Yet another Mars architecture

RGClark · 2013-09-28 06:51:01

RobertDyck wrote:

...The JPL manager calmly claimed all technologies in his plan are demonstrated, including rendezvous with manned vehicle. He also referred to sample return as a $4 billion mission.
In another talk, Robert Zubrin said for the same weight as Curiosity, you could land a fully fuelled return vehicle and a tiny rover to collect samples from the immediate vicinity.
I would like to propose an alternative. Since the 2020 rover is a copy of Curiosity, which is great but by 2020 it will be "been there, done that". So my proposal is to replace that mission with a less expensive one. Rather than land a fully fuelled return vehicle, instead use ISPP. Fully demonstrate Robert Zubrin's ISPP, which means bringing hydrogen from Earth. If this requires another technology demonstrator in a laboratory on Earth, then do so. The Mars lander would include a rover about the size of Sojourner. While Spirit and Opportunity were the size of a golf cart, and Curiosity the size of an SUV, Sojourner was the size of a radio controlled toy car. Return the sample directly to Earth, similar to JPL mission "Stardust"...

Thanks for that. I've seen cost estimates for NASA's version of a Mars sample return mission as high as $10 billion. I think it can be done for two orders of magnitude cheaper than that. I'll write about it in an upcoming blog post.

Bob Clark

RGClark · 2013-09-28 07:03:28

GW Johnson wrote:

...
My point is, under NASA's own rules, radiation is not a show-stopper for sending men to Mars. These rules are at least 20 years old now. Why this is being ballyhooed in the press of late is a mystery to me, unless it is really being used to justify deciding not to go...
GW

It's not just the press. It's NASA's own scientists saying we can't do a manned Mars mission under the current radiation limits at the 1 year to 1-1/2 year travel times currently planned for a Mars mission.
This is why I support lunar derived propellant depots. You would have virtually unlimited propellant supply that would allow high departure speeds to cut the transit times.

Bob Clark

GW Johnson · 2013-09-29 13:05:32

Hi Bob:

I'm beginning to think the NASA scientists stirred, or are being used to stir, this radiation-danger thing up in the press. It seems fundamentally to be a political / budgetary thing, cloaked in "technical difficulties" that just do not bear up to close examination.

We could have sent men to Mars successfully with a high probability of getting them home alive, starting about 1995. We'd learned enough about microgravity and radiation by then to know how to cope. As I said above, that crew shouldn't fly again outside LEO. I'd say here that they could expect increased problems with cancers in old age, relative to the rest of us. Somewhat increased, but not a lot.

The other problems are long-voyage food (good old heavy frozen food solves that one), and space-enough-to-stay-sane (a Skylab volume for no more than 6 solves that one). Then there is the lander. If you let it be big, it can be one-stage and reusable: a real ferry or landing boat.

That's worth doing, because you get to land men more than once at each of more-than-one site. It's still enormous trouble to send men two-way to Mars. Why go to all that trouble for just one landing? That just flag-and-footprints nonsense.

GW

RobertDyck · 2013-10-12 12:12:05

In a previous post in this discussion thread I described an alternative mission architecture. I would like to compare with Mars Direct, and show how NASA could do it.

According to Robert Zubrin's book "The Case for Mars", his Mars Direct mission plan could have been done with Russian Energia rockets. However, since Energia is smaller than his proposed Ares launch vehicle, it would require 3 Energia rockets per mission. Furthermore, his first mission sends a second ERV following the hab. As long as the hab lands close to the first ERV, that second ERV will start the second mission. If something goes wrong, that first ERV must land beside the hab. Assuming everything does go well, then the last mission will still need a second ERV. Just for backup. So Mars Direct requires:

First mission:
- 1 Ares for ERV
- 1 Ares for hab
- 1 Ares for backup ERV
total: 3 Ares (the one he designed), or 3 Ares V, or 3 SLS (full-size upper stage, advanced SRBs)
or
- 1 Energia for ERV
- 1 Energia for cargo lander
- 1 Energia for hab
- 1 Energia for backup ERV
total: 4 Energia (with upper stage)

