International Space Station (ISS / Alpha)

RobertDyck · 2015-03-14 21:51:03

kbd512: We could continue to talk about which technologies NASA needs. But I keep squirming about this "work bee" or "space bobcat". If you want humans to work on a satellite, should the work be done at ISS or in-place? You could replace the whole thing with an automated tug that brings the satellite to ISS, where astronauts could work on it with full support from the station. That would require a service module, rendezvous sensors, inertial guidance sensors, video cameras, and end effector. That's all. Then we could debate exactly how much propellant the service module would need. How much change in orbital altitude and inclination is required? How much mass for satellites it will move? ISS already has Dextre for robotic service, plus astronauts with EMU suits and tool kits.

You mentioned emergency return capsule. One option is Dragon. NASA had planned on X-38 as the crew return vehicle. Originally designed for 4 astronauts. The US habitation module was designed to provide life support and accommodation for 4 astronauts. Then some politician claimed Russian Soyuz could not be counted on for crew return from the Russian side of ISS. So they demanded X-38 expanded to 7 astronauts. That required packing them like sardines, and wouldn't fit spacesuits. Even with that, it required expanding X-38. Those changes increased cost. Congress didn't want to pay for the cost increase, so cancelled it. Ironic; Soyuz has been the reliable workhorse, and now we're stuck with nothing else for crew transport. And after the US hab was cancelled, life support was added to Node 3 and the science module. This was restricted to 3 astronauts instead of 4, because Soyuz could only return 3. But Dragon can return 7. So will CST-100.

In the early 1960s, NASA worked on a light-weight low-cost crew return system. It was called MOOSE: Man Out Of Space Easiest. A large plastic bag with 2 main compartments. An astronaut in a spacesuit would climb into the front compartment, then zip it closed. Use an aerosol can to fill the back compartment. The can would have spray foam, which would quickly harden. Doing this with the astronaut inside creates a form fit around his spacesuit. And fold-out sections of heat shield to be placed over the backside. This creates an aeroshell around the spacesuit. A parachute would strap to the spacesuit chest. A couple containers of food, water, and survival kit. All fit in pockets of the large plastic bag before filling with foam. And the foam was designed to crush on impact with ground. And a hand-held retrorocket for de-orbit. Yup, this means parachuting from orbit.

Terraformer · 2015-03-15 05:35:20

There was also a plan to paraglide from orbit - FIRST Re-Entry Glider..

Though MOOSE would be fun, I guess, I'd prefer to take the FIRST glider out of there.

SpaceNut · 2015-03-15 09:10:56

Looks to me that if the satelite could not be grappled by the canadian arm that the work bee craft is what we would want and this could be even tele robotic controlled quite easily with additional camera's. I would vote for a space docking bay to bring it into so that real work could be done and from the experinces that we have had with hardware that could not be replaced our undone when in a spacesuit we should mitigate the risk....

The "emergency return capsule" was another Congress, Nasa Duh... at that moment that did not make sense, since
we could fit the maximum crew into more than one vehicle just fine as there is always more than enough vehicles docked at the station at one time. One could always jump into the trash disposal unit (progress) in the space suit and survive..with help from Ocean pick up if we can not send it towards land.

The individual life pods have been around for a long time and do make a bit of sense but it makes another layer of complexity for the station within the stations design layout as with the more branches or arms to the station that there are the more single units need to be put into various locations for a what if use. This would be quite applicable for earth as once we are done we can breath the air regardless of whether we are near the landing site that we wanted.

If this was a Mars orbital bail out we would need a fast response capability to where ever the crew would land or way more supplies, plus the heat sheild would need to be made larger as well as the parachute diameter for use. Both do look in the realm of possible. The inflatable Rogallo wings would take care of the need to make the heatshield bigger and give it a better landing location accuracy.

kbd512 · 2015-03-15 09:50:26

Rob,

I was thinking about something a little more sophisticated than MOOSE and a lot less sophisticated than Dragon / CST-100 / Orion and significantly smaller. The capsule needs minimal avionics and attitude control for EDL, life support systems so space suits are not absolutely required but still permit use of pressure suits, weigh as little as possible, and be robust enough for long duration space flights.

