Author Topic: Mars Direct updated for the 21st Century  (Read 8534 times)

Offline redliox

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Mars Direct updated for the 21st Century
« on: 05/01/2017 04:14 PM »
Initially I began a thread in the SpaceX department inquiring about applying the ITS booster toward the original Mars Direct effect vehicles.  MATTBLAK quoted:
Quote
The traditional Mars Direct by Robert Zubrin and David Baker had Direct vehicles of about 45 tons being sent on Trans-Mars Injection. This is about what the SLS Block II with 'Dark Knights' solid boosters could achieve with an Exploration Upper Stage. If the corestage was redesigned for 5x RS-25E and the EUS had slightly higher thrust engines, this could raise the Direct Vehicle's masses to about 50 tons.

We probably need to have a new thread about Mars Direct redesigned for alternate launch vehicles such as New Glenn, Vulcan/ACES and Falcon Heavy

When Baker and Zubrin conceived Mars Direct back in the 1990s there was only the space shuttle and, at best, the Titan rockets available with no signs of commercial rocketry beyond the ULA monopoly or perpetually-stalled-pie-in-the-sky plans within NASA.  20 years later now, we miraculously have a new world opening up despite the end of the space shuttle.  There may quickly be a huge range of options Mars Direct launchers to utilize for a plan created when there essentially were none.

The thread rules are the following:
1) Assume we wish to land 20+ metric ton vehicles onto the Martian surface with as minimal an architecture as possible - i.e. at least 2 but not more than 4 vehicles and launchers per expedition to Mars
2) Debate any launch vehicle from any company so long as it has the ability to throw over 20 metric tons to Mars
3) Focus discussion on launch vehicles that are active as of 2010 onward; we are trying to update Mars Direct's options
4) Discuss the ITS booster as a launcher but NOT the ITS spaceship as one; the spaceship isn't a launch vehicle by itself applicable to Mars
"Let the trails lead where they may, I will follow."
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Offline sevenperforce

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Re: Mars Direct updated for the 21st Century
« Reply #1 on: 05/01/2017 08:17 PM »
Build your 20-tonne vehicle with methalox engines, loft it as the upper stage on Falcon Heavy, refuel it in LEO, and send it on its way.

As long as you can aerobrake at Mars, you're golden.
« Last Edit: 05/01/2017 08:17 PM by sevenperforce »

Offline KelvinZero

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Re: Mars Direct updated for the 21st Century
« Reply #2 on: 05/18/2017 10:32 AM »
This is something I sort of wanted to ask before but this makes it a bit more topical.

around the 3 minute mark, he says that if you can refuel a vehicle in orbit it's a very valuable thing to do.

Would it still count as Mars Direct (Updated for the 21st century) if it had many many refueling flights?

My loose understanding is that a large number of flights is against his philosophy.. but wouldn't that simply change if it became a standard proven practice?

The 21st century might be defined by F9R becoming mundane. The first stage to get that huge amount of fuel for an all chemical mission to mars into LEO is a huge part of the cost but IMO a small part of the architecture.

Offline MATTBLAK

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Re: Mars Direct updated for the 21st Century
« Reply #3 on: 05/18/2017 11:52 AM »
Dual launches of 50+plus ton Commercial launchers could send 25-to-30 metric ton spacecraft on their way - be they Dragon-derived or the traditional 'Tuna Can' Mars Direct ships. Though, I've always had a bit of a soft spot for blunt-biconic spacecraft, which the Dragon 2.0 has more than a passing resemblance to. Using 2x Falcon Heavy in it's fully expendable mode allows for 120 tons into Low Earth Orbit. I once wrote a paper (too many details to reproduce here, and a bit obsolete in details) on how to do a basic 2 or 3 man Sortie/Flags/Footprints Martian mission to 'break the Dragon of impossibility's back and prototype a pioneering Manned Mars Mission. Larger, long stay missions could come later...

With the following, I'm drawing a broad sketch - some might go; "Yeah, but hang on - how does it..." Details might come later in a more detailed 'white paper' that I'll hammer out, if I get time. Then real engineers and scientists like Dr Pietrobon for instance could crunch the numbers, if they were so inclined...

A: A Dragon 2 based Earth Return Vehicle is pre-deployed to Martian orbit with a Transit Hab docked to it's nose - inflatable or stretched Cygnus-derived. The Dragon ERV has an extended Trunk that has a 'Propulsion Pallet' fueled by about 20 tons or more of hypergolics and powered by a cluster of Dracos. We broadly assume that this craft had been braked into Martian orbit previously by an expendable, storable propellant propulsion stage.

B: On the surface of Mars at a pre-chosen landing site are 2x upgraded Red Dragon Cargo landers. One contains a Solar/RTG/Stirling generator unit for ISRU and Expedition surface power. The other has food, water, tools and equipment - including a simple Apollo-style Martian Roving Vehicle - carried in a conformal, aerodynamic 'bulge' shell on the outside hull of the Dragon. A matching conformal shell on the other side carries other gear. Once emptied, this Cargo Lander can also act as a Surface Habitat.

C: As near as possible (200 meters or less) to the pre-landed Cargo/Hab Dragons is a third craft: A Dragon based Mars Ascent Vehicle. The only cargo this craft lands is a supply of Hydrazine fuel. A small robot rover unspools a power cable from the Power Cargo lander and plugs it into the Ascent Vehicle. The Ascent Vehicle sucks in and cracks Martian CO2, dumping Carbon Monoxide overboard and storing Liquid Oxygen in it's oxidizer tanks.

CREW LAUNCH: In fully expendable mode, a Falcon Heavy places into LEO a crewed Red Dragon spacecraft with a propulsion pallet-equipped Extended Trunk. It carries 2x Astronauts. A second Falcon Heavy launches with a small Transit Hab attached to the top of it's second stage. The Transit Hab will mass about 7 tons with it's supplies and equipment if it's based on an enhanced Cygnus, or lighter if an inflatable. The second Falcon Heavy's upper stage retains about 50 tons of propellant from it's ascent to orbit. The Crewed Dragon docks with the Transit Hab mounted atop the Falcon second stage and the combined crafts burn out of Earth orbit on Trans-Mars Injection; using all of the Falcon stage's propellant and most of the crewed Dragon's propulsion pallet. Enough fuel is retained in the propulsion pallet for 2 or 3 course correction burns or an abort burn past Mars if necessary later in the mission. The Transit Hab contains enough crew contingency supplies for a months-long cruise back to Earth if needed. But during a nominal mission; these supplies would be jettisoned, along with the Trans Hab.

The Crew Dragon cruises to Mars and when on final approach, the Transit Hab and Trunk are jettisoned and the crewed Red Dragon performs a direct entry descent to the Martian surface, right near the pre-deployed Dragon assets. Depending on when the precise years the Launch windows are set in, and on the trajectory used; the surface stay and exploration would be anywhere from two to four weeks. The crew would then have to board the now fully-fueled Mars Ascent Dragon and climb to rendezvous and dock with the Earth Return Dragon vehicle...

