Has Dr. Zubrin Addressed Mars Direct Objections? - A few questions?

Dayton3 · 2004-12-11 14:51:49

I think GSN that you're expecting too much of the first manned mission to Mars.

I've conceded that I would use a larger booster for Mars Direct and go to a five man crew. But expecting more early on is asking too much.

A crew of five on Mars would be able to do one hell of alot of science in 18 months. Even with a rather spare equipment loadout.

And whether we go with bare bones Mars Direct or a "Battlestar Galactica" sized mission, ANY program can be canceled by the U.S. or fail to capture the imagination of the American public.

You simply CANNOT build a program "too big to abandon".

GCNRevenger · 2004-12-11 14:58:15

"I've conceded that I would use a larger booster for Mars Direct and go to a five man crew. But expecting more early on is asking too much."

But its NOT asking that much more! If you have the superbooster or abandon the direct-flight requirement with 1960's tech NTR engines, you can reach payload masses large enough for a practical, sustained base. This is not an impossible joke like Bush-I's SEI! It would likly cost no more then the stupid ISS does... The difference in capabilities required between MarsDirect and what are needed for small-scale perminant habitation are simply not all that large.

RobS · 2004-12-11 15:50:30

I just went through the Design Reference Mission; here are some notes in the form of a fact sheet. It provides some numbers to mull over. The parenthetical information (DRM 1-15) means "Design Reference Mission, chapter 1, page 15" so I have even provided footnotes so others can dig further. Sorry I don't have the URL handy; I used a paper copy i printed out a year or two ago.

-- RobS

Design Reference Mission Specifications (Summary)

Launch Vehicle: Able to place 225 tonnes into low earth orbit (or two 110-tonne launches would be used). It would also use a TMI stage with four NERVA engines, Isp 900 seconds, thrust 15,000 pounds [67,000 newtons]. This can deliver 100 tonnes of cargo to Mars orbit or 65 tonnes of cargo to the surface or 50 tonnes to the surface on a faster six-month trajectory (DRM 1-18, 1-19). The NERVA engines are jettisoned after TMI and are not reused.

Crew size: Six

Flight Cycles: Three (more are possible later, obviously, but the design is for three; 2007, cargo; manned flights, 2009, 2011, 2014). In 2009 Earth and Mars are farthest apart.

Transit Time: 180 days when Mars and Earth are farthest apart; 130 days when they are closest.

Arrival Orbit: 250 by 33,793 kilometers, 1-sol (DRM 1-19). This orbit keeps the orbital parts of the mission more or less above the surface outpost at all times.

Habs: All are 7.5 meters in diameter and bilevel and use as much common design as possible. Three types are necessary: surface laboratory, transit-surface habitat, Earth return habitat (DRM 1-22). (Note: 7.5 m diameter = 24.6 feet, floor area 475 sq feet or 44 sq meters). The earth-return habitat is “volume rich” for the crew. The mass of each habitat is about 53 tonnes (about 24 tonnes permanent elements and 29 tonnes consumable elements).

Mars surface laboratory is sent out first, before any crew. Top level, science labs; lower level, storage, convertible to greenhouse. Each mission uses the other two items. Each crew, on landing, moves and connects their transit-surface habitat to the science lab (and any other transit-surface habs left by previous crew) thereby building up a large surface facility.

The Mars transit/surface habitat masses 53.90 tonnes, including 10 tonnes structure, 17.5 tonnes consumables, 6 tonnes life support (including 3 tonnes of stuff that gets used up), 2.5 tonnes health care, 4 tonnes for EVAs (1 tonne equipment and 3 tonnes of stuff that gets used up), 2 tonnes thermal control, 3.5 tonnes spares/margin (DRM 3-82). This is twice the mass of Mars Direct for 50% more crew. The descent lander that carries the hab to the surface has a dry mass of 4.7 tonnes and can hold up to 30 tonnes of methane/LOX (DRM 3-82) The transit-surface habitats have big wheels so they can e moved up to half a kilometer and docked to another hab (see picture, DRM 3-83).

Power: Nuclear reactor able to produce 150 kw electric plus solar arrays for interplanetary transportation, able to produce 30% as much on the Martian surface. Design lifetime 15 years(DRM 1-22) Mass (including radiators) 14 tonnes (DRM 3-113)

Alternative power source: solar. To generate 120 kilowatts with a tracking array would require 19.6 tonnes; nontracking arrays would mass 33.5 tonnes (DRM 3-113). In both cases, a clear sky is assumed, no dust storms!

