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#51 2007-05-08 12:53:46

quasar777
Member
Registered: 2002-05-05
Posts: 135

Re: Combining the Rover and Hab - Go RV'ing!

i don`t think a mobile rig would have room for a greenhouse. & would an expedition bring feces all the way back to a stationary base? i guess maybe if it was kept outside a vehicle.

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#52 2015-02-23 21:26:39

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 10,650

Re: Combining the Rover and Hab - Go RV'ing!

NASA's Moon-Bound Geology Lab that Never Quite Got Off the Ground

GM completed the MOLAB (or "MGL" for "Mobile Geological Laboratory") in 1964 for NASA's use in the Apollo astronaut program.

hg1ljangsj2vkb6ptddw.jpg

The size of the MOLAB (20 feet tall, 8200 pounds) made it difficult to transport into space; it could only ride aboard a Saturn V.

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#53 2015-03-04 20:28:43

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 10,650

Re: Combining the Rover and Hab - Go RV'ing!

Another topic here is Marsdrive Mission Design[ of which It appears that MarsDrive is no more a website but only a facebook presence now.

I want to copy the discusion from another topic to where it really should be takling place so as to keep the other topic on target.

kbd512 wrote:

I think three CL-ECLSS subsystems are required for the surface habitat.  The tech currently in development is efficient enough in terms of mass and volume to make this possible.

If we want mobile surface exploration, then I think we should seriously consider minimal mass and capability ascent vehicles and forgoing emplaced habitats for electric/methalox hybrid Winnebagos.  The crew should land in two or perhaps three mobile surface habitats near the ascent vehicle.  If all vehicles are functional, then our Martian road warriors start a year long convoy-style road trip across Mars.

SpaceNut wrote:

I do want CL-ECLSS and it is a mandatory end goal when it works but we should plan for even a partial system with backups for equipment failure.

There was a topic that did talk about the Winnebago approach to mobility of exploration and it does require small cargo drop zones along any planned path that a crew would follow as it does explore but in the end they finish at a MAV site as a final encampment.

That said we are now talking 2 different travels to Mars and reasons for going even thou we say that we are going for science. Its clear to me that the science returned are different from each and if I had my way a dual mode exploration would be run in parallel.

kbd512 wrote:

I mentioned the mobile exploration architecture because it would seem to make sense to design a mission that permits you to travel to supply caches spread across the surface of Mars if you really distrust your ECLSS engineers that much, scout for potential staging sites for future exploration or settlement activities, and perform field science while you're at it.

I read into what you asked as wanting to know how much mass and in what configurations we'd have to stage it on Mars.  The short answer is that not having reliable CL-ECLSS is cost prohibitive.  If we wanted to, we spread supplies across the surface of Mars for contingency scenarios.  However, you then have to travel to those resupply sites.  Would it not make infinitely more sense to have redundancy for your ECLSS, or simply have replacement parts and tested & approved methods of field repair, and use ISRU for collecting oxygen and water rather than trying to ship all of it there?

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#54 2015-04-12 16:53:42

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 10,650

Re: Combining the Rover and Hab - Go RV'ing!

Forwarding posts which are targetting this discusion:

kbd512 wrote:
Tom Kalbfus wrote:

Lets look at it another way. If you are on Mars, for what purpose would you try to reach orbit, if not to return to Earth?
If there was some other part of Mars you wanted to go to, wouldn't it make more sense to take a surface vehicle? Blasting off into orbit takes a lot of fuel, and most landers are designed to leave parts of themselves behind when they take off again, so they typically aren't reusable. If you want a second landing, you will have to bring a second lander, now it is possible but expensive to have two surface missions going at the same time on different parts of the planet.

You mean like a habitat failure or some kind or loss of supplies required for sustainment?

Even if your rover won't run or your habitat has a hole in it, you still need air, food, and water.  If you can make it to an ascent vehicle, hopefully the MTV fared better than whatever caused you to cut your Martian travel plans short.

In my plans, there are two 20t pressurized rovers (electrically driven, solar powered M113 derivatives) and a habitat module that's more pressurized storage than a place I intend for the astronauts to live.  My boys and girls are wild red rovers, not squatters.  Martian cavalry, such as it were.

In any event, both the rovers travel convoy style for mutual protection.  If either vehicle has a major malfunction, the other is immediately available to collect the astronauts from the stranded vehicle and either assist with repairs or return to the storage habitat for parts to fix the busted rover.

If a repair can't be effected, then absent a spare rover the surface exploration mission is largely over.  They could either mill about their base site for the remainder of their time on Mars or return to an orbital station for a new dragon lander (no rovers if the rovers aren't close enough to drive themselves to the new site, but them's the breaks) and open a new base site.