Now; this bare-bones basic mission concept could be augmented with extra equipment and modules launched every launch window - more Mars surface power units and supplies landed to increase the Martian stay to more than a year. An inflatable surface Habitat to allow the crew to increase to 3 or even 4 Astronauts... And a larger Transit Hab to allow room and supplies for a larger crew, outbound to Mars...

Yes; I know this isn't as grandiose or 'sexy' as either Elon's Interplanetary Colonial Transport system, or even NASA's slightly nebulous plans... But that's the point! Do it fast, do it minimalist and 'dirty', and break ground - 'guerilla' fashion. But it would still be asking a great deal of both the available technology and also the tech that is still to come.
« Last Edit: 10/06/2017 02:14 PM by MATTBLAK »
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Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #4 on: 10/06/2017 05:49 AM »
I haven't been here for a while, mostly because of other commitments.

However, going back over where I've been before and thinking about it freshly, there is still one thing that remains an absolute for me. That's a fully propulsive landing for the crew. One of the things that grates on me about Musk's vision (apart from the absurdity of the whole idea of a colony) is the idea of sending civilians into space for several months of zero g and then subjecting them to 4 to 6 gs on Mars entry. I think we can and should do better than that.

What has changed however is Elon Musk has convinced me that its okay to burn a lot of fuel. This changes several things.

One is that you can afford to get people to Mars in more like 3-4 months than 6-8 months.

Another is I'm less worried about there being sufficient fuel for a propulsive Mars lander.

Another is that I don't have to worry about solar electric propulsion.

Can I do this with a minimal number of vehicle types. Pretty much.
Can I do this with a minimal number of launches. Perhaps.

No, I haven't thought through the detail but I still think its worth doing cargo and crew landings separately.
« Last Edit: 10/06/2017 05:52 AM by Russel »

Online Archibald

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Re: Mars Direct updated for the 21st Century
« Reply #5 on: 10/06/2017 07:47 AM »
Musk wants BFR stage 2 to be able to land on Moon and Mars. The major differencies are delta-V and atmosphere.
 I feel that, in the days of BFR 2016 and Red Dragon, the plan was "screw Mars atmosphere, we will land fully propulsive on Mars just like on the Moon." Unfortunately, Mars atmosphere is a harsh mistress, and decided otherwise. Musk has to concede some kind of aerodynamic braking, see the small delta wing on 2017 BFR.

At the end of the day

a) Mars atmosphere is a giant PITA, no Earth, no Moon, but in the middle of the two. No heatshield and burns, but no full propulsive landing either, because stronger gravity and atmosphere.

b) using a similar vehicle to land on Moon and Mars is quite difficult. LEM and MEM were to be markedly differents.

c) Musk tactic to get around this is "think big". Big propellant mass provides large delta-V and with enough delta-V you can land anywhere on the solar system. This is really a brute force approach, but then again, Musk understand were are stuck with chemical propulsion for a very long time, and the only way to get around chemical propulsion is "think big" and "propellant depots".
« Last Edit: 10/06/2017 07:49 AM by Archibald »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #6 on: 10/06/2017 09:43 AM »
This is where I take exception with the commonly held concept that cargo and humans have to be landed together in one big ship and thus also where I take exception with Elon.

If you've got a very heavy vehicle then yes, Mars atmosphere is a pita and a fully propulsive landing is very expensive fuel wise. And that's precisely where you're at if you insist on landing people on the same vehicle as cargo.

However, if you separate cargo from people then the numbers work out a lot differently. You can land cargo exactly how Elon proposes. In fact without people on board there are optimisations you can perform because you have the freedom to pull even higher gs. Likewise, people don't weigh much and its not that costly to land them fully propulsively. Another point worth repeating is that you'd like a fast transit to Mars. That means more fuel. And if you're taking cargo on the same flight then that's even more fuel that you didn't need to use, which could be used to better advantage in other ways.

Again, where people go wrong is the almost universally held notion that it all has to come down to Mars surface in a single vehicle.
« Last Edit: 10/06/2017 09:44 AM by Russel »

Offline envy887

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Re: Mars Direct updated for the 21st Century
« Reply #7 on: 10/06/2017 02:02 PM »
This is where I take exception with the commonly held concept that cargo and humans have to be landed together in one big ship and thus also where I take exception with Elon.

If you've got a very heavy vehicle then yes, Mars atmosphere is a pita and a fully propulsive landing is very expensive fuel wise. And that's precisely where you're at if you insist on landing people on the same vehicle as cargo.

However, if you separate cargo from people then the numbers work out a lot differently. You can land cargo exactly how Elon proposes. In fact without people on board there are optimisations you can perform because you have the freedom to pull even higher gs. Likewise, people don't weigh much and its not that costly to land them fully propulsively. Another point worth repeating is that you'd like a fast transit to Mars. That means more fuel. And if you're taking cargo on the same flight then that's even more fuel that you didn't need to use, which could be used to better advantage in other ways.

Again, where people go wrong is the almost universally held notion that it all has to come down to Mars surface in a single vehicle.

There is no way to land on Mars (or the Moon) besides than propulsive landing. You can get rid of hypersonic retropropulsion, but you can't get rid of propulsive landing.

Offline the_other_Doug

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Re: Mars Direct updated for the 21st Century
« Reply #8 on: 10/06/2017 04:05 PM »
This is where I take exception with the commonly held concept that cargo and humans have to be landed together in one big ship and thus also where I take exception with Elon.

If you've got a very heavy vehicle then yes, Mars atmosphere is a pita and a fully propulsive landing is very expensive fuel wise. And that's precisely where you're at if you insist on landing people on the same vehicle as cargo.

However, if you separate cargo from people then the numbers work out a lot differently. You can land cargo exactly how Elon proposes. In fact without people on board there are optimisations you can perform because you have the freedom to pull even higher gs. Likewise, people don't weigh much and its not that costly to land them fully propulsively. Another point worth repeating is that you'd like a fast transit to Mars. That means more fuel. And if you're taking cargo on the same flight then that's even more fuel that you didn't need to use, which could be used to better advantage in other ways.

Again, where people go wrong is the almost universally held notion that it all has to come down to Mars surface in a single vehicle.

There is no way to land on Mars (or the Moon) besides than propulsive landing. You can get rid of hypersonic retropropulsion, but you can't get rid of propulsive landing.

And this is the crux of where people don't get how SpaceX is changing the paradigm.  If you think of each delivery vehicle as a truck, the old paradigm had you design and build a different type of single-use truck for each individual piece of cargo -- manned or unmanned.  SpaceX is building one multi-purpose truck that can carry all sorts of cargo to all sorts of places.  You don't spend a year optimizing a truck to carry cargo over the mountains -- you just add tire chains and head on up the hill.

