Smallest Human Ascent or Descent Lander for Mars Or Earth

RobertDyck · 2015-04-01 08:42:23

My plan started as a modification of Mars Direct. In 1999 through 2002, we didn't have Falcon Heavy, or Delta IV Heavy, so rather than re-invent the wheel, I just said use the same Ares launch vehicle as Mars Direct. But today we have another issue. Remember that President Obama cancelled Constellation, but Congress brought it back. The reason was to support jobs in their congressional districts. So rather than fight Congress, I suggest sticking with SLS. Yes, it's expensive. But any mission to Mars is a lot easier with a true heavy lift launch vehicle, and the real kicker is its easier to get Congress to approve your plan if you go along with what Congress already wants to do. That strokes their ego. Boeing, Lockheed-Martin, ATK, and others learned this long ago. For one thing, if you cancel SLS then you have to close the Michoud assembly facility in Louisiana, and the SRB casting operation of ATK in Utah. That means you fight against Congressmen and Senators from Louisiana and Utah. And my plan means absolutely no Congressman has to worry about jobs in his/her district, because the Orion engineers will be the guys who design the Mars spacecraft. Yes, there's the danger of cost control, but after talking with some of the engineers at Mars Society conventions, I've learned the engineers are actually good men and women. The problem is corporate executives from "Old Space" companies. So perhaps we need a new corporation to lead the effort. But the Columbia disaster, NASA redirected funds from ISS operation to restoring Shuttle to flight. That meant some engineers were laid-off, but those engineers didn't stay unemployed. That got new jobs with a different company, one of the contractors to restore Shuttle to flight. So the same guys & gals did the work, just a different corporation employing them. I expect the same with this. That is, engineers and technicians for Orion will be transferred to the Mars project. The only question is which company will get the contract.

GW Johnson · 2015-04-01 14:47:05

Back to the "smallest capsule" that is the title of this topic. Somewhere above I saw something about "entering steeper to reduce peak heating". That's not what happens in my oversimplified spreadsheet, and it's not what happened with the warheads on the missiles from which our launchers sprang. If you enter steeper below horizontal, the time gets shorter, so everything: gees, heating rate, all of it, gets bigger. They all depend upon something divided by time.

I got lowest heating rates by going to very shallow entries, low ballistic coefficients, and very blunt objects (largest effective nose radius). That was true for Mars entries as well as Earth entries, just the detailed numbers were different. My consistent problem on Mars was low altitudes at end of hypersonics, altitudes still over-predicted in my over-simplified spreadsheet that was really only intended for steep warhead entry.

The JPL guys talking about how difficult EDL is with big objects confirm everything I think I know about this. I got my Mars atmosphere model from them, and the results of their use of the same 1953-vintage analysis (a paper by Justus and Braun, I think it was). I had to go back to an old 1960's reference to correct the US-to-metric units conversion error that Justus and Braun made, though. "Dare trust no one", as Hercule Poirot would say.

All that being said, the smallest entry vehicle possible for one man here on Earth is the MOOSE concept. It would work. It would scare 20 years off your life riding it down, but that's better than dying in space. Wanna know (really) why MOOSE was never implemented? Because there was zero control over your landing point. Could be land, more likely ocean. And because in the 1960's and 1970's there was (1) no way to determine where the MOOSE rider would come down, and (2) no way to reach him before he died of thirst, drowned, or was eaten by sharks, even if you knew where he was. Since he would die anyway, what was the point?

Things have changed since then. We have GPS and satellite navigation, so we have a way for a MOOSE rider to tell folks where he came down, even though it's still pretty random. Today, there's a lot high probability we could reach the guy before he dies of thirst, drowns, or gets eaten by sharks. In other words, it'd work a lot better today, especially if you had a fast response team ready to go anywhere in the world at 500 knots to retrieve him. You could indeed use MOOSE as an emergency bailout system for ISS or any other thing in orbit. In point of fact, the Columbia crew could have gotten home alive that way.

The foam heat shield of MOOSE would indeed work at Mars, entry there is just not as severe. But, you'd have to do something quite different once the hypersonics are over. As best I know, any chute a man could wear would still let him travel at low supersonic speeds as he hit the ground. The air is just too thin.

I dunno what the answer is to the terminal landing problem for a space-suited man, but my intuition tells me there is one.

Assuming we solve that problem, then the original reasons we didn't MOOSE on Earth crops up on Mars: (1) no way to tell where he came down, by 1000's of km, and (2) how do you reach him quick enough to do any good, even if you knew where he was?

