Riding to Mars in a capsule?

mcs_seattle · Dec 1, 2005

Is the CEV plan really to send people to Mars, riding the entire way there and back in vehicle the size of capsule? I hope I missed something about the plan because that sounds quite miserable.

tohaki · Dec 1, 2005

Without having looked at the plans I would imagine that part of the spacecraft structure would be a large Salyut'ish module which the CEV CSM was docked into.

elguapoguano · Dec 1, 2005

The "capsule" portion would be used for return through the Earth's atmosphere. The CEV is made as a modular design, so a habitation mod would be attached to the capsule, perhaps as the Mars lander it's self... 6 month ride in only a capsule, not feasable. <div class="Discussion_UserSignature"> Don't let your sig line incite a gay thread ;>) </div>

spacefire · Dec 1, 2005

the CEV for Mars would have to have a shelf life of over a year if it were to undergo the trip. At the same time it would have to carry 6 astronauts (the established minimum for a trip to Mars) so it would have to be the proposed LEO taxi version. If the CEV ever gets built, adapting it for a Mars mission might be tougher than expected and might boost its weight past the capabilities of the solid booster. <div class="Discussion_UserSignature"> http://asteroid-invasion.blogspot.comhttp://www.solvengineer.com/asteroid-invasion.html </div>

najab · Dec 1, 2005

>the CEV for Mars would have to have a shelf life of over a year if it were to undergo the trip.But for the vast majority of that time it could be in a powered-down state, or power would be supplied by the main hab module.

dobbins · Dec 1, 2005

It's a modular system. Hook up a different service module to the capsule and you have a different service life.

radarredux · Dec 1, 2005

> Is the CEV plan really to send people to Mars, riding the entire way there and back in vehicle the size of capsule?/i> No, they would not spend their entire time in the capsule; although, Scientific American recently had an article about inducing hybernation in mammals that normally do not. Maybe by 2020 we can put humans into hybernation and ship them to Mars in little pods. The cover story for a recent Popular Mechanics issue is Buzz Aldrin's approach for reaching Mars using spacecraft that continuously orbit between Earth and Mars. In his proposed approach, the CEV would rendezvous with this spacecraft, at which point the humans would transfer to the larger part of the spacecraft (which would rotate for gravity). The humans would then re-enter the CEV for the return to Earth's atmosphere. Shuttle Guy has mentioned a plan in which the CEV would not go to Mars at all, but the Mars Return Vehicle would rendezvous with the CEV as it approached Earth, the crew would transfer, and then only the CEV would return to Earth's atmosphere. With the exception of the hybernation scenario (which, as far as I know is not being considered), the crew would spend most of their time in a larger spacecraft component. Zubrin has his plans (books available). I think a Bigelow inflatable might make a good option.

mikejz · Dec 1, 2005

I have a related question, how 'directional' is the radiation in interplanitary space? In other words if I put the manned part of a Mars Mission on one side the vehical and pointed the other end towards the Sun, would that prove to be an effective shield?

j05h · Dec 1, 2005

the problem w/ Cyclers is that the crew-vehicles have to catch up with the cycler at both ends of the trip - there is no savings in delta-V, only in Earth/LEO-Cycler mass. This makes a lot of sense once we are sending hundreds or thousands to Mars at a time. Mike- radiation, especially during solar storms, is largely omnidirectional. You want to be shielded in all directions. Josh <div class="Discussion_UserSignature"> <div align="center">We need a first generation of pioneers. </div> </div>

mcs_seattle · Dec 2, 2005

Thanks With space matters I have a hard time knowing when to trust what I think is common sense. In this case it didn't make sense to spend such a long time so confined. But it other matters, what I think would be common sense ends up being absolutely opposite. Mark

henryhallam · Dec 2, 2005

This is the same way the CEV will be used to go to the Moon. The lunar architecture is L1 rendezvous? The LSAM will go all the way from L1 to the surface and back?

nacnud · Dec 2, 2005

No, the CEV stays in space, LLO in this case, while the crew transfer to a dedicated lander/hab. They need to trasfer back to the CEV after the mission in order to return to Earth, ie there is not direct abort from Luna surface to Earth.

