Minimal Manned Mars Mission - 2*Briz = doable! + a NEA

[DBowman]

2 hours ago, fredinno said:

making wet workshops during transit is really a recipe for disaster

I'm inclined to agree with you re the wetlab. It seems like such a lifted mass waste, but it's not like the stage is usable as a nab without significant stage redesign and in transit work (though they have plenty of time).

One of the proposed Saturn MLV extensions would have had the extra grunt to loft another 13 ton to LEO, so it probably could have done the CSM+ESM+Skylab style dry converted upper stage. (KSP Apollo Applications challenge)

[DBowman]

An idea to save 100s of pounds of RCS.

They planned to use RCS to resist spinning up the flywheels that had been consumed maintaining attitude against the solar wind. See if this makes sense:

• imagine the problem as a craft wanting to maintain the sun at 90 degrees
• but the solar wind is pushing net pushing a little forward of the center of mass, generating some torque clockwise, say to Jeb's left
• that torque is resisted by bleeding off / adding angular momentum to a flywheel
• eventually the flywheel is either stopped or has reached max rpm - it's saturated
• they planned then to generate torque 'the other way' via RCS and resist by spinning up / bleeding off angular momentum to the fly wheel
• couldn't they just roll the craft 180 degrees, Jeb is now upside down with the solar wind torque pushing to his right - it's pusing the right way to de-saturate the flywheel.
• that would eliminate the need for a few hundred pounds of RCS fuel

have I missed something?

Edit:

yes I am  what I propose will actually do nothing.

They need to rotate 180 degrees around the Sol-COM axis. This is maybe a little like Soyuz orbiters spin regime, as I understand it a 'flat spin' keeping it's solar arrays sun-ward - not sure if they worry about the COM given the short duration flights - probably not.

Also I'll have to read up some more - their issue is not simply saturating / exhausting the spin but precessing the gyro to gimbal lock.

Edited February 18, 2016 by DBowman
fix what I missed

[fredinno]

11 hours ago, DBowman said:

I'm inclined to agree with you re the wetlab. It seems like such a lifted mass waste, but it's not like the stage is usable as a nab without significant stage redesign and in transit work (though they have plenty of time).

One of the proposed Saturn MLV extensions would have had the extra grunt to loft another 13 ton to LEO, so it probably could have done the CSM+ESM+Skylab style dry converted upper stage. (KSP Apollo Applications challenge)

Really, the only way you could increase Saturn V capacity was by adding boosters- the rocket was the max. length it could be. So yeah, with a set of F-1 powered LRBs, you could do a dry workshop in a single launch. Practically, though, you'd do LEO assembly instead.

[AngelLestat]

When someone talk about simplicity, it means try to avoid sci-fi solutions or very complex systems or mechanism when they are no needed.
Example..  magnetic shielding or a new type of propulsion that requires development, money and time.

But you will not send an old computer that weighs 100 kg and use super old OS that requires 5 times more money in software development, just with the excuse that it worked in a 1990 spacecraft.
Use the last tech that we use commercially and just add redundancy in case the other 2 or 3 fails.

Quote

No fancy recycling: oxygen recycling via Sabatier etc - ISS experience is that it's troublesome (breakdowns, mystery smells, fire hazard, nasty chemicals are part of the device). Similarly for Elektron electrolysing H2O. Maybe the ISS zeolite bed and vent to vacuum for CO2 removal might be okay.

 

Forget to use something from the ISS life support, is old as hell (1960), weights a lot and function really bad.
A modern PEM electrolysis device will weigh 20 times less and you can have extra redundancy, it will work much better and consume less energy.
I guess that a modern life support using modern devices could save you a lot of weight, it will make the trip more safe.
One thing to have into account.. that each kg you save, it makes the whole mission much cheaper and safe.. Because the real inconvenients are deltav and how to land heavy payloads in mars, that is the most hard to do in which all effort should be focus. 

Quote

Pressure bottled oxygen: Cryostorage is probably more compact and lighter but pressure storage should be almost as good mass wise and is much simpler. Oxygen candles sound cool (as it 'burns' it generates oxygen, how the emergency oxy on a passenger plane works) but massy and there were fire incidents with them on ISS.

If you place your oxygen tank in a key place of your ship, it will not heat and it would not require cooling..  and even if it does, it does not add any complexity..   those things does not add difficulties, Instead have a huge tank at big pressures might add.

Edited February 6, 2016 by AngelLestat

[Nibb31]

54 minutes ago, AngelLestat said:

When someone talk about simplicity, it means try to avoid sci-fi solutions or very complex systems or mechanism when they are no needed.
Example..  magnetic shielding or a new type of propulsion that requires development, money and time.

But you will not send an old computer that weighs 100 kg and use super old OS that requires 5 times more money in software development, just with the excuse that it worked in a 1990 spacecraft.
Use the last tech that we use commercially and just add redundancy in case the other 2 or 3 fails.

That's not how aerospace engineering works.

If you use the last tech that is available commercially, and you find out that it fails due to the extreme thermal, vibrational, or radiation environment, then the other 2 or 3 systems that you added for redundancy are likely to suffer the exact same fault. You've just added 3 times the necessary weight and lost a mission because you skimped on the price of using aerospace certified equipment.

Another example is SpaceX using off-the-shelf struts for its helium tanks instead of certified hardware. Sure, those struts were probably much cheaper and on paper they had the same strength, but once exposed to extreme cold and extreme vibration, they were used outside of their design parameters and failed.

There are some places where you can use off-the-shelf parts, but in most cases there are perfectly good reasons why aerospace engineers stick to certified components.

 

[fredinno]

1 hour ago, AngelLestat said:

When someone talk about simplicity, it means try to avoid sci-fi solutions or very complex systems or mechanism when they are no needed.
Example..  magnetic shielding or a new type of propulsion that requires development, money and time.

But you will not send an old computer that weighs 100 kg and use super old OS that requires 5 times more money in software development, just with the excuse that it worked in a 1990 spacecraft.
Use the last tech that we use commercially and just add redundancy in case the other 2 or 3 fails.

 

Forget to use something from the ISS life support, is old as hell (1960), weights a lot and function really bad.
A modern PEM electrolysis device will weigh 20 times less and you can have extra redundancy, it will work much better and consume less energy.
I guess that a modern life support using modern devices could save you a lot of weight, it will make the trip more safe.
One thing to have into account.. that each kg you save, it makes the whole mission much cheaper and safe.. Because the real inconvenients are deltav and how to land heavy payloads in mars, that is the most hard to do in which all effort should be focus. 

If you place your oxygen tank in a key place of your ship, it will not heat and it would not require cooling..  and even if it does, it does not add any complexity..   those things does not add difficulties, Instead have a huge tank at big pressures might add.

I don't think that's how oxygen tanks work... Thay'll boil off regardless of what you do, (other than cool the tanks down) TBH.

[DBowman]

3 hours ago, AngelLestat said:

But you will not send an old computer that weighs 100 kg and use super old OS that requires 5 times more money in software development, just with the excuse that it worked in a 1990 spacecraft.
Use the last tech that we use commercially and just add redundancy in case the other 2 or 3 fails.

 

2 hours ago, Nibb31 said:

If you use the last tech that is available commercially, and you find out that it fails due to the extreme thermal, vibrational, or radiation environment, then the other 2 or 3 systems that you added for redundancy are likely to suffer the exact same fault. You've just added 3 times the necessary weight and lost a mission because you skimped on the price of using aerospace certified equipment.

I think this is one of the central conundrums, these are trade-offs without necessarily obvious right answers. 'Luckily' launcher vehicles tend to be 'lumpy' in payload to LEO; if you are below the max payload there is no 'bonus' for further reducing mass, if you are above it then you have to compromise or there is no viable mission. The ISS LS does seem large, heavy and break down prone. So for example I'd pref LiOH which reliable, safe, can be radiation shielding, and might produce H₂O (depending who you are talking to) - but I cannot make that mass fit on an existing launcher so I have to back down to ISS style CDRA.

The biggest problem for new tech, even new builds of old principals, is having confidence it will run as it should without problems for 700 days. Which means either it's got to be something that is in use with statistics or you have to incur the cost and have the critical path lead time to run your own tests. For example testing the forward osmosis for urine is fairly simple; obtain from the supplier bag manufactured as long ago as possible and test efficiency up to 700 days since manufacture and put a few people on the 'urine diet' for two years or until the doctors are confident they are in equilibrium. Other things would be more complex and expensive to do, like 'fix' Souz H₂O₂ problem.

[AngelLestat]

5 hours ago, Nibb31 said:

That's not how aerospace engineering works.

I don't care how old style aerospace engineering works (which already show how inefficient it is and it can not take us anywhere unless they waste 100 billions.
I am only concern on how physics and probability works.

Quote

If you use the last tech that is available commercially, and you find out that it fails due to the extreme thermal, vibrational, or radiation environment, then the other 2 or 3 systems that you added for redundancy are likely to suffer the exact same fault. You've just added 3 times the necessary weight and lost a mission because you skimped on the price of using aerospace certified equipment.

sorry, but..  we can not do thermal tests?   or vibrational tests?   or even some radiation tests?
We can do all of them, the radiation test with a proton beam used for medicine.. it does not cover the full radioactivity range from space but it gives you a good idea on the amount of Single event upsets (0-1) that you will be dealing and how much devices in parallel you need.
Then if you want to study degeneration of materials, any scientific accelerator facility would be enough to simulate years of exposure in hours.

In the ISS they use all the time 68 IBM and 32 Lenovo laptops using windows 7 or linux, all in lan or wifi, with servers and other phones.
With no redundancy. 
The IT guy said they found a very similar amount of errors that a computer in ground will have.
http://www.cnet.com/news/interview-the-space-stations-it-guys/

 
Also not sure why you said that I will add 3 times the necessary weight?? what?   The orion computers are 3 or 5 very old (energy intensive and big mass), and they work in parallel. Not sure how my method will add more weight?

All the money you save in software development and operation can go to solve other issues.

Quote

Another example is SpaceX using off-the-shelf struts for its helium tanks instead of certified hardware. Sure, those struts were probably much cheaper and on paper they had the same strength, but once exposed to extreme cold and extreme vibration, they were used outside of their design parameters and failed.

What is the problem?  they lose a rocket.. but now they fix the issue and they continue ruling..
They need to lose like 5 rockets a year to equal the same cost that NASA would spent trying to do the same thing..

5 hours ago, fredinno said:

I don't think that's how oxygen tanks work... Thay'll boil off regardless of what you do, (other than cool the tanks down) TBH.

heh, they boil regardless of its conditions?  XD
I guess tanks follow physics, they need to be over certain temperature and at certain pressure to boil off.
If you keep those temperatures low, there is no need to concern.

2 hours ago, DBowman said:

The biggest problem for new tech, even new builds of old principals, is having confidence it will run as it should without problems for 700 days. Which means either it's got to be something that is in use with statistics or you have to incur the cost and have the critical path lead time to run your own tests. For example testing the forward osmosis for urine is fairly simple; obtain from the supplier bag manufactured as long ago as possible and test efficiency up to 700 days since manufacture and put a few people on the 'urine diet' for two years or until the doctors are confident they are in equilibrium. Other things would be more complex and expensive to do, like 'fix' Souz H₂O₂ problem.

heh, that is why it is a lot cheaper try venus first.
But when you focus in a tech problem and you study the old methods vs the new ones.. You will realize that in many of those can be highly improved without adding risk. I can not tell you what is the best for each case.. But I study the electrolysis case with the electron from the ISS, and its terrible the decision they took even in the year they were designing the ISS.
It was clearly evidence that the new PEM devices will work better, but they choose the MIR solution just because was used before.
Now is the thing that more problems generate in the ISS.

Edited February 7, 2016 by AngelLestat

[DBowman]

1 hour ago, AngelLestat said:

heh, that is why it is a lot cheaper try venus first.

The trajectory in this post is a 500 day Venus-Mars flyby, only 25% longer than the 1967 NASA proposal, might as well go for a two for one. (Admittedly I've not looked at pure Venus flyby trajectories at all).

6 hours ago, fredinno said:

Thay'll boil off regardless of what you do, (other than cool the tanks down) TBH.

Too much to hope that the boil off rate would be close to the consumption rate ... they must cool them. The 1967 guys opted for cryo O₂ so I guess I'll re-evaluate, the pressure tanks are heavy and bulky...

[fredinno]

5 hours ago, AngelLestat said:

I don't care how old style aerospace engineering works (which already show how inefficient it is and it can not take us anywhere unless they waste 100 billions.
I am only concern on how physics and probability works.

That still has a lot of influence on "new-style" aerospace engineering. SpaceX's stuff really isn't innovative aside from reuse. Everything on its expendavble version has been done before- earlier things like Pegasus and Atlas-Centaur by "Old Space companies" were a lot more innovative overall.

 

"Old space" and "New Space" are really pretty similar- just one is more conservative and profit-oriented than the other.

5 hours ago, AngelLestat said:

sorry, but..  we can not do thermal tests?   or vibrational tests?   or even some radiation tests?
We can do all of them, the radiation test with a proton beam used for medicine.. it does not cover the full radioactivity range from space but it gives you a good idea on the amount of Single event upsets (0-1) that you will be dealing and how much devices in parallel you need.
Then if you want to study degeneration of materials, any scientific accelerator facility would be enough to simulate years of exposure in hours.

In the ISS they use all the time 68 IBM and 32 Lenovo laptops using windows 7 or linux, all in lan or wifi, with servers and other phones.
With no redundancy. 
The IT guy said they found a very similar amount of errors that a computer in ground will have.
http://www.cnet.com/news/interview-the-space-stations-it-guys/

 
Also not sure why you said that I will add 3 times the necessary weight?? what?   The orion computers are 3 or 5 very old (energy intensive and big mass), and they work in parallel. Not sure how my method will add more weight?

All the money you save in software development and operation can go to solve other issues.

You can never really know for sure unless you go out into space and test it. Also, Orion uses 3 rad-hardened computers since it needs to pass through the Van Allen, while having little chance of all three breaking down. A non- rad hardened one would need a lot more copies of itself to do the same.

5 hours ago, AngelLestat said:

What is the problem?  they lose a rocket.. but now they fix the issue and they continue ruling..
They need to lose like 5 rockets a year to equal the same cost that NASA would spent trying to do the same thing..

The problem is that the more rockets you lose in comparison to successful ones, the more customers will move away from your company- especially if you spend your rockets on expensive GEO sats.

[Nibb31]

18 hours ago, AngelLestat said:

I don't care how old style aerospace engineering works (which already show how inefficient it is and it can not take us anywhere unless they waste 100 billions.
I am only concern on how physics and probability works.

Luckily for us, the industry doesn't care what you think about them either?

Quote

sorry, but..  we can not do thermal tests?   or vibrational tests?   or even some radiation tests?

Exactly. That's the process that's referred to as "certification". It involves a lot of testing, design work, and it costs a lot of money. Which is why space-rated hardware costs more.

You can't afford to put systems through certification every year. Once it's certified, 

Of course, the certification process is more stringent for vital systems that are exposed to space than for auxiliary systems like a laptop or a watch than fly inside a shirt-sleeve environment.

Quote

We can do all of them, the radiation test with a proton beam used for medicine.. it does not cover the full radioactivity range from space but it gives you a good idea on the amount of Single event upsets (0-1) that you will be dealing and how much devices in parallel you need.
Then if you want to study degeneration of materials, any scientific accelerator facility would be enough to simulate years of exposure in hours.

In the ISS they use all the time 68 IBM and 32 Lenovo laptops using windows 7 or linux, all in lan or wifi, with servers and other phones.
With no redundancy. 
The IT guy said they found a very similar amount of errors that a computer in ground will have.
http://www.cnet.com/news/interview-the-space-stations-it-guys/

Yes. And those laptops went through a whole certification process to make sure that they don't present a hazard to the space station. The same is true for the Nikon cameras. Any piece of hardware that goes up to the ISS has to go through a screening process to make sure that it doesn't put the crew or the station in danger. The certification is not as hard as for rad-hardened life-support equipment, but it still exists. If NASA needs laptops for Orion, they will need to be rad-hardened and vacuum-hardened.

Oh, and because that screening process takes a lot of time, many of the items are not "off-the-shelf" because they are actually obsolete. NASA uses Thinkpads that are sometimes a couple of generations behind, not because they are stupid, but because it makes good sense to use certified hardware instead of certifying new hardware every year, and because it makes sense to minimize spares by having only one or two different laptop models on the station to minimize spare parts., even when you need to send up a new one.

Quote

 
Also not sure why you said that I will add 3 times the necessary weight?? what?   The orion computers are 3 or 5 very old (energy intensive and big mass), and they work in parallel. Not sure how my method will add more weight?

You said "just add 3 for redundancy". If you have one certified system you don't always need 3 of them. Redundancy isn't just adding 3 of everything, especially when you're using an identical off-the-shelve system that wasn't designed to be used in space. If you expect it to fail, then adding 3 of the same is just adding dead weight, not redundancy.

Good redundancy is to have systems that serve different functions but can be used in place of something else. For example, instead of sending one big computer with 2 spares, you split the functions between 4 smaller computers and add 1 spare. In computer terms, that would be RAID5 vs RAID1. That's why avionics computers don't need to be 2016 Alienware gaming machines, even if the Alienware machines are cheaper. 

The Orion computers are actually the same off-the-shelf flight computers as the Boeing 787. They are not old or energy intensive. They are hardened and custom built for the job, with MIL-STD interfaces. This is what a certified off-the-shelf avionics computer looks like:

Good luck replacing it with a cheap laptop.

Quote

All the money you save in software development and operation can go to solve other issues.

What is the problem?  they lose a rocket.. but now they fix the issue and they continue ruling..
They need to lose like 5 rockets a year to equal the same cost that NASA would spent trying to do the same thing..

NASA isn't in the business of launching commercial satellites. 

 

Edited February 7, 2016 by Nibb31

[fredinno]

7 hours ago, Nibb31 said:

NASA isn't in the business of launching commercial satellites. 

And when they were, it ended disastrously... (Challenger)

[AngelLestat]

16 hours ago, DBowman said:

The trajectory in this post is a 500 day Venus-Mars flyby, only 25% longer than the 1967 NASA proposal, might as well go for a two for one. (Admittedly I've not looked at pure Venus flyby trajectories at all).

Too much to hope that the boil off rate would be close to the consumption rate ... they must cool them. The 1967 guys opted for cryo O₂ so I guess I'll re-evaluate, the pressure tanks are heavy and bulky...

Fly by to the moon may have sense..    but fly by to mars or venus or both..  sounds like a sick joke on the astronauts, all that dose of radiation, months and months of travel with psychological issues, just to see mars 1 day through the windows and stay in that can all the way back..  if the astronaut reach earth again.. can be a nice guy as dr mann in interstellar.

 Havoc mission lasted 440 days, 1 month in orbit, 1 month in the clouds.
In case you want to reduce the radiation doses you need to spent a lot more time in venus 1.2 years.
Transit: 112 days go, 96 days back.

 

12 hours ago, fredinno said:

That still has a lot of influence on "new-style" aerospace engineering. SpaceX's stuff really isn't innovative aside from reuse. 

Calling spacex: "a no innovative company.." is like calling Tesla: "a no innovative inventor".

9 hours ago, Nibb31 said:

Luckily for us, the industry doesn't care what you think about them either?

why spacex is in the top of the space industry then?   

9 hours ago, Nibb31 said:

Exactly. That's the process that's referred to as "certification". It involves a lot of testing, design work, and it costs a lot of money. Which is why space-rated hardware costs more.

Sorry, but I never said that you should no test your things...  I just said that you should use the top of the technology every time you can. Because when you not do that, all cost skyrockets.
Those test cost nothing, the test that cost money is things you test in space, crash test, or anything that requires launch things to high altitude. The software development is the most expensive in everything related to electronics.

9 hours ago, Nibb31 said:

Yes. And those laptops went through a whole certification process to make sure that they don't present a hazard to the space station. The same is true for the Nikon cameras. Any piece of hardware that goes up to the ISS has to go through a screening process to make sure that it doesn't put the crew or the station in danger. The certification is not as hard as for rad-hardened life-support equipment, but it still exists. If NASA needs laptops for Orion, they will need to be rad-hardened and vacuum-hardened.

They are just normal laptops with normal components..  the only important there was the vibration test that depends on the quality of the manufacture company. They use win7, so they are new compared to all the things that NASA use.
One of those problems is because when they start a project, they already start using old tech, then after 10 or 15 years of delay in turtle development speed, their tech has 15 or 20 years old, which increase a lot the cost because nobody remember how that thing work and you dont have support because that thing is no in the market anymore.
Also.. many other techs appear in that time which make your whole design totally outdated and pointless vs new approaches.   

9 hours ago, Nibb31 said:

You said "just add 3 for redundancy". If you have one certified system you don't always need 3 of them.

Why orion does then?

 

9 hours ago, Nibb31 said:

Redundancy isn't just adding 3 of everything, especially when you're using an identical off-the-shelve system that wasn't designed to be used in space. If you expect it to fail, then adding 3 of the same is just adding dead weight, not redundancy.

This topic is being derail, and for one weird reason according to one moderator.. is always my fault..
I explain this already.. the only thing that matters is deterioration (that can be tested and even find some shielding chosen its location), and Single event upsets that are solved with software or connecting devices in parallel. 

9 hours ago, Nibb31 said:

The Orion computers are actually the same off-the-shelf flight computers as the Boeing 787. They are not old or energy intensive. They are hardened and custom built for the job, with MIL-STD interfaces. This is what a certified off-the-shelf avionics computer looks like:

Good luck replacing it with a cheap laptop.

How much money and software development will need?  
You can not run any modern app in case you found that some may be usefull.  

You can design anything you want.. but if it cost more than the people is welling to pay.. then you stay in home.
That is reality.

[DBowman]

10 minutes ago, AngelLestat said:

Fly by to the moon may have sense..    but fly by to mars or venus or both..  sounds like a sick joke on the astronauts, all that dose of radiation, months and months of travel with psychological issues ...

500 days is not even close to current duration records for solo yachtsmen, time in the can is the least of your problems - read some books, do some blogging ...

[tater]

A manned flyby mission seems pretty pointless to me. 

Manned spacefight is a stunt. It's a stunt I'm particularly fond of, but that doesn't change what it is. For the price/mass to Mars of such a mission we could send fabulous orbiters and landers, even sample return, instead. What that won't do is create excitement for space, I get that. The last section of the proposal talks about adding excitement via EVA, IMAX, etc. Sorry, it's not that exciting to see a stunning Mars shot that happens to have a spacesuit in the foreground. 

I think that adding "excitement" is a real thing for manned flight, since the main purpose is to generate interest, and a sense of adventure frankly. This is where Mars One actually has a fragment of a single good idea in their sea of nonsense. The whole "reality show" aspect is not as silly as it sounds. I have no desire to see the soap opera aspect of people thrown together for a few years, but the idea that there might be a way to make a popular program about such a mission that is on TV often is actually intriguing given the true goal of manned flight. Of course I don't think a flyby has the excitement level, honestly a lunar landing would be more spectacular in that sense. Land an enclosed rover capable of long drives, and a hab. Have them do stuff on the surface for a while, ideally someplace visually interesting. 

[AngelLestat]

2 hours ago, DBowman said:

500 days is not even close to current duration records for solo yachtsmen, time in the can is the least of your problems - read some books, do some blogging ...

I am the book guy..  and I also sail. My dad and mom love those stories, they have 3 books of solo trips around the world in sail boats. And we saw 5 movies at least.

It has no point in comparison..  I am not saying that the astronaut can not handle that..  but all that effort for nothing.. or 1 day of window..   All that money invested and you can show only 2 days to the people on earth.

All those health problem related to zero-g and the high doses of radiation... We can plan these missions, but I guess we will never see one like this.  

Edited February 7, 2016 by AngelLestat

[DBowman]

3 hours ago, tater said:

A manned flyby mission seems pretty pointless to me.

Manned spacefight is a stunt. It's a stunt I'm particularly fond of, but that doesn't change what it is. For the price/mass to Mars of such a mission we could send fabulous orbiters and landers, even sample return, instead. What that won't do is create excitement for space, I get that. The last section of the proposal talks about adding excitement via EVA, IMAX, etc. Sorry, it's not that exciting to see a stunning Mars shot that happens to have a spacesuit in the foreground

...but what kind of stunt is it? going over Niagara Falls in a barrel or flying across the Pacific the first time? even a pure stunt can usefully inspire - who comes back from watching tumblers and trapeze artists and doesn't just for a moment consider 'what would that be like?', 'what does that take?' - at the least you get a renewed respect for the unlikely capability of people.

My initial thoughts on Inspiration Mars were 'pointless stunt', but on thinking about it I changed my mind:

• This small and simple enough to be fundable. NASA DRAs are 35 Billion USD. Even Inspiration Mars got caught up in scope creep with multiple lifts and on orbit assembly, 2.5 Billion USD. A minimal direct one shot is much cheaper, Falcon Heavy + a Soyuz is 0.1 Billion USD ( plus more costs I know, and Soyuz has the H₂O₂ problem ). Small simple and done would be better than large useful and never done.
• The long duration medical data is pure science useful, and manned space useful. It's not enough to motivate the trip, it's not the cheapest way to get the data, but if the trip was on it would be criminal not to gather the data and it must have a dollar value somewhat less than getting it from ISS (because after 15 year we seem not to to have bothered). 
• If you have real plans for a manned Mars program (Elon Musk maybe, NASA maybe) then it sure makes sense to do flybys. You can shake out parts of the tech stack, build experience with the operating procedures, etc - you can do this while still grappling with the real hard problems of aerocapture (do it!), Mars EDL, and ascent. All the reasons they did the Apollo flyby.
• Long duration flybys could conceivably use people as a 'force multiplier' for autonomous components. You can throw a craft into a companion orbit to Mars so they do an 'extended flyby' where they spend months within a few light seconds for Mars, taking 30 mins out of the 'control loop' could greatly increase the flexibility, rate, and amount of data gathering possible from landed elements. Automated systems are getting better and better, but really still not that great and 'man on Earth in the loop' must really slow things down.
• I think there would be some drama associated with the flyby, e.g. will (did) the maneuver engine fire near Mars to tweak the trajectory for a return, was enough ablator added to the capsule. That kind of ephemeral drama might help sell the idea of doing the flight and maybe get some support dollars, but there is a longer term awe and inspiration factor. A a selfie of a helmeted face with crescent Mars and an Earth star could be as iconic as the 'earthrise' photo. The moon was different after you could look up and think 'we' stood there and ran that dust through our gloved fingers, Mars and Venus will be different after you can look at the first star of evening and think 'we' threw someone close enough to almost touch that and got them back safe.

[Bill Phil]

Here's my question: Why go minimal at all? Yeah, I understand cost issues and other aspects, but you might as well go full out, especially since it might only have a total cost of 1 trillion USD. And current global spending on space is about 70 billion, so, over enough time and with enough collaboration, it could be done. GWP is over 70 trillion USD. And it might not even cost a trillion, especially with advanced tech and design processes, plus a huge industry and a huge global economy. And if it's full out, we might even get a bigger space industry that could stay that way...

[DBowman]

4 minutes ago, Bill Phil said:

Here's my question: Why go minimal at all? Yeah, I understand cost issues and other aspects, but you might as well go full out, especially since it might only have a total cost of 1 trillion USD.

Sure why not spend a spare trillion I think doing something minimal is only going to increase to odds of doing something more substantial. The minimal isn't big enough to starve any existing programs and having some deep space action could stir up interest and desire for bigger things. Minimal is all upside and no downside.

[Bill Phil]

18 minutes ago, DBowman said:

Sure why not spend a spare trillion I think doing something minimal is only going to increase to odds of doing something more substantial. The minimal isn't big enough to starve any existing programs and having some deep space action could stir up interest and desire for bigger things. Minimal is all upside and no downside.

The downside is the lack of redundancy. If the ship breaks, you get a dead crew. And then a dead space program. If you have a huge fleet, and a ship breaks, you can rescue most of the crew.

[DBowman]

5 hours ago, AngelLestat said:

I am the book guy..  and I also sail. My dad and mom love those stories, they have 3 books of solo trips around the world in sail boats. And we saw 5 movies at least.

It has no point in comparison..  I am not saying that the astronaut can not handle that..  but all that effort for nothing.. or 1 day of window..   All that money invested and you can show only 2 days to the people on earth.

All those health problem related to zero-g and the high doses of radiation... We can plan these missions, but I guess we will never see one like this.  

I love '(hum)man against the odds' stories; Shackleton & Douglas Mawson in the Antarctic,  and Reihhold Messner's solo Everest without supplemental oxygen (overturning accepted wisdom and practice on two counts).

I think the radiation risk is not too bad. From my reading so far it seems like the dose received will be more or less in line with NASAs life time limit for a career astronaut (which is 4x a nuclear plant worker lifetime dose), I think I recall they are more conservative than the Europeans. I haven't done a detailed investigation yet. After 500 days in the can the astronaut probably wont mind that it was a once in a lifetime deal.

7 minutes ago, Bill Phil said:

The downside is the lack of redundancy. If the ship breaks, you get a dead crew. And then a dead space program. If you have a huge fleet, and a ship breaks, you can rescue most of the crew.

I don't think the loss of one guy would kill the space program, though I think you are right that it would come up if the flyby lost the crew.

Redundancy can be very expensive. Imagine a Minimal Multiply Redundant flyby:

• 2x Each craft has to be double volume, consumables, with double LS machinery 
• 2x2x That larger craft might kick the mass over the 'direct launch' threshold doubling the launches per vehicle and adding a docking failure point and maybe shifting the transfer propellant to non cryo => increasing the mass again...
• 2x3x maybe adding another launch and docking for the transfer propellant
• 2x3x2x Then we need two of these, and they have to fly in formation or docked to be usefully redundant

So just one back up makes the mission at least ten times as expensive and much more complex, with many more failure points. 

Many of the big spending programs have plenty of scope to kill the crew. Small is simple, simple is safe, worst case you don't loose too much/many.

Edited February 8, 2016 by DBowman

[Bill Phil]

1 hour ago, DBowman said:

I love '(hum)man against the odds' stories; Shackleton & Douglas Mawson in the Antarctic,  and Reihhold Messner's solo Everest without supplemental oxygen (overturning accepted wisdom and practice on two counts).

I think the radiation risk is not too bad. From my reading so far it seems like the dose received will be more or less in line with NASAs life time limit for a career astronaut (which is 4x a nuclear plant worker lifetime dose), I think I recall they are more conservative than the Europeans. I haven't done a detailed investigation yet. After 500 days in the can the astronaut probably wont mind that it was a once in a lifetime deal.

I don't think the loss of one guy would kill the space program, though I think you are right that it would come up if the flyby lost the crew.

Redundancy can be very expensive. Imagine a Minimal Multiply Redundant flyby:

• 2x Each craft has to be double volume, consumables, with double LS machinery 
• 2x2x That larger craft might kick the mass over the 'direct launch' threshold doubling the launches per vehicle and adding a docking failure point and maybe shifting the transfer propellant to non cryo => increasing the mass again...
• 2x3x maybe adding another launch and docking for the transfer propellant
• 2x3x2x Then we need two of these, and they have to fly in formation or docked to be usefully redundant

So just one back up makes the mission at least ten times as expensive and much more complex, with many more failure points. 

Many of the big spending programs have plenty of scope to kill the crew. Small is simple, simple is safe, worst case you don't loose too much/many.

Even so, going all out would have a lot of overlapped investment. You could potentially have an entire fleet of Mars capable vessels, and if you can use them a bunch of times, that 1 trillion could pay for 2, 3, or more expeditions with an extra 500 billion.

[DBowman]

17 minutes ago, Bill Phil said:

Even so, going all out would have a lot of overlapped investment. You could potentially have an entire fleet of Mars capable vessels, and if you can use them a bunch of times, that 1 trillion could pay for 2, 3, or more expeditions with an extra 500 billion.

Sure, if you planned 3 craft anyway then just doubling their crew capacity would provide substantial redundancy for only 2 or 3 times the cost vs 8 to 12 times for a single 'direct' style craft.

'doubling up' a single 'direct' craft is the worst case in terms cost multiplier for redundancy, but to make the flyby as cheap as possible that's where you end up. Say the minimal flyby cost 0.2B, going redundant would blow it out to 2.0B, I'd bet most of the potential astronaut passengers would say 'just send me in a single solo craft and we'll split the redundancy money'.

[Bill Phil]

1 hour ago, DBowman said:

Sure, if you planned 3 craft anyway then just doubling their crew capacity would provide substantial redundancy for only 2 or 3 times the cost vs 8 to 12 times for a single 'direct' style craft.

'doubling up' a single 'direct' craft is the worst case in terms cost multiplier for redundancy, but to make the flyby as cheap as possible that's where you end up. Say the minimal flyby cost 0.2B, going redundant would blow it out to 2.0B, I'd bet most of the potential astronaut passengers would say 'just send me in a single solo craft and we'll split the redundancy money'.

...

I was referring to the ultimate return on investment. Not the redundancy. Most of the money for an all out expedition is overhead and launch costs. But once it's in orbit, it's an asset. And if it's capable of going to Mars and back four or five times, along with the rest of the fleet, then it's a better investment than the minimal mission would be.

Heck, if you're real smart about your design you could get the cost down by quite a large margin, with the same returns.

[Nibb31]

Redundant ships simply aren't practical. Some early Mars mission designs involved sending two ships so that one is a backup of the other, but there are multiple problems with this architecture:

- If your two ships are identical, then they both have the same failure modes. If one has a technical problem, then the other is likely to have the same problem at one point, and you end up with two stranded ships and crews instead of one.

- Sending one interplanetary ship and keeping the other at home waiting for a rescue simply isn't practical because RV with the other ship on a solar orbit requires either a huge expenditure in dV or waiting for the proper window which can take years. Solar orbits are big !

- If you send your two ships on the same trajectory, they will tend to drift apart and will require a lot of dV to RV if necessary. You might as well save yourself the trouble and just dock them before they leave Earth,  In that case, you have one big ship with twice everything. Since each ship probably has its own redundancy, you save weight by having one big ship that shares those redundancies. In the end, you might as well just build one single ship in the first place.