Second mission:
- 2 Ares or SLS
or
- 3 Energia

My architecture uses a reusable vehicle for interplanetary transit. So the vehicle can be optimized for operation in space. That's better than the capsule of the Mars Direct ERV. And since it was designed to use Russian Energia launch vehicles, it doesn't require the full SLS. Current development work for SLS are for 4 main engine, each the same as the Space Shuttle main engine. And 2 solid rocket boosters, each the same as the Shuttle. Interim upper stage will use a single J-2X engine, and small fuel tanks. It will lift 70 metric tonnes to LEO. The full version will replace the upper stage with a full size one, using 2 engines but the same J-2X; and larger fuel tanks. And it will replace the solid rocket engines with a new "yet to be developed" advanced solid rocket. With all that the full size SLS will lift 130 metric tonnes to LEO. As a comparison, Saturn V could lift 118 metric tonnes to 185km orbit at 28° inclination, according to Encyclopedia Astronautica.

When I said Mars Direct could be done with 3 SLS launches for the first mission, and 2 for each mission thereafter, that means SLS with the full size upper stage and advanced solid rocket boosters. If the advanced solid rocket boosters are not available, then Mars Direct would require an additional launch.

My architecture would require:

First mission:
- 1 SLS for MAV (full-size upper stage, existing SRBs)
- 1 SLS for lab & pressurized rover (full-size upper stage, existing SRBs)
- 1 Falcon 9 for ITV
- 1 SLS for TMI stage (interim upper stage, existing SRBs)
- 1 Falcon 9 for lander & unpressurized rover
- 1 Falcon 9 for Dragon
- 1 Atlas V 402 for Dream Chaser

Second mission:
- 1 SLS for MAV (full-size upper stage, existing SRBs)
- 1 SLS for lab & pressurized rover (full-size upper stage, existing SRBs)
- 1 SLS for TMI stage (interim upper stage, existing SRBs)
- 1 Falcon 9 for lander & unpressurized rover
- 1 Atlas V 402 for Dream Chaser

Third mission:
- 1 SLS for MAV (full-size upper stage, existing SRBs)
- 1 SLS for TMI stage (interim upper stage, existing SRBs)
- 1 Falcon 9 for lander & unpressurized rover
- 1 Atlas V 402 for Dream Chaser

Note: This never uses the new advanced solid rocket booster. So development of that could be cancelled. So this means my architecture requires fewer SLS launches, although it does require Falcon 9 and Atlas V.

Also, the ITV could use artificial gravity. The spent TMI stage could be attached with a tether, just like Mars Direct, and spun for centrifugal force. And for return, the TEI stage could also be attached with a tether and spun. So artificial gravity both ways.

Last edited by RobertDyck (2013-10-12 12:14:44)

RGClark · 2013-10-12 15:11:34

RobertDyck wrote:

In a previous post in this discussion thread I described an alternative mission architecture. I would like to compare with Mars Direct, and show how NASA could do it.
When I said Mars Direct could be done with 3 SLS launches for the first mission, and 2 for each mission thereafter, that means SLS with the full size upper stage and advanced solid rocket boosters. If the advanced solid rocket boosters are not available, then Mars Direct would require an additional launch.
My architecture would require:
First mission:
- 1 SLS for MAV (full-size upper stage, existing SRBs)
- 1 SLS for lab & pressurized rover (full-size upper stage, existing SRBs)
- 1 Falcon 9 for ITV
- 1 SLS for TMI stage (interim upper stage, existing SRBs)
- 1 Falcon 9 for lander & unpressurized rover
- 1 Falcon 9 for Dragon
- 1 Atlas V 402 for Dream Chaser
....

How many Falcon Heavy launches would it take for a single round-trip mission?

Bob Clark

RobertDyck · 2013-10-13 22:52:05

RGClark wrote:

How many Falcon Heavy launches would it take for a single round-trip mission?

Getting Energia to fly again would be easier.

Energia could lift 88 metric tonnes without its upper stage, to 200km orbit @ 51.6° inclination. SLS with existing SRBs and interim upper stage is expected to lift 70 metric tonnes to 185km orbit @ 27° inclination. Falcon Heavy is expected to lift 53 metric tonnes to 185km orbit @ 28° inclination.