JonClarke · Dec 2, 2005

As I recall Griffin specifically mentioned in his announcement of the ESAS archiecture that the CEV would carry a six person crew for mars missions. Most high profile US Mars mission studies have been six man, including those of the STG in the late 60's, the SEI of the late 80's and the DRM of the 90's. Russian missions concepts have included both 4 and 6 man versions. There will be a full 500 day ground simulation of a Mars mission in Moscow in the near future. this has a 6 man crew. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

mattblack · Dec 2, 2005

I've seen suggestions over the years that a 5-person crew is optimum, with the sixth as a 'spare' (no, really!) Many studies, especially the famous ones like Zubrin's 'Mars Direct' have suggested four people (2x EVA teams) for keeping the needed consumables and therefore the vehicle sizes down. Vehicle sizes & consumables quantity: 25% percent difference between crew of 4 & 5, BIG 50% percent difference between crew of 4 & 6. A): Where the CEV Mars missions are concerned; one strong mission architecture concept would be a "Mission Module" for the crew to live in, added to the basic lunar ESAS configuration, essentially a Habitat volume for the 6 or 7 month outbound journey. It would have a pressurised volume approximately the same as 1.5x or 2x a Shuttle Mid-deck area. B): Three Module Stack: CEV+MM+MSAM. Crew boards MSAM shortly before Mars arrival and the CEV+MM, their design lives over, are discarded into space. The MSAM lands not far from a pre-deployed Mars Cargo/Ascent Vehicle (MCAV) that took to the surface a pressurised Rover, mini-nuclear reactor and fuel factory, Exploration tools and consumables on its lower stage. The MCAV's upper section is an unfuelled Ascent Stage; topped with a CEV crew capsule. C): The fuel factory, powered by the reactor, sucks in the Martian air and combines it with the stock of hydrogen it brought from Earth. This fills the Ascent Stage tanks and when departure day comes, the crew climbs into the capsule and flies into Martian orbit. D): Awaiting them is a pre-deployed Earth Return Vehicle (ERV) which consists of a LOX/Methane propulsion stage, topped by a Mission Module. The Ascent Stage and Crew capsule docks with the ERV, drops the Ascent engine package and burns out of Martian orbit for the return to Earth. E): Shortly before Earth arrival, the Crew capsule with its heatshield undocks from the rest of the ERV and enters Earth atmosphere for a land or sea tou <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

nacnud · Dec 2, 2005

With regards to (C) there is now strong evedence of water ice on Mars and therefore an accessable source of hydrogen. I would like to see the first mission take a feed stock of hydrogen but perhaps mission after that won't need to. This also introduces the possiblity of LOX/LH rockets for accent and return.

spacefire · Dec 2, 2005

Dave, allow me to speculate a little on the design of the CEV. If the 6 men/person LEO Taxi version is gutted down to the strictest minimum systems to 'shuttle' astronauts to the ISS, will it still have the ability to last in space for a year? For instance, to ride to LEO where you are still protected by the Van Allen belts there is no need for radiation shielding. Now I don't know if the CEV incorporates that, but, say it were to go to Mars and be used as a lifeboat in case your hypothetical ferry ship fails and the crew has to transfer to the CEV for ther est of the trip, it should have some sort of shielding et least from one direction. That would make the CEV bound for Mars possibly even heavier than the one used for Lunar operations. <div class="Discussion_UserSignature"> http://asteroid-invasion.blogspot.comhttp://www.solvengineer.com/asteroid-invasion.html </div>

nacnud · Dec 2, 2005

The only realistic sheilding light enough form an initial Mars trip will probably have to be water, this would also double as water for the crew and be built into the crew hab module. I very much doubt there will be extra sheilding in the CEV. If the Hab fails then your gona be stuffed for oxygen and power, radiation although inportant isn't a prority compared to those two.

dobbins · Dec 2, 2005

http://www.space.com/missionlaunches/odyssey_radiation_030313.html

spacefire · Dec 2, 2005

so there is no reason for the CEV to ride all the way to Mars and back? <div class="Discussion_UserSignature"> http://asteroid-invasion.blogspot.comhttp://www.solvengineer.com/asteroid-invasion.html </div>

mattblack · Dec 2, 2005

Oh, absolutely! <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

mattblack · Dec 2, 2005

>>If the Hab fails then your gonna be stuffed for oxygen and power, radiation although inportant isn't a prority compared to those two.<< The Mars Lander has enough consumables for about 18 months on Mars, so along with the CEV's air and water, they would have enough supplies if a major fault occurred to the MM's systems. The choice would then be: 1): Continue to Mars and use the pre-deployed backup MCAV's consumbles. 2): Abort past Mars for an interplanetary cruise back to Earth: The combined Delta-V of the CEV & MSAM should be designed into the architecture for this course-correction redundancy. <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

JonClarke · Dec 2, 2005

Hu matt Lot's of good stuff here, I will try and comment on several posts at once. CREW SIZE: I have seen studies saying that 5 is the minimum number to cover the essential skills. For some reason their is a dislike of odd numbers of crew on long missions, I don't know if there is any science to back this up. But certainly people have suggested an extra person to provide redundancy as you suggest, or more likely, to provide extra help when needed. Four is the realistic minimum for anything more than a flg a footprints style mission, although I have seen numbers as low as three. I think the highest I have seen proposed in the last 30 years is 15 (Case for Mars 1986), 8 is the next highest (ISU 1991). As you say, engineering concerns, mainly mission mass, push towards small crews. Mission productivity and safety push towards larger crews. Six is a good compromise, although I think four is doable. MISSION ARCHIECTURE: Griffin has said that the NASA DRM version 3.0 would be the starting point for Mars mission planning. The archiecture you prose has some similarities but also differences. Is yours based on a source, or is it one you have thought up as likely? It certainly has some interesting features. LIFEBOAT MODES If the spacecraft you are travelling in to or from Mars fails completely you are dead. There is no way a CEV can provide a lifeboat without it being as big as the main spacecraft. People sometimes talk about a second spacecrft to provide a shelter but I don't think it is realistic or neccessary. provding a fellet on unneeded spacecraft is a great way of doubling your cost without increasing your return. It's not going to happen. Either people will go without it or not go at all. I don't think this is a big problem. The backup spacecraft would have to launch within minutes of your main one for there to be any chance of a deep space rendezvous. <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

mattblack · Dec 3, 2005

The architecture I've proposed is largely my own, but I've run it by a couple of people. I've thought that since the CEV's design life is 6 months, and most transit times to Mars have been in the neighbourhood of that figure: Then 6 months would do for the outbound part of the mission, where the CEV would act as the Command Cockpit. The Mission Module, about 20 tons(?) in mass would be the outbound Habitat, similar in size to an ISS MPLM (see pic below), with the Mars Surface Access Module left largely alone in the sense that it's consumables would be untouched and left for the Mars surface mission. If you added up the total estimated cubic volume for a crew of six, with the three modules: CEV -- 600 cubic ft, MM -- 2000 cubic ft (not including food & water containers), and the MSAM -- 1000 cubic ft (not inc. etc). This would give give approx. 3600 cubic ft of pressurised volume for the crew. Living quarters, exercise & medical equipment, food pantries, engineering workshop, science experiments, waste recycling & disposal etc. A bit tight for 6 people, sure, but still more than twice the volume of a Space Shuttle's flightdeck and Mid-Deck combined. With the outbound CEV & MM disposed of before Mars arrival, the Mars Lander crew later move onto the Mars Ascent Vehicle and ERV. These craft, in spite of being in standby mode for many months, would be essentially "fresh" spaceships not continuously manned and operated for the total 2.5 years of the whole mission. With this redundancy of "fresh"(!) ships every few months, the engineering demands on reliability would be drastically reduced and would give the crew a fighting chance of all sorts of combined abort modes. This is consistant with the Mars Reference 3.0 architecture that Mike Griffin has been referring to. And if you look at the design of the ESAS Lunar Surface Access Module; that craft does appear to be a bit over-engineered for the moon. It almost appears to be a c <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

mattblack · Dec 3, 2005

MPLM internal volume, largely emptied. Picture from STS-102. <div class="Discussion_UserSignature"> One Percent of Federal Funding For Space: America CAN Afford it!! LEO is a Prison -- It's time for a JAILBREAK!! </div>

JonClarke · Dec 3, 2005

Interesting stuff. You need to get hold of a copy of Wiley and Pranke's "Human space flight". It's invaluable. It has all the formula for caculating masses, volumes etc. for missions of different lengths. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

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