More options means a far greater return for our efforts.

Of course all of page http://www.newmars.com/forums/viewtopic.php?id=7233&p=5 it continues and now with my post from page 6

SpaceNut wrote:

Wow popcorn and where is the movie?
Oh I see still wanting a machine that is proposed... BAE to Offer Hybrid Electric Vehicle to Replace Army's Bradley Armored Personnel Carrier Shane McGlaun (Blog) - July 27, 2010 10:30 AM

The core hybrid vehicle platform from BAE is expected to tip the scales at 53 tons and meet the mobility requirements of the Army at that weight. The vehicle platform is designed to still meet mobility requirements of the Army at 75 tons. That extra weight range allows the vehicle to evolve as the needs and demands of the Army change.

But wait a minute its Hopes Dim for BAE’s ‘Green’ Combat Vehicle By Brendan McGarry Wednesday, January 22nd, 2014 5:40 pm

BAE conceived of a hybrid-electric vehicle that could operate on diesel or electric power, with lithium-ion batteries that recharge when braking. Think Toyota Prius, only super-sized and with tracks, armor and a gun turret. In addition to better gas mileage, the design would offer fewer moving parts and faster acceleration, officials have said.
Still, it’s no fuel-sipper. At a hulking 70 tons — about the weight of an Abrams and more than twice that of a Bradley — the vehicle would get less than a mile per gallon of fuel.
The Army in recent years repeatedly described the Ground Combat Vehicle as one of its top acquisition priorities. The service had planned to buy about 1,900 of the vehicles at a cost of as much as $17 million apiece, or $32 billion.

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#55 2015-04-12 16:57:24

SpaceNut
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From: New Hampshire
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Posts: 10,650

Re: Combining the Rover and Hab - Go RV'ing!

The reasoning for continuing it here is that we have come to a conclusion that landing the crew in a vehicle ready to roam the surface would be a necessity if we can not land within 100m of any permanent habitat via a beacon, gps system or someother method that might be invented before we go and with the thought that the main science is to roam or explore rather than to set up shop for continued, returns to Mars.

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#56 2015-04-13 04:07:43

kbd512
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Registered: 2015-01-02
Posts: 1,187

Re: Combining the Rover and Hab - Go RV'ing!

I think it's reasonable for the astronauts to walk up to 1km on the surface of Mars to the habitat, but for any distances over 1km the habitat should really come to you.

The 15t-17t payloads representative of realistic mobile surface exploration mission elements are an intermediate step for initial exploratory missions before we begin continuous surface operations using static habitation modules ranging in mass between 40t and 80t.  Think of it as an ADEPT and mobile surface habitat technology demonstrator mission to land something that's useful for surface exploration and provides contingency astronaut retrieval.

In any event, the main selling point for development of mobile habitation elements is not contingency operations, but field science.  The exploratory missions need to locate sites with lots of water in the ground that's relatively easy to extract.  Once those sites have been found and experimentation conducted to confirm the feasibility of obtaining the water, then we can decide where to land the static habitation modules and how many personnel can be continuously supported using local resources.

Baby steps…

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#57 2015-04-13 11:49:40

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,712
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Re: Combining the Rover and Hab - Go RV'ing!

What if you had as part of your descent vehicle something resembling a lunar rover,  but with an inflatable operator's cabin?  Say a range around 10-50 km?  If you land within that distance,  you can just motor your way to destination.  If that takes a sleep period,  you have the inflatable operator's cabin.  Sort of a pup-tent-on-wheels.  Any merit to that idea?

As to multiple vehicles landed at 1 site,  I'd think the min distance would be around 100 m,  with a max around 1 km.  With too close,  you risk damage from rocket blast,  and rocket blast-thrown rocks.  Too far,  and it compromises your everyday operations.  The real trouble is using in-situ-produced propellant:  you gotta be close enough to drag the hoses.  Unless,  the propellant is made and stored in the vehicle that is going to use it. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#58 2015-04-14 03:26:22

kbd512
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Registered: 2015-01-02
Posts: 1,187

Re: Combining the Rover and Hab - Go RV'ing!

GW Johnson wrote:

What if you had as part of your descent vehicle something resembling a lunar rover,  but with an inflatable operator's cabin?  Say a range around 10-50 km?  If you land within that distance,  you can just motor your way to destination.  If that takes a sleep period,  you have the inflatable operator's cabin.  Sort of a pup-tent-on-wheels.  Any merit to that idea?

Well, you could include a mini rover but then you'd increase the weight of the EDL solution you're landing in to something that would definitely require retrorockets.  Everyone seems to want to increase the weight of the human EDL solution.  Of course that provides more options after EDL, but it also causes as many problems as it solves- problems that are more expensive to design solutions for and far more difficult to properly test.

GW Johnson wrote:

As to multiple vehicles landed at 1 site,  I'd think the min distance would be around 100 m,  with a max around 1 km.  With too close,  you risk damage from rocket blast,  and rocket blast-thrown rocks.  Too far,  and it compromises your everyday operations.  The real trouble is using in-situ-produced propellant:  you gotta be close enough to drag the hoses.  Unless,  the propellant is made and stored in the vehicle that is going to use it. 

GW

If you don't land with retrorockets, then blast from retrorockets is not a consideration.  HIAD + parachute + airbags may ultimately be required for a soft landing in a micro capsule, but that's as complicated as I would want to get for a human EDL solution.  As far as landing accuracy is concerned, if you can land within 30km or so of the landing area, then a real rover like a M113/MTVL can reach you in one to three hours.  I think it's reasonable to expect a capsule to land within 30km of its target, even a capsule using parachutes.  Our landing accuracy is already far better than that.

Rather than exerting yourself and wasting precious oxygen, you're better off relaxing in your capsule or perhaps taking your first steps on Mars and waiting for the retrieval vehicle to come to you.  The micro capsule solution includes one or two contingency oxygen bottles and a water bottle, but that's it.  Take a nap and wait for the cavalry to arrive.  There will be at least two of four MTVL's making their way to you, guided by your team mates from orbit.  Robotic MTVL operation using radio beacon homing is available as a backup.

If we're really that concerned about this, the answer is a solid oxide electrolysis unit to make oxygen from Martian CO2.  Your micro capsule would then carry solar panels to power the oxygen generation unit and provide heat, rather than carrying extra oxygen bottles.

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#59 2015-04-14 11:58:11

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,712
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Re: Combining the Rover and Hab - Go RV'ing!

I don't have any access to the fancy chute data or trajectory models that the JPL guys have.  I just ran some very crude estimates with an ordinary round personnel chute.  Subsonic CD = 1.2-ish,  dia=24 ft.  About the min weight to get it to open is around 90 lb.  About the max weight safe to carry is 300 lb (soldier+gear).  Those are canopy loadings W/A = .2 lb/sq.ft min to open,  and W/A = .66 lb/sq.ft max safe.  Here on Earth,  sea level terminal velocities compute as 12 ft/sec at 90 lb,  and 22 ft/sec at 300 lb.  That's pretty close to real life.

I used the same high-end canopy loading data,  factored down for weight on Mars at .38 gee,  and got .25 lb/sq.ft,  which is still greater than the min opening loading.  I got a comparable terminal dynamic pressure of 0.21 lb/sq.ft (was .17 to .55 on Earth),  but at Mars,  the surface density ratio to Earth standard is 0.006-ish.  That dynamic pressure at such a low density gives a terminal velocity of 170 ft/sec.  0-to-30-ish ft/sec touchdown velocity is OK.  100+ is not.  If you lower the canopy loading (lower weight per unit blockage area) to get a lower velocity,  you risk the chute never opening at all. 

As I said,  the JPL guys have better data and more experience,  but numbers like mine tell me a chute and an airbag probably won't do the job to land men on Mars.  You'll need a retrorocket blast to keep from smacking the surface too hard.  It's worse at higher elevations,  too. 

GW

Last edited by GW Johnson (2015-04-14 16:04:45)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#60 2015-04-14 18:27:19

kbd512
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Registered: 2015-01-02
Posts: 1,187

Re: Combining the Rover and Hab - Go RV'ing!

GW,

Is there no possible way to increase the size of the chute and have it deployed successfully?

What about an inflatable stiffeners?

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#61 2015-04-14 18:35:39

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 10,650

Re: Combining the Rover and Hab - Go RV'ing!

The reason for clearance above the surface is due to the cold temperatures and the metal brittleness of impact as with a low clearance of a tank like unit we would need to tread real slowly as the rovers wheels have ilustrated.....

I think there has been some work on this combination but basically thats a hypercone type device only with strings attacked versus that of being an expandable shield air break....

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#62 2015-04-14 19:26:39

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 10,650

Re: Combining the Rover and Hab - Go RV'ing!

GW Johnson wrote:

What if you had as part of your descent vehicle something resembling a lunar rover,  but with an inflatable operator's cabin?  Say a range around 10-50 km?  If you land within that distance,  you can just motor your way to destination.  If that takes a sleep period,  you have the inflatable operator's cabin.  Sort of a pup-tent-on-wheels.  Any merit to that idea?