My mission plan counts on the MAV acting as the TEI stage. That permits all return fuel via ISPP. And it's kept simple: direct throw from the surface of Earth to Mars, direct entry into Mars atmosphere, and when it launches only one rendezvous required. Robert Zubrin has argued against Mars orbit rendezvous, instead designing for direct launch from Mars surface to Earth surface. The manned spacecraft is assembled at ISS, but all pre-launched stuff is direct launched. Splitting the MAV into parts with assembly in LEO would really complicated it.

Bottom line: Falcon Heavy is too small.

JoshNH4H · 2013-11-14 23:48:17

(Replying primarily to the closely related post in the SLS thread)

Well, there's no need to reduce the size of the mission if you're willing to do it with more launches. In that scenario, given orbital assembly and fueling two 53 tonne launchers would be equivalent to one 106 tonne launcher. Especially if you get creative about how you split things in half it doesn't seem unreasonable to me to propose that you could do a Mars-Direct class mission with Falcon Heavies.

Tom Kalbfus · 2013-11-15 00:32:44

Well you know Robert, if you want to do a Mars Direct with Energia rockets, you had better call up Vladimir Putin, as far as I know about Russia's political structure, all you have to do is convince one man, him, that sending Cosmonauts to Mars would be a worthwhile endeavor.

JoshNH4H · 2013-11-15 00:47:16

Given US relations with Russia at this point, it seems highly unlikely that the US and Russia will be the primarily collaborators on a human mission o Mars.

RobertDyck · 2013-11-15 01:07:17

That would require 2 Falcon Heavy launches for each of the MAV, and lab/rover. I sized the Interplanetary Transit Vehicle as a the same as a single ISS module. The lander is a capsule with inflatable habitat. Considering the assembly launched to Mars with crew has the ITV, lander, and Dragon all docked together, the TMI stage would be substantial. That would require 2 Falcon Heavy launches as well. So that means the 3 SLS launches become 6 Falcon Heavy.

Remember the ITV includes a Nextel 440 parasol for aerocapture and aerobraking, as well as OMS and RCS thrusters. It will aerocapture into highly eliptical, high Mars orbit. It won't aerobrake into low orbit, it will remain in high orbit so it doesn't require much fuel to depart. But it does have to stabilize its orbit. And when returning to Earth, it will aerocapture again, but then aerobrake down to ISS orbit. Then it has to stabilize that orbit and rendezvous and dock with ISS. So that requires some fuel.

You could use a soft module for the ITV as well: a Bigelow hab. It would be bigger than an Expandable Activity Module, but not as big as BA330. If you made it shorter, say 2.5 metres instead of 9.5 metres, it would be a single floor 6.7 metre exterior diameter. That would allow launch in a current fairing, then expand on-orbit. But remember since this will use artificial gravity, it'll need a rigid floor. Probably suspended by cables from the hab core. But don't expand it too big, or it'll require large TMI and more importantly TEI stages.

I wonder if that could be rearranged, as you suggested. Instead of launching the ITV on Falcon 9, and the TMI stage on one SLS or two Falcon Heavy; could that be arragned so the ITV requires one Falcon Heavy, and the TMI stage just one more? If so, the first mission would require 6 Falcon Heavies, 2 Falcon 9, and when it returns to Earth, one Altlas V 402 for a DreamChaser to bring the astronauts down. Astronauts would ride the Dragon up, but it would remained docked as a lifeboat/escape-pod for the next mission.

RobertDyck · 2013-11-15 01:28:12

I still think one option is a Canadian led international mission. That would use Energia, with participation by ESA (France, Germany, UK, Italy, etc), Australia, possibly Japan, and maybe others. But with Russia providing the big rocket, the US would not be included.

The other option is the US does it, with little participation by any other country.

RobertDyck · 2013-11-15 12:38:40

You realize splitting the MAV and cargo lander, requiring on-orbit assembly, requires adding rendezvous and docking systems. That means RCS thrusters, docking collar with shock absorbers and latch, and radar for targetting. You guys argue that on-orbit assembly is well known, but adding this much will probably make the mission not happen. And yes, it does work that way. Switching from a larger launcher such as SLS or Energia to Falcon Heavy does not make the mission happen, it makes the mission NOT happen.

Keep it simple, or go home.

Last edited by RobertDyck (2013-11-15 13:29:08)

JoshNH4H · 2013-11-15 12:57:14

I believe Zubrin has proposed a mission that could be done using FH launches. Are you familiar enough with the proposed architecture (Some details here) to say how you find it notably deficient?