Pressurized Rover: Radius of operation, 500 km; duration, up to 10 working days at a remote site, two weeks remote operation total; up to 16 hours per day of EVA capacity; nominal crew, 2; emergency capacity; 4. Has an emergency dynamic isotope power system (DIPS) able to produce 10 kw electricity (mass of DIPS 1.1 tonnes; DRM 3-115). Design lifetime of all surface transportation: 6 years (DRM 1-22). Two will be sent to Mars; each will include a detahable power trailer that can be used to power other things as well. Mass 16.5 tonnes each (DRM 3-107).

Unpressurized rover: Three sent, mass 4.4 tonnes each (DRM 3-107).

TROVs (Telerobotically operated rovers): These are like the MERs; mass 440 kg each; three will be sent in the first cargo mission (DRM 3-109-110).

Surface Science Payload: Total 2370kg for first mission, including field geology package, geoscience lab instruments, exobiology lab, biomedical/bioscience lab, geophysics, meteorology, 10-meter drill (DRM 3-52). Total of 23,000 kg for the second mission, including a 20,000 kg drill capable of drilling 1,000 meters. Total of 4,070 kg for the third crew, including 1,000 kg meteorlogy lab.

ISRU System: It can produce 5.8 tonnes methane, 20.2 tonnes LOX (for the MAV) and 23.2 tonnes water, 4.5 tonnes breathing oxygen, 3.9 tonnes nitrogen/argon buffer gas. All of these are liquified and stored (DRM 3-101). The first ISRU plant masses 4.8 tonnes (DRM 3-105). The second ISRU system is smaller (2.2 tonnes).

Mars Ascent Vehicle (MAV): Surface mass, 65 tonnes at landing, including reactor and 40 tonnes of cargo. In-situ resource utilization produces nearly 30 tonnes of oxygen and methane. (DRM 1-10). Ascent delta-v: 5600 m/sec (DRM 1-21). Ascent fuel masses 26 tonnes. Specific impulse is 379 seconds. The ascent vehicle tankage and engines (dry mass, minus capsule) is 2.6 tonnes. The MAV uses two RL-10 engines modified to use methane. The ascent crew capsule is 4 meters in diameter, 2.5 meters high, holds 6, and has a mass of 2.8 tonnes (DRM 3-86).

Earth Return Vehicle (ERV): Delivered to Mars orbit about 4 years before needed. Consists of a TEI stage, an earth-return transit habitat, and a capsule for Earth landing (DRM 1-21). The TEI stage uses two RL-10 engines and has a dry mass of 5.2 tonnes, able to hold 52 tonnes of LOX/methane. The return hab masses 53.9 tonnes, like the transit-surface hab (it has an identical mass breakdown). The hab has a photovoltaic array capable of making 30 kilowatts at Mars aphelion. The ECCV (Earth landing capsule) masses 5.5 tonnes and can keep the crew alive several days as well as having parachute/parafoil for Earth landing.

Future Missions: Land in the same place as the first mission to build up a surface facility (DRM 1-16) because the primary goal should be to determine “how humans can inhabit Mars” is more important than “scientific data return” (DRM 1-8). Also, the accumulated scientific equipment allows expanded scientific return eventually (DRM 1-28).

Ground Operating Team: 1,000 people (as opposed to about 20,000 in the olden days)(DRM 3-132).

Euler · 2004-12-11 19:01:08

The hab is 8 meters/25 feet in diameter, has two levels each with about 50 square meters/500 square feet, and has a TOTAL mass of 25 tonnes, but that includes supplies, furniture, a pressurized rover, and scientific equipment. The structure is given as 5 tonnes, the life support system as 3 tonnes. ...The ERV cabin has a 3 tonne mass with a 1-tonne life support system.

For life support, 3 tons is a bit light for a 4 person P/C LSS, but it might be achievable with some more development (though the power plant to run it would also be several tons). Expecting to only need 1 ton for a 4 person P/C LSS is just foolish. What I don't understand is if Zubrin realized that it would weigh at least 3 tons on the fist hab, why did he think that he could get away with only 1 ton on the ERV?

RobS · 2004-12-11 19:02:58

The ERV's life support system has to run for six months only; the Hab's for 24+ months (6 months to Mars, 18 months on Mars).