As to multiple vehicles landed at 1 site,  I'd think the min distance would be around 100 m,  with a max around 1 km.  With too close,  you risk damage from rocket blast,  and rocket blast-thrown rocks.  Too far,  and it compromises your everyday operations.  The real trouble is using in-situ-produced propellant:  you gotta be close enough to drag the hoses.  Unless,  the propellant is made and stored in the vehicle that is going to use it. 

GW

I think you are thinking of something simular to this

170069main_influnarhab01-330.jpg

only on a flat bed style rig under the assembly the initial part would be a ridgid structure with the larger part being the inflateable which we would want.

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#63 2015-04-15 16:18:40

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,712
Website

Re: Combining the Rover and Hab - Go RV'ing!

Well,  that's sort of like what I had in mind.  Maybe not quite so big.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#64 2015-04-15 16:24:58

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,712
Website

Re: Combining the Rover and Hab - Go RV'ing!

KDB512: 

I had not thought about inflatable stiffeners for a chute to force it open for low canopy loadings.  Intriguing idea.  If I understand your idea correctly,  you are proposing not a ballute,  but something somewhere in-between a ballute and a parachute. 

I rather think that if opening can be forced in some way,  then a large-enough canopy are might be fitted to a small-enough weight to achieve a survivable landing speed on Mars.  That's been a real problem up to now. 

I'd caution that you need to be well-subsonic before even attempting such a thing,  though.  Inflatable structures don't generally do well under supersonic air loads.  The exception is real ballutes,  but only sometimes. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#65 2015-04-17 01:54:39

kbd512
Member
Registered: 2015-01-02
Posts: 1,187

Re: Combining the Rover and Hab - Go RV'ing!

GW Johnson wrote:

KDB512: 

I had not thought about inflatable stiffeners for a chute to force it open for low canopy loadings.  Intriguing idea.  If I understand your idea correctly,  you are proposing not a ballute,  but something somewhere in-between a ballute and a parachute. 

I rather think that if opening can be forced in some way,  then a large-enough canopy are might be fitted to a small-enough weight to achieve a survivable landing speed on Mars.  That's been a real problem up to now. 

I'd caution that you need to be well-subsonic before even attempting such a thing,  though.  Inflatable structures don't generally do well under supersonic air loads.  The exception is real ballutes,  but only sometimes. 

GW

GW,

I want to use HIAD to bleed as much speed as we reasonably can (I can't think of any reason why HIAD could not reasonably be expected to slow the micro capsule to subsonic speeds), dump HIAD and the service module it's attached to (getting rid of most of the mass of the reentry system), leaving only the capsule and its parachute system.  An inflatable ring attached by line to the edges of the canopy would deploy the parachute.  The ring would serve two purposes.  The first, obviously, is deployment of a parachute that would not otherwise open.  The second would be control.  By varying the area of the opening between specific sections of the ring and the edges of the canopy by tugging on risers connected midway between the lines that connect the ring to the canopy, it should be possible to steer the capsule towards the landing beacon by increasing the volume of air permitted to flow between a specific portion of the canopy and the ring.

There has to be some way to avoid using rockets for anything other than reentry and attitude control.

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#66 2015-04-17 09:27:40

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 2,712
Website

Re: Combining the Rover and Hab - Go RV'ing!

I'm not familiar with all the acronyms for the inflatable and flexible heat shield concepts.  But I do know that these are all still quite experimental right now.

One at least I hope "proves out" well enough to be a technology ready-to-apply in time to make the mission/vehicle design decision.  That happens early in the process of selecting architecture and launchers,  so something needs to mature in the very next few years,  if we expect to really use it. 

I'm not sure why you seem to want to avoid landing rockets at all costs.  It has been a proven staple with most of the landers on Mars so far,  and has been used "in the field" by the Russians for delivering battle tanks to the battlefield by parachute.  That technology is closer to be ready to apply than any of the flexible heat shield concepts,  because of that pedigree. 

Myself,  I'd use for entry a flexible heat shield to lower ballistic coefficient if it can be made ready in time;  if not,  maneuvering on a conventional heat shield plus supersonic retropropulsion should fill that bill. 

Once doew to near Mach 2-2.5-ish,  a supersonic ringsail chute might have time to slow you just barely subsonic.  That technology has been demonstrated on Mars with the probes,  butt will need scaleup for manned vehicles. 

Once subsonic,  we either use some sort of subsonic landing chute (if that can be made ready in time),  or if not,  retropropulsive landing (something we already know how to do). 

There is a lot of merit to a potentially-survivable chute landing approach (assuming one can be developed in time) backed up with landing rockets.  Use one or both,  as you need,  since conditions vary so widely on Mars.  If one fails,  you have the other.  That sort of suspenders-and-belt thinking is what one has to do to ensure crew survival. 