My expectation would be that the fairing size of the Falcon Heavy (It looks like it's just 5.2 m) would be the biggest issue. Inflatable or otherwise expandable heat shields are probably (maybe?) out of the question for the first manned mission.

Six Falcon Heavy launches isn't that much in terms of payload. It's 318 tonnes, less than the payload that could be launched by 2 Ares V rockets when those were under development. Remember DRM 5.0, which proposed 6 Ares V launches for a Mars Mission? That was clearly a terrible architecture, but we're still talking about something on the same order as Mars Direct.

I really like your proposal to keep the actual transfer vehicle in a highly elliptical orbit. It's a real mass saver since you can use an architecture like Mars Semi-Direct (Using In-Situ Propellant Production) for a small Mars Ascent Vehicle without having to either land your transfer hab on the surface of Mars or mate your Mars Ascent Vehicle with the transfer hab in a LMO.

The delta-V for an inbound Hohmann, assuming you already have escape velocity, is .6 km/s (Accounting for the Oberth effect). Reasonably, it will cost you about 1 km/s to go from your HEMO (Highly Elliptical Mars Orbit) to your Transfer Orbit. Assuming Methlox (It doesn't make much sense to use Hydrogen given the low delta-V or long storage times), that means that your mass ratio will be just 1.3. Bonus points if your MAV can be designed to handle Earth Entry without mass penalty (Probably not reasonable).

I would be receptive to claims that H2/LOX could be synthesized in your HEMO from Water, reducing the storage time. However, this is probably not worth it. It only reduced the Mass Ratio to 1.25.

RGClark · 2013-11-16 15:00:30

In addition to the radiation dangers, longer stays in space are now known to damage eyesight:

Does space travel damage eyesight?
An increasing number of astronauts who've spent a month or more aboard the International Space Station are visiting the optometrist.
By The Week Staff | March 14, 2012.
http://theweek.com/article/index/225533 … e-eyesight

Astronauts And Mice Return From Space With Altered Eyes.
By Francie Diep Posted 10.25.2013 at 4:00 pm

When he rocketed up to the International Space Station in March 2009,
NASA astronaut Mike Barratt needed glasses to see things in the distance.
When he returned to Earth in October, he no longer had trouble seeing
far-off objects-but he suddenly needed reading glasses. By the time he
talked with CNN in 2012, his vision still hadn't returned to normal.
http://www.popsci.com/article/science/a … tered-eyes

The debilitating effects of zero-g for bone and muscle loss are also well known now. The bone loss in zero-g proceeds at a rate 10 times that of rate of the elderly suffering from osteoporosis.

Expedition 37 returned to Earth from the ISS Monday evening:

A Warm Welcome for the Crew - YouTube

Karen Nyberg looked pretty wiped out after the landing. Luca Parmitano looked pretty energetic. Fyodor Yurchikhin was somewhere in between.
Karen also didn't appear at the news conference with the other two astronauts, on doctors orders:

Expedition 37 Discusses Mission - YouTube

I'm not making a comment about the effects of long space exposure on women, by the way. Sunita Williams seemed pretty energetic on her return from the ISS, while Chris Hadfield looked wiped out after his.
What I am arguing is that NASA should be focusing on short travel times for Mars missions. You can't afford to have 1/3rd of the crew members incapacitated for days or even weeks when the crew lands. Not even a 6 month travel time using nuclear propulsion that NASA scientists have proposed would be sufficient.
However, by first setting up propellant stations on the Moon, the travel time could be cut to weeks instead of months.

Bob Clark

RobertDyck · 2013-11-17 16:08:56

Bob Clark: Wouldn't your goal be achieved with artificial gravity? We don't need a magical, yet-to-be-invented propulsion technology. We can do it now.

Do you have a porkchop plot showing characteristic energy (C3) for transit time to Mars in weeks?

GW Johnson · 2013-11-17 16:47:45

Artificial gravity is not at all hard to achieve in a "slender baton" shape composed of docked modules. You put the hab at one end, the engines at the other. It spins end-over-end and is quite stable, as we see every Friday football night all across America. You can have what we evolved in, one full gee, with a 56 m radius at the very tolerable 4 rpm. That's quite doable, today.