-- RobS

Dayton3 · 2004-12-11 19:32:06

"I've conceded that I would use a larger booster for Mars Direct and go to a five man crew. But expecting more early on is asking too much."
But its NOT asking that much more! If you have the superbooster or abandon the direct-flight requirement with 1960's tech NTR engines, you can reach payload masses large enough for a practical, sustained base. This is not an impossible joke like Bush-I's SEI! It would likly cost no more then the stupid ISS does... The difference in capabilities required between MarsDirect and what are needed for small-scale perminant habitation are simply not all that large.

I do not care about a base on Mars. Nor do I care about developing new technology to make the missions easier and more efficient.

Nor I suspect do most of the American people, Congress or any administration.

Sure it would be nice, and if we can develop one as an extension of long duration Martian stay times (40 months instead of 18 on the surface) then fine. That would be great.

All I and I suspect most people care about it getting a manned AMERICAN crew to Mars and safely back AS SOON AS POSSIBLE as CHEAPLY as possible.

First, lets get a crew to Mars and back, break the ice (politically, beauracratically, and all that) and then develop things from there.

We get the first couple of manned missions....THEN we can work on making sure it all doesn't die like Apollo.

Alot of people think that the design reference mission is simply NASAs way of making the mission too complicated to do at all. Because NASA as an institution has no interest in Mars.

Euler · 2004-12-11 19:47:35

The ERV's life support system has to run for six months only; the Hab's for 24+ months (6 months to Mars, 18 months on Mars).

That should not make such a huge difference. You might need some extra spare parts for the Hab's system, but you should not get a 3 fold reduction in weight just by shortening the mission duration to 6 months. Based on experience designing Transhab's LSS, The DRM assumes a LSS mass of 4661 kg in each vehicle(to support 6 people).

RobS · 2004-12-11 22:49:32

It sounds strange to me, too. My copy of the Design Reference Mission has the surface-transit habitat and the Earth-return habitat massing exactly the same, line by line (the charts are on pages 3-82 and 3-92). Both charts have life support systems massing 3.0 tonnes dry mass and 3.0 tonnes of consumables (filters and replacement parts I suppose). Both habitats also have 17.5 tonnes of consumables for the crew (food and such).

-- RobS

GCNRevenger · 2004-12-11 23:59:20

Rob & Euler: http://ares.jsc.nasa.gov/HumanExplore/E … ...m#Title

You guys are looking at the older original version and not the updated one.

The new one tosses the idea of the backup pre-landed HAB/LAB, makes the decent stage of the MAV double as the acent stage, and generally tightens its belt a bit. It employs an 80MT class SDV launcher and sends up the TMI stages seperatly from crew about 90 days apart. A better analysis of what is needed for the aerobrake shield too.

Oh, and the nuclear reactor mass includes modest shielding, so a few tons might eliminated if there were an easy way to pile up Mars dirt around it.

I think the reason that the surface and ERV habs weigh the same consumeables/LSS wise is as a safety feature. If the HAB fails, then the ERV will need to operate for much longer (2.5yrs) to get back to Earth. So yeah it only has to run for six months if everything goes right, but if there is an emergency then the extra supplies would be needed.

Dayton:

I think you are letting your lust-for-red-dust overcome your judgement... I strongly believe that we shouldn't go to Mars half-way like we did to the Moon, that we either go there with the ultimate goal in mind of staying somewhere down the line, or its better not to go at all.

Losing the inertia after all the economic and political capital spent to just barely get to Mars and back is unacceptable; you HAVE to think about what to do after the initial landings before they happen, in order to minimize the expense of the REAL mission to Mars, to leave the Earth perminantly.

Exploration and perminance are two sides of the same coin, if you try and seperate them and sell only the exploration side, that is all you will get and the true dream will die for another generation or two.

NASA DRM is not too complicated! It can and should be done as opposed to the impossibly optimistic flags & footprints MarsDirect, and would wind up costing half what the ISS would. Once NASA returns to the Moon and regains the trust of the nation, then with only an additional $1 billion a year, NASA could afford to embark on a one hundred billion dollar decade-long Mars program (which would still not cost more then the ISS).

Although NASA is not hurting for the money, it would be wasting $30-40 billion on MarsDirect that we will just largely throw away after its done is a terrible waste of time, money, and faith. We can afford to do more then just plant flags and take pictures, and so we should... Hence MarsDirect, even if it could be fixed somehow (NTR TMI?), it would be a bad investment.