GW

Last edited by GW Johnson (2015-04-17 09:34:10)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#67 2015-04-20 00:43:41

kbd512
Member
Registered: 2015-01-02
Posts: 1,187

Re: Combining the Rover and Hab - Go RV'ing!

GW Johnson wrote:

I'm not familiar with all the acronyms for the inflatable and flexible heat shield concepts.  But I do know that these are all still quite experimental right now.

Very experimental, but also very promising based on previous tests.

GW Johnson wrote:

One at least I hope "proves out" well enough to be a technology ready-to-apply in time to make the mission/vehicle design decision.  That happens early in the process of selecting architecture and launchers,  so something needs to mature in the very next few years,  if we expect to really use it.

HIAD is further along than ADEPT, but there's no reason to believe that both of these technologies won't "prove out".

GW Johnson wrote:

I'm not sure why you seem to want to avoid landing rockets at all costs.  It has been a proven staple with most of the landers on Mars so far,  and has been used "in the field" by the Russians for delivering battle tanks to the battlefield by parachute.  That technology is closer to be ready to apply than any of the flexible heat shield concepts,  because of that pedigree.

Retro-propulsion increases the weight and complexity of the solution.  The use of rockets for de-orbiting the micro capsules is mandatory, but if there's a way to avoid using rockets for landing, then I think we should make every effort to avoid it.  Apart from pure development costs, it's also a question of how many times we can test the solution and in how many different ways.  Micro capsules are so small and light that we can test a dozen or so at Mars before we ever put humans in them.

What does one or perhaps two landings of a multi-person vehicle tell you about that vehicle's performance in the wildly varying atmospheric conditions on Mars?  Two tests is hardly a rigorous testing program.  Let's face facts.  If NASA or its favorite contractors design a multi-person EDL solution for Mars, it will be anything but inexpensive or simplistic.

GW Johnson wrote:

Myself,  I'd use for entry a flexible heat shield to lower ballistic coefficient if it can be made ready in time;  if not,  maneuvering on a conventional heat shield plus supersonic retropropulsion should fill that bill.

A hard heat shield necessarily increases the mass and size of the reentry vehicle.  If it's not apparent yet, those are the two things I want to hold to avoid.

GW Johnson wrote:

Once doew to near Mach 2-2.5-ish,  a supersonic ringsail chute might have time to slow you just barely subsonic.  That technology has been demonstrated on Mars with the probes,  butt will need scaleup for manned vehicles.

My thinking was that HIAD would slow the vehicle to subsonic speeds, the mass of the service module and HIAD would be dumped, and a large subsonic ringsail with an inflatable ring for rapid deployment would permit the capsule to soft land without further complication.

GW Johnson wrote:

Once subsonic,  we either use some sort of subsonic landing chute (if that can be made ready in time),  or if not,  retropropulsive landing (something we already know how to do).

My take on this is that we design the solution we intend to use that we can actually afford to use.  Timeline is a make-believe issue for space exploration.  Decades after it was first proposed, there is still no real timeline for manned Mars exploration.  It's always two or three decades into the future.

The combination of micro capsules, M113/MTVL for surface habitation and exploration, and a MTV that doesn't weigh more than ~85t is about making the mission affordable from a launch costs and development perspective by keeping mass requirements to F9H sized pieces and using single purpose solutions rather than trying to design multi-purpose mission components.

Instead of spending the time and money to design a combination multi-person descent/ascent vehicle that can land with pinpoint precision, a technology set to land a habitat module that weighs as much as a fully loaded 737, or a MTV so massive that it virtually requires SLS, we could build something along the lines of what I suggested for just a fraction of the time and cost of the conventional wisdom solutions.

GW Johnson wrote:

There is a lot of merit to a potentially-survivable chute landing approach (assuming one can be developed in time) backed up with landing rockets.  Use one or both,  as you need,  since conditions vary so widely on Mars.  If one fails,  you have the other.  That sort of suspenders-and-belt thinking is what one has to do to ensure crew survival. 

GW

The only real merit to my human EDL solution is affordability.  Powered multi-person descent vehicles that include contingency provisions for the crew and a fully fueled ascent vehicle are definitely the way to go if funding is available.  It isn't and won't be for quite some time to come.  I'd rather we focused effort on what we can afford to design and test with today's funding realities rather than pout about what we think we should have.  There are still things we can do to ensure that progress is made towards our exploration goal, however slowly.  I think economically feasible human and cargo EDL solutions and a real mobile surface exploration capability are a good start.

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