Solve those 3 issues, and something like MOOSE becomes practical. But you'll have to think way outside the box to solve them.

GW

Terraformer · 2015-04-01 15:01:28

Could a jetpack work? Possibly using a hybrid rocket?

SpaceNut · 2015-04-01 20:58:16

I was thinking...

http://en.wikipedia.org/wiki/Mars_Pathfinder

Mars Pathfinder directly entered Mars atmosphere in a retrograde direction from a hyperbolic trajectory at 6.1 km/s using an atmospheric entry aeroshell (capsule) that was derived from the original Viking Mars lander design. The aeroshell consisted of a back shell and a specially designed ablative heatshield to slow to 370 m/s (830 mph) where a supersonic disk-gap-band parachute was inflated to slow its descent through the thin Martian atmosphere to 68 m/s (about 160 mph). The lander's on-board computer used redundant on-board accelerometers to determine the timing of the parachute inflation. Twenty seconds later the heatshield was pyrotechnically released. Another twenty seconds later the lander was separated and lowered from the backshell on a 20 m bridle (tether). When the lander reached 1.6 km above the surface, a radar was used by the on-board computer to determine altitude and descent velocity. This information was used by the computer to determine the precise timing of the landing events that followed.
Once the lander was 355 m above the ground, airbags were inflated in less than a second using three catalytically cooled solid rocket motors that served as gas generators. The airbags were made of 4 inter-connected multi-layer vectran bags that surrounded the tetrahedron lander. They were designed and tested to accommodate grazing angle impacts as high as 28 m/s. However, as the airbags were designed for no more than about 15 m/s vertical impacts, three solid retrorockets were mounted above the lander in the backshell. These were fired at 98 m above the ground. The lander's on-board computer estimated the best time to fire the rockets and cut the bridle so that the lander velocity would be reduced to about 0 m/s between 15 and 25 m above the ground.

http://www.nasa.gov/centers/glenn/about … spbag.html

When the Mars Pathfinder spacecraft entered the Martian atmosphere, it was traveling about 17,000 miles per hour. A parachute and rocket braking system slowed the spacecraft to about 50-60 miles per hour.

SpaceNut · 2015-04-01 21:05:39

The other thing that would be different for mars would be to possibly use something simular to the skycrane for a full powered descent as the astronaut is by far less massive than the rover which means we could fire the rockets for a longer period of time as less thrust is needed to break the descent speed.

The path down would be monitored by the orbiting satelites as to landing site but still the accuracy is a problem if nothing is on the ground to be used to help with the landing process.

kbd512 · 2015-04-01 22:42:51

GW,

Is there any reason why it would be impossible to slow the capsule to subsonic velocity using lift from the inflatable heat shield, at which point a more effective parachute could be deployed?

I need to know the drag coefficient for the type of supersonic parachute that Pathfinder used and what the density of the atmosphere is between 15km and the surface if you have that information. You seem to have some goodies that JPL provided to you, so I thought I'd ask.

The velocity of Pathfinder was between 50m/s and 60m/s when it fired its retrorockets. Any idea what that velocity would have been if it used the same parachute and weighed half of what it did?

Heck, MSL's velocity was only ~80m/s at ~1.6km in altitude when it fired its retrorockets. Is there some reason why it's not possible to skirt around the requirement for retro-propulsion with more altitude and a lighter payload?

SpaceNut,

I'm trying to avoid using sky cranes, retrorockets, and even supersonic parachutes if it's possible to use inflatable heat shields and subsonic parachutes only. Steering control for the parachute is as fancy as I want to get. The goal here is to land the astronaut and a couple extra oxygen bottles a few hundred meters from the mobile habitats and that's it. Two mobile habitats will be in the landing area to collect the four astronauts.

GW Johnson · 2015-04-03 09:12:29

Kdb512:

I honestly don't know how slow you could get with a big supersonic chute and an inflatable heat shield. The ringsail chutes they have using are a variation on the ribbon chutes I was familiar with. Max opening speed is Mach 2.5, from what I read. I don't have any data on such chutes, but the subsonic drag coefficient ought to be somewhere in the vicinity of 1 to 1.2, based on blockage area. I think the biggest of these ever made is 100 m dia (Curiosity's chute). I believe from what I read that they got Curiosity down subsonic, but had to do the skycrane thing for landing. Terminal speed on the chute must have been substantial.

I got an "average" Mars atmosphere from a Justus and Braun document. At altitudes, variations from this can be half an order of magnitude. Variations there are far larger percentage-wise than here. An abbreviated form of the profiles in tabular and graphical form is posted on my blog site http://exrocketman.blogspot.com. The article posts data for Earth Mars and Titan, and is dated 6-30-12, so you'll have to scroll down quite a ways to find it. There is a by-date navigation tool on the left.

If you can reach Mach 2.5 at high enough altitudes, chutes can work. The terminal velocity depends upon the mass loading onto the chute canopy. That's pretty much the same phenomenon as ballistic coefficient. Heavier mass loadings are higher terminal speeds. Heavy enough is supersonic. And the entire effect is altitude dependent, via the density that figures into dynamic pressure.

The problem on Mars is that terminal velocities at zero altitude are always substantial (50-100 m/s or more) at any practical canopy loadings. Some sort of terminal braking is always required for a survivable touchdown. That "air" is just too thin for things to resemble what we can do here.

GW

Terraformer · 2015-04-03 16:00:00

Could we use a jetpack then? Perhaps using a H2O2 monoprop, as is done currently, or maybe even a Propane fuel with it?

SpaceNut · 2015-04-03 18:14:37

Having an inflateable heatshield that could morph into a lifting body or even into a plane as it gets past max heat loading could be the ticket to glide down with rather than using a parachute but in the last under 10 meters we will need some sort of braking rocket to bleed off that last bit of energy to reduce the G's that we would feel upon impact.

kbd512 · 2015-04-03 20:14:31

No matter how small, development and testing of altimeter triggered retrorockets that work perfectly, every time, on another planet is sure to be insanely expensive. If there's a simpler and less expensive option to successfully complete EDL for humans, then that's what we should work on until the Orion and SLS spending projects are over. Once we've blown enough cash on those two projects without meaningful result or someone at NASA grows a pair and says what needs to be said to the morons in Congress, then we can develop two stage multi-person landers that can return to the MTV if they land substantially off-course.

At no time have I thought that my solution was in any way optimal, but a $3B total outlay over six years is eminently reasonable compared to the alternatives. Any multi-person lander with contingency supplies that includes a fully fueled ascent vehicle is far, far preferable to my solution.

If we have reasonably priced and fully tested EDL solutions for humans (HIAD + Parachute) and cargo (ADEPT + retro-propulsion), I think we stand a far better chance of going to Mars than if there was no solution because we had to wait ten or more years for funding availability. ADEPT and retro-propulsion are a little further away than HIAD and parachutes; just far enough that I think two separate approaches to solving the problem is appropriate.

Even in the Martian atmosphere, I have a hard time believing that we would not achieve a substantial reduction in velocity before touchdown with a payload that's less than half the mass of Pathfinder, using the same size/type parachute, and an inflatable aeroshell capable of generating more lift than the rigid aeroshells used by Pathfinder and MSL. We may still need some sort of airbag to absorb the impact on touchdown, but if it's possible to only use HIAD and a parachute, that's the way to go.

I am submitting a request for MarsGRAM data to NASA so that I or someone else can determine what the feasibility of soft landing 150kg or less without retro-propulsion would be.

SpaceNut · 2015-04-03 21:01:00

Well if Nasa had continued on Companies Team Up For Advanced Airbag Landing And Flotation System For Orion Vehicle

ILC Dover and Airborne Systems airbags being tested at NASA Langley in 2007. (Airborne airbags are red.) The companies will be combining the best features of their impact attenuation systems for the Orion singular landing system design study.

Modeling and Simulation of the Second-Generation Orion

Airbag Landing Impact Performance Optimization for the

Status of the Development of an Airbag Landing System

Development of an Airbag Landing System for the

Happy reading

RobertDyck · 2015-04-04 05:46:49

Ironic. Mercury had an airbag system. The heat shield was discarded after the parachute deployed. An airbag between heat shield and capsule was inflated. That airbag meant even if Mercury landed on land such as an island, the astronaut would still survive. There were concerns about the heat shield coming loose. One mission had a telemetry warning, so they asked the astronaut to keep the rocket pack attached during atmospheric entry. The straps that hold the rocket pack on would hold the heat shield in place. Because of that warning, the airbag was not included with Gemini. Orion was supposed to use the same system, and deliberately land on land. (Awkward sentence structure. Using the word "land" as a verb and noun. Could I just say "deliberately land" vs "splash down"?) A dry land return meant recovery by a flatbed truck with truck crane, and a minivan for astronauts. And perhaps a HMMWV (military Humvee) with marines to secure the site. That would be a lot less expensive than an entire aircraft carrier battle group. That's what was used to recover Mercury, Gemini, and Apollo.

kbd512 · 2015-04-05 20:34:07

Thanks for all the input on this. After consideration of all the potential problems, micro capsules are most definitely Plan B. However, if Plan A (development of a proper multi-person lander combined with a fully fueled ascent vehicle) is so expensive as to be unworkable, then I think Plan B should receive some consideration because it's still better than no plan at all, which is what we currently have.

Rob and GW, thank you for the criticism of this plan. Every plan needs a reality check. I still think Plan B is workable, but it would most definitely require further experimentation just to prove feasibility. It may only be workable under specific atmospheric conditions on Mars.

So far, I've come to the conclusion that any significant navigational error with a micro capsule is likely to result in the death of the astronaut inside, once you commit the inflatable aeroshell and parachute have to work perfectly because there's no abort-to-orbit capability as with a multi-person lander, and the density variability of the Martian atmosphere may make the size of the parachute required to guarantee a soft landing without airbags or retrorockets impractical. To my knowledge, a soft landing on Mars without airbagas and/or retrorockets has never been done, so this may be impractical. However, the payloads in question were also substantially heavier than the micro capsule would be, so if the payload is light enough and an inflatable aeroshell can bleed speed quickly enough, landing on a parachute alone may still be practical.

GW Johnson · 2015-04-06 08:14:01

The lander problem is quite important to solve, and it really helps to have multiple solution paths. I saw a story the other day that some groups are encouraging NASA to mount an orbit-only first mission in the 2030's. It's so hard and expensive to get there, that I think if we do that (and not land) on the first trip, there won't be a second trip. Not in the 21st century.

That being said, the big impediment to chute-assisted landings on Mars is high canopy mass loading in air that is just too thin. Retrorockets for terminal deceleration at touchdown are a means to solve that dilemma that has been done successfully before. In the 1960's, the Russians developed a way to air-drop battle tanks by chute onto the battlefield (never mind the risks of the transport being shot down).

They did it to compensate for a highly-mass-loaded canopy that had an unsurvivably high terminal descent speed. The solution was solid retrockets mounted on the riser connection nexus just above the payload, triggered to fire barometrically at the last-second altitude. It actually worked.

On Mars, you need proportionately-larger retrockets, you need variable impulse (not solids) because of the factor 3+ variability in local density conditions, and you need a different triggering mechanism because pressure altitude will be entirely too unreliable. And, as we have already discussed, an overall descent design that causes you to come out of hypersonics high enough for a chute to do any good.

As for the triggering mechanism, I'd suggest radar or lidar. Acoustics would be unreliable because (1) you're likely moving 1/4-to-1/2 speed of sound already, (2) it's likely very noisy about a fast-moving vehicle, and (3) locally-windy conditions would be noisy.

For variable-impulse delivery out of the retrorockets, go with liquids or hybrids, where you have engine cutoff capability.

These ideas pertain to any lander designs at any scale, as long as chutes are involved.

GW

RobertDyck · 2015-04-06 11:59:41

Development of X-38 included a chute. It used the X-24A body shape, which is lighter than HL-20, but has a problem with control a low speed including landing. You don't want lack of control on landing, that's asking for a crash. They solved it by adding a parafoil. This required the largest parafoil ever built. They came up with a method to stage reefing, to open the chute without tangling lines and without ripping the fabric. I thought that defeated the point; the mass of a giant parafoil defeats the mass saving of the lifting body shape. HL-20 can land on wheels on a runway like the Shuttle. DreamChaser uses the HL-20 shape.

Anyway, the military used this research by NASA to develop a large parafoil. They now have 2 models of military parafoil. One can drop a HMMWV (Humvee). The other a light tank. The Humvee cannot be loaded with heavy equipment. Or drop a pallet of supplies. There was some discussion of the same retrorocket idea as the Russians, but what I read (published through the media for the public) is they didn't use that. Instead they just stack empty cardboard boxes beneath the vehicle. The cardboard crushes on impact, reducing impact force to something the vehicle can survive. Don't try to ride the Humvee as it parachutes down; cardboard boxes for impact may be enough for a vehicle, but not enough for a person. I saw a movie that showed a Humvee pushed out the back of a cargo plane using this system, and some actor rode in one of the vehicle seats. Special effects; don't try to do it in real life. Real military operations would have soldiers jump out of the aircraft behind the vehicle, and parachute down separately. Then walk over to the vehicle.

I find it interest to learn the Russians did it in the 1960s, but the American military just a few years ago.

I am also quite frustrated by proposals to leave astronauts stranded in Mars orbit. I use the word "stranded", because orbit has zero gravity and micrometeoroids. And Mars does not have a magnetosphere, so Mars orbit has twice as much radiation as ISS. That was measured by Mars Odyssey. Mars surface has roughly half as much radiation as ISS, or a quarter Mars orbit. And a lander can reduce radiation further with sandbags filled with Mars regolith piled on the roof. The safest place in the solar system, next to the surface of Earth, is the surface of Mars. If you're going to go at all, land all crew.

Triggering mechanism: Yes, the ones GW just mentioned come to mind. You would use one of them. I saw a presentation at a Canadian Space Agency conference. That manufacturer wanted their LIDAR to be used for a large, heavy lander on Mars.

I still point out the PowerPoint by the ADEPT team showed the lowest mass was a mix of heat shield, parachute, subsonic retrorockets, and finally landing legs with shock absorbers like the Apollo LM or Mars Phoenix. Of course that depended on ADEPT as the heat shield; a deployable heat shield that expands to catch enough air to slow sufficiently that it comes out of hypersonics high enough for a parachute to work.

I posted this before:

Slide 6 for ADEPT has a little graphic to land on Mars, with 4 options to land 40 MT (assume metric tonnes) landed payload.
#1: 23m umbrella heat shield during aerocapture, then expand to 44m at transition between hyper- & supersonic, then subsonic retro-thrust. Finally terminal descent and landing. Total mass before entry: 90mT
#2: 33m aerocapture, remain 33m during hyper- & supersonic, begin retro-thrust at transition between super- & subsonic. Terminal descent and landing. Total mass: 87mT
#3: 23m aerocapture, remain 23m hyper- & supersonic, supersonic retrothrust. Terminal descent and landing. Total mass: 81mT
#4: 23m aerocapture, parachute opens supersonic, subsonic retrothrust. Terminal descent and landing. Total mass: 78mT

Last edited by RobertDyck (2015-04-06 17:37:28)

kbd512 · 2015-04-06 13:01:56

Rob,

I would never suggest leaving any of the crew in orbit around Mars. My assumption has always been that they're all going to the surface. All other suggested approaches to landing humans involve vehicles that are many times the mass of what I've suggested and have a hard requirement for retro-propulsion. I understand that ADEPT, or something like it, is an absolute requirement for cargo and therefore the same tech would be available for crewed landers. However, there's virtually no chance that a lander that requires retro-propulsion would be less expensive or time consuming to develop.

NASA is either lying about the problem or overly concerned with radiation, but I think the MTV will have adequate radiation shielding or they won't go. I would think that any responsible planner would have to at least consider the possibility that once the crew arrives at Mars that they can't all land, or land at all, or are prevented from using the free return trajectory to abort. If there's no one aboard the MTV and something fails while the crew is on the surface, there are few possibilities for repair.

Any potential for stranding applies equally to any landing scheme. As previously stated, if a single multi-person lander with the entire crew aboard fails, then the entire crew is lost and the mission is lost. If each person has their own lander, loss of one lander doesn't cause instant loss of mission. I'm not overly concerned with a single or multi-person lander failure, but any honest assessment of what happens after a lander failure indicates the obvious.

GW Johnson · 2015-04-06 18:38:33

If you have an adequate transit vehicle, then you have radiation shielding adequate for Mars orbit. Period. If not, your mission design is inadequate, pure and simple.

There is absolutely nothing wrong with a crew spending significant time in orbit about Mars. All it takes is 20 cm water about the designated shelter volume.

If you cannot manage that, you have zero business going in the first place. There is NOTHING in this universe as expensive as a dead crew. Radiation shielding for X-class CME's is NOT optional. Period.

We are not worried so much about galactic cosmic radiation, we are worried about X-class solar flares. 20 cm water will do the trick, and it ONLY needs to be about the designated shelter. That is NOT hard to do. Water, wastewater, and frozen food all qualify as shielding materials.

Myself, I would divide the stay at Mars into two phases: (1) initial exploration of multiple sites, based from LMO, and (2) send everybody and all the vehicles to the "best" site as determined "in the field" from phase 1. This sort-of rules out ISRU sent ahead, though, because you absolutely CANNOT know which site will make your ISRU work best.

The landing accuracy problem is solvable with a guidance system homing-in upon a transponder sent down by the first vehicle to any one site. This does presume that lift forces and this guidance are available during the hypersonics of entry. Your inaccuracies will then mostly derive from time spent hanging from a chute (if any). Which is another reason to like supersonic/hypersonic retropropulsion over chutes.

The "stranding" issue then devolves to just which landing vehicles that fail to function. During my "phase 1" (LMO-based), you take extra landers to be based from orbit, including an allowance for rescue propellant. Just go down and retrieve them.

During my "phase 2" (surface-based at "best" site), you fly suborbitally from whatever site you are basing from. This may require propellant-from-Earth, but if ISRU is as good as everybody seems to think it will be, it can come from the definition of "best site" via ISRU.

"Suspenders-and-belt", plus "armored codpiece", that's how you keep from killing a crew.

GW

SpaceNut · 2015-04-06 19:25:45

So we have a landing demonstrator to work out and since we are targeting small landers the more that we can build and even cube satelite size counts for proof of acccuracy to any transponder style of homing in on the landings site after the initial craft is landed the better.

The shelter size is dependant on how often the crew must be in it as well as how many crew members there are on the mission. Once we have the cubic demensions then we could figure out the mass of the water or other radiation protection schemes.

RobertDyck · 2015-04-06 23:45:10

GW, I see what you're saying. But I still point out that Mars atmosphere blocks a lot of radiation. And completely eliminates micrometeoroids; they burn up 30km or higher above the surface, depending on size of meteoroid. And you have gravity. Yes, you keep arguing for artificial gravity for the transit vehicle, which means both have that so no difference. But NASA so far is absolutely afraid of artificial gravity. The bureaucrats are afraid of anything new, so someone is going to have to demonstrate it in space before they even consider it.

Robert Zubrin has argued strenuously for his plan. It was very valid in 1989 & 1990, but I argue some aspects are obsolete. For example, he said don't build a space station in Earth orbit. Well, we have it now, so let's use it. NASA wanted a life support system that could recycle 95% of water and oxygen, but he argued to go with what existed at that time. Robert Zubrin said if we wait for a 95% efficient life support system, it would be the 21st century before we're ready to go. Well, it is the 21st century now; we've pissed away so much time that the 21st century caught up with us. And ISS only needs a few additional specific pieces of equipment to make it 95% efficient. He argued for initial exploration by humans, not robotic explorers. Some who like robots would argue, but my point is this is now moot because robotic exploration is essentially complete. We should send a robotic lander to each potential site, specifically designed to evaluate for the human base. I waffle between a lander with tiny rover like Pathfinder, or MER rover. But definitely an MSL rover would be *way* overkill.

And we need to test/demonstrate ISPP with a robotic Mars lander. Either a sample collection arm like Phoenix, or tiny rover like Sojourner. You definitely don't need an MSL size rover. And you don't need multiple Mars sample return missions, just one to demonstrate ISPP.

The beauty of ISPP designed by Robert Zubrin and David Baker is that it uses Mars atmosphere. Not Mars permafrost. One reason is Mars atmosphere is already well characterized, so we don't need any further data. But the real beauty is the atmosphere is the same across the planet. So ISPP works the same anywhere on the planet.

Or are you talking about ISRU for construction material? That's tricky. You'll never find a single site that has all resources you would want. Have to pick which you want to focus on. Curiosity found hematite and cristobalite, the first is iron ore, the second can be melted to form glass. There's abundant plagioclase feldspar in Mars soil everywhere. The trick is to find plagioclase with more than 70% anorthite (calcium aluminum silicate). If it has too much albite (sodium aluminum silicate) it won't dissolve in acid. The Bayer process extracts aluminum from bauxite, you can reverse the pH to do it with plagioclase feldspar high in anorthite. So iron, glass, and aluminum all in one spot! And Curiosity hasn't found ice, but soil minerals that release water when baked; about 2 pints per cubic foot of soil. Great! Would be nice to get other metals as well, such as copper for electrical wiring, but as I said you aren't going to find everything at one spot.

kbd512 · 2015-04-07 00:15:33

RobertDyck wrote:

GW, I see what you're saying. But I still point out that Mars atmosphere blocks a lot of radiation. And completely eliminates micrometeoroids; they burn up 30km or higher above the surface, depending on size of meteoroid. And you have gravity. Yes, you keep arguing for artificial gravity for the transit vehicle, which means both have that so no difference. But NASA so far is absolutely afraid of artificial gravity. The bureaucrats are afraid of anything new, so someone is going to have to demonstrate it in space before they even consider it.

NASA needs to get over their fears of artificial gravity and use it for the benefit of their explorers. Humans don't fare well without it.

RobertDyck wrote:

Robert Zubrin has argued strenuously for his plan. It was very valid in 1989 & 1990, but I argue some aspects are obsolete. For example, he said don't build a space station in Earth orbit. Well, we have it now, so let's use it. NASA wanted a life support system that could recycle 95% of water and oxygen, but he argued to go with what existed at that time. Robert Zubrin said if we wait for a 95% efficient life support system, it would be the 21st century before we're ready to go. Well, it is the 21st century now; we've pissed away so much time that the 21st century caught up with us. And ISS only needs a few additional specific pieces of equipment to make it 95% efficient. He argued for initial exploration by humans, not robotic explorers. Some who like robots would argue, but my point is this is now moot because robotic exploration is essentially complete. We should send a robotic lander to each potential site, specifically designed to evaluate for the human base. I waffle between a lander with tiny rover like Pathfinder, or MER rover. But definitely an MSL rover would be *way* overkill.

NASA's manned space program is still busily pissing away funding on things that won't ultimately permit them to explore our solar system. Obama gave them an opening and they didn't take it. It's time to start serious development of closed loop ECLSS, active radiation shielding, and ISRU. Our propulsion technology is near to where it must be to support sustainable exploration activities, but after three decades of throwing money at various high-risk, high-payoff technologies we still don't haven't CL-ECLSS, ARS, ISRU, or an affordable HLV. If we don't right the ship now, NASA is at substantial risk of having its manned space program shut down by short-sighted politicians.

RobertDyck wrote:

And we need to test/demonstrate ISPP with a robotic Mars lander. Either a sample collection arm like Phoenix, or tiny rover like Sojourner. You definitely don't need an MSL size rover. And you don't need multiple Mars sample return missions, just one to demonstrate ISPP.

The sooner, the better.

RobertDyck wrote:

The beauty of ISPP designed by Robert Zubrin and David Baker is that it uses Mars atmosphere. Not Mars permafrost. One reason is Mars atmosphere is already well characterized, so we don't need any further data. But the real beauty is the atmosphere is the same across the planet. So ISPP works the same anywhere on the planet.

Unfortunately, the Martian atmosphere isn't the same everywhere on the planet except in general composition. We still need ISPP, so we have to find a way to make it work.

RobertDyck wrote:

Or are you talking about ISRU for construction material? That's tricky. You'll never find a single site that has all resources you would want. Have to pick which you want to focus on. Curiosity found hematite and cristobalite, the first is iron ore, the second can be melted to form glass. There's abundant plagioclase feldspar in Mars soil everywhere. The trick is to find plagioclase with more than 70% anorthite (calcium aluminum silicate). If it has too much albite (sodium aluminum silicate) it won't dissolve in acid. The Bayer process extracts aluminum from bauxite, you can reverse the pH to do it with plagioclase feldspar high in anorthite. So iron, glass, and aluminum all in one spot! And Curiosity hasn't found ice, but soil minerals that release water when baked; about 2 pints per cubic foot of soil. Great! Would be nice to get other metals as well, such as copper for electrical wiring, but as I said you aren't going to find everything at one spot.

We're many decades away from mining building materials on Mars. That shouldn't stop us from locating the resources and experimenting with the most efficient methods of obtaining them, but it'll be quite some time before we can actually use them.

Last edited by kbd512 (2015-04-07 00:54:11)

RobertDyck · 2015-04-07 02:39:32

kbd512 wrote:

NASA needs to get over their fears of artificial gravity

And criminals *need* to stop committing crimes. Just saying it doesn't make it happen.

GW, another point. You said any government funded mission to Mars would most likely only happen once. That means no way to do the human scouting that you describe. Any human mission means one trip from Mars orbit to the surface and back. One. No mission will park in Mars orbit and send multiple excursions to the surface. We just don't have propellant for that. In fact, to make a single mission affordable, we have use ISPP for just one.

Mars sample return can be done as a Scout class mission. That means a budget between $300 million and $485 million, including data analysis. Analyzing returned samples may cost more, in fact scientists would go nuts over samples. Keeping a sample return mission that low is possible, but only if you use ISPP, and don't use a large rover.

Actually, I'm uncomfortable with sending robotic probes to potential sites for human exploration. That's too many robotic probes. JPL sent a lot already. We should be able to select a location with data from existing robotic explorers: orbiters, landers and rovers.

So build a permanent base with the first human mission. And park a reusable Interplanetary Transit Vehicle at ISS. Then if politicians cancel any further exploration, a commercial corporation could use that reusable vehicle to return to the permanent base.

kbd512 · 2015-04-07 13:49:52

RobertDyck wrote:

And criminals *need* to stop committing crimes. Just saying it doesn't make it happen.

You're absolutely correct. I like to write letters and make phone calls to my Congressmen and Senators and anyone else I think might listen who could actually do something about it. I have no idea what effect I have, if any, but it won't stop me from trying.

RobertDyck wrote:

GW, another point. You said any government funded mission to Mars would most likely only happen once. That means no way to do the human scouting that you describe. Any human mission means one trip from Mars orbit to the surface and back. One. No mission will park in Mars orbit and send multiple excursions to the surface. We just don't have propellant for that. In fact, to make a single mission affordable, we have use ISPP for just one.

Think positively, Rob. Would anyone complain if NASA built an orbital station at Mars? Certainly not I. The longer we maintain a presence there, the better. For whatever reason, all space agencies love their space stations. Let's build the next space station at Mars.

RobertDyck wrote:

Mars sample return can be done as a Scout class mission. That means a budget between $300 million and $485 million, including data analysis. Analyzing returned samples may cost more, in fact scientists would go nuts over samples. Keeping a sample return mission that low is possible, but only if you use ISPP, and don't use a large rover.

Could we analyze samples at a space station at Mars?

RobertDyck wrote:

Actually, I'm uncomfortable with sending robotic probes to potential sites for human exploration. That's too many robotic probes. JPL sent a lot already. We should be able to select a location with data from existing robotic explorers: orbiters, landers and rovers.

You're probably right.

RobertDyck wrote:

So build a permanent base with the first human mission. And park a reusable Interplanetary Transit Vehicle at ISS. Then if politicians cancel any further exploration, a commercial corporation could use that reusable vehicle to return to the permanent base.

Even though it's what we ultimately need to do, construction of a permanent base would take many years. A handful of F9H launches or two SLS launches and we could have an orbital station delivered. From there, we could stage Red Dragons for future or contingency use, cache spares and supplies, and use tele-robotic rovers to explore as much of the surface as we can before we send humans. If the MTV's use electric propulsion, we could refuel there, too.

Argon may not be as good as Xenon, but there's plenty of it in the Martian atmosphere. Seems like a shame to drag all that propellant from Earth just to get back there. Finally a socially acceptable use for Profac? Just a thought.

GW Johnson · 2015-04-07 13:54:30

"Any human mission means one trip from Mars orbit to the surface and back. One. No mission will park in Mars orbit and send multiple excursions to the surface." -- I'm not sure that is really true. Only an accountant would take that as a given.

It's a lot of trouble and expense to send men all the way to Mars, and get them back alive. It almost doesn't matter how you assume this is to be done, it's going to be expensive at this time in history, pretty much no matter what. Although, many on these forums point out how the estimates have been inflated, something with which I do agree. And that's a whole 'nother can of worms I don't intend to address here.

The "one-mission = one-landing" idea is a holdover from the Apollo flag-and-footprints stunt landings we did 1969-1972 on the moon. Only the last one had a degreed geologist on board, and only 3 of the 6 had rover cars to drive. So only 3 saw much of the moon at all. Sadly, most of the real lunar exploration / science has been done since, with no more human visits.

Those moon landings were simply not "exploration" in the more fundamental sense that describes what the Europeans were trying to do in North America about half a millenium ago, flawed as their efforts were. Nearly every one of those voyages visited multiple sites after going to all the trouble that it was to cross the Atlantic in those days. Nothing else made any common sense. "Screw the money, let's pursue some common sense", that's the real history lesson to be learned.

I submit that's still true today, regarding deep space exploration. What is the point of spending all those resources and efforts if you only see one site? All of human history tells us that no matter where we go, every site is different. Visiting only one makes no more common sense now than it did half a millennium ago, or in the stone age. Technologically, we're in just about the same position: just barely able to make the voyage.

Those are the sources of my predilection for an orbit-based first mission with multiple landers, using propellant-from-Earth. Visiting more than one site is an ancient exploration imperative. It has nothing to do with budgets or politics. Those are but transitory. The urge to explore is ancient. It only makes sense to maximize the exploration return, not minimize resources spent.

That being said, I do indeed recognize that "bang-for-the-buck" return-on-investment applies here. Oh yes. But if you do not truly explore, Mars is all cost and no benefit. And that is why I see most of the minimalist mission designs that visit one site only, as essentially flag-and-footprints stunts. Even if they do make some of their own propellant. We saw one site. So what?

GW

Tom Kalbfus · 2015-04-07 14:12:13

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.

kbd512 · 2015-04-07 14:54:22

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.

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