The old paradigm would cost the better part of a trillion dollars to land four to six people on Mars.  The new one is planned to bring that down to a few billion.  You do the math... ;)
-Doug  (With my shield, not yet upon it)

Offline DreamyPickle

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Re: Mars Direct updated for the 21st Century
« Reply #9 on: 10/06/2017 04:13 PM »
The architecture proposed by SpaceX already has dedicated crew and cargo craft. The plan showed 4 cargo and 2 crew landings for the initial setup of the ISRU plant. Sending crew and cargo on different trajectories can already be done. Not much detail was shown for those cargo vessels but they might even be unpressurized and have large openings for unloading extremely voluminous cargo.

They chose to use a single outer-mold-line for all the S2 variants because reentry is difficult and it gets harder for bigger spacecraft. For Mars the current record is Curiosity at less than 1 ton. Developing *multiple* reentry systems would require a lot of extra effort for no gain.

Red Dragon (since cancelled) would have been nice to have for initial scouting. But it's not it would have been useful beyond the first couple of missions. It would be inefficient for cargo and using it for crew would imply a separate orbital-only transit habitat.

Having as few distinct components as possible is an excellent way to keep costs down.

Offline blasphemer

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Re: Mars Direct updated for the 21st Century
« Reply #10 on: 10/06/2017 04:20 PM »
This is where I take exception with the commonly held concept that cargo and humans have to be landed together in one big ship and thus also where I take exception with Elon.

Who says cargo will have to be landed together with people? I am sure there will be an unmanned, cargo only BFR spaceship variant as well as a manned one. But there is no point in designing entirely different vehicles for cargo and for crew, that would be a waste of resources, IMHO. In the end humans are just an especially fragile type of cargo anyway..

Offline guckyfan

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Re: Mars Direct updated for the 21st Century
« Reply #11 on: 10/06/2017 04:32 PM »
This is where I take exception with the commonly held concept that cargo and humans have to be landed together in one big ship and thus also where I take exception with Elon.

Who says cargo will have to be landed together with people? I am sure there will be an unmanned, cargo only BFR spaceship variant as well as a manned one. But there is no point in designing entirely different vehicles for cargo and for crew, that would be a waste of resources, IMHO. In the end humans are just an especially fragile type of cargo anyway..

They could probably reduce g-forces for passengers when they don't have the max payload weight. Maybe that is what Russels post is pointing at. Otherwise I have no idea.

Edit: fixed quote
« Last Edit: 10/06/2017 04:33 PM by guckyfan »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #12 on: 10/06/2017 10:13 PM »
There is one thing you cannot escape with Elon's architecture

4 to 6 gs on Mars entry for passengers.

Offline Lars-J

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Re: Mars Direct updated for the 21st Century
« Reply #13 on: 10/06/2017 10:19 PM »
There is one thing you cannot escape with Elon's architecture

4 to 6 gs on Mars entry for passengers.

What way of landing do you propose that would have reduced G forces that differ significantly from that?

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #14 on: 10/07/2017 07:41 AM »
There is one thing you cannot escape with Elon's architecture

4 to 6 gs on Mars entry for passengers.

What way of landing do you propose that would have reduced G forces that differ significantly from that?

As stated - a fully propulsive landing.

As a rough guide. Velocity (relative to atmosphere) of Mach 5 at atmospheric interface (135Km altitude). Slowing to Mach 3 at roughly 50Km altitude. There is a velocity vs altitude envelope that results in acceptable heating for a vehicle with minimal thermal protection.

Such a landing does not require high g forces. Its a trade between efficiency (gravity loses) and fuel but its not that hard to constrain it to 2 gs and keep most of it under 1.5 gs.

Yes, it uses more fuel than an approach that relies on drag. But its a vehicle that doesn't require a massive heat shield and is exposed to lower aerodynamic stress. Hence the extra fuel is partly compensated for in a less massive vehicle.

Now the reason I bring this up in this thread is because Elon has basically said that we can get fuel into low Earth orbit cheaply. Therefore we don't need to be as obsessed with fuel mass as has been the case in previous architectures. He's saying that rocket fuel is cheap and big dumb rockets are cheap (especially when reusable), so why not have an architecture that does indeed burn a lot of fuel.

You still need to land cargo and there's no reason not to land it in the manner Elon proposes. However, humans are only a small proportion of the mass landed on Mars and we can afford to be generous with fuel for human landings. Especially if its less costly to get the fuel there in the first place.


Just for the sake of something concrete to talk about here.

Imagine we borrow the earth side of Elon's architecture. A big, reusable rocket. A big, reusable spacecraft with wings.

Let me add one more item. A lander with either drop tanks or an extra stage. How you package this is up to you, but its not large relative to the overall spacecraft.

On approach to Mars, the crew move to the lander, detach and at the correct time fire the engines or burn the extra stage and then fire the lander's engines.

The main part of the spacecraft lands ahead of the crewed lander.  The crew then land nearby.

The rest of the architecture is as Elon proposes. You have a reusable spacecraft sitting on Mars. You refuel that and travel directly back to Earth.

I can imagine all sorts of variations on this. I'm just putting it up as a starting point.


« Last Edit: 10/07/2017 07:56 AM by Russel »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #15 on: 10/12/2017 10:45 AM »
Initially I began a thread in the SpaceX department inquiring about applying the ITS booster toward the original Mars Direct effect vehicles.  MATTBLAK quoted:
Quote
The traditional Mars Direct by Robert Zubrin and David Baker had Direct vehicles of about 45 tons being sent on Trans-Mars Injection. This is about what the SLS Block II with 'Dark Knights' solid boosters could achieve with an Exploration Upper Stage. If the corestage was redesigned for 5x RS-25E and the EUS had slightly higher thrust engines, this could raise the Direct Vehicle's masses to about 50 tons.

We probably need to have a new thread about Mars Direct redesigned for alternate launch vehicles such as New Glenn, Vulcan/ACES and Falcon Heavy

When Baker and Zubrin conceived Mars Direct back in the 1990s there was only the space shuttle and, at best, the Titan rockets available with no signs of commercial rocketry beyond the ULA monopoly or perpetually-stalled-pie-in-the-sky plans within NASA.  20 years later now, we miraculously have a new world opening up despite the end of the space shuttle.  There may quickly be a huge range of options Mars Direct launchers to utilize for a plan created when there essentially were none.

