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So I'm up at 3:00 am once again and I find myself watching NASA TV when they just happen to be showing their animation of what they call the Mars Reference Mission v4.0. If anybody has seen this (I think they showed it in Chicago last year.) feel free to sound off on what you think about it. Is it just me or does this thing look way more complex than it needs to be. I mean the mission architecture includes assembling the TMI stage and the hab in LEO. I think that the ISS has shown us how well orbital assembly projects turn out so it's strange that NASA would want to go in that direction. Even more disturbing is that fact that the animation appears to use the Space Shuttle as the launch vehicle in the assembly process. :hm: I mean, I wouldn't count on the shuttle hauling my dirty laundry into orbit anytime soon, let alone sections of a multi-billion dollar interplanetary vessel. That fact that the mission requires something like six launches before the ship even leaves Earth orbit increases my scepticism of this even more. It doesn't even end there. upon arrival in Mars orbit the hab has to dock with what appears to be a descent stage that also contains a fully fueled ascent module, that was apparently put there by some other HLV launch. This then goes to the surface. Upon launch from Mars there is yet another orbital rendezvous with the TMI stage that then tranports the crew back to Earth. By not using any sort of Martian resource utilization this design further adds to the bulk and cost of the mission. All in all we're talking about 7 or 8 launches to complete the mission. For engineers this program will be their greatest fantasy or their worst nightmare depending on what side of the equation they are on, but to me it just seems too long and far too expensive of a project. Even if Mars Direct was beefed up to satisfy the NASA safety police it would still be a cheaper mission that could be accomplished on a much faster timetable. The engineering acronym KISS applies here big time. I just don't want the new SEI to die the way the old one did back in 1989. I might be wrong about some of this, I only saw the dang animation and a very brief summary of this way back in August so my information may be off. I just want to no what you guys think.
Ben Barrett ???
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NASA TV at three A.M. showing an animation of the Mars refrence mission?
It's old content to fill air space. Nothing to concern ourselves with. In short, the views expressed by the show do not accurately reflect the current mission plans or take into account the recent program shifts made by NASA. Implementation of the VSE invalidates the refrence mission.
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I'm not familiar with that particular mission plan... the DRM-III and DRM-IV plans aren't really a single "plan" but rather a collection of plans with some common componets and more-or-less a "baseline" mission.
The mission I like most is the baseline DRM-III plan: three vehicles of similar mass are launched to Mars seperatly, all three use aerobraking to slow down on the Mars leg of the trip.
-A fully fueled ship to return from Mars orbit to Earth, powerd by chemical engines (LOX/Methane), possibly aerobraking into Earth orbit at missions' end.
-Mars Acent Vehicle, ISRU fuel plant, and much of the surface payload (rover, drill rig, etc). Used to get from the Mars surface into orbit to transfer crew to the ERV. Probobly base it off a CEV capsule, which will already have a LOX/Methane powerd second stage/service module. The capsule could serve as the reentry vehicle for Earth return too. The ISRU plant only makes fuel for acent and ground vehicles/heavy equipment.
-HAB module that the crew rides out on is sent the following launch window, and lands near the MAV. Probobly has a spare nuclear reactor, light rover, and a few other items. Both it and the MAV lander would likly be powerd by LOX/Methane to save on mass.
Each payload would be launched by a 80-100MT inline Shuttle-derived heavy launcher, optimized for large diameter payloads and placement into LEO, not Earth-escape. Each payload would dock to a seperate rocket stage of similar mass sent up by the SDV, and would be nuclear powerd to minimize propellant mass. One the stage pushes the vehicle to Mars, it would undock and be nudged into Solar orbit with remaining RCS fuel. Thanks to the HAB module being sent to LEO first, you could opt to launch the crew seperatly on a very safe CEV launcher rather then putting them in the HAB.
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So, you do have a total of six launches of a modest (and fairly cheap) Shuttle-derived launch vehicle, likly within NASA's capability even with reduced staff. The HAB and ERV modules are much bigger then their MarsDirect counterparts, the former having about tripple the floor space and the later quadruple (maybe more), which I think is a showstopper otherwise and permits bringing a crew of six. Perhaps eight if you omit laboratory space and have room for "bilge" storage.
And, each payload would have much much larger payload margins then MarsDirect would thanks to the use of two medium/heavy launch vehicles and nuclear engines rather then one big heavy/heavy vehicle with chemical engines, although it does suffer somewhat from orbital circulization penalties. Splitting up the mission into three peices instead of two makes a world of difference, giving you tripple the surface payload for only a modest increase in complexity. LEO rendezvous makes it possible to launch the crew seperatly too, unlike MarsDirect. These items are the biggest showstopper for me why MarsDirect is not a good plan.
Some tradeoffs are involved of course... Martian fuel is only leveraged to launch the MAV into Mars orbit and to fuel ground vehicles, which reduces the bennefit of ISRU. On the other hand, you no longer have to lift the whole mass of the ERV and the fuel to put it on course for Earth, radically reducing the Mars launch mass. This makes a whole world of difference to the size of the ERV, plus adds one interesting option... Suppose the ERV aerobrakes into LEO on the Earth end, is refuelled/resupplied (TEI stage/supplies, TMI nuclear rocket, use crew CEV for Earth return) and send the ERV into Mars orbit, then use a new "Mega MAV" to ferry the crew down to the surface base and back at the end of the mission... Presto, semi-reuseable crew ship to Mars, using only two HLLVs instead of six. And MarsDirect? Well, it doesn't have any reuseability options.
Edit: Oh, and putting the HAB into orbit first lets you test it to make sure it works before comitting a crew to Mars. In MarsDirect, once those clamps are released on the launch pad in Florida, its Mars or bust.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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In Mars Direct and Mars Semi Direct architectures the facilities left on the surface on Mars are, with resupply, reusable.
Jon
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I think that is debateable, these items will have been put through some years of work, so you best not put faith in them to keep crews alive or to get them home.
Plus, for early missions, you won't want to go to the same site over and over again (unless you find Martian life maybe...), in which case the original items will get older and older as they sit there. Focus on finding acessable water and life first with the early missions, and then pick a site for a perminant base to send sturdier purpose-built hardware to.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Thanks guys I've been out of the loop for a little while. I saw this plan back in August at MSC 7 in Chicago and I thought it looked way to costly. Anyway as far as being able to check out the hab in Mars orbit. Wouldn't you be able to check the Hab in Mars Direct right before you had to aerocapture and still be able to use the free return trajectory to abort back to Earth, or is there a point of no return? I like the idea that GCNRevenger posted about reusing the ERV. It would almost be like a mini cycler. This could drive down the cost of future missions significantly. Good Thinking.
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If they had gone with "colonization" rather than "visit and return" they would have had to build a new vehicle (oddly rectangular) with the length of the space shuttle given entirely over to habitat space and fourty feet wide strapped to a slightly larger fuel tank.
The four colonist team would have had to live off ration packs for the voyage but they would have had the sort of room you could live in.
On Mars it would have looked like an oversized mobile home without wheels. If you throw in a forward deployed carry-all (necessarily assembled on crew arrival) that is designed to carry that mobile home across the surface, even better. It would cost the same as a NASA reference mission (20-50 billion).
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If they had gone with "colonization" rather than "visit and return" they would have had to build a new vehicle (oddly rectangular) with the length of the space shuttle given entirely over to habitat space and fourty feet wide strapped to a slightly larger fuel tank.
The four colonist team would have had to live off ration packs for the voyage but they would have had the sort of room you could live in.
On Mars it would have looked like an oversized mobile home without wheels. If you throw in a forward deployed carry-all (necessarily assembled on crew arrival) that is designed to carry that mobile home across the surface, even better. It would cost the same as a NASA reference mission (20-50 billion).
Um. Yeah... Space mobile home to nowhere, with no way to get down or come back.
"Anyway as far as being able to check out the hab in Mars orbit. Wouldn't you be able to check the Hab in Mars Direct right before you had to aerocapture and still be able to use the free return trajectory to abort back to Earth, or is there a point of no return?"
No, I mean that using the DRM plan, you could check the Mars ship before you even left Earth orbit, so you could be much more sure that it survived launch undamaged and would last for the trip versus going directly from Florida to Mars. In the MarsDirect plan, as soon as you launch, you are comitted to go all the way to Mars and back.
As far MarsDirect abort options (not aerobreaking at Mars, instead slingshotting back to Earth), the HAB only has a fairly small amount of rocket fuel by the time it reaches Mars, about 1km/sec worth of Delta-V for landing engines, which I doubt would be enough for such a major course correction to put you on a trajectory back to Earth... I don't know though, gravity assist might be enough to do the job. Some issues however:
-You must aerobrake at Earth to slow down, increasing heat shield demands substantially, especially at extra high transit speeds, which would very likly make the HAB too heavy for the standard Ares rocket
-No artifical gravity, you would have to cut loose the Ares rocket stage to orient for course correction burns. Up to two years in zero-G in that super-cramped tin can...
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Ya mean as opposed to the "Pegasus" in the BBC documentary-miniseries Space Odessy with their big monster of a nuclear powered ship, their tiny little lander and their philosophy that Space and Mars should be for science only, not colonization.
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GCNRevenger wrote:
"I think that is debateable, these items will have been put through some years of work, so you best not put faith in them to keep crews alive or to get them home."
Why? Current space station modules have continuous operating lives, with maintainance, of at least 10-20 years. Mars lander modules would have been inhabited for only 18 months. If they were powered down and partially depressured they should be available for use for many years, if required. They may also serve as centres for a range of robotic operations as well.
I agree the the most likely scenario is that many different sites will be visited at first, resulting a scattering of temporary camps across the surface. However these previous sites would be useful as backups and field camps. Also sooner or later a site will be identified that will provide a base for a longer term base, and the older modules will remain in use.
So to me it makes much for sense to assume that Mars modules will have nominal operating lives of 20 years, if if this is not always utilised.
Jon
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As each hamlet (team of six) fails or passes (and advances to a village(51-999)...town(1000-9999)...city(10000+)) on the results of its site resource survey, the 'fails' get pushed to 'later development' before we commit too greatly to the expense. The 'passes' get the next wave of systems, increasing levels of power supply, If one site has large deposits of nickle, copper, aluminium, then we are going to drop processing equipment in close proximity.
If a 'failed' community falls in the energy corridor between the nuclear reactor and the 'passed' city then they will probably get the power on and be able to grow as a consequence.
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