What If we HAD to get to Mars on Short Notice

Dayton Kitchens · 2007-01-09 13:20:44

Come now GCN,

go big or not at all.

Surely then bigger is better.

GCNRevenger · 2007-01-09 16:08:35

Come now GCN,
go big or not at all.
Surely then bigger is better.

How snide of you.

Big is good, too big is bad.

Dayton Kitchens · 2007-01-09 16:57:31

Come now GCN,
go big or not at all.
Surely then bigger is better.
How snide of you.
Big is good, too big is bad.

Ah I see.

Dr. Robert Zubrins Mars Direct is too small.

The guy suggesting nuclear powered rovers as big as Hab modules it too big.

But GCNRevenger's mission plan is JUST RIGHT...................

GCNRevenger · 2007-01-09 18:19:04

Ah I see.
Dr. Robert Zubrins Mars Direct is too small.
The guy suggesting nuclear powered rovers as big as Hab modules it too big.
But GCNRevenger's mission plan is JUST RIGHT...................

It isn't my plan, its NASA's. The Design Reference Mission, aka "DRM," the third iteration of which is the best and most complete. I like this plan for the most part, with an adjustment or two. And yes, it is just about right.

Why is it so hard to believe that Bob is just wrong?

Dayton Kitchens · 2007-01-09 19:37:15

Ah I see.
Dr. Robert Zubrins Mars Direct is too small.
The guy suggesting nuclear powered rovers as big as Hab modules it too big.
But GCNRevenger's mission plan is JUST RIGHT...................
It isn't my plan, its NASA's. The Design Reference Mission, aka "DRM," the third iteration of which is the best and most complete. I like this plan for the most part, with an adjustment or two. And yes, it is just about right.
Why is it so hard to believe that Bob is just wrong?

Because NASA saw fit to junk most all of its previous manned mission architecture and adopt the foundation elements of Mars Direct until they started gold plating it.

NASA dropped opposition class missions.

NASA dropped orbital assembly.

NASA dropped manned orbiting "motherships" at Mars.

NASA adopted in situ resource utilization.

NASA adopted long surface stay times.

NASA adopted the use of large boosters (instead of orbital assembly).

One man effectively altered virtually all NASA mission planning.

All that has gone on since Dr. Zubrin presented Mars Direct has been gold plating.

Why is it so hard for you to believe he is right?

Oh yeah, the "numbers".

Why is it so hard for you to accept high risk to astronauts?

As though Manned Mars Missions should be like taking the subway downtown.

GCNRevenger · 2007-01-09 21:12:29

Nonsense, NASA was never serious about the Battlestar Galactica plan, it was an SEI "spoof" to make doing anything except fly Shuttle in circles forever sound completely unrealistic.

NASA was also considering, I'm sure, using heavy rockets for a Mars mission following the Apollo program. It just never got anywhere since the rug was pulled out from under them by Nixon, USAF et al when Shuttle became the only acceptable plan.

NASA's adoption of ISRU is incidental, and in fact it isn't even unnecessary for DRM to work. It is possible to skip it, powering the MAV entirely with imported fuel, though it will reduce surface payload somewhat.

And long surface stays being Bob's invention? Please, its just common sense to go with the long-stay option versus the short with all the trouble of going to Mars. Crediting common sense to Zubrin? I would go so far as to state that NASA intentionally opted for the short stay to make it look unpalatable and hugely expensive.
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And yes, Zubrin's numbers are crazy. Only 500kg for the entire surface hardware package, 1400kg for the pressurized rover (a Camry weighs more then that!), >60REM radiation dose, etc etc etc. Zubrin, either through blind fault or willful fraud, simply defined down what was possible and useful until it fit his desired price tag.

High risk is not acceptable, astronauts should be saying "bye, see you soon" not "bye, hope I see you again"

Dayton Kitchens · 2007-01-09 22:33:52

They aren't going to find evidence of life proof of the lack of it on the first mission to Mars anyway unless its a blind stroke of luck.