The thread rules are the following:
1) Assume we wish to land 20+ metric ton vehicles onto the Martian surface with as minimal an architecture as possible - i.e. at least 2 but not more than 4 vehicles and launchers per expedition to Mars
2) Debate any launch vehicle from any company so long as it has the ability to throw over 20 metric tons to Mars
3) Focus discussion on launch vehicles that are active as of 2010 onward; we are trying to update Mars Direct's options
4) Discuss the ITS booster as a launcher but NOT the ITS spaceship as one; the spaceship isn't a launch vehicle by itself applicable to Mars


Having had more time to reflect on this I'll make some observations.

1. A lot of Mars architectures equate mass with cost which leads to a lot of time and energy being spent either on exotic propulsion (SEP), minimising the number of Earth launches, or on having impractically small interplanetary transport vehicles.

2. Elon makes the correct observation that rocket fuel is cheap and that with a big reusable booster, lofting hundreds or thousands of tonnes of fuel into LEO is not that expensive.

3. What really costs is development of complex, reliable systems. Another pointer towards reusability and adaptability of basic designs.

So, if you had an ITS scale reusable booster you have a lot of options in terms of throwing mass at Mars. That can allow us to do things that weren't previously considered - such as fuel depots in Mars orbit and fully propulsive crew landers.

I also admit to preferring Mars semi-direct over Mars direct. I didn't like sending people back from Mars on something that is unrealistically minimal and fragile. Likewise I don't like Elon's scheme because of the sheer scale of earthmoving and processing that would be involved.

I do like Elon's basic spaceship design. Yet another winged lander. I'm not suggesting copying the ITS spaceship or at least not something at the same scale. As stated before, I'm not fond of inflicting 4-6 gs on people but that doesn't stop us doing this to cargo.

So where does that leave me in a practical sense? As I understand it, the "winged" form lander (or indeed anything with some lift) could be used as an Earth return vehicle and lander and if so the g forces can be constrained. Correct me if I'm wrong. Certainly you could have a go at a double-dipped landing. So I'll work with that.

I do want people to land on Mars fully propulsively. It follows that they need the same or a similar vehicle to return to Mars orbit. Therefore the Earth return vehicle must be parked in Mars orbit and it must have sufficient fuel for the return to Earth. Again, if your starting point is an ITS scale booster then I think you've got a pretty good chance of throwing that quantity of fuel to Mars orbit.

So, now we have an architecture that looks something like this:

Start with something that looks like Elon's plan. A big reusable booster and a reusable spacecraft (only its not for 100 people. Its only for 6-8 people). A decently fast trajectory to Mars. Followed by a burn to reduce speed. Followed by an aerocapture pass. Now you're in Mars orbit.

Your crew now climb into a lander and descend. The lander features either an expendable first stage or drop tanks. At the end of the mission the crew use a similar or the same vehicle to ascend. They then use the same spacecraft left parked in Mars orbit to return to Earth and land.

What about cargo? Well why not use the same basic design. A "winged" spacecraft adapted for cargo (doesn't contain the life support) and sent on a direct entry to Mars. This can be done ahead of time and on a lower energy trajectory. Again, adapting a design saves development costs.

I'll leave the reader to fill in the blanks. All I'm saying is that if Elon can make the launch to Earth orbit costs low enough (and I believe he can) then things got a whole lot easier. We can afford to burn more fuel to get to Mars sooner and indeed we can do the same on the way back. That's one problem solved. We can be more generous with cargo (may take more than one cargo landing vehicle depending on scale). And we can afford to keep spare fuel in Mars orbit and given the scale of things we can afford to keep enough fuel in Mars orbit to supply multiple ascents/landings and have room left over for visiting Martian moons.

Offline Nathan2go

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Re: Mars Direct updated for the 21st Century
« Reply #16 on: 10/14/2017 09:38 PM »
I think the important change that NASA needs to make is to support the SpaceX Mars vision and plan, but to be politically viable, it can't entirely abandon its other "stuff".  For the moment, NASA has to keep SLS as part of the plan, but can say commercial companies will carry part of the mission payload. 

NASA has to get the first set of astronauts back, and can embrace ISRU, but I don't think they can go so far as to be dependent on water collection, and making enough propellant for a BFS on the first trip.  They have the MOXIE oxygen generator on the Mars 2020 rover, so I think they can plan to make oxygen (but not H2 or methane) for the return trip.

NASA should embrace the methalox BFR ship outer-mold-line, not as a reusable 2nd stage, but as an expendable lander/ascent vehicle for Mars and the Moon.  Shrink it sufficiently (e.g. 7m diameter, 120 ton landed mass) so that in addition to being compatible with the BFR booster, it could also be carried by SLS and New Glenn.

With the mission split between NASA/SLS and commercial companies, maybe some of the flights will load propellant in LEO, and maybe the SLS flights will load in a high orbit (like DSG) or avoid propellant transfer and dock with loaded departure stages.  But there's not much value in having a DSG or solar electric propulsion.

By the way, I still like the Mars Direct style direct return from the surface of Mars, to the surface of Earth.  Even if the crew space is very cramped, it's worth it because eliminating mission critical Mars orbit rendezvous operations makes it safer.  Doing it as a re-usable requires high performance engines and structures, but it should be manageable as an expendable, perhaps with 2 stages (booster plus capsule and service module).

The 9m dia. BFS has a gross landing mass of 150+85=235 tons on Mars.  A 7 m dia. scale-down should be able to land 117 tons.  Of that, say 40 tons is the Earth return vehicle with payload, and 53 tons is methane for the return trip.  It would make 190 tons of O2, for a Mars take-off mass of 283 tons (just 23% of BFS).  Unlike Mars Direct, the propellant is not made by a nuke before the crew arrives: the crew builds a solar PV array to power the system, which they can bring over by truck, since it may not fit in the same lander with the return vehicle.

As in Mars Direct, NASA would commission two kinds of landers: an Earth Return ship, and a single-use payload lander.  This modified mission also allows SpaceX to use their own lander to bring mission elements.  The crew can fly out on the SpaceX BFS, or the NASA payload lander (in a hab).

Once the base is built-up enough to have full methalox production, the BFSs can return home, and the NASA landers and return ships are no longer needed.  Of course SLS can be cancelled as soon as NASA is confident that private companies can launch the NASA landers.
« Last Edit: 10/14/2017 09:46 PM by Nathan2go »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #17 on: 10/15/2017 03:06 AM »
Perhaps a topic for a separate thread but Mars Direct doesn't just result in cramped conditions. It compromises safety in numerous and often subtle ways. So whilst its fair to describe transfer in orbit as mission critical, the risks in Mars Direct are often unrecognised and understated.

Having wide margins and redundancy really does matter.  Anyhow I'll continue to advocate indirect until we have the kind of ISRU capability thst Elon advocates. And frankly I don't believe that can or will happen in early missions.

Offline Patchouli

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Re: Mars Direct updated for the 21st Century
« Reply #18 on: 10/19/2017 12:40 AM »
I wonder could an ACES or F9 upper stage lift both a Dragon V2 and a BA-330 or DOS module for use as the ERV habitat off the surface of Mars?
As this would be within the landed payload of a cargo BFS.