RobertDyck · 2004-12-12 11:54:32

NASA got $14.77 billion in 2000, $15.0 billion in 2003, and $15.378 billion in 2004. The $16.2 billion budget request for 2005 was approved by congress, but that was right after the election and Bush was supported in Texas and Florida. Don't expect a $0.822 billion budget increase in a single year again. I would like to see NASA's budget double, but I doubt it'll happen.

Ad Astra · 2004-12-12 14:00:21

The VSE plan was to pass the FY2005 budget with a $900 mil increase over FY2004 to $16.2B, followed by yearly increases only to match inflation. So it's doubtful we will see another increase this big betwwen now and 2020.

BWhite · 2004-12-12 14:08:39

The VSE plan was to pass the FY2005 budget with a $900 mil increase over FY2004 to $16.2B, followed by yearly increases only to match inflation. So it's doubtful we will see another increase this big betwwen now and 2020.

I agree with this. Thus, how can we expect a new clean sheet booster?

Use shuttle derived to

a) finish ISS
b) throw mass to the Moon
c) assemble more robust Mars mission using two launches

Use a lightweight crew taxi to ferry crew to assembled bigger vessels that remain in LEO, perhaps to be re-used.

GCNRevenger · 2004-12-12 16:49:59

That is still on the order of $80-90 billion dollars over a decade. Enough to do the job. I'd like to reiterate that we don't know the cost for sure of Shuttle Derived in development or flight costs, but an "Ares class" one will probobly be pretty expensive. I still think that the superbooster's launch costs should be considerd versus pairs of smaller Shuttle-C type vehicles; if there is a signifigant savings, it may well be worth the cost.

As for A&B, it looks like neither will be happening. Payload modifications and last-mile guidence of ISS payloads makes launch on ANY vehicle but Shuttle prohibitively difficult. CEV requirements also seem to spell out multiple uprated EELVs instead of "light" HLLV like Shuttle-C.

"Use a lightweight crew taxi..."
There is no such thing. A good crew taxi will not be light weight, and a light weight taxi will not be a good one. Reuseability costs should be compared to total vehicle costs too. Bringing back the "service module" of a capsule would be difficult, and a winged vehicle cannot fly to the Moon and back for VSE.

RobertDyck · 2004-12-12 17:29:19

Use of a space taxi has often been considered by NASA. When they looked at the VASIMR engine they intended to spiral out of LEO to near escape unmanned, then send the crew in a dedicated small vehicle to join it before TMI. It wasn't specified whether the space taxi would be reusable or expendable. The post Columbia report recommended separation of crew from cargo; again that requires a small space taxi. If we are to use ISS at all we need some way to get crew up there. In one conversation I had with a NASA person at the workshop on November 30, she said NASA needs some way of transporting down-mass. By that she means a method to get experiments down from ISS. The science module is built with racks that accept standard science drawers, so you only need to get drawers down. A space taxi could carry a few drawers.

It is true that a reusable space taxi is only efficient from Earth surface to LEO. However, a lunar architecture today would use Earth orbit rendezvous, not lunar orbit rendezvous. There are now several ways to produce oxygen from lunar regolith. Although fuel is much more difficult, oxygen only requires energy. If you use lunar oxygen for return to Earth, it's more efficient to go directly to lunar surface and back. To further reduce mass sent to the Moon, add a reusable heat shield for aerocapture and aerobraking. The heat shield could be fabric, same material as the outer layer of thermal blankets on Shuttle (the white parts). That doesn't talk about reusable vs. expendable, but I point out that once you bring the entire vehicle back to Earth orbit it's easy to make it reusable.

With a reusable space taxi to LEO, and a reusable Lunar transfer vehicle from LEO to Lunar surface, and a reusable ITV from LEO to Mars orbit, we have a highway to space. Reusable vehicles ensure sustainable exploration and development. I talked about using the MAV as the TEI stage for the ITV, and now using Lunar oxygen to return a Lunar mission to Earth, but the rest of the fuel will have to be transported from Earth. All these reusable vehicles will create a demand for in-space produced fuel. Can anyone say "asteroid mining"?