Rather than containing multiple backup subsystems and weeks of supplies, this is a final alternative for getting to the surface of Earth or Mars from orbit.

SpaceNut · 2015-03-15 11:34:58

The question I have for "what if", is under what conditions do we bail and try to land and under what situation do we just seal each module to allow for them to seperate from what would be a disasterous condition? Of course upon seperation each needs there own mini life support, navigation ect until rescue can be achieve or until they can recouple back together again as a station with the offending modules neutralized.

RobertDyck · 2015-03-15 11:55:15

Terraformer: the inflatable glider looks good, but doesn't work. Gemini was supposed to use this, instead of a round parachute. Not for thermal phase of re-entry, Gemini had a Mercury-style heat shield for that, the glider wing would just replace the parachute. The problem is tests always resulted in the inflatable structure folding under load. So they went with round parachutes. Work on this continued after Gemini, and evolved into the parafoil and hang glider. So one option is MOOSE with a parafoil instead of round parachute.

kbd512: I don't see Congress paying for yet another spacecraft. They already paid for Orion, Dragon, and CST-100, and there is continuing discussions about DreamChaser. And yes, I want to see DreamChaser fly. That's 4 American spacecraft; I don't see a 5th. But if you want a minimum weight spacecraft to do what you just described, that's Soyuz. Do you realize how cramped Soyuz is? The descent module has 20 minutes of life support, just enough to de-orbit and land. The orbital module has 2 weeks of life support. The Soyuz descent module has a titanium alloy hull, and shaped with hemisphere top, heat shield, and side wall angle optimized for minimum weight. The American designed Apollo D2 (designed one year before Soyuz) had exactly the same shape, because this is the optimum for absolute minimum weight. Soyuz is capable of long term storage in space, and has been proven as the reliable crew return vehicle. And Soyuz needs the service module to deliver it to ISS. Actually, the 1960s version of Soyuz designed to carry Russian cosmonauts to lunar orbit and back, the equivalent to Apollo CSM, had a larger service module. That one was called Soyuz LOK (Lunar Orbit Craft - the Russian word for Craft starts with "K"). The Soyuz model used to service space stations (Salyut/Mir/ISS) has a smaller service module, just enough to do the job. Basically, what you're describing is Soyuz without the orbital module. The orbital module has an aluminum alloy hull, and spheroid shape, so minimum weight and designed to be discarded. If you want astronauts to ride Soyuz to the space station, and breathe while they do so, then the orbital module is required.

What I'm saying is we currently have Dragon v2, CST-100, Orion, DreamChaser, and Soyuz for crew. And for cargo we have CRS Dragon, Cygnus, ATV, and Progress. There was also the Japanese HTV, but that won't likely fly again. That's enough. I don't see anyone paying for another.

kbd512 · 2015-03-15 20:47:40

SpaceNut wrote:

The question I have for "what if", is under what conditions do we bail and try to land and under what situation do we just seal each module to allow for them to seperate from what would be a disasterous condition? Of course upon seperation each needs there own mini life support, navigation ect until rescue can be achieve or until they can recouple back together again as a station with the offending modules neutralized.

Here's what I see these capsules being utilized for:

1. Emergency return of single crew members from ISS for medical conditions

Ideally we'd have a flight surgeon aboard ISS to contend with medically emergencies, but if that's not always possible then we need a way to return infirm personnel without a lot of fuss.

2. Unscheduled ISS crew additions or transfers/swaps due to changing mission requirements

If several crew members suffer from illness at the same time, perhaps we'd elect to dispatch a doctor if the cost was sane. If a crew member for an outbound exploration flight was injured or ill, maybe we'd just replace him or her with a member of the backup flight crew. Let's say one of our sophisticated life support, power, or propulsion subsystems for our exploration craft doesn't pass a checkout and requires a few parts and a skilled technician to correct the issue. No problem, we'll send him, his tools, and a few parts to fix it.

3. Temporary abandonment of permanently occupied spacecraft due to fire or release of hazardous substances that require an emergency depressurization

This should be pretty self-explanatory.