The facts remain, until Zubrin came along, NASA didn't have even the remotest possible manned Mars mission architecture.

And I think its vital that space exploration remain "dangerous" to build public support.

No danger. No heroes. No heroes, no budget.

cIclops · 2007-01-10 06:59:11

They aren't going to find evidence of life proof of the lack of it on the first mission to Mars anyway unless its a blind stroke of luck.
The facts remain, until Zubrin came along, NASA didn't have even the remotest possible manned Mars mission architecture.
And I think its vital that space exploration remain "dangerous" to build public support.
No danger. No heroes. No heroes, no budget.

Zubrin's contribution was the concept of "living off the land" and it's unlikely that the first mission will depend on ISRU based fuel for the ascent vehicle.

Space exploration is dangerous enough already, there's no need to add more danger. A three year mission to Mars will have more than enough danger and excitement to keep the public fascinated. It's the next mission and the ones after that that will inevitably lose pubilc support. That's why it is essential to make the architecture affordable and practical. Doing a cheapo mission is the best way to ensure limited results and the effect of a disaster would probably terminate the whole program once the media got their teeth into blaming NASA for not doing it right.

Who says fossils won't be found on the first mission? The site will be carefully chosen to optimize the chances and 18 months exploration by a crew of six will be capable of finding them in a wide area if they exist.

Tom Kalbfus · 2007-01-10 09:02:09

They aren't going to find evidence of life proof of the lack of it on the first mission to Mars anyway unless its a blind stroke of luck.
The facts remain, until Zubrin came along, NASA didn't have even the remotest possible manned Mars mission architecture.
And I think its vital that space exploration remain "dangerous" to build public support.
No danger. No heroes. No heroes, no budget.
Zubrin's contribution was the concept of "living off the land" and it's unlikely that the first mission will depend on ISRU based fuel for the ascent vehicle.

Why not? The technology can be proven without going to Mars, and there is also a sample return mission that's slated to test ISRU. I think by the time we send people to Mars, we should know what were doing and not be afraid that Martian carbon dioxide will not react properly to make fuel.

Dayton Kitchens · 2007-01-10 09:08:35

They aren't going to find evidence of life proof of the lack of it on the first mission to Mars anyway unless its a blind stroke of luck.
The facts remain, until Zubrin came along, NASA didn't have even the remotest possible manned Mars mission architecture.
And I think its vital that space exploration remain "dangerous" to build public support.
No danger. No heroes. No heroes, no budget.
Zubrin's contribution was the concept of "living off the land" and it's unlikely that the first mission will depend on ISRU based fuel for the ascent vehicle.
Space exploration is dangerous enough already, there's no need to add more danger. A three year mission to Mars will have more than enough danger and excitement to keep the public fascinated. It's the next mission and the ones after that that will inevitably lose pubilc support. That's why it is essential to make the architecture affordable and practical. Doing a cheapo mission is the best way to ensure limited results and the effect of a disaster would probably terminate the whole program once the media got their teeth into blaming NASA for not doing it right.
Who says fossils won't be found on the first mission? The site will be carefully chosen to optimize the chances and 18 months exploration by a crew of six will be capable of finding them in a wide area if they exist.

I disagree.

I think a disaster would actually increase public support by the American people by "wanting to show we could get it done".

Challenger and Columbia didn't kill the shuttle program. Thats despite the fact that most NASA observers said after Challenger that "the next shuttle we lose will be the last one that flies".

cIclops · 2007-01-10 10:46:16

Why not? The technology can be proven without going to Mars, and there is also a sample return mission that's slated to test ISRU. I think by the time we send people to Mars, we should know what were doing and not be afraid that Martian carbon dioxide will not react properly to make fuel.

An ISRU unit large enough to produce the many tons of fuel for ascent to LMO will be heavy and landed as separate cargo. The risk of the crew not being able to reach an ISRU fueled ascent vehicle and it not working will be too high for the first mission. ISRU makes sense initially for long term life support and rover propulsion. Given enough time and money to debug the technology maybe crew can eventually rely on it for the journey home. AFAIK there's not even a mission planned to test ISRU yet, it seems far too premature to base the whole Mars architecture on it.