Cosmic radiation is simply not yet shieldable by humans in space. But a 2.5 year mission falls pretty close to the current annual and career exposures for astronauts. That is not the radiation bugaboo, solar flares are. The very worst solar flare exposures are shieldable with 20 cm of water, which also halves the cosmic radiation exposure without secondary shower effects. Any habitat for a 2.5 year mission will require water and wastewater tanks. Just wrap them around your designated solar storm shelter. Would not hurt to wrap some more of them around the sleeping spaces.

The real problem is something no one talks about: food for 2.5 years in space. The current technology is good for 12-18 months max. Frozen food is a lot heavier and more voluminous, but it works, and it has been demonstrated for decades, and potentially, centuries.

Face it, a manned Mars mission vehicle will be big, heavy, and assembled in LEO of docked modules. You can (and should) simply forget one-launch/one-mission. Bad model. We already know how to do everything we need, in order to get a crew there and back again, alive and healthy. We have known since we built the ISS.

Nuke rockets just make it smaller and cheaper. Too bad there aren't any. There once were.

GW

RobertDyck · 2013-11-17 22:09:27

I'm thinking food that needs to be cooked. The bread machine was invented by a high school student. A national science fair offered to fly on the Space Shuttle the winning entry. It had to fit in a Get-Away Special. This student claimed astronauts need to eat, and would appreciate fresh bread. So his machine made bread in space. It worked. As soon as the Shuttle landed, Betty Crocker offered the kid money for the patent.

My sister gave me a used bread machine for my birthday this summer. She likes garage and yard sales; popular every weekend during the summer in this city. She bought a machine that has a lot of settings. Gave me her old one, she bought new but had a few years. Very simple: white or whole wheat bread (or dough, or a couple other settings I don't use), light/medium/dark crust. Press "Start". Wait 3 hours for white, or 3:40 for whole wheat. The manual has a number of bread recipes. I altered the whole wheat recipe: skip "vital wheat gluten", replace the egg with a table spoon of starch and a little more water. It tastes great!

I use soy milk because in my house fresh milk tends to spoil before I use it. Soy milk powder from a store called the "Bulk Barn" is just soy milk. No carageenan or xanthan gum, no sugar or salt, no vitamin D or calcium carbonate, no preservatives. It's just soy milk (defatted soy flour). Great for cooking and baking, but don't try to mix a glass and drink it. Keeps a very long time in an open container. I purchase 1kg of powder at a time, it's consumed before it spoils. Will keep even longer if refrigerated. Since it's powder, a sealed bag should last longer than a Mars mission without refrigeration.

Food can be "canned" with a plastic bag. Lighter than metal cans or glass jars. Canned food will typically last 10 years. Sugar will last longer: typically 25 years. Brown or yellow sugar needs to maintain moisture level, so keep in sealed bags. (The recipe for whole wheat bread includes brown sugar. I use yellow instead.)

A few years ago, grocery stores carried stew in heavy plastic bags with a cardboard sleeve to print their fancy label. Lighter to transport, so should cost less. However, stores charged more. They do that with anything new. Use scissors to open instead of a can opener. Didn't sell, so stores stopped carrying it. Outdoors stores continue to carry them for many more years. Lighter to carry in a backpack. The point is this is established technology, nothing new.

Instead of dehydrated spaghetti, bring dry spaghetti. Just cook it. I tried to cook spaghetti in my microwave oven, with a Pyrex mixing bowl instead of a metal pot. It works. Had to boil it just as long, but it means a spacecraft doesn't need a stove. Dry pasta is rated for a little over 2 years storage, as long as you keep it dry.

Last edited by RobertDyck (2013-11-18 12:56:49)

RobertDyck · 2013-11-17 22:19:10

My architecture uses on-orbit assembly for the manned vehicle. Assembled at ISS. But I would prefer the unmanned stuff be sent directly, surface of Earth to surface of Mars. It greatly simplifies everything. But if all we have is Falcon Heavy, it can be done. Of course I expect the military contractors involved with SLS will find an excuse to claim it won't work, and convinece Congress to not fund it. Lobbyists will say "buy my stuff" and "their stuff is bad".

JoshNH4H · 2013-11-17 22:51:36

Are there any particular benefits from assembling at/near ISS as compared to any old orbit, even if you're expecting Russia to do your launching for you? Have you considered that doing on-orbit construction near the ISS might pose a risk to the station?