4. Capability backup to prevent the failure of a more sophisticated landers from scrubbing a necessarily expensive mission

Let's say for a moment that we'll launch landers as separate cargo ahead of the crew that will use them instead of trying to attach them to our deep space transit vehicles so as to keep payload and propulsion system masses sane, thus limiting the cost of missions by forgoing the use of insanely expensive lift vehicles like SLS. If the lander is inserted into the wrong orbit, never makes orbit, or has some other technical problem that inhibits its use, then the crew can still get to the surface.

5. If the capsules were reusable, then our explorers could use surface vehicles and small cranes to retrieve the capsules after landing, attach the capsules to much smaller ascent vehicles on the surface of Mars, and potentially have a second way of returning to the deep space transit vehicle after their surface stay has been completed

I just think that smaller and simpler backup ascent vehicles should also be considered.

Do we necessarily have to put all of our astronauts in one vehicle? I don't think we do. Having options is a good thing. If our Red Dragon has some sort of technical malfunction that prevents us from using it as intended, then the money and effort expended for a surface mission isn't an instant total loss.

Every capsule system developed thus far is completely over the top of what's required for backup and emergency use. The t/Space shuttlecock capsule was the right design for simplified EDL, but it was larger and more sophisticated than necessary.

kbd512 · 2015-03-15 21:08:56

RobertDyck wrote:

kbd512: I don't see Congress paying for yet another spacecraft. They already paid for Orion, Dragon, and CST-100, and there is continuing discussions about DreamChaser. And yes, I want to see DreamChaser fly. That's 4 American spacecraft; I don't see a 5th. But if you want a minimum weight spacecraft to do what you just described, that's Soyuz. Do you realize how cramped Soyuz is? The descent module has 20 minutes of life support, just enough to de-orbit and land. The orbital module has 2 weeks of life support. The Soyuz descent module has a titanium alloy hull, and shaped with hemisphere top, heat shield, and side wall angle optimized for minimum weight. The American designed Apollo D2 (designed one year before Soyuz) had exactly the same shape, because this is the optimum for absolute minimum weight. Soyuz is capable of long term storage in space, and has been proven as the reliable crew return vehicle. And Soyuz needs the service module to deliver it to ISS. Actually, the 1960s version of Soyuz designed to carry Russian cosmonauts to lunar orbit and back, the equivalent to Apollo CSM, had a larger service module. That one was called Soyuz LOK (Lunar Orbit Craft - the Russian word for Craft starts with "K"). The Soyuz model used to service space stations (Salyut/Mir/ISS) has a smaller service module, just enough to do the job. Basically, what you're describing is Soyuz without the orbital module. The orbital module has an aluminum alloy hull, and spheroid shape, so minimum weight and designed to be discarded. If you want astronauts to ride Soyuz to the space station, and breathe while they do so, then the orbital module is required.

Rob,

The only capsule systems that we've developed thus far are all far larger and more sophisticated. Even Soyuz is larger and more sophisticated than necessary for what this capsule would be used for. This is a single man capsule, intended to provide functionality already noted, and not intended to replace the functionality of any existing capsule system.

RobertDyck · 2015-03-15 23:00:30

kbd512: They have crew return capability right now. It's called Soyuz. No need for anything more. If you seriously want a single person escape system, then build MOOSE. It would have to be small, light-weight, and inexpensive. In other words, MOOSE.

Medical evacuation was a major design feature of HL-20. It had the ability to replace seats with a bed/stretcher. DreamChaser is very much based on HL-20, so will have that same capability. But all spacecraft have the ability to transport a crew member in a seat. And all astronauts receive paramedic training, including emergency dental work.

Modules do have ability to close off for emergency pressure control and fire control. Mir had to do it once. ISS had less serious incidents.

Your suggestion for ascent sounds complicated. You do realize that Mars is a planet, with atmosphere and 0.38G gravity. That means ascent is far more involved than the Moon. So ascent isn't a simple patch you can add to a dedicated cargo lander. Furthermore, your statement assumes the transit vehicle has propellant. Any sane Mars mission uses ISPP, which means you need to bring propellant for the entire return to Earth from Mars surface. I suggested using the ascent vehicle as the TEI stage, which requires substantial propellant tanks. Robert Zubrin and his partner David Baker came up with an ERV that launches directly from Mars surface. Either way, ascent is non-trivial.