Euler · 2004-12-12 17:31:32

The VSE plan was to pass the FY2005 budget with a $900 mil increase over FY2004 to $16.2B, followed by yearly increases only to match inflation. So it's doubtful we will see another increase this big betwwen now and 2020.
I agree with this. Thus, how can we expect a new clean sheet booster?

You could try to convince the Air Force to build the HLLV. They spend more money on space than NASA anyway, and their budget generally increases much faster than inflation.

Mad Grad Student · 2004-12-12 17:58:07

Hold up one second. GCN, exactly what kind of Mars mission type do you favor? Perhaps I've worded my arguments poorly, but supporting Mars direct, I was trying to support the idea of two launches, one for a hab and one for an ERV that goes direct from Mars's surface, as in The Case for Mars. Granted, I would prefer the early-as-possible approach and trying to use as much off-the-shelf technology as possible, but that's not the critical part of Mars direct I was trying to support. I think we might have been arguing over nothing.

GCNRevenger · 2004-12-12 21:11:55

To be quite frank... screw the ISS. Forget about any more servicing flights of any kind with any craft except as a side bennefit of VSE hardware. Period. In such a case, a reuseable taxi is an unessesarry extravagance until you'll be making alot of flights.

If you are already having to launch the TLI stage and the crew, then you might as well not bother with making the system reuseable and just put the crew in a capsule both ways.

Making your vehicle so it can get from LEO to Luna and back to LEO with enough fuel for the next TLI burn is going to make it pretty big/expensive, and you will need a great deal of fuel for it most likly especially lugging the aerobrake shield. While you can make LOX on the Moon from oxides the energy demand of such an operation is going to be prohibitive and not possible for early missions. Even cracking water would be questionable on that scale.

There is also the problem of time... if you do recover the Lunar vehicle in LEO it is going to have to sit a while between missions, and storing the Hydrogen fuel for long periods may be problematic. A condenser could be added, but thats going to add signifigantly to the mass/energy budget too.

Overall though, such vehicle has one big inherint problem: Payload. That in order to be able to carry signifigant payload from LEO to Luna, you are going to have to carry a large amount of fuel from Luna to LEO. This ship of yours and the fuel plant to feed it keeps getting bigger the more I think about it... Asteroid mining is for the next half of the century for certain.

The idea that this or a Mars cycler will magically open a "highway to space" though is fiction, that the capacity of such a system of reasonable size will be so small that it won't be practical to do anything with it. On the Moon end, it will require a fairly massive logistical operation, and it would only really save you one launch per trip, so I think this is a hard sell versus an HLLV w/ TLI. On the Mars end, the ITV concept can't carry the kind of payloads needed without serious quantities of fuel in LEO, which will be easier just to send from Earth.

BWhite · 2004-12-12 21:22:38

As for A&B, it looks like neither will be happening. Payload modifications and last-mile guidence of ISS payloads makes launch on ANY vehicle but Shuttle prohibitively difficult. CEV requirements also seem to spell out multiple uprated EELVs instead of "light" HLLV like Shuttle-C.

If this proves true, then 2020 will arrive and we will see we still lack the capability to do anything worthwhile. Maybe that is the real objective of the VSE after all. ???

SpaceNut · 2004-12-12 21:27:05

Last I knew the last-mile guidance system was being worked on by the DART program. As to the cost of developing a SDV no matter what flavor it is, Would it really cost all that much to design? We already have a good cost estimate for all the pieces that would make it up.

GCNRevenger · 2004-12-12 21:31:40

Hold up one second. GCN, exactly what kind of Mars mission type do you favor? Perhaps I've worded my arguments poorly, but supporting Mars direct, I was trying to support the idea of two launches, one for a hab and one for an ERV that goes direct from Mars's surface, as in The Case for Mars. Granted, I would prefer the early-as-possible approach and trying to use as much off-the-shelf technology as possible, but that's not the critical part of Mars direct I was trying to support. I think we might have been arguing over nothing.

What I want to see happen for Mars?

-Ditch the "direct" part of the return leg. Combining the ERV and MAV as in MarsDirect places unrealistic restraints on the ERV, and so the NASA DRM three-ship aproach should be employed. This lends to future modification of re-use of the ERV someday perhaps, and sending "bulk" MAVs without ISRU plants & gear is easier than ERVs once a base is established.

-Double the payload of MarsDirect, make it on the order of 50MT as in NASA DRM, which is the kind of payload masses needed to establish perminantly, like a ~1MWe refuelable reactor, a pre-built HAB dome, or ISRU capabilities an order of magnetude beyond "exploration-class" stuff.

-Six crew minimum, which gives you much more manpower per mission while still being affordable... the size of crew needed for serious science or base construction, since robots will not likly be advanced enough for the task alone. Preferably with the option for eight if the HAB is launched without laboratory space/equipment once a base is established.

-Employ either the two-shot "light HLLV" (~100MT, like Shuttle-C with RS-68 & five-segment SRB) or build a vastly more powerful "super HLLV" with 200-250MT capacities in order to achieve this. Building a Shuttle-derived vehicle above 100MT like Ares may involve excessive modification. Solid-core NTR engines for TMI should likly be standard, with investigation of simplified high-thrust expendable Timberwind style engines.

-Don't skimp on the crew safety. Either include an escape option or don't launch the crew on the HAB. Sufficent floor space for psychological concerns. Radiation shielding aproved by medical scientists and not zealous nuclear engineers. Include the full 3-year LSS supply on the ERV. Etcetera.

Bascially, go and explore for the first fiveish missions planet-wide... maybe stop off at the Moons on the way home later on... but go with hardware that can be used to do more then just explore so you don't have to start from scratch. But most of all, DO NOT build the mission to be "just enough" to get our boots red.

GCNRevenger · 2004-12-12 21:40:43

As for A&B, it looks like neither will be happening. Payload modifications and last-mile guidence of ISS payloads makes launch on ANY vehicle but Shuttle prohibitively difficult. CEV requirements also seem to spell out multiple uprated EELVs instead of "light" HLLV like Shuttle-C.
If this proves true, then 2020 will arrive and we will see we still lack the capability to do anything worthwhile. Maybe that is the real objective of the VSE after all. ???

Well then we'd have to go clean-sheet. This might not be a bad thing, it would probobly yeild a vehicle with substantially lower flight costs.

RobertDyck · 2004-12-12 23:20:21

GCNRevenger, you should have seen Robert Zubrin's presentation about Lunar mission architecture at this year's Mars Society convention. He proposed assembly in LEO and an expendable capsule. It was still better than lunar orbit rendezvous. What I'm saying is a little different: replace the ablative heat shield with high purity silica fabric like the exterior of Shuttle, and return to LEO. That means you don't need parachutes or floatation airbags or landing rockets any other recovery systems. And certainly don't bring fuel for more than one trip.

Back to Mars: The single floor Hab for Mars Direct has plenty of room. Apollo had 6.17 m^3 habitable volume or 2.06 m^3 per person. Gemini had 2.55 m^3 habitable volume or 1.275 m^3 per person. The single floor Hab was 8.4 m outside diameter, I'm not sure how thick the walls were but for ease of calculation let's say 8 m inside diameter and 2 metre high ceiling. That makes 100.53 m^3 habitable volume or 25.1327 m^3 per person. Just how much space do you need? I said before that astronauts do require a separate stateroom, the BUNC at FMARS isn't enough, but the single floor version of MD is. MDRS was built with staterooms. I also said for psychological reasons we need to ensure all astronauts have the ability to go outside very sol. I think the solution is to send someone other than you.

I would prefer reusable vehicles to ensure sustainability. But if we can't have that, then MD is perfectly acceptable. I don't think the cost of my plan is higher than MD, but we would need to add a lot more detail and get the bean counters involved. But waiting another generation before considering even starting? This is New Mars, the discussion board for the Mars Society. The Mars Society was established to get a manned mission to Mars as soon as possible, definitely within our generation. If you're argument is to bulk-up the mission as an excuse to sell really big rockets, and hold the entire mission plan hostage until we get that, then you're in the wrong place.

I'll throw you a bone: When I first joined the Mars Society my repeated question was: "Where's the money?" You see, multiple billions of dollars, perhaps trillions of dollars are available if the venture is profitable. That's the catch: profit. But I came to the conclusion that asteroid mining and transporting settlers to Mars are profitable businesses. So I stopped asking "Where's the money?" and instead simply ask how I can get in on that profit. Richard Branson believes suborbital joy rides are profitable, and Robert Bigelow believes there's profit in space hotels. Ok, let's get going. If you want some other motivation I suggestion you simply find it, but nothing will happen if you just sit around waiting. The only reason it's cheaper to go now is Congress invested billions of dollars on the EELV program to ensure America has a competitive commercial launch vehicle, and NASA invested in TransHAB and other space inflatables. Progress has been slow but money was spent and work was done. Nothing will happen if you sit around waiting. As Robert Zubrin says, "History is not a spectator sport."

GCNRevenger · 2004-12-13 01:13:55

If you are honestly and with a straight face using the "one and half man" Gemini space capsule as an argument in any shape form or fasion versus a Mars HAB module, then you really shouldn't be making a judgement on HAB size.

It is quite clear to me that the top floor of the HAB is at least somewhat too small (25-50%) if for no other reason then there is so little contiguous space... it doesn't matter if you have a million square meters if its all broom closets. Frankly, you sound just like Zubrin does when he is making a medical judgement about safe radiation doseage... that he's guessing on the optimistic side to sugar-coat the plan.

You also continue to parrot the "but they can go outside!" argument... well no, they can't actually, because they'll be in space for a year solid. And on Mars suit gasses will be at a premium, since every time you go out, your not using the recycling LSS for the duration. No lower deck "rec room" either in transit. The situation with the ERV is even worse... it can't even get any rocks back much less the crew.

Now about that history thing... You may recall that we did actually start getting somewhere, put humans on the Moon. We did it in the shortest marginally safe time span (and it nearly got some of them killed) with spectacular sucess, just as MarsDirect seeks to do, get there NOW... but then look what happend. I want to see man on Mars too, but seeing it sooner only to leave and stop again is too high a price. Perhaps you and the good Doctor Z could use a little history lesson...

We do it right the first time, and go with the clearly stated eventual goal of going to STAY from the first day of the program. Not some wishy-washy "vision," but to build rockets and vehicles big enough to make it happen without having to start over from nothing after we get our boots red... That staying on Mars should be the goal, and not a quaint after-thought. It is technologically and economically within our grasp!

If it costs more and takes longer, so be it, that is then just the price of doing business. I am willing to wait to do this thing properly, and not half-way in a blind rush like Apollo again. Yes it will be expensive, quite expensive, but it isn't at all unreasonable for what you get... it wouldn't cost any more then the ISS will. The fastest and smallest way is going to get us nowhere in the end; the parallels are striking if you think about it...:

~Apollo and MarsDirect place time as paramount, that it must be done as fast as possible, NOW, no matter what.
~Both Apollo and MD use a rocket that is too large to build in number, but too small to send anything except the most minimal gainful mission, if that.
~Neither arcitecture has any real hope of becomming more then what they were and would have to be gutted and essentially replaced with somthing more capable.
~Neither arcitecture places much importance on doing anything besides get there and back... and thats all they would do.

In Apollo's defense, the stated goal was to get to the Moon as fast as possible period, and they invested the huge reasources that it took to get the job done. But Zubrin, Zubrin thinks (or at least feigns to) his dinky design could somehow be more then a flags/footprints mission, and is so zealous to see it done that he has forsaken good analysis to cut the costs, and he has gone too far... I am not holding anything hostage: Mars is the one demanding a more capable arcitecture... larger masses, larger crews, larger margins then MarsDirect offer are obviously required. And so larger they will be.

RobertDyck · 2004-12-13 08:15:38

First, Gemini is not "one and a half man"; it was a very efficient design for 2 astronauts. I have seriously suggested using a similar design for descent from Mars orbit to Mars surface, use an inflatable habitat. The example was to illustrate realistic vehicle sizes. Hollywood likes to show gigantic ships that would be luxurious for 10 times as many astronauts. I think you watched too many movies, in real life exploration is not done on a luxury cruise liner like Queen Mary 2. Have you ever been on a cruise ship? I took a day trip on a small ocean liner once, and got a tour of Voyager of The Seas while final preparations were being made. At the time my girlfriend worked for Royal Caribbean so I got on the employee tour, they were still installing chandelier and other finishing touches. That ship is huge, but that's due to the 3,114 passengers. A http://www.royalcaribbean.com/findacrui … ]stateroom is 160 square feet including bathroom, closet, twin beds that can be pushed together for a single double bed. Some staterooms have a small desk and loveseat; others replace the desk and loveseat with Pullman beds, bunk beds with folding upper bunk. That's 6 passengers in 160 square feet. You can get a larger suite; what was the largest suite, half a million dollars for a cruise? But a basic stateroom with Pullman beds has 160 / 6 = 26.67 square feet per person. That's a luxury cruise liner.

By the way, if you compare me to Robert Zubrin, I take it as a compliment.

A 6 month voyage requires more room than Gemini or Apollo, but the single story habitat of Mars Direct is fine. I presented a white paper on surface spacesuits at the NASA conference on November 30. I filed 3 papers on EVA suits and life support systems, but the conference organizer asked me to combine them into a single presentation. As mentioned earlier in this thread, a lithium-ion battery with 1500 charge/discharge cycle life is available Commercial-Off-The-Shelf but you have to be careful of temperature. A NASA employee at the conference said they're working on a lithium-ion battery and testing with NASA's temperature swings gives it 500 cycles. There are 500 sols on Mars so 1 battery lasts the whole mission. You could bring a spare as backup, but that's equipment not a consumable. I also mentioned the microwave regeneration of silver oxide granules for CO2 sorption. That is reusable indefinitely and returns CO2 to the habitat when it's regenerated, after the astronaut returns. A mechanical counter pressure suit uses sweat as coolant so it doesn't have a water sublimator or circulation tubes. Mars is cold so controlling heat means the outer layer is best built as a parka and ski pants with a dust protection vest under the parka. When the astronaut gets hot he/she just opens the parka or jacket and lets it flap in the breeze. Yes, an MCP suit is that simple and there is breeze on Mars; thin air means thin breeze, but it does exist. All this means the only suit consumable is electricity and drinking water lost as sweat.

Apollo surface stay was hours. Later missions lasted a couple days. The 90-day report (Battlestar Galactica) called for 2-4 weeks on Mars surface. Mars Direct calls for 14 months in 1999, longer in later years as Earth and Mars move away from each other in orbit around the sun. Transit time also goes up a few days. Or are you waiting for Mars to swing back? I think it'll be close again in 2016. Hmm, the timeline I gave calls for landing in 2016! Coincidence? It was based on probes already planned and launch windows, but the fact that 2016 is again a close approach means that should be our target date. But Mars Direct is not Apollo. I also want to start establishing a permanent presence on Mars, but MD is not Apollo!

Robert Zubrin called for human exploration in 1990, with first landing in 1999. The argument was manned exploration was better than robotic. Well, we've had the robotic exploration so that argument is moot now. I argue we should pick a location and send all manned missions to the same spot starting with the first mission. That will enable accumulation of equipment for a permanent base, not as a giant base construction mission but simply accumulating left-overs from science missions. Once started we can send a larger base construction mission later, but we need to start small or we'll never get started at all.

BWhite · 2004-12-13 09:40:31

Robert Dyck,

GCNRevenger's acceptance of a Mars mission built on two light HLLV (upgraded shuttle C) is probably the fastest way to Mars. Even faster than classic Mars Direct since Ares is a developmental step beyond an upgraded shuttle C.

Money? Using multiple shuttle C+ with no Ares development costs is probably cheaper than Mars Direct with Ares. And shuttle C+ will have assorted uses Ares may be just too big to justify, right now. Of course, Ares can be developed off a shuttle C+ as a straightfoward program.

When I listened to Robert Zubrin speak (both in Chicago and Boston) he said he was agnostic about choice of HLLV.

= = =

One branching point I see is nuclear thermal. With nuclear thermal, an Earth return ship could be parked in Mars orbit rather easily. Without nuclear thermal, pushing fuel to Mars orbit seems to be both expensive and risky due to boil-off concerns. The MAV ascent vehicle hits low Mars orbit and discovers empty fuel tanks. ;-(

Robert Zubrin's Case for Mars plainly contemplates the possibility of nuclear propulsion but we need to get over the idea that JIMO actually will assist human flight and just build some nuclear ships that can push people.

GCNRevenger, building political momentum for an all chemical Mars Direct makes it more likely that a nuclear add-on gets funded. To say Mars must wait for nukes and then to say that nukes are too sensitive, politically is merely subterfuge for saying "No" to Mars, period.

Get the public behind an all chemical Mars mission and then explain why we need nuclear propulsion as an "add on" - - since saying "No" to Mars is high on the political agenda of a surprisingly large number of "Moon-first and only" people, I want as few show stopping obstacles as possible.

Edited By BWhite on 1102952603

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Re: Has Dr. Zubrin Addressed Mars Direct Objections? - A few questions?

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