GCNRevenger · 2007-01-10 11:32:10

Who says we won't find life on the first mission? We will have a general idea where water is or was, be able to travel long distances to promising sites, and drill underground to find living or dead microbes. You don't know we won't find life if we go with enough people and equipment.

I CAN say that we won't find life if we don't look! The chance that bacteria of any sort, alive or dead, are just sitting on the surface is next to nothing. The only way we will have a chance is if we can visit many possible sites and dig underground when we get there. We can do neither with MarsDirect.

You think that space travel has to be dangerous in order to garner public support? Well thats stupid, you completely discount the lesson of the Shuttle disasters. When astronauts die for nothing, because some NASA execs decided to cut corners, then the credibility of the agency is jeopardized. And without that, the dream is dead. It doesn't matter if the astronauts were volunteers either, all the public and Congress will see is that they died, it won't matter that they were personally prepared to risk it.

You don't know how close a bullet we dodged, how close we came to simply being shut down since the people who matter questioned if NASA was competent anymore. Twice now men have died for nothing, because NASA brass decided to cut corners, or concerns weren't important because of expediency. A third time, and this time a far more publicized event, might be the last. At the least, NASA brass must be able to stand up and truthfully claim that they did all they could reasonably do, and their lives were not risked for nothing.

MarsDirect even if it did work will accomplish nothing , and by nature of its not-even-shoestrings design takes serious and unnecessary risks that a slightly larger mission could avoid by nature of its larger mass margins. So, if people die with MarsDirect or worse, people will rightfully call for NASA's head, but not with DRM-sized missions.

The time of "we have to see this through" being the prevailing sentiment about spaceflight outside of NASA is over, it was over the minute the Apollo-11 capsule set down in the ocean and the existential justification of beating the Soviets was over. NASA got lucky with the Shuttle disasters, the chance that they will get lucky a third time is not an acceptable risk.
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As far as the technical risk of ISRU, I think that we should use it for the first mission. The plant and the ascent vehicle will be sent as one payload on the launch opportunity before the crew is sent. During this time, the ISRU plant will do its thing, and the ascent vehicle fuel tanks will be loaded, before the crew ever leaves Earth.

If we can't land a HAB within a short rover ride of the MAV/ISRU plant, then we have no business going to Mars at all until we do. Accurate landing is critical to future missions to build a base, so if we don't have the technology to do it on the first missions, we won't have this necessary tech for the base building missions that must following closely on their heels. We can already aim that well with the Mars rovers and they are simple ballistic things, we will be able to land accurately just fine I think.

cIclops · 2007-01-10 13:46:38

As far as the technical risk of ISRU, I think that we should use it for the first mission. The plant and the ascent vehicle will be sent as one payload on the launch opportunity before the crew is sent. During this time, the ISRU plant will do its thing, and the ascent vehicle fuel tanks will be loaded, before the crew ever leaves Earth

Which means the ascent vehicle will be waiting for about three years before the crew uses it, and the LO2 has to be kept topped up unless the tanks are heavily insulated and the ISRU is guaranteed to operate for two plus years. No it's too much risk for the first mission, a small navigational error, a broken rover or ascent vehicle and the crew are doomed. The MSL has a landing zone error of about 10 km, but the HAB will have to use a totally different technology. EDL is one the hardest things to do on Mars. Putting it deeper into the critical path is not a good idea IMO. See if the sample return guys want to risk their whole mission on an ISRU fueled ascent vehicle. Keep it simple, land the crew with their ascent vehicle, then they have a direct abort mode available to LMO if they can't reach the HAB. They'll still have 30 days to explore. Be safe not sorry.

GCNRevenger · 2007-01-10 15:05:46

I don't agree, whatever Earth-return vehicle will also have to loiter in Mars orbit for three years likewise with the same propellants according to the plan. Unless you want to send the crew to Mars before an ERV is safely in orbit of course... If we can do that in Mars orbit, you can do the same with the same technology on the Martian surface.