Perhaps you're thinking of publicity images from Mars One. That's a plan from a Dutch businessman who is trying to raise funds. His plan is blatantly one-way. His images show multiple small Red Dragon craft on Mars surface, with assumption that many have pre-landed cargo. But none are capable of returning to space. They're all one-way, land only. Launching Red Dragon to Mars would require Falcon Heavy, and would have landing ability only, no ascent. But of course that means astronauts would be stuck in a capsule in zero-G for transit to Mars. They would be seriously deconditioned on landing. And an MIT analysis shows settlers would die just weeks after arriving. Do you realize that with Mars One, any applicants have to pay money? You don't get paid to go to Mars, rather you have to pay. And it's one way. All applications have to pay, and there were over 100,000 applications. Getting the point? I hesitate to call it a scam, but it's set up as a money making operation. Mars One claims it's "not for profit", but they're raising funds to pay for their equipment at expense of applicants.

Last edited by RobertDyck (2015-03-16 10:18:37)

kbd512 · 2015-03-16 01:37:12

Rob,

Soyuz is big enough to return three people and it weighs around 3t. If it was scaled down, then that might work. I think we're talking about two different things. From what I gather, you want to use something the size of Soyuz or a contraption that looks it was made for a Redbull stunt.

I understand that ascent from Mars isn't like ascent from the moon, but the larger and more sophisticated an ascent vehicle is, the more complicated and expensive it becomes.

Put another way, which would you think would be easier to test on the surface of Mars, a very small single person capsule designed to simply get the astronaut from the surface to the deep space transit vehicle or a four to six person ascent vehicle, equivalent in complexity to Orion, designed for various abort scenarios and carrying weeks of provisions?

If it's not a good idea to design Battlestar Galactica transit vehicles, why is it a good idea to design large multi-seat ascent vehicles? If it fails or never works to begin with and you don't have a backup, you're a permanent resident or, more likely, dead. At the going rate for sending payloads to Mars, can we afford a backup ascent vehicle if they're as big and heavy as the designs that have been proposed in recent years?

RobertDyck · 2015-03-16 08:00:53

I'm not sure why you want an escape pod for a single astronaut. Congress wanted a single vehicle to evacuate all crew from ISS, not just the American side. Why are you obsessing about this? Soyuz transports crew to/from ISS, it isn't designed for emergency escape, but can be used for that. As long as there's a way out, there's no need for a separate escape vehicle.

For Mars, you again obsess about current obsession. Look at the entire mission, not just one component. To keep cost down, the mission requires ISPP. The only question is how to apply that. Mars Direct lands the Earth Return Vehicle on Mars. One argument I've made is why land on Mars the return capsule for Earth, just to lift it off again? That includes a heat shield, parachute, heavy titanium hull, and all the other stuff for Earth atmospheric entry and landing. Instead leave that parked in Mars orbit. One person made a presentation at a Mars Society convention that the interplanetary transit vehicle should be parked in highly eliptical, high Mars orbit. That way it's barely in Mars orbit at all, so won't require much propellant to depart for Earth. This orbit would have a very low periapsis, and very high apoapsis. Great idea! Let's use that. This won't require Battlestar Galactica, but will require something larger than a coffin. We have seen with Skylab, Salyut, Mir, and ISS that to survive 6 months in zero-G requirs regular exercise. A Dragon capsule doesn't have room for exercise equipment. In the discussion threat "updating Mars Direct", I suggested modifying a Dragon capsule to be the ERV. That included a single exercycle. The seats of the lower row would be replaced: one seat with an ISS toilet, one with an exercycle, the other with storage. Do you really want to spend 6 months in that? A better ERV would be as large as the upper floor of the Mars Direct habitat. Although that could be done with the same exercise equipment as ISS, it would be better to use artificial gravity. But to do this with ISPP, you need some way to raise propellant from Mars. Rather than a separate vehicle, I have suggested simply making propellant tanks of the Mars ascent vehicle larger. And you can avoid complication of on-orbit propellant transfer by simply using the MAV as the TEI stage. But to keep this MAV as simple and light as possible, the crew cabin would not be pressurized. Just seats and a fairing, astronauts would wear spacesuits during ascent. Although, if the capsule is the attachment to the ITV, then pressurizing could add structural strength. But no life support, just suits for life support. This isn't Battlestar, it's rather spartan.

You tried to characterize a single multi-seat ascent vehicle as "large". A single vehicle requires a single guidance system, single docking hatch, single rocket engine or set of engines with gymbals. Separating one single vehicle for 4 astronauts into 4 separate vehicles for one astronaut each, will increase total mass dramatically.

Last edited by RobertDyck (2015-03-16 09:20:39)

GW Johnson · 2015-03-16 08:29:58

I would caution that relying on technologies and hardware with no experience behind it is a bad idea. A lot of the mission designs I have seen do exactly that, thus having single-point failure modes that will kill crews.

A lot of these proposals rely inherently on ISPP. But what if it doesn't function up to par "in the field"? Then what do you do? The aluminum tires on Curiosity are but the latest example of what I am talking about. Sometimes things just do not work.

You might not get away with minimum mass when you design-in ways-out, but you are far less likely to incur the catastrophic cost of a dead crew. I'm for ISPP, but for the first trip (or trips?), the mission should be designed to achieve its base mission and get the crew home alive assuming ISPP does not work. Then if it does work, you just get to accomplish a lot more. No details here, what I am suggesting is a strategy, not tactics.

I really would also caution that providing full gee artificial gravity for the crew is very important, even though it's not a minimum-mass thing we can do. They'll be fit enough at Mars if you don't, but not fit enough to return to Earth. A lot of these missions propose a free return. That was an 11 gee ride from the moon, at higher speeds from Mars, it could easily be 15 gees. A weakened crew simply won't survive that.

Just food for thought, guys.

GW

RobertDyck · 2015-03-16 09:35:07

I have recommended robotic sample return. Simply as a technology demonstrator for ISPP. My point is the same argument you're making, GW, that any technology that human lives depend on has to be thoroughly tested first.

Terraformer · 2015-03-16 09:36:42

Re. ISPP, I don't think there are any serious proposals to actually test the system for the first time in Martian conditions *whilst the crew is there*. Mars Direct had it done before - no fuel, the crew don't launch. Mars Sample Return proposals use it without any humans relying on it. As long as you make sure the fuel is there before launching the crew, it shouldn't be any worse than not using it. Any extra that's produced can be used during the mission itself, to allow a more thorough mapping of the planet using things like suborbital rockets and long-range mobile bases.

GW Johnson · 2015-03-16 13:52:58

The other thing to worry about is what missions there might actually be. My best guess for the next 20 years is a very small handful of unmanned-probe rovers and fixed landers. And I do mean small: maybe 1 more big rover, and maybe 3-4 small things, rovers and fixed together.

That's really not enough to "prove out" your ISPP, now, is it? Be honest with yourself. Not just demo it, PROVE that it works, regardless of circumstances and human error. THAT'S what you bet lives on.

And, I have also been off in the corner crying that "the emperor has no clothes" all alone: I think that there will most likely be one, and only one, government-funded manned mission to Mars, if any at all. If that trip goes only to Phobos or Mars orbit, there will be be NO government funded manned landing! One trip, that's it. IFF we even get the one! (IFF = "if and only if".)

That means any subsequent trips will be funded by private entities. There are a tiny precious few visionary enough to do this. I'm sorry, but Boeing and Lockheed ain't part of that crowd.

The upshot is, which I have also been warning about, any base had better be established on the first-and-only government trip. Otherwise, it will be multiple further decades before even a visionary private entity funds a return trip.

GW

RobertDyck · 2015-03-16 14:40:35

GW, now I don't know what you're talking about. ISPP has already been demonstrated as a brass board at Pioneer Astronautix, Robert Zubrin's company. What I said robotic sample return. That PROVES it works. Any mission plan, whether Mars Direct or mine, involves producing propellant on Mars before any astronauts leave Earth. Mars Direct has the ERV produce propellant, mine lands the MAV unmanned ahead of time. In both cases the propellant tanks (both fuel and oxidizer) are confirmed full before astronauts leave Earth.

I had said my plan would build a base with the first trip. I had hoped a second mission would add a second, redundant laboratory, but if we only get one lab with one mission, then Ok. We can do that. And my mission plan includes a reusable ITV, so you don't have to worry about SpaceX trying to send astronauts in a Dragon spacecraft. SpaceX (or whoever) could operate the ITV for subsequent missions.

SpaceNut · 2015-03-16 17:45:45

RobertDyck wrote:

To keep cost down, the mission requires ISPP.

I am going to put the last 5 entires in the other topic In-Situ Propellant Production, design a opensource demonstrator to keep this one on topic. That said the other not mature enough systems which rely on insitu process as well as for life support long term do not seem to measure up to the quote from RobertDyck which is cost, and of course reliability...

kbd512 · 2015-03-16 18:22:10

RobertDyck wrote:

I'm not sure why you want an escape pod for a single astronaut. Congress wanted a single vehicle to evacuate all crew from ISS, not just the American side. Why are you obsessing about this? Soyuz transports crew to/from ISS, it isn't designed for emergency escape, but can be used for that. As long as there's a way out, there's no need for a separate escape vehicle.

Rob,

I want a micro capsule designed to survive descent to the Martian surface and a return ride back to the MTV. It would contain an astronaut in a pressure suit seated in a removable fabric seat affixed to the walls of the capsule with bungee cords. The astronaut's suit will contain the avionics for descent/ascent. He or she will "plug-in" to the capsule to control the capsule. The capsule itself will have a battery, a miniature attitude control system with enough storable propellant to de-orbit the capsule, and a manually operated parachute.

RobertDyck wrote:

For Mars, you again obsess about current obsession. Look at the entire mission, not just one component. To keep cost down, the mission requires ISPP. The only question is how to apply that. Mars Direct lands the Earth Return Vehicle on Mars. One argument I've made is why land on Mars the return capsule for Earth, just to lift it off again? That includes a heat shield, parachute, heavy titanium hull, and all the other stuff for Earth atmospheric entry and landing. Instead leave that parked in Mars orbit. One person made a presentation at a Mars Society convention that the interplanetary transit vehicle should be parked in highly eliptical, high Mars orbit. That way it's barely in Mars orbit at all, so won't require much propellant to depart for Earth. This orbit would have a very low periapsis, and very high apoapsis. Great idea! Let's use that. This won't require Battlestar Galactica, but will require something larger than a coffin. We have seen with Skylab, Salyut, Mir, and ISS that to survive 6 months in zero-G requirs regular exercise. A Dragon capsule doesn't have room for exercise equipment. In the discussion threat "updating Mars Direct", I suggested modifying a Dragon capsule to be the ERV. That included a single exercycle. The seats of the lower row would be replaced: one seat with an ISS toilet, one with an exercycle, the other with storage. Do you really want to spend 6 months in that? A better ERV would be as large as the upper floor of the Mars Direct habitat. Although that could be done with the same exercise equipment as ISS, it would be better to use artificial gravity. But to do this with ISPP, you need some way to raise propellant from Mars. Rather than a separate vehicle, I have suggested simply making propellant tanks of the Mars ascent vehicle larger. And you can avoid complication of on-orbit propellant transfer by simply using the MAV as the TEI stage. But to keep this MAV as simple and light as possible, the crew cabin would not be pressurized. Just seats and a fairing, astronauts would wear spacesuits during ascent. Although, if the capsule is the attachment to the ITV, then pressurizing could add structural strength. But no life support, just suits for life support. This isn't Battlestar, it's rather spartan.

This capsule serves only two purposes, it gets the astronaut to the surface of Mars with minimal gadgetry and returns the astronaut to the MTV. Irrespective of wether or not we have massive ascent vehicles for multiple crew members or small single crew member ascent vehicles, the requirements don't change. However, there's a huge cost differentially associated between designing and testing a manned bucket on a parachute and a massive multi-stage ascent vehicle. If the massive, complicated ascent vehicle fails, it likely kills everyone and the mission is over. If one astronaut out of four or six doesn't make it back to the MTV, the mission isn't a total failure.

Using very small and light descent/ascent capsules mean using tech we already have experience with for the manned systems as opposed to something we've no experience with whatsoever. We already have LOX/CH4 engines with the performance required to get single astronauts off the surface of Mars. We can easily test small capsule systems on comparatively inexpensive launch vehicles and we can actually afford to test them many times and in different ways.

RobertDyck wrote:

You tried to characterize a single multi-seat ascent vehicle as "large". A single vehicle requires a single guidance system, single docking hatch, single rocket engine or set of engines with gymbals. Separating one single vehicle for 4 astronauts into 4 separate vehicles for one astronaut each, will increase total mass dramatically.

Come on, Rob. All the MAV designs I've seen have multiple engines, multiple propellant tanks, 30 to 60 days of rations, a bathroom, a shower, and on and on.

If we plan to use ISPP to fuel any ascent vehicle, there's not going to be a significant mass differential between four small launch ascent systems versus one massive ascent system. I don't want to replicate every last component of an exploration class capsule in miniature, I want to use a minimalist approach to simplify descent/ascent for astronauts.

We should continue testing with technologies that permit us to land more massive payloads, but that technology is very new and has never been tested on Mars. If a cargo landing attempt fails, we'll simply send a replacement and try again with a modified design. If that same scenario happens with the entire crew, there's a 50/50 chance it will end the program.

Regarding highly elliptical orbits and other nonsense like that, we didn't do that for our manned lunar missions and I can't think of a compelling reason to start now. So what if you save a few a km or two of dV? At what cost? The MTV should be parked in LMO.

Every single component of the mission architecture can't be a gold plated swiss army knife or we'll never be able to afford it and therefore we simply won't go to Mars.

RobertDyck · 2015-03-16 18:56:14

kbd512 wrote:

Come on, Rob. All the MAV designs I've seen have multiple engines, multiple propellant tanks, 30 to 60 days of rations, a bathroom, a shower, and on and on.

Bullshit. Even the Mars Direct ERV doesn't have a shower. Any Mars Ascent Vehicle only gets astronauts from Mars surface to a vehicle parked in Mars orbit. No rations, no bathroom, no shower, etc. You're confusing the Interplanetary Transit Vehicle with the MAV. Get your terms right.

And any vehicle to lift crew to Mars orbit is not going to be simple. It isn't a bucket with a parachute. Ascent requires rocket engines, fuel tanks, guidance, etc. And even if astronauts could get to orbit, they're dead of the vehicle in Mars orbit can't depart. An ITV dependant on ISPP will require propellant delivered from Mars surface.

kbd512 wrote:

We should continue testing with technologies that permit us to land more massive payloads, but that technology is very new and has never been tested on Mars.

Test test test. At some point you have to fish or cut bait. Yes, some technologies require testing. But have you seen the Apollo LM? Landing on a planetary surface has been done. Yes, testing a large landing with Curiosity was a good idea. But it's now done. Next is an ERV or MAV, landed unmanned but for a manned mission. For that matter, we don't have to test human response to zero-G. That's been tested to death. Any more old technologies you want to mention?

kbd512 wrote:

Regarding highly elliptical orbits and other nonsense like that, we didn't do that for our manned lunar missions and I can't think of a compelling reason to start now. So what if you save a few a km or two of dV? At what cost? The MTV should be parked in LMO.

Apollo didn't use ISPP. And the Moon has a lot less gravity. And the Moon doesn't have an atmosphere for aerocapture. When you use aerocapture, the periapsis will dip into the atmosphere. Stabilizing orbit requires lifting periapsis just barely out of the atmosphere. That's where the highly elliptical part comes from. And Apollo didn't have modern computers, they had a human maintaining the command module and using his eyes to scout the surface. You have to be low and stable altitude for eyes to make out anything useful.

kbd512 wrote:

Every single component of the mission architecture can't be a gold plated swiss army knife or we'll never be able to afford it and therefore we simply won't go to Mars.

You have that backwards. Dropping to low Mars orbit requires more propellant. Returning to Earth from that orbit requires even more. The point of a highly elliptical high Mars orbit is to use aerocapture, with close to no propellant at all. And minimize propellant for return. Dropping to circular low Mars orbit is gold plated.

kbd512 · 2015-03-16 20:47:41

RobertDyck wrote:

And any vehicle to lift crew to Mars orbit is not going to be simple. It isn't a bucket with a parachute. Ascent requires rocket engines, fuel tanks, guidance, etc. And even if astronauts could get to orbit, they're dead of the vehicle in Mars orbit can't depart. An ITV dependant on ISPP will require propellant delivered from Mars surface.

I intended for the buckets with the parachutes to travel to Mars attached to the MTV. I intended for the empty rockets, less capsules to be delivered to the surface of Mars ahead of the crew, fueled using ISPP, and the buckets re-attached to the tops of the rockets after the crew descends to the surface.

RobertDyck wrote:

Test test test. At some point you have to fish or cut bait. Yes, some technologies require testing. But have you seen the Apollo LM? Landing on a planetary surface has been done. Yes, testing a large landing with Curiosity was a good idea. But it's now done. Next is an ERV or MAV, landed unmanned but for a manned mission. For that matter, we don't have to test human response to zero-G. That's been tested to death. Any more old technologies you want to mention?

Curiosity is nowhere near the weight class of an empty MAV. Have you watched any JPL presentations on this? Why do you keep bringing up zero G? What does that have to do with any of this?

RobertDyck wrote:

Apollo didn't use ISPP. And the Moon has a lot less gravity. And the Moon doesn't have an atmosphere for aerocapture. When you use aerocapture, the periapsis will dip into the atmosphere. Stabilizing orbit requires lifting periapsis just barely out of the atmosphere. That's where the highly elliptical part comes from. And Apollo didn't have modern computers, they had a human maintaining the command module and using his eyes to scout the surface. You have to be low and stable altitude for eyes to make out anything useful.

Apollo also didn't land on another planet with an atmosphere tens of millions of kilometers from home. As far as scouting is concerned, what are human eyes going to pick up that a high resolution radar system can't?

RobertDyck wrote:

You have that backwards. Dropping to low Mars orbit requires more propellant. Returning to Earth from that orbit requires even more. The point of a highly elliptical high Mars orbit is to use aerocapture, with close to no propellant at all. And minimize propellant for return. Dropping to circular low Mars orbit is gold plated.

The MTV will most likely have electric propulsion, so it can take the dV hit to spiral in/out of LMO. Aerocapture trades propellant mass for thermal protection mass. Between torching the MTV in the upper atmosphere of Mars and burning some more propellant, I'd burn more propellant.

Last edited by kbd512 (2015-03-16 20:48:22)

RobertDyck · 2015-03-16 21:31:38

The next size up from Curiosity is the ERV for Mars Direct, or MAV for my mission plan. Either way, it's the component that's landed unmanned. Once that succeeds, and ISPP fills propellant tanks, then send crew.

NASA continues to test humans in zero-G. It was tested by Mercury, Gemini, Apollo, Skylab. But they didn't stop there, they continued to test zero-G on multiple Shuttle missions. And continue to test zero-G on ISS. Shannon Lucid's response to zero-G after 6 months on Mir exactly matched prediction. How many times do we have to test the same thing? Same with landing.

And no, we won't use any sort of propulsion that requires spiralling out of orbit. You don't want long duration exposure to Earth's radiation belts for any craft that has humans on board. And Mars Odyssey measured interplanetary radiation during solar minimum, Curiosity measured it during solar maximum. Or close enough to minimum/maximum. The result was 2 to 3 times as much radiation as ISS. You don't want humans to experience that for any great length of time. Get through the Van Allen Belts quickly, then get to Mars quickly. For return, again dash quickly home. Long duration also has life support issues. