to include the reactor (which I would also like to mount in tension) as well as the radiators. I'll wait before going that far until this design survives qualified criticism. ;D
 

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1) Why the forward swept supports? Looks beefier'n needed.
2) The propellant tanks should not be on a tether. Propellant lines like to be rigid pipes, not floppy hoses. And the closer to the engines, the better. Reduces mass.
3) The reactor should be as far from the crew as possible. With a design like this, projecting it forward *slightly* would make a measure of sense. When the ship starts tumbling, having the reactor and it's heavy shield well forward will stabilize that part of the ship.
4) With a low acceleration design like this, having the radiators projecting forward is acceptible. if the radiators are fixed items, rather than folding, then forward projecting radiators become downward hanging radiators during tumble. And since tumble has a much greater g-loading than acceleration, that's best.
 
Actually the center element is a truss as opposed to a tether...it's just small. I can make it bigger, unsweep the "wings." I intended to mount the reactor well forward of the crew module though I have no reference as to what such a spacecraft reactor should or might look like in the future...or now for that matter.
 
Funny question...how many fusion rockets strapped together would it take to get to mars one way in say 34 hours? I'm talking about, and forgive my shoddy math, a one way - brachistochrone flight plan like...I dunno...a 252km/s velocity achieved via a 16 hr burn time @ .75g followed by a 16 hr braking burn into Mars orbit.
 
prolific1 said:
Funny question...how many fusion rockets strapped together would it take to get to mars one way in say 34 hours?

Again, math:
1> distance = 36 million miles = 58 million km = 58 billion meters
2> half that distance = 29,000,000,000 meters (the distance covered in "boost," the other half covered in "braking)
3> time to cover 29gigameters = 34/2 = 17 hours = 61,200 seconds
4> uniform acceleration required found from this equation...

distance = 1/2 * acceleration * time squared
D = 0.5*A*T^2
A = 2*D/(T^2) = 2*29,000,000,000/(61,200^2) = 15.5 meters/sec^2 = 1.6 gees

So at a minimum, you'd need a propulsion system capable of providing an average acceleration of 1.6 gees for 34 hours. Realistically, ain't no such thing on the horizon.

The total delta V would be about (2*61,200)*15.5 = 1,897,000 meters per second. dV = exhaust velocity * mass ratio.

If your exhaust velocity was 4415 meters/sec (Isp = 450, SSME), your mass ratio would be 4125, which is insane. If your exhaust velocity was 981,000 m/s (Isp = 100,000 = advanced fusion engine), your mass ratio would be 1.9, which is feasible.

So from an Isp standpoint, a fusion engine could do it. But from a thrust standpoint, not a chance in hell. Glenn Research Center's "Discovery II" manned Jupiter fusion vehicle assumed an Isp around 40,000 seconds, but a thrust of only 6,000 or so pounds, giving an acceleration measered in milligees. Strapping on more engines won't help, as the T/W of the engines alone is far below wha you need for the full vehicle.
 
Hmmmn. Taking a moment for the brush fire in my brain to be extinguished.

This question emerged because I was wondering what it would take, and if it takes centuries for it to be a reality so be it, for travel to Mars to be as short as a long flight to a distant country?

Dude your genius knows no bounds...or my feebleness Whichever works.
 
prolific1 said:
This question emerged because I was wondering what it would take, and if it takes centuries for it to be a reality so be it, for travel to Mars to be as short as a long flight to a distant country?

What, like 18 hours? that'd be 9 hours (32,400 sec) to reach the halfway point, requiring an average acceleration of 5.6 gees. 5.6 gees for *18* hours would be pretty damned rough. So if you want to get there that fast, you'll need to develop a few things in addition to an especially badass propulsion system
1) Star Trek style artificial gravity ("inertial dampers" whatever)
or
2) 5th Element style suspended animation
or
3) Abyss-style breathable fluids

I'd bet that 2) and 3) are both doable on a timescale of decades. 1) is something that will have to await something on the scale of Medusa, I woudl think.
 
prolific1 said:
Actually at what point can we find some equilibrium with this figure? Like 72hours? More?

Not sure what you mean.

Also, keep in mind that 36 million mile distance from Earth to Mars is at closest approach (opposition), and happens only once every 26 months or so. At conjunction, however, Earth and Mars can be as far as about 250 million miles. Getting there in 18 hours will damn near require warp drive.

elongationA.jpg
 
Not sure what you mean.

What I meant is what is the fastest that can be achieved with the thrust capability of a Fusion engine? For example...if not 36hours then how about 2 days, 3 days, a week?

So from an Isp standpoint, a fusion engine could do it. But from a thrust standpoint, not a chance in hell.

Basically how much of this unrealistic ambition need be rolled back before it becomes real?
 
prolific1 said:
Not sure what you mean.

What I meant is what is the fastest that can be achieved with the thrust capability of a Fusion engine? For example...if not 36hours then how about 2 days, 3 days, a week?

A = 2*D/(T^2) => (T^2)=(2*D)/A => T = sqrt ((2*D)/A)

Assume 10 milligee acceleration... 0.0981 m/sec. T = sqrt ((2*29,000,000,000)/0.0981) = 769,000 seconds = 8.9 days for the first leg, 17.8 days total.
 
Strangely the Penn State University ICAN II, with all its Anti-Matter glory, is only talking about 2 week transit time to Mars if I recall. Don't get me wrong, that's pretty damn quick, but it ain't blowing my mind like the Fusion deal.
 
let me put this way

Fusion is "Cheaper" as the Anti-Matter glory

because the manufacture cost
anti matter has to be "produced" in a 28 GeV particle accelerator.
those are expensive Hardware with high maintenance and operational costs !

for trip to Mars you need grams of Anti-matter
until now CERN has produced NINE (9) antihydrogen atoms

the great Robert L. Forward made in 1980s for USAF a Feasibility study
for the use of Anti-matter as fuel for USAF AIRCRAFT and Spacecraft.
he proved it can work but for high cost for Infrastructure
so the cost for one milligram Anti-matter would be around $1.2 billion dollar (in today value)

and for now, no one has put Anti-matter Magnetic trap container in Rocket and Launch it
(and Rocket launch are very violent events for the Payload)

On rocket engine how use Anti-matter (Forget Star Trek )
first is the Thermal Rocket (similar to NERVA engine)
Anti-matter is shot in block of tungsten, who gets redhot, cooled by Hydrogene and this true nozzle
this engine works better as NERVA, only limited by the melting temperature of the tungsten
that's at 3695 Kelvin (NERVA Kiwi series work at 2370 K )

second one its a "Photon Drive"
were Anti-matter and Matter annihilation inside a magnetic nozzle
40% of the output are gamma rays (need heavy shielding)
60% are high energy particles called pion
they move at 94% lightspeed for 21 meters,
then pion decay into particles called muons
who move 1850 meter until they decay into positrons and electrons
those muons can be used to heat Hydrogene to hot plasma and increase the trust
but engine nozzle is 1,871 kilometer or 1.162 miles long !

a variation on this theme is to use those Muons for fusion for deuterium and triton
 
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Michel Van said:
Fusion is "Cheaper" as the Anti-Matter glory because the manufacture cost .......

True, for now. However, as I see it, once (if?) antimatter (AM) becomes a commodity, rather than a science project, prices are bound to go down. After all, the two places in the world today that routinely create AM (CERN and Fermilabs) were not designed for that purpose. Even using the same technology, a plant optimized for the production of AM is bound to be more efficient, giving us higher output and lower cost (don't ask me by how much - I have no idea).


Michel Van said:
first is the Thermal Rocket (similar to NERVA engine)
Anti-matter is shot in block of tungsten, who gets redhot, cooled by Hydrogene and this true nozzle
this engine works better as NERVA, only limited by the melting temperature of the tungsten
that's at 3695 Kelvin (NERVA Kiwi series work at 2370 K )

second one its a "Photon Drive"
were Anti-matter and Matter annihilation inside a magnetic nozzle
40% of the output are gamma rays (need heavy shielding)
60% are high energy particles called pion
they move at 94% lightspeed for 21 meters,
then pion decay into particles called muons
who move 1850 meter until they decay into positrons and electrons
those muons can be used to heat Hydrogene to hot plasma and increase the trust
but engine nozzle is 1.871 kilometer or 1,162 miles long !

a variation on this theme is to use those Muons for fusion for deuterium and triton
http://en.wikipedia.org/wiki/Muon-catalyzed_fusion

You forgot a couple of options:

The gas-core AM engine, where a small amount of AM is injected into a propellant stream (H2, water, whatever). The AM annihilates with part of the propellant, and the energy released heats the remaining propellant, which is ejected to produce thrust.

When you say "...those muons can be used to heat Hydrogene to hot plasma and increase the trust", this would create a so-called plasma-core AM engine (my personal favourite). Of course, you also reduce the specific impulse compared to a beam-core ("photon drive") AM engine.

These engines (gas, plasma and beam core) are described, with projected performance data, on http://www.projectrho.com/rocket/rocket3c2.html

Another intriguing option is the AM sail (http://www.daviddarling.info/encyclopedia/A/antimatter-driven_sail.html), where the inside/rear-side of a space sail is coated with a thin layer of fission fuel. This layer is then bombarded with AM particles. These induce fission in the sail's coating, and the ejected fission products bounce off the sail to produce thrust.

In short: Antimatter! Turning a boring day into a fun day ;D

Regards & all,

Thomas L. Nielsen
 
Lauge said:
The gas-core AM engine, where a small amount of AM is injected into a propellant stream (H2, water, whatever). The AM annihilates with part of the propellant, and the energy released heats the remaining propellant, which is ejected to produce thrust.

Sadly, that's not likely to work very well. The reaction products of a proton/anti-proton reaction will very likely pass right through a cloud of even compressed hydrogen with minimal interaction. You need something like tungsten as sort of a heat exchanger.

Sigh.

OK, I had to dig deep through several backups to find this... my aborted "Spacecraft Design for Science Fiction Writers" book. Last updated, 2004. I thought it was going to be a pretty unique sort of thing, but then http://www.projectrho.com/rocket/ came along and pretty much made it moot. Anyway, here's a cut&paste from it ("XXX" implies not positronic porn, but Data To Be Entered, at some point)...

An Antimatter Primer

As science fiction writers and readers know, rocket fuels don’t get much better than antimatter. Antimatter is, as far as physicists have been able to determine, just like normal matter, except that the charges on the particles are reversed. There appears to be an anti-particle for every particle known… anti-protons and positrons being the particles of greatest interest here. Where this is important is that since the charges of a proton and an anti-proton are reversed, they will attract each other (whereas protons repel each other), and, upon contact, they destroy each other and liberate surprising quantities of energy as related by E=MC². This is two orders of magnitude more energy released per kilogram than is done by nuclear fission reactions and about XXX more energy released per kilogram than by chemical reactions.

For antimatter based rocketry, the antiproton and the positron are the particles to pay attention to. Each proton is about 1800 times more massive than each electron; the same mass ratio applies for antiprotons and positrons, thus the energy density is vastly higher for an antiproton system than for a positron system. The functionally best systems will be those based on anti-hydrogen… while antiprotons will always remain a very low-density cloud of plasma (and positrons even more tenuous), anti-hydrogen will be far denser and easier to deal with in bulk. Clearly anti-hydrogen cannot be manipulated with pipes and pumps as hydrogen can, but it can, with effort and skill, be physically manipulated with magnetic fields.

Anti-hydrogen is the highest up the antimatter periodical table that can be realistically imagined for anything remotely resembling the near future. In order to produce anti-helium, two anti-hydrogen atoms would need to be fused together, and to make useful quantities of the stuff, a vast number of such fusions would be required. This would, obviously, require a very good fusion reactor with absolute control over every particle within it. We have not yet produced a decent hydrogen-based fusion reactor, and an anti-hydrogen fusion reactor would be much more complex. Worse yet, anti-helium would not buy the users much. It would be far more difficult to freeze to a solid and manipulate than would be anti-hydrogen; consequently, it would be a low-density cold gas… lower density by far than anti-hydrogen ice. To get to something really valuable, further fusion still would be required… and we simply have no good idea how to do that even with normal matter. For all practical purposes, barring some rather startling discoveries, the existence of anti-aluminum, say, or anti-iron will have to be predicated on the notion of finding a large lump of it floating in deep, low-dust space (which would be a startling enough discovery).

Anti-hydrogen is known to exist in the natural world, but the known sources are quasars and exploding galaxies many millions or billions of lightyears away. Antimatter needs to be manufactured. And it has been; the principles on how to make the stuff are well know. The process is, however, vastly inefficient, required many XXX times more energy input than the antimatter could ever unleash. Antimatter production today is spectacularly expensive, with estimates of $XXX per microgram of anti-protons. The cost is, however, decreasing; current production is entirely experimental, not true production line work; and it is safe to assume that new inventions and discoveries will improve the cost by several to many orders of magnitude.

And fortunately, the cost of antimatter does not need to drop to anything remotely like the cost of conventional materials in order for it to become cost competitive. A single stage launch vehicle with the payload capacity of the Space Shuttle would require only a few tons of water and 35 (xxx?) milligrams of antimatter to attain the same orbit.

As mentioned a little earlier, the antiproton and the positron are the two antiparticles of greatest interest for antimatter-based propulsion systems. There are other antiparticles, such as antinuetrons, but they would be even more difficult to manufacture and deal with, and would provide no advantages The physics of the different annihilation reactions will be described. Remember, the reader does not necessarily need to have all of this explained to him or her, any more than a reader of a novel that includes a jetliner needs to have the physics of high temperature multi-stage turbine combustors explained.

Proton-antiproton annihilation reactions do not produce the “pure energy” so often mentioned in science fiction, but instead release a small blizzard of lesser, but very energetic, particles. Specifically, the typical reaction will produce an average of 1.6 π0 mesons (or pion, without electrical charge) and 1.6 charged π+ mesons and 1.6 π- mesons (a pion with either a positive or negative electrical charge). These pions will both be moving at relativistic speeds. The combination of the rest mass of the particles (140 MeV for the charged pions and 135 MeV for the π0 meson) and their kinetic energy (about 252 MeV per pion) gives a total energy release of 1876 MeV (or about 3E-10 Joules). But the reactions aren’t over. The neutral pion nearly immediately (90 attoseconds) decays into two gamma rays with an energy of about 200 MeV each. The charged pions decay in about 70 nanoseconds (a range of about 21 meters in free space, as the pions are moving at about 94% lightspeed) to a neutrino and an unstable charged muon. The neutrino carries off about 22% of the charged pion energy; and given that there is no known way to capture neutrinos in numbers even remotely useful, this energy can be considered as lost. The muon in turn decays within 6.2 microseconds (or a range of more than a kilometer and a three quarters in free space) into two neutrinos and either an electron and a positron. Again, the neutrino energy is lost. The positrons can be expected to react with the electrons from other reactions (or with electrons in engine structures or propellants), giving off two 0.511 MeV gamma rays. The end result is that approximately 50% of the energy of an unintercepted proton:antiproton reaction will be forever lost as neutrinos.

The distance charged pions travel prior to decay is larger than most foreseeable rocket engines, and the gamma rays from the neutral pion can also be intercepted by a material structure of some type. Gamma rays are intercepted by material structures with exponential attenuation, which means that if one centimeter of, say, lead will absorb 90% of the gamma rays, another centimeter will absorb 90% of the remaining gamma rays, another centimeter will absorb 90% of the gamma rays that got through the first two centimeters, and so on. A further, more detailed discussion of gamma ray shielding is in the XXX chapter. While this means that modest increases in shield/heat exchanger thickness will greatly reduce the gamma ray flux, mathematically the gamma rays are never entirely blocked. Charged pions are a different story. They are not exponentially attenuated, but instead have definite ranges within certain materials, depending upon the kinetic energy of the pions. While gamma rays are eventually stopped by impacting atomic nuclei, the pions lose kinetic by excitation of the electrons of the atoms they move through.

It has been found that a cylinder of tungsten 28 centimeters in diameter and 28 centimeters in length would, if the proton:antiproton reaction were occurring in its geometric center, absorb virtually all of the initial 200MeV gamma rays, as well as the charged pions (by absorbing them prior to their decay, the energy that would have gone into neutrinoes is retained). This absorbed radiation can be used in a number of ways for propulsion, generally to transfer energy to a working fluid. Unfortunately, the absorption of the pions by the tungsten is through collisions with nuclei, with the result that not only is the pions energy absorbed by the tungsten, but the tungsten becomes a neutron emitter. The tungsten becomes radioactive (though not as bad as a nuclear rocket).

It is of course possible that some technology could be invented that would in some way utilize the energy otherwise lost through the neutrinos. But there is as yet no theoretical justification for such a system, and there are ways of utilizing the charged pions directly for thrust prior to their decay.


In contrast, electron:positron reactions are much simpler… and have in fact already been described. The reaction gives off two 0.511 MeV gamma rays; these gamma rays are much more readily absorbed than are the pions.
 
big THX to Scott and Thomas to bring my clumsy English in to better words :-[

something allot forget if they design Manned Mission
the Cost for Development and Mission cost, build, launch and running it!

i run in that trap for Comic strip proposal Wat include Interplanetary manned mission

ODYSSEY (after Homer, Not Kubrick)
how use "Trimodal NTR" System
a Nerva type with injection of oxygene for increase the trust, for get out Orbit
the reactorcore is use to generating electricity for the ship (A turbo-Brayton cycle)
and powered Ionengines for cruse (to reduce flytime)

ODYSSEY is build from several Moduls launch by Energia like Rocket
main engine Module NTR (include turbopumps for LANTR )
several module makes 60 meter long cylinder with radiators (Brayton cycle)
who seperate main engine Module from Mission module
in middle of cylinder is Ionengine modul and two communication antenna
then comes Mission Modules like Lander or cargo
on top Habitat Module and "Lifeboat" with Earth return module
on side comes Fuels and oxydiser tanks (lox/Lh2 and Lox/Methane)
the ship spins for artificial gravity durnig transit

Development cost on ODYSSEY
There costly R&D on two enginesystem NTR/LANTR and Ionengine
in real world NASA killed NERVA and keep R&D on Ionengine on a shoestring budget !
next to that R&D on heavy lift rocket and cost for Infrastructure and building them.
Mission Cost
a Dozen launches in low orbit to assemble ODYSSEY
you know at NASA dit to Saturn V production line
ODYSSEY Program cost would be over $500 Billion Dollars :eek:

Wat was comicstrip story about ?
it about Europe 30 year after a Nuclear war in in 1960s
so ODYSSEY wend fast in my archive.
and i change it to cheaper Boeing Integrated Manned Interplanetary Spacecraft.
http://www.astronautix.com/craft/imis1968.htm
 
Pretty cool Michael. I would love to see your work.

I've been writing mostly short fiction (on a variety of subjects). My first few designs were to simply address my belief that it will be several decades before a manned Mars effort happens and what it could look like.

All the crazy math that Scott helped me with after is for a more fun idea.
 
prolific1 said:
Pretty cool Michael. I would love to see your work.

I've been writing mostly short fiction (on a variety of subjects). My first few designs were to simply address my belief that it will be several decades before a manned Mars effort happens and what it could look like.

All the crazy math that Scott helped me with after is for a more fun idea.

sadly,
i presented my proposal and rest of my work at Belgium and French Comic Publisher
and get my but kick :mad:
they wanted Fantasy, Fantasy and Fantasy and again Fantasy
because some one made with Fantasy "Lanfeust de Troy" in 1994 a Comic Superblockbuster
since then there a Fantasy insanity at Belgium and French Comic Publisher

even one Publisher ask me make infam copy of Lanfeust, i refused
but he found another moron to do it and wend bankrupt ;D

for the moment i work on serveral proposal, who i gona present a german Publisher
or i start to make Superhero comic for DC or Marvel :-\

let see if i lucky this time...
 
Yeah nuclear thermal solid core for Mars is probably good enough. ISP of 800 s or so? The largest power nuclear reactor ever tested was actually a solid core nuclear rocket.

When going further you start looking into other things to have higher ISP...
 
Mr. Blam...more...er...math questions. Let's just say I had some really friggin awesome engine(s) of some nuclear fashion dreamed up in a secretive gubmint lab - that could accelerate at 1g for as long as needed, say half way to the old Red Dustball - brachistochrone like and all. How long would it take to get there? The 18hour bit was a flattening experience and 16 days more like a Carnival Cruise. The reason I ask is because the more plausible spher o mak deal accelerated in Milligees.
 
prolific1 said:
Mr. Blam...more...er...math questions. Let's just say I had some really friggin awesome engine(s) of some nuclear fashion dreamed up in a secretive gubmint lab - that could accelerate at 1g for as long as needed, say half way to the old Red Dustball - brachistochrone like and all. How long would it take to get there? The 18hour bit was a flattening experience and 16 days more like a Carnival Cruise. The reason I ask is because the more plausible spher o mak deal accelerated in Milligees.

Once again, it depends on just how the planets are alligned. At opposition, distance is 36 million miles (29 M km for half of the trip). At conjunction, 250 million miles (200M km halfway). So at 9.81 M/sec^2 average acceleration...

D = 0.5*A*T^2 => T = sqrt ((2*D)/A)

T = sqrt ((2*29,000,000,000)/9.81) = 21.4 hours halfway = 42.7 hours total
T = sqrt ((2*200,000,000,000)/9.81) = 56 hours halfway = 112 hours total
 
I was directed to a little ol' book called: Future Spacecraft Propulsion Systems by
Paul A. Czysz and Claudio Bruno by my friend (well not really - we only spoke once) Yigal Ronen from BGU in Israel. He had some apparently revolutionary idea for using Americium 242 in nuclear rockets as a propellant and an energy source or something. All way over my head. He was a cool chap though and though he himself couldn't go into to detail how his idea might appear (being a Nuclear Physicist and not an Aerospace Engineer) he did pass along the title to a rather robustly sized (500 pages) book on the subject. Now all I gotta do is come up with $150 and I can score me a copy.
 
prolific1 said:
I was directed to a little ol' book called: Future Spacecraft Propulsion Systems by
Paul A. Czysz and Claudio Bruno by my friend (well not really - we only spoke once) Yigal Ronen from BGU in Israel. He had some apparently revolutionary idea for using Americium 242 in nuclear rockets as a propellant and an energy source or something. All way over my head. He was a cool chap though and though he himself couldn't go into to detail how his idea might appear (being a Nuclear Physicist and not an Aerospace Engineer) he did pass along the title to a rather robustly sized (500 pages) book on the subject. Now all I gotta do is come up with $150 and I can score me a copy.

While you're saving up your money, you can read parts online:
http://books.google.com/books?id=aI9QhDA4AVwC&printsec=frontcover&dq=Paul+A.+Czysz&cd=1#v=onepage&q=&f=false
 
http://www.nextbigfuture.com/2016/09/nasa-innovative-advanced-concepts.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+blogspot%2Fadvancednano+%28nextbigfuture%29&utm_content=FaceBook
 

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