It just needs to reach Mars orbit as a departure stage can have been left in LMO ahead of time.
« Last Edit: 10/19/2017 12:43 AM by Patchouli »

Offline envy887

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Re: Mars Direct updated for the 21st Century
« Reply #19 on: 10/19/2017 02:53 AM »
I wonder could an ACES or F9 upper stage lift both a Dragon V2 and a BA-330 or DOS module for use as the ERV habitat off the surface of Mars?
As this would be within the landed payload of a cargo BFS.

It just needs to reach Mars orbit as a departure stage can have been left in LMO ahead of time.

If you're leaving a return stage in LMO, why not leave the ERV hab there also?

I don't think there's any way to keep a ACES full of LH2 fueled long enough for a Mars return. Boiloff is going to catch up with it eventually.

Offline Patchouli

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Re: Mars Direct updated for the 21st Century
« Reply #20 on: 10/19/2017 03:28 AM »

If you're leaving a return stage in LMO, why not leave the ERV hab there also?

I don't think there's any way to keep a ACES full of LH2 fueled long enough for a Mars return. Boiloff is going to catch up with it eventually.
Yah the hab could be left in LMO  if it's not being used on Mars such as a separate BFS being used for the surface hab I was mostly thinking about getting everything on one BFR.
I'm also not sure if ACES would have enough thrust to weight  it depends on the version and what engine is used but hydrogen boil off was one reason I figure the F9 US might be a better choice for an ascent stage.
The kerosene probably can sit inside it for the entire mission and lox can come from residual propellants in BFS or the Merlin can be switched to a derated Raptor or a cluster of Chase-10s and all the propellants can come for BFS.
If the BFS solar arrays could be removed and deployed on the ground they might be able to power enough ISRU for a small MAV just enough to lift a Dragon into LMO.

« Last Edit: 10/19/2017 03:39 AM by Patchouli »

Offline envy887

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Re: Mars Direct updated for the 21st Century
« Reply #21 on: 10/19/2017 07:32 PM »

If you're leaving a return stage in LMO, why not leave the ERV hab there also?

I don't think there's any way to keep a ACES full of LH2 fueled long enough for a Mars return. Boiloff is going to catch up with it eventually.
Yah the hab could be left in LMO  if it's not being used on Mars such as a separate BFS being used for the surface hab I was mostly thinking about getting everything on one BFR.
I'm also not sure if ACES would have enough thrust to weight  it depends on the version and what engine is used but hydrogen boil off was one reason I figure the F9 US might be a better choice for an ascent stage.
The kerosene probably can sit inside it for the entire mission and lox can come from residual propellants in BFS or the Merlin can be switched to a derated Raptor or a cluster of Chase-10s and all the propellants can come for BFS.
If the BFS solar arrays could be removed and deployed on the ground they might be able to power enough ISRU for a small MAV just enough to lift a Dragon into LMO.

It might be a lot easier to just to land a hypergolic ascent stage inside BFS and crane it to the surface with Dragon sitting on top. the total mass including Dragon would be about 35 tonnes.

Offline Patchouli

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Re: Mars Direct updated for the 21st Century
« Reply #22 on: 10/21/2017 02:22 AM »
The super Dracon could be used for ascent but it would need a vacuum nozzle for better ISP and possibly internal changes to handle firing for that long.
Could be a good excuse to keep the AJ-10 in production though the RD-861K or RD-0216 might be a better choice.
« Last Edit: 10/21/2017 02:33 AM by Patchouli »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #23 on: 11/07/2017 03:14 AM »
I was thinking. The only version of Mars Direct (genuinely direct - no Mars orbiting stuff) that has made sense to me is Elon's version.

I think Elon is more driven by reusability than by conceptual elegance.

I believe that the reailities of (very) large scale fuel manufacture on Mars means that any kind of direct return from Mars will come after earlier missions that don't depend on industrial scale mining. But its still worth contemplating.

So have you guys considered a scaled version of Elon's vehicles? Perhaps with the ability to land methane but with indigenous oxygen?

Offline Norm38

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Re: Mars Direct updated for the 21st Century
« Reply #24 on: 11/08/2017 04:16 AM »
Zubrin's original Mars Direct plan was presented as a response to NASA plans that were rapidly spiraling out of control, for little gain. Recall that the NASA plan had astronauts spending only 30 days on the surface but around 500 days in space. Mars Direct put astronausts on the surface for hundreds of days. Regardless of the transportation architecture, Zubrin won on that point.

Zubrin proposed something that could be built in with existing tech, rather than waiting decades. Of course now it's 20 years later anyway.  But the plan is still to use off the shelf tech or close to it. That means embracing rapid reuse. That extra mass in LEO gives us even more capable ships with achievable mass fractions. That means even less reason to brake into orbit, have separate landers, separate assent stages, orbital docking, etc.

Launch the ships, fuel them up and go.

Offline CuddlyRocket

Re: Mars Direct updated for the 21st Century
« Reply #25 on: 11/08/2017 11:37 PM »
I believe that the reailities of (very) large scale fuel manufacture on Mars means that any kind of direct return from Mars will come after earlier missions that don't depend on industrial scale mining. But its still worth contemplating.

So have you guys considered a scaled version of Elon's vehicles? Perhaps with the ability to land methane but with indigenous oxygen?

There won't be a scaled vehicle. That simply means additional development costs for a second vehicle for no apparent advantage. Scaling means you also scale propellant and cargo capacity and smaller rockets are less efficient.

As for taking methane to Mars; the BFS has a propellant mass of 1100t, 20% (220t) of which is methane. Its cargo capacity is 150t, so even if all the cargo is methane you can't take enough of it! You could take hydrogen - you only need 55t (plus tanks etc) - as long as you can accommodate everything else you need in the remaining cargo capacity.

You can get water and therefore hydrogen from the atmosphere. All you need is power and time (you could contemplate a mixture of such ISRU hydrogen and cargo hydrogen). Alternatively, you could mine it - 55t of hydrogen needs 495t of water; an 8-metre cube of ice will suffice!

I suspect that the first missions will have on-board ISRU propellant plants that will store propellant in their own tanks. Once there's enough, a manned mission will go. Eventually the plant will be removed from the initial spacecraft enabling them to return to Earth and be reused.

Offline guckyfan

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Re: Mars Direct updated for the 21st Century
« Reply #26 on: 11/09/2017 06:13 AM »
The payload capacity of a tanker is more than 150t. Also going back on an energy efficient trajectory won't need 100% propellant. In case of an emergency sending the methane for the return flight and sourcing the LOX locally would be entirely feasible.


Offline freddo411

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Re: Mars Direct updated for the 21st Century
« Reply #27 on: 11/09/2017 10:08 PM »
Initially I began a thread in the SpaceX department inquiring about applying the ITS booster toward the original Mars Direct effect vehicles.  MATTBLAK quoted:
Quote
The traditional Mars Direct by Robert Zubrin and David Baker had Direct vehicles of about 45 tons being sent on Trans-Mars Injection. This is about what the SLS Block II with 'Dark Knights' solid boosters could achieve with an Exploration Upper Stage. If the corestage was redesigned for 5x RS-25E and the EUS had slightly higher thrust engines, this could raise the Direct Vehicle's masses to about 50 tons.

We probably need to have a new thread about Mars Direct redesigned for alternate launch vehicles such as New Glenn, Vulcan/ACES and Falcon Heavy

When Baker and Zubrin conceived Mars Direct back in the 1990s there was only the space shuttle and, at best, the Titan rockets available with no signs of commercial rocketry beyond the ULA monopoly or perpetually-stalled-pie-in-the-sky plans within NASA.  20 years later now, we miraculously have a new world opening up despite the end of the space shuttle.  There may quickly be a huge range of options Mars Direct launchers to utilize for a plan created when there essentially were none.

The thread rules are the following:
1) Assume we wish to land 20+ metric ton vehicles onto the Martian surface with as minimal an architecture as possible - i.e. at least 2 but not more than 4 vehicles and launchers per expedition to Mars
2) Debate any launch vehicle from any company so long as it has the ability to throw over 20 metric tons to Mars
3) Focus discussion on launch vehicles that are active as of 2010 onward; we are trying to update Mars Direct's options
4) Discuss the ITS booster as a launcher but NOT the ITS spaceship as one; the spaceship isn't a launch vehicle by itself applicable to Mars


First off, let me state that Zubrin's Mars Direct architecture brought several new and important innovations into serious consideration.

* Utilizing several launches to accomplish the mission
* Surface rendezvous  (brings both benefits and risks)
* Prepositioning of supplies
* ISRU for a substantial portion of the mission's requirements
* Preference for long surface stay.
* Safety features in some redundancy of alternate vehicles.

These elements are widely considered to be reasonable, desirable and even most alternative architectures would include these or try to justify any lack of these with arguments about tradeoffs.

If we consider Musk's ITS architecture we notice some new and important innovations:

* more economical operational launch costs; reusablity;  -- cross subsidizes by commercial applications
* reasonable spacecraft / lander and booster development costs -- cross subsidized by commercial applications
* Serious effort to create a virtuous economic ecosystem to fund space travel.
* Serious work done on the EDL problem
* Embracing on orbit refueling  -- mass to Mars can scale upward
* Embracing ISRU on Mars -- Methalox rockets becoming a reality

Granted, Elon has not made the above list a complete, actual reality yet.   It is plausible to suppose that SpaceX will get there on its current trajectory.

To my eye, Elon's first couple of flights to Mars look very much like Mars Direct.   Zubrin's ideas did not have a hope to be funded.  It is not clear how Elon's Mars ambitions will be fully funded, but he does have both enormous financial and technical clout.   It is plausable to think that either private investors, philanthropists, and/or the government will step up and contribute the rest of money to make a Mars effort a reality.





Offline tdperk

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Re: Mars Direct updated for the 21st Century
« Reply #28 on: 11/12/2017 02:26 PM »
One of the things that grates on me about Musk's vision (apart from the absurdity of the whole idea of a colony) is the idea of sending civilians into space for several months of zero g and then subjecting them to 4 to 6 gs on Mars entry. I think we can and should do better than that.

A colony populated by those who can afford to go is only as absurd as launch prices / pound make it.  There is no reason why a mature MethaLOx launch system needs to be more than $500k to move 5 tons of settler and gear to Mars.

Why you think there is a issue sending people and cargo when there is no reason to doubt there will be many cargo only missions is a different question.

As for travel vs. EDL g's, there is nothing moving around can help them with in the way of surviving, so all they need to do for those few minutes is lay there.
« Last Edit: 11/14/2017 11:01 AM by tdperk »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #29 on: 11/30/2017 02:32 AM »
I can't comment on the absurdity of a colony because its off topic. But I can say that 5 tonnes per colonist is hopelessly unrealistic.

What I will say that is on topic is that 6gs is a lot of force on a civilian plucked at random. What makes it worse is months of bone loss in zero g.

Its not a case of grinning and bearing. Its a case of being stretchered out.

Offline MickQ

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Re: Mars Direct updated for the 21st Century
« Reply #30 on: 11/30/2017 11:40 PM »
I can't comment on the absurdity of a colony because its off topic. But I can say that 5 tonnes per colonist is hopelessly unrealistic.

What I will say that is on topic is that 6gs is a lot of force on a civilian plucked at random. What makes it worse is months of bone loss in zero g.

Its not a case of grinning and bearing. Its a case of being stretchered out.

Years ago when I was a lot younger and fitter I pulled 6.5 g in a jet fighter for about 20 seconds.  Not being a dedicated pilot, I was wrecked for a good 24 hours afterwards.  A barely trained person enduring those g's for 5+ minutes during EDL is going to suffer for days.

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #31 on: 12/01/2017 12:48 AM »
And we're not talking headaches either. We're talking a whole bunch of people with fractures and other medical issues strapped into chairs a long way up.

Offline KelvinZero

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Re: Mars Direct updated for the 21st Century
« Reply #32 on: 12/01/2017 03:52 AM »
Years ago when I was a lot younger and fitter I pulled 6.5 g in a jet fighter for about 20 seconds.  Not being a dedicated pilot, I was wrecked for a good 24 hours afterwards.  A barely trained person enduring those g's for 5+ minutes during EDL is going to suffer for days.
What actually were the issues. Was it all the blood forced into your legs? Lack of blood to the brain?

If someone was flat in a properly supporting bed, wouldn't it be pretty similar to the pressure of being under 6 feet of water?

https://en.wikipedia.org/wiki/High-G_training

Vertical quote: This seems to be talking about vertical acceleration, as you would experience in a roller coaster or jet doing a turn:
The g thresholds at which these effects occur depend on the training, age and fitness of the individual. An untrained individual not used to the g-straining maneuver can black out between 4 and 6 g, particularly if this is pulled suddenly. Roller coasters typically do not expose the occupants to much more than about 3 g

Horizontal quote: This seems to be talking about flat on your back.
The human body is considerably more able to survive g-forces that are perpendicular to the spine.
...
Early experiments showed that untrained humans were able to tolerate 17 g eyeballs-in (compared to 12 g eyeballs-out) for several minutes without loss of consciousness or apparent long-term harm.[3]

« Last Edit: 12/01/2017 05:10 AM by KelvinZero »

Offline guckyfan

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Re: Mars Direct updated for the 21st Century
« Reply #33 on: 12/01/2017 05:34 AM »
I am pretty sure the 6g mentioned in 2016 are a peak value, not sustained over the whole braking time. Also what about the new reentry method? More total braking over a longer period, but what about peak values? I suspect they will be lower, but don't know.

Earth reentry for point to point is different of course but there the max g will be in the range that commercial flight customers will be OK with it.

Offline tdperk

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Re: Mars Direct updated for the 21st Century
« Reply #34 on: 12/02/2017 06:39 PM »
What makes it worse is months of bone loss in zero g.

Its not a case of grinning and bearing. Its a case of being stretchered out.

Never yet been the case.

Offline Nathan2go

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Re: Mars Direct updated for the 21st Century
« Reply #35 on: 12/02/2017 10:09 PM »
To my eye, Elon's first couple of flights to Mars look very much like Mars Direct.   Zubrin's ideas did not have a hope to be funded.  It is not clear how Elon's Mars ambitions will be fully funded, but he does have both enormous financial and technical clout.   It is plausable to think that either private investors, philanthropists, and/or the government will step up and contribute the rest of money to make a Mars effort a reality.
Mars Direct was pitched as a government Mars program.  Government Mars missions have the handicap of requiring the Astronauts to come back within a short time frame, and this requirement drives a lot of cost&difficulty in the mission, perhaps to the point the mission is impossible.  Privately funded missions don't have this constraint.

I think a more likely outcome is that NASA finds a way to buy, say $2B worth of BRF launches every year, maybe for a lunar village, maybe for a Mars orbiting basecamp, whatever.  SpaceX uses the profits to fund their own Mars program.

In the SpaceX Mars program, the main reasons to send astronauts is so they can construct a space port (with a 150 ton cargo unloading crane) and propellant plant large enough to send back multiple BFS departures every 24 month window.  This could easily be a 3 year job for 10 people, and involve 4-10 single-use BFS payloads.  If something goes wrong, there is no emergency return option; the crew just waits until the next BFS arrives with spare parts and then continues their work.

Once the first re-usable BFS returns from Mars, likely empty (because why take the risk?), NASA would be shamed into funding a permanent government base and large exploration program.  The prudent NASA move would be to spend a few years building up cargo on the Mars surface, before ever sending the first NASA crew.  That way, SpaceX would have much experience getting the ships back to Earth before the first human return trip.

Zubrin convinced the space community that a 30 day surface mission was too short (i.e. "flags and footprints" is not a sufficient initial goal).  I think the first SpaceX crew will go for a 7+ year surface stay; it's the safest option, plus it creates a larger toe-hold for a future colony.  Eventually, crew rotations may shorten to 2 years, but initially, the rocket flights will be so dangerous that if you survive, you might as well stay a while.

I think that if SpaceX can self-fund an unmanned (expendable) BRS landing on Mars, then they will be able to find investors to back a larger program to build a base with propellant production.  At that point, NASA can't tell the public that Mars is to too hard, or it's 20 years in the future.  The big aerospace companies will be able to share a $100B NASA Mars program, so they'll push hard for it, including cutting deals with SpaceX and their investors.
« Last Edit: 12/02/2017 10:29 PM by Nathan2go »

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #36 on: 12/04/2017 02:49 AM »
Its not comparable.

6 fert of water or roughly 2 metres exerts an isostatic pressure of roughly 20Kpa. That's a force of about 3.8 tonnes over the surface areacof an average male human. However we don't notice this because we are mostly bags of water and water and the internal pressure balances the external pressure.

An acceleration applied in one direction is an entirely different proposition. Everything gains "weight". Skin, muscle, in fact anything not rigid  applies oressure to wverything that is rigid. You wnd up with forces applied to joints and bones in directionsat odds with the direction of force they grew to support.

Now if you take a bunch of civilians and trained and screened them and subjected them to several minutes at 6 gs and they survived happily then I'd make the judgement call that they fit to land  in the immediate future.

However take the same people and give them months of weightlessness with resulting bone density loss - and all bets are off.

Large numbers of casualties stretched down from the top of a tall lander in space suits is a big exercise and it adds to other risks at a critical phase.

Offline KelvinZero

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Re: Mars Direct updated for the 21st Century
« Reply #37 on: 12/04/2017 04:50 AM »
Russel, you skipped this bit.

https://en.wikipedia.org/wiki/High-G_training
The human body is considerably more able to survive g-forces that are perpendicular to the spine.
...
Early experiments showed that untrained humans were able to tolerate 17 g eyeballs-in (compared to 12 g eyeballs-out) for several minutes without loss of consciousness or apparent long-term harm.


Offline MickQ

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Re: Mars Direct updated for the 21st Century
« Reply #38 on: 12/04/2017 10:52 AM »
Years ago when I was a lot younger and fitter I pulled 6.5 g in a jet fighter for about 20 seconds.  Not being a dedicated pilot, I was wrecked for a good 24 hours afterwards.  A barely trained person enduring those g's for 5+ minutes during EDL is going to suffer for days.
What actually were the issues. Was it all the blood forced into your legs? Lack of blood to the brain?

If someone was flat in a properly supporting bed, wouldn't it be pretty similar to the pressure of being under 6 feet of water?

https://en.wikipedia.org/wiki/High-G_training

Vertical quote: This seems to be talking about vertical acceleration, as you would experience in a roller coaster or jet doing a turn:
The g thresholds at which these effects occur depend on the training, age and fitness of the individual. An untrained individual not used to the g-straining maneuver can black out between 4 and 6 g, particularly if this is pulled suddenly. Roller coasters typically do not expose the occupants to much more than about 3 g

Horizontal quote: This seems to be talking about flat on your back.
The human body is considerably more able to survive g-forces that are perpendicular to the spine.
...
Early experiments showed that untrained humans were able to tolerate 17 g eyeballs-in (compared to 12 g eyeballs-out) for several minutes without loss of consciousness or apparent long-term harm.[3]


I don't know the actual medical reason but I felt as if I had just done a full day's hard labour in about 5 minutes.  I was physically exhausted after the flight.

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #39 on: 12/04/2017 02:40 PM »
Kelvin that's still for healthy people who haven't lost bone density in zero g.

Offline envy887

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Re: Mars Direct updated for the 21st Century
« Reply #40 on: 12/04/2017 07:38 PM »
I can't comment on the absurdity of a colony because its off topic. But I can say that 5 tonnes per colonist is hopelessly unrealistic.

What I will say that is on topic is that 6gs is a lot of force on a civilian plucked at random. What makes it worse is months of bone loss in zero g.

Its not a case of grinning and bearing. Its a case of being stretchered out.

Years ago when I was a lot younger and fitter I pulled 6.5 g in a jet fighter for about 20 seconds.  Not being a dedicated pilot, I was wrecked for a good 24 hours afterwards.  A barely trained person enduring those g's for 5+ minutes during EDL is going to suffer for days.

Mars entry and descent after a fast transit is only about 8,000 m/s of delta-v. That's 3 minutes at 5 g or 2.5 minutes at 6 g. 5 minutes at 6.5 g would be over 22,000 m/s of delta-v.

Ballistic entries on Soyuz go over 8 g and also scrub off about 7,500 m/s of delta-v without injuring crew returning from months of zero-z on ISS. The Soyuz 7K-ST No. 16L abort hit 15-17 g for a few seconds without harming the crew. And Soyuz crash-lands at the end of all that.

Offline KelvinZero

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Re: Mars Direct updated for the 21st Century
« Reply #41 on: 12/04/2017 08:38 PM »
Kelvin that's still for healthy people who haven't lost bone density in zero g.
My understanding is that for colonists, the trip time has to be only 3 months in order to reuse the BFS each synod.

We have a lot of experience with that timeframe, including reentry afterwards. A lot of medical science has been done to model the effects, and predict the effects of exercise (or lack of)

It also isn't happening tomorrow. There will be experience with small crews to Mars. Probably there will be experience with moon bases. Maybe colonists will need some sort of regimen. Personally I think anyone choosing to go to mars should first spend a year in a simulated Mars base on earth. It is not something to do on a whim like buying an airline ticket. This could also help prevent disease outbreaks in flight, and help with developing mars base technology.

The big unknown at the moment seems to be long term bone health in moon and mars gravity. Maybe even a single synod in Mars gravity will be debilitating. As far as I know, that could still be a show stopper. Im not claiming to be an expert though. Perhaps science can already make a very good guess. We will know before it progresses to 100 colonist trips though.

Offline tdperk

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Re: Mars Direct updated for the 21st Century
« Reply #42 on: 12/05/2017 12:43 AM »
Kelvin that's still for healthy people who haven't lost bone density in zero g.
My understanding is that for colonists, the trip time has to be only 3 months in order to reuse the BFS each synod.

We have a lot of experience with that timeframe, including reentry afterwards. A lot of medical science has been done to model the effects, and predict the effects of exercise (or lack of)

It also isn't happening tomorrow. There will be experience with small crews to Mars. Probably there will be experience with moon bases. Maybe colonists will need some sort of regimen. Personally I think anyone choosing to go to mars should first spend a year in a simulated Mars base on earth. It is not something to do on a whim like buying an airline ticket. This could also help prevent disease outbreaks in flight, and help with developing mars base technology.

The big unknown at the moment seems to be long term bone health in moon and mars gravity. Maybe even a single synod in Mars gravity will be debilitating. As far as I know, that could still be a show stopper. Im not claiming to be an expert though. Perhaps science can already make a very good guess. We will know before it progresses to 100 colonist trips though.

I believe we already know a full year in uG on the ISS is not a showstopper.  I have no reason to think the 1/3rd G of Mars would be.  Potentially worthwhile sending up a well chained chimp and returning them first.

Or a volunteer.

Offline KelvinZero

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Re: Mars Direct updated for the 21st Century
« Reply #43 on: 12/05/2017 05:00 AM »
I believe we already know a full year in uG on the ISS is not a showstopper.  I have no reason to think the 1/3rd G of Mars would be.  Potentially worthwhile sending up a well chained chimp and returning them first.

Or a volunteer.
I think there is time to work it out too. Supposing Mars does turn out to be a failure, eaten by space goat or something, we could just choose another direction like asteroid colonies and space habitats with full 1g spin gravity. I personally expect significant LEO space tourism before mars, if Elon really achieves the "747 of space" that the plan hinges on. BFS carrying 100 colonists probably doesn't happen until at least 3 or 4 synods and a lot of experience in cislunar space could happen before that, if this thing is flying regularly.

Offline guckyfan

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Re: Mars Direct updated for the 21st Century
« Reply #44 on: 12/05/2017 07:04 AM »
I believe we already know a full year in uG on the ISS is not a showstopper.  I have no reason to think the 1/3rd G of Mars would be.  Potentially worthwhile sending up a well chained chimp and returning them first.

Or a volunteer.
I think there is time to work it out too. Supposing Mars does turn out to be a failure, eaten by space goat or something, we could just choose another direction like asteroid colonies and space habitats with full 1g spin gravity. I personally expect significant LEO space tourism before mars, if Elon really achieves the "747 of space" that the plan hinges on. BFS carrying 100 colonists probably doesn't happen until at least 3 or 4 synods and a lot of experience in cislunar space could happen before that, if this thing is flying regularly.

Point to point on earth may be before mass settlement on Mars. But I am very sure it will be after establishing a base on Mars. If no other reason it is overcoming regulatory hurdles taking time.

Offline Russel

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Re: Mars Direct updated for the 21st Century
« Reply #45 on: 12/05/2017 12:35 PM »
I believe we already know a full year in uG on the ISS is not a showstopper.  I have no reason to think the 1/3rd G of Mars would be.  Potentially worthwhile sending up a well chained chimp and returning them first.

Or a volunteer.

I think there is time to work it out too. Supposing Mars does turn out to be a failure, eaten by space goat or something, we could just choose another direction like asteroid colonies and space habitats with full 1g spin gravity. I personally expect significant LEO space tourism before mars, if Elon really achieves the "747 of space" that the plan hinges on. BFS carrying 100 colonists probably doesn't happen until at least 3 or 4 synods and a lot of experience in cislunar space could happen before that, if this thing is flying regularly.

I don't think we need a full g of spin gravity. My bet is that a lot of ill effects of zero or micro gravity go away with as little as 0.1g.  Enough for there to be a clear sense of "up". Musculoskeletal issues may be a different issue and I don't think we have enough data to know what "minimal" g is.

Also I remain skeptical of exposure of civilians to months of zero g and then subjecting them to 6gs, even for a minute. Case not closed imo.

- Its not that hard to generate a modest level of spin gravity.
- Its just not necessary to land humans on Mars with aerodynamic braking. Fully propulsive landing is entirely feasible. After all its only 4ish Km/s. Its not Earth.
« Last Edit: 12/05/2017 12:38 PM by Russel »

Offline KelvinZero

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Re: Mars Direct updated for the 21st Century
« Reply #46 on: 12/05/2017 03:53 PM »
Just inserting another of my hobby horses. VR and expansive environments plus some sort of treadmill and elastic bands to simulate gravity. Or maybe an exoskeleton. I don't think it would be very heavy.

VR needs a bit more development, but this has the potential to keep you in better condition than just having gravity in a cramped cabin, and also satisfy psychological needs for entertainment and space, and could perhaps have practical purposes on Mars for teleoperation.
« Last Edit: 12/08/2017 08:53 PM by KelvinZero »