RobertDyck · 2013-11-17 23:55:49

ISS will act as the construction shack. Housing, life support, power, etc. for astronauts. The parasol for aerocapture/aerobraking will have to be deployed, will need astronaut involvement. And station arm can grab cargo, so docking equipment can be simplified. Don't need shock absorbers like an APAS docking collar & hatch. Spacecraft are already optimized to go there, so rendezvous and docking systems are "off the shelf". In fact, the first astronauts will ride a Dragon spacecraft up. That Dragon will be docked to the Mars vehicle, and stay docked as the lifeboat/escape pod. So assembly at ISS means Dragon has already proven that route. The Mars craft will rendezvous and dock with ISS upon return, so we don't even need a return spacecraft ready. Astronauts can hang out at ISS for a couple days if necessary. DreamChaser is designed to support ISS, so fetching astronauts from there will be trivial.

Of course you realize I see preparation for Mars as the main purpose for the station. They cancelled the centrifuge module, as well as commercial research. So what's left? We can upgrade life support to test/demonstrate equipment that will be used for Mars. And we can use it as a construction shack and "bus station". So rather than "risk to the station", I see this as justifying the station.

But your argument would be valid for an unmanned ship. The MAV would be very similar to Robert Zubrin's ERV; just with a very simplified capsule. There may be complaints about sending a nuclear reactor to ISS. While the manned vehicle would be assembled while docked to the station, the unmanned stuff would not be designed to dock. So it wouldn't have to be assembled in the vicinity at all. To maximize launch mass for the propulsion module, the unmanned vehicles could be assembled at 185km @ 28° inclination. Or perhaps lower? The orbit should be stable for a couple months, just for safety.

By the way, ISS was not put where it is for Russians. Astonautix has a 1968 NASA document with requirements for the Shuttle included requirements for a station. It was expected to do Earth observations. The orbit was 400km @ 50° inclination. Today it's at 400km +/-, and 51.6° inclination. So the only concession for Russia was increasing inclination 1.6°. That's trivial.

Last edited by RobertDyck (2013-11-17 23:56:56)

GW Johnson · 2013-11-18 12:37:30

I like what I read about the dried and "canned" foods, just above. Add in the frozen food capability that I suggested, and you have almost the same menu capability we have down here. The only thing missing is fresh foods, which would requite some sort of garden. We can do without that, as proven by the 90+ day war patrols US navy diesel-electric subs undertook routinely in the Pacific during WW2. A few of those went close to 150 days. They had dried, canned, and frozen foods in those pigboats. It worked. Crews stayed healthy, although "happy" is not something one associates with war. We still do the same thing today in our nuke boats.

I'd like to add the notion of thawing the occasional frozen brisket and doing barbecue (and other options). My wife has an oven brisket recipe that will add pounds to you just from the smell while cooking! You cannot do that sort of cooking in zero gee, either: convection ovens don't work without gravity to drive the convection. Good cooking smells inside the vehicle (or home) add to the happiness of those inside. We've known that since we tamed fire, over a million years ago.

With foods like that, we are talking about cooking with free-surface water, such as spaghetti. You don't do that in zero-gee. So, we are inherently talking about implementing spin "gravity" here. I like that, because it makes all sorts of life support processes far easier, including water and wastewater management. Makes going to the bathroom far easier, too. And real bathing becomes possible again. Not to mention avoiding all the microgravity diseases we are still uncovering.

A spin gravity hab on a vehicle long enough for one gee is a rather large assembly, right at 112 m long. You simply cannot launch a thing like that in a single shot, not even with an SLS, or even a Saturn 5. There, I just went and shot down the SLS team arguments that you cannot go to Mars with just Falcon-9/-H and Atlas-H/Delta-H.

But you cannot be a brain-dead bureaucrat and understand that argument, when politics yells far louder. Politics is government, which is invariably run by committees, whether elected or appointed. A committee is a life form with six or more legs and no brain, just as Heinlein said. That's why I am not sure the first manned trip to Mars will be a government mission. A motivated visionary private outfit like a Spacex might get there first.

If you know exactly where you are going to land on Mars, and you also have robot precision landing capability, and also you have robot collision avoidance capability during your landings, then landing unmanned stuff direct surface-to-surface makes sense. But, if you are missing any one of those three things, then it does not make sense, because you are guaranteeing that some kind of failure will occur. Failures that will most likely be lethal for any crew sent there. Or else you will spend a lot more than you planned on, re-trying to land the replacements for the stuff you lost or landed too far away, before you send the crew.

Since I don't see all three things in existence and ready-to-go, I'd prefer basing from orbit on the first mission, if for no other reason than safety and limiting the potential for lost cargoes. Even more important, given a reusable lander, that basing from orbit also enables landings at more than one interesting site (and there are many, don't kid yourself).

What's the point of going to the trouble of sending people all that way, as difficult as it is, and just land at one site? That smacks of the Apollo "flags-and-footprints" nonsense. You have to ask yourself "Why do we send people at all?" Answer: We send men to do the exploring that our machines cannot do.

One has to have a very clear picture of why we go and what we intend to do while there, before settling on mission architectures. Doing that out of order ends up producing nonsensical designs and wasting a lot of effort. Mission objectives must come first, and will dictate some (not all) of the constraints within which your mission architectures must operate. Then you select the "best" one of those.

I gave you the fundamental mission objective just above ("We send men to do the exploring that our machines cannot do"). Now you have to correctly define what you mean by "explore". We have millennia of experience to support that definition of "explore", too. It should mean to find out the answers to two very-deceptively-simple questions: (1) "what all is there?", and "where exactly is it?"

That's not Texas drawl, I meant them exactly as I wrote them, word for word. Think about it for a while. For one thing, you'll need a real drill rig, because some of those answers could be on the order of km underground, just like here at home. Ask anyone in the mining or petroleum industries, if you don't believe me. Mining water there will be very much like mining coal here.

Once you've thought about that, then you understand exactly why "flags-and-footprints" missions are total nonsense. It actually was nonsense long ago when we went to the moon with Apollo. Most of the real discoveries about the moon have come from probes sent since then. The Apollo astronauts couldn't do any real exploring, until they took the car on the last 3 landings. Even so, they did not have a drill rig. Sampling only up to half a meter down found very little of what we wanted to know.

Guys, I really recommend docked-module assembly in LEO, and on-orbit basing at Mars, for the first mission. I like using the ISS as a base and home for the assembly workers, that makes a lot of sense. A docked assembly will require a lot of launched modules. Better to bite the bullet and just do it that way, even if you have to launch more thrown weight than some other notions. That flexible orbit-based, multiple-landings exploration trip will tell you where you really want to set up your first base. It'll very likely be one of the sites you just explored. If and only if it is, then you can start that base on the that first trip. You might or might not get to do that, and that outcome (either way) has to be part of your mission plan.

GW

JoshNH4H · 2013-11-18 13:01:11

You make reasonable points. I would question if you might be able to reduce launch mass (and perhaps get a more useful waystation/potential future fuel depot) out of launching some kind of Bigelow Module with a CanadArm attached to do the assembly. In my mind there are also questions about whether the ISS will still be there by the time a Mars mission happens. I think NASA currently expects it to come down around 2020. If you don't launch by then, it's possible that whatever consortium you cobble together will have to pay the full cost of operations itself. This is especially true if you plan to do the mission with no US involvement.

In terms of justifying the station, if you don't think that it's justified itself (At $100,000,000,000 it's tough to imagine that it has, but it's a matter of opinion of course) I'd recommend not throwing good money after bad in an attempt to make it look like it has. You've made a fairly strong case for the utility of space stations in orbital assembly, but the fact that we've thrown a lot of money at the ISS in the past doesn't justify continuing to do so in the future.

By the way, the ISS is not used primarily for Earth observations. We have automated satellites for that now, which were not available to anything near the extent that they were in 1968. Space Station Freedom, were it built, would have had a 28.5 degree orbit, and it's fairly well known that we only went to the 51.6 degree orbit to accommodate the Russians. In any case, if you're really serious about planetary observation you'd want to go for a polar orbit, which would after all cover 100% of the planetary surface.

RobertDyck · 2013-11-18 14:21:42

I see the ultimate objective to be human habitation. A permanent base is a step to settlers. Robert Zubrin argued in 1989 for human exploration. If it was done, we could have had human explorers by 1999. He argued we don't need robotic exploration, just send people. That was valid, but robotic explorers were sent. Like it or not, it's done. Now that we have that, we have enough data to choose a permanent base location. So do it, build the base starting with the first human mission.

Exploration can be done with rovers. Notice I included an unpressurized rover with the lander for safety. Again, in case it lands too far from the "ride home". But I included a pressurized rover with the cargo lander. The cargo lander would deliver a lab, and life support would be fed from the habitat that comes with astronauts. But what if the crew lander with hab lands too far? Then life support in the pressurized rover can supply the lab. So the lab and pressurized rover are a backup hab. If everything works perfectly, then the pressurized rover can be used for extensive and far exploration.

This architecture includes an expendable TMI stage. The MAV acts as the TEI stage, also expendable. But both can be replaced by reusable equipment. When fuel depots are established in Earth orbit and Mars (either orbit or surface), with tankers to deliver fuel, then a reusable propulsion stage can be docked/attached. To deliver crew from Mars orbit to the surface, a reusable Mars shuttle. I had envisioned something based on DC-XA. It may not be optimal for Earth with its thick atmosphere, I argue DreamChaser is more efficient. But it is optimal for Mars, with both thinner atmosphere and lower gravity. Now that SpaceX is working on reusable rockets, they could adapt one for Mars.

Once Mars has a reusable shuttle, that could be used to explore the entire planet. Design it from the beginning to have enough fuel to launch, land, launch again, and land again. All on a single load of propellant. It may have the option of achieving orbit and rendezvous/dock with the ITV just once, or suborbital hop twice. "Twice" means out to a site for exploration, then back to base. Remember the ITV will be in highly elliptical, high Mars orbit. So reaching that will take a lot of propellant. Would such a vehicle be able to do suborbit twice?

Orbit vs direct entry: my architecture will place the manned vehicle in Mars orbit. Then the lander will descend. However, unmanned vehicles will direct enter. Mars vehicles have precision landing, look at how well Curiosity did. And when I attended the 4th Canadian space exploration workshop at CSA headquarters in 2005, one representative from a Canadian company was trying to sell his equipment. They make LIDAR, and wanted the rover to map terrain beneath during descent. Software was to include collision avoidance. This would enable precision landing. So Canada was already working on it. The problem is Parliament didn't approve funding for the Canadian Mars rover. Good news is Europe's current plan is to buy the ExoMars rover from Canada; add their instruments, and their launch vehicle. With all the orbiters and landers we already have, I argue we can choose where we're going. MRO has already imaged Curiosity, Spirit, and Opportunity on Mars, so we have high precision orbital imagery. So we have all the requirements listed by GW Johnson.

Last edited by RobertDyck (2013-11-18 14:41:46)

JoshNH4H · 2013-11-18 14:58:07

I can't say I disagree on any of the general statements made in your post. I think that we can absolutely go out there, and what's more we can make a profit on it (if private money is running the show) or have booming, self-supporting national colonies on the Moon or even moreso on Mars (if public money is being used).

When it comes to specific architectures, I'm liable to nitpick and disagree with any proposal I find to be suboptimal in any way. But I'm sure you knew that anyway

GW Johnson · 2013-11-18 15:48:53

Hi Josh! I nitpick, too. Can't help it.

RobertDyck -- most of the reusable Mars landers (aka Mars ferries) that I have seen are more or less conical, sort of an Apollo capsule or DC-X shape. I don't see why not that such a design capable of reaching high orbit once, couldn't do a suborbital hop twice. I've never run the numbers, but it's just rocket equation / mass ratio work.

All:

We're slowly iterating into a consensus here on mission architecture. I still favor taking big drill rigs. To support a base or colony will require mining subsurface ice. That doesn't work out very well if the ice is in thin veins or small lenses, you have to process too big a volume to get any return. We need thick veins or massive formations, to make this energetically (and effort-wise) affordable.

You cannot get that info from orbit, or any of the landers we have ever sent, including Curiosity. Mm or cm simply is not km of penetration. (Nor did we do it on the moon when we had astronauts there: 0.5 m is also inadequate.)

Gonna have to drill around a km or two deep to find the real ground truth at any site. There is no way around that. Not at this time in history.

GW

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