Manned Mars mission poll

[NSEP]

11 hours ago, DAL59 said:

This could also have military applications.  

So what you mean is infantry and probably even vehicles being deployed by rocket?

If so, well it sounds cool, but please note that landing a super expensive bomb with people and valuable cargo inside near a warzone where everybody can shoot it down because its very easy to notice is not really the best idea.

Can micrometorite protection also deflect and protect itself from bullets and missles?

[tater]

I think the idea of using this as a troop transport from the 1960s assumed surprise. You'd not land in a hot zone, you'd land nearby, and them move the troops, not drop into he middle of an enemy army. Phil Bono, the granddaddy of BFR.

Study from 1966:

1200 troops.

 

[Nibb31]

It still seems like a bad plan:

- An incoming BFS would be pretty obvious to detect and probably to intercept to.

- The BFS shown in Musk's presentation needs a BFB to take off again, a huge crane to restack the whole thing, and a rather big propellant farm.

[tater]

Yeah, I think the military use is not huge. They would not be concerned with recovery to take off quickly, this is the sort of thing that would be used for rapid deployment, and losing the vehicle is just part of the math. Aside from major powers (where such a system would be useless, anyway), I think detection and interception would not be a thing.

Such a troop deployment would look like a bunch of stealth aircraft and Wild Weasels sweeping across to the target area time on target just a handful of minutes before landing to clear the LZ if required.

It's not a likely use, however. I'd think Space Command would be more interested in having something available at short notice that has way more useful capacity than X-37. 

[DDE]

@tater @Nibb31 This raises the interesting topic of Single Stage From and To Orbit vehicles... which are, however, pure sci-fi.

[tater]

BFR isn't SSTO, though. The Bono designs had drop tanks (see image above on the CVN).

This thread is about manned Mars, however.

Assuming someone wanted to pay billions for such a trip (NASA), they'd want abort modes, etc. Really, this means loading the crew with a crew vehicle, since once any Mars trip does the TMI burn, they don't have many abort options. The Lockmart version does, I suppose, with 2 of everything, and abort to orbit. The DRA/DRMs have similar architectures---achieve orbit, then sortie to surface. BFS doesn't have this capability, even if you sent 2, and left one in orbit.

If you look at the MADV (LM lander) it is atop SLS Block 1B, and looks like with EUS below. MADV masses ~110 tons (wet). NASA has a MDV/MAV design that is 12m wide any 9m high, for example (lands, then stages off the middle and leaves). Any NASA adoption of SX in a Mars mission could then allow another contractor to build the sortie vehicle. 

I only say this because if NASA does something, it's going to use multiple contractors, or not happen, generally. That's how the sausage is made.

 

Aside: proof LM has the landers sitting on top of SLS, no fairing.

http://lockheedmartin.com/content/dam/lockheed/data/space/photo/mbc/MBC_Updates_IAC_2017.pdf

[DAL59]

1 hour ago, DDE said:

Single Stage From and To Orbit vehicles... which are, however, pure sci-fi.

Actually, ARCA space industries will launch an SSTO by next year.  They have already built the test suborbital rocket.  

16 minutes ago, tater said:

they'd want abort modes,

Zubrin suggests that Musk slows his ITSs to a 6 month trip, for a free return trajectory and more cargo.   

The thing is, the boeing plan is slower timescalewise than the Musk plan, and despite re-usability, doesn't seem practical for large scale, mass produced colonization, given that it takes an entire decade of assembly per ship, which can then only hold 4 people.  

Some of the Boeing concepts involve solar electric propulsion, which does not make sense, given that it would actually take longer to get to Mars than with ordinary chemical rockets, and is harder to ISRU, and requires more R&D.  

[tater]

33 minutes ago, DAL59 said:

Actually, ARCA space industries will launch an SSTO by next year.  They have already built the test suborbital rocket.  

I'll believe ARCA is a thing when it flies.

 

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Zubrin suggests that Musk slows his ITSs to a 6 month trip, for a free return trajectory and more cargo.   

Caro is likely volume limited on a crew vehicle as shown. Radiation risks are real, something Zubrin badmouths without actually knowing anything about it, IMO.

Longer mission means more consumables. That said, for a first crew mission, a free return makes some sense.

 

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The thing is, the boeing plan is slower timescalewise than the Musk plan, and despite re-usability, doesn't seem practical for large scale, mass produced colonization, given that it takes an entire decade of assembly per ship, which can then only hold 4 people.  

This thread is about a manned Mars mission. Flags, and footprints. This is not about colonization, which is not going to happen any time soon.

BFR could be used for a manned Mars mission, hence it's reasonable to discuss it here. Colonization is another thread.

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Some of the Boeing concepts involve solar electric propulsion, which does not make sense, given that it would actually take longer to get to Mars than with ordinary chemical rockets, and is harder to ISRU, and requires more R&D.  

They use solar electric to pre-position assets. Send the landers ahead. Send some of the tanks and hab units ahead. Send Orion/hab sections (2 of them) on a faster transfer.

Edited October 3, 2017 by tater

[DAL59]

1 hour ago, tater said:

when it flies.

 

Should be ready in November.  The surprising thing is, they have less than 50 employees! 

1 hour ago, tater said:

Radiation risks are real

The ITS's fuel tank should provide more than enough shielding from solar flares, and cosmonauts have been exposed to equivalent doses of cosmic rays.  

Though this is slightly off topic, using the ITS as a troop carrier would actually be hard to shoot down, given its speed and possibility for point defense guns.  

[tater]

8 minutes ago, DAL59 said:

Should be ready in November.  The surprising thing is, they have less than 50 employees! 

Again, I'll believe it when I see it. If they start testing with any cadence I might literally see it, it's only a few hours from here.

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The ITS's fuel tank should provide more than enough shielding from solar flares, and cosmonauts have been exposed to equivalent doses of cosmic rays.  

Solar flares can be mitigated by the spacecraft via pointing it the right way, this is true.

Cosmonauts have NOT been exposed to the same doses of GCRs, however. Cosmonauts have never left LEO. In LEO, almost 50% of GCRs are removed instantly because the Earth is in the way. Apollo astronauts experienced a full GCR dose for Earth-Moon transit times (i.e.: ~6 days), then mitigated doses in LLO, and on the surface (because the Moon blocked nearly half of them).

No human has ever been exposed to isotropic GCRs for months.

Edited October 3, 2017 by tater

[DAL59]

They have been exposed to an equivalent, though lower intensity, dose, that lasted longer.  Anyway, it has been precisely measured by Curiosity during transit.  

[Bill Phil]

52 minutes ago, DAL59 said:

They have been exposed to an equivalent, though lower intensity, dose, that lasted longer.  Anyway, it has been precisely measured by Curiosity during transit.  

I think that it's been established that a small dose/time over a long period is not inherently equal to a larger dose/time over a smaller period, given that total radiation dose is equal.

[DAL59]

True, but it is only a factor of exactly 2.

(Due to occlusion by Earth)

[tater]

30 minutes ago, DAL59 said:

They have been exposed to an equivalent, though lower intensity, dose, that lasted longer.  Anyway, it has been precisely measured by Curiosity during transit.  

879 days over multiple missions, at a half dose. Radiation exposure is not entirely cumulative, so the body may repair during the periods between missions. 

So possibly comparable for short stay mission architectures. With an n of a few people with long lifetime flight durations. For a spacex mission, of course, they stay til they make propellant.

[DAL59]

Remember, when they are on the Martian surface, the galactic radiation is halved.  Even ignoring solar radiation, a conjunction class mission gives more radiation than an opposition class.    

15 hours ago, NSEP said:

Can micrometorite protection also deflect and protect itself from bullets and missles?

Bullets- Yes.  Far less kinetic energy than space debris.

Missiles- Probably not.  They would be fine during close blasts due to heat protection though.  

If you want a discussion on this though, you should start your own thread.  

[KerikBalm]

On 9/27/2017 at 1:56 PM, Northstar1989 said:

Carrying Capacity

Mathematicians love to argue this question, but they don't really seem to understand the concept of Carrying Capacity- it is not a matter of the maximum population an ecosystem can COMFORTABLY accommodate- it is a matter of the maximum population an environment can sustain, period.  Keeping that caveat in mind, HowStuffWorks gives a decent introduction to the concept for the non-scientist:

http://science.howstuffworks.com/environmental/green-science/earth-carrying-capacity.htm

The strict definition of Carrying Capacity would say as many as 40 Billion people might be the number- but based on my knowledge of Virology, I suspect infectious diseases will limit the human population well below that point... (hence my estimate of 12-24 billion)

Your link states between 2 and 40 billion, you take that to mean to 40 billion... I think that's quite a stretch.

Most estimates place it at 10 or under sustainable, but higher numbers can be sustained for a while (but that would actually be over the carrying capacity, as its a more long term condition) if we use fossil fuels and underground aquifers to increase food production (as we already do) and don't factor in long term climate change and aquifer depletion (droughts may get very bad).

On 9/27/2017 at 12:24 PM, Northstar1989 said:

No, just so much no.  Science on Earth coats land, food, and various other resources to sustain.  When Mars is self-sufficienct, it will be able to feed and house its own scientists- which means, for all perpetuity, humanity will be able to support a larger scientist population.

...

Eventually we are going to hit a hard population-cap (my knowledge of Bioligy leads me to guesstimate somewhere between 12 and 24 billion people, depending on how much of the environment we are willing to sacrifice).  At that point, colonizing Mars and the Moon will be the ONLY way to increase the humssn population sooner.  We might as well get a head-start on that, since we will reach Earth's population-limit long before Mars does.

Maxing population doesn't mean much and shouldn't be a goal in and of itself, and mars and the moon would be a drop in the bucket for Earth. 

I don't know what your degree in biology is... but unless its ecology, your bio knowledge doesn't mean much for answering the question. I've got a MSc in Molecular biology and a PhD in cell biology. I'm a published scientist with multiple *first* author publications... but my expertise doesn't give me much authority for answering carrying capacity questions.

Mars doesn't have a magical science multiplier. Martian scientists won't be better equipped to study high energy fusion reactors, or cancer treatments, or... pretty much most areas of science.

They would have a much easier time getting stuff into orbit though... I can see an advantage towards manufacturing spacecraft in lower gravity environments. The moon can't provide much propellant on its own, but mars can... but then you might as well colonize ceres if it really does have significant subsurface ice...

I really don't see the point of a flag and footprints mission on mars when that money could probably by an under-the-ice robot on Europa

[DAL59]

 

 

I really don't see the point of a flag and footprints mission on mars when that money could probably by an under-the-ice robot on Europa

On an unmanned Europa mission, the probe would have to deal with radiation, communication time delays, and the inability to repair itself.  Enceladus is probably the better place to go, or we should send people to high Jupiter orbit to teleoperate.  

[KerikBalm]

All the problems you listed above are much easier to solve than those involved with sending humans to mars.

[tater]

23 minutes ago, KerikBalm said:

All the problems you listed above are much easier to solve than those involved with sending humans to mars.

Far worse with humans, since we tend not to care quite as much about a lost spacecraft as a lost human  

[KSK]

On 10/4/2017 at 9:18 PM, DAL59 said:

On an unmanned Europa mission, the probe would have to deal with radiation, communication time delays, and the inability to repair itself.  Enceladus is probably the better place to go, or we should send people to high Jupiter orbit to teleoperate.  

That sounds about right for this forum. Clearly the way to solve one complicated mission is to replace it by another, even more complicated one.