Also, re-lanuching the HAB module or any portion thereof back into Mars orbit is not going to happen. Once the HAB descends from Mars orbit, following which the crew cannot transfer to the ERV for emergency return in space, the crews' survival will hinge on being able to reach the previously delivered MAV vehicle by land. The HAB cannot weigh any reasonable amount large enough to accommodate that much fuel, you are talking about double the payload mass at least.

And if the MAV is going to be carried on the same mega-vehicle as the HAB, then later on when we DO think we are ready for ISRU, then the ISRU plant cannot be pre-positioned, thus the MAV will land with its fuel tanks empty without yet another flight for the ISRU plant earlier.

The extreme size of the MAV/HAB combo will also need a much more powerful lander, a different aerobrake shell than the ERV, and a different means of TMI. You would not have a "normal" size lander either if you wanted to send the MAV/ISRU plant in the future separately.

If you did preposition the MAV/ISRU plant in the future once we are "comfortable" with the technology, you would have to drop back down to the "normal" sized HAB and associated hardware. There is no good reason to have a giant mega-HAB if it is not going to carry the MAV.

Furthermore, LOX/Methane engines are standard for all engines on all three vehicles, HAB/MAV/ERV. Without their added performance versus storable propellants, it is unlikely the mission can be carried out with a reasonable number of Ares-V rockets.

Again, the crews' life will not hinge on ISRU working: the crew isn't even going to set foot in a rocket until the ISRU plant is finished producing fuel for the ascent vehicle.

This risk is a conscious trade off for more payload, and I think its a good one. This really is not that big of a risk either, the HAB will have the luxury of descent from lower velocities than vehicles sent directly from Earth, and its descent will be powered for much of the trip down permitting significant cross-range adjustment.

And really, if we can't do that safely, then our technology is just not ready to send people to Mars.

Oh, and tell the sample return people they can have triple the mass of sample, and they are at least going to pause.

cIclops · 2007-01-10 16:04:36

I don't agree, whatever Earth-return vehicle will also have to loiter in Mars orbit for three years likewise with the same propellants according to the plan. Unless you want to send the crew to Mars before an ERV is safely in orbit of course... If we can do that in Mars orbit, you can do the same with the same technology on the Martian surface.

According to DRM III the ERV will use NTP. The ascent vehicle needs 39 mT of fuel which requires ISRU because the descent vehicle can't land that much. DRM III assumes 40 mT can be landed on the surface, that's 50 times the amount possible right now (MSL weighs 775 kg). It's a hard problem. The crew may need to land in two ships, each with an ascent vehicle.

Also, re-lanuching the HAB module or any portion thereof back into Mars orbit is not going to happen.

Agreed, the HAB should stay on the surface where it belongs. It should be landed separately and the crew travels to it.

Furthermore, LOX/Methane engines are standard for all engines on all three vehicles, HAB/MAV/ERV. Without their added performance versus storable propellants, it is unlikely the mission can be carried out with a reasonable number of Ares-V rockets.

And how much LO2/LCH4 will be left in the ERV 3+ years after launch?

This risk is a conscious trade off for more payload, and I think its a good one. This really is not that big of a risk either, the HAB will have the luxury of descent from lower velocities than vehicles sent directly from Earth, and its descent will be powered for much of the trip down permitting significant cross-range adjustment.
And really, if we can't do that safely, then our technology is just not ready to send people to Mars.

That may well be the bottom line

Dayton Kitchens · 2007-01-10 16:22:17

I thought even in the DRM that the crew traveled in the Hab to Mars, landed in the Hab on Mars, and lived in the Hab on Mars.

To me that makes the most sense.

GCNRevenger · 2007-01-10 16:34:20

Um no, the "baseline" DRM-III ERV will be sent to Mars with nuclear rockets, but will return with chemical rockets like DRM-I. DRM-III included mention of other options such as nuclear return too, but I don't like those ideas as much as the basic one, which is itself a direct derivative of DRM-I. In any event, a nuclear powered ERV would have to have active fuel condensers since Hydrogen boils off so fast, which would be mission critical. The ERV in DRM-III just carries extra propellant and lives with the slow boiloff rate of O2/Me, which really is not that bad, only a few percent after 6-12mo. The ERV doesn't have landing gear, surface equipment, etc so it can carry quite a bit of fuel.

DRM-I, if memory serves, considered sending the MAV with full fuel tanks and had the payload to do it. However this would come at the cost of the pressurized rover, drill, and most of the surface science hardware.

And the baseline DRM-III does indeed have the crew leaving Earth, traveling to Mars, and living in the one and only HAB of the mission. They would then transfer to the MAV, which would meet the ERV in orbit for the return trip. I think you read one of the "alternative options" instead of the baseline mission, cIclops.

That is the bottom line, and it is an acceptable risk with a large payoff. Dividing the crew into two separate vehicles isn't a good idea.

Edit: there really isn't a "have your cake and eat it too" arrangement I don't believe.

Dayton Kitchens · 2007-01-10 21:28:33

DRM-III does seem like a reasonable option in many ways. I suppose I could even live with a six man crew. Though for what its worth, I've read somewhere that interpersonal dynamics work best with an odd numbered crew so perhaps five might be a better option.

This of course wasn't necessarily the intent of this thread. I was just suggesting what an absolute barebones mission would look like.

I'm afraid in so many ways that we're all here arguing the wrong thing when we should be over in Political Outreach trying to determine a political strategy for getting presidential and congressional authorization of a manned Mars program.

GCNRevenger · 2007-01-11 13:51:53

Barebones depends on what you are wanting to accomplish

-Minimum relatively safe, useful mission is DRM-III with pressurized rover, heavier payload capacity/larger crew, and future options for upgrade.
-Minimum relatively safe but not useful mission would be MarsDirect resized for a smaller crew and a marginally more powerful launch vehicle (eg 150MT), but would lack practical upgrade options.
-Not safe and useless, nor can be upgraded, is Bob's regular MarsDirect.

Dayton Kitchens · 2007-01-11 22:06:50

You've pretty much convinced me that that the original Mars Direct is not practical.

I've wondered though if it might be better to pursue the middle option you mentioned.

Treat the first Mars Mission as more a "proof of concept" mission than one where you maximize scientific return or maximize base building assets.

And I've wondered.

What if a manned Mars program is "shuttlized"?

That is, the program gets presidential and congressional approval and is in fact mandated...but NASA discovers that they've been given a budget (in the case of the shuttle) where they can only afford to build an orbiter but not a booster?

GCNRevenger · 2007-01-12 07:35:35

Then NASA had better say, loud and clear upfront, what it needs to do it and plainly say that it cannot be done for less.

Dayton Kitchens · 2007-01-12 07:44:07

Then NASA had better say, loud and clear upfront, what it needs to do it and plainly say that it cannot be done for less.

Government agencies do not tend to do that.

GCNRevenger · 2007-01-12 08:39:58

Then NASA had better say, loud and clear upfront, what it needs to do it and plainly say that it cannot be done for less.
Government agencies do not tend to do that.

They do when their survival is at stake, as it is for NASA.

Palomar · 2007-01-12 09:18:02

...at the rate things are progressing the past 30 years, I'd say if we had to get to Mars on short notice we'd be screwed.

cIclops · 2007-01-12 15:19:35

...at the rate things are progressing the past 30 years, I'd say if we had to get to Mars on short notice we'd be screwed.

Getting there is a hard problem but not as hard as getting back. It's doable one way relatively quickly, say in 10 years given the funding. The "hold and build" model is one way to do it. The first crew of six on Mars would stay indefinitely, they would be resupplied regularly as they built up infrastructure and explored. The capability to return two crew would be possible in the first cycle. Additional crew would be added as the base expanded. The plan would be to maintain a permanent presence and slowly grow it as capabilities were established. Some of the initial crew might never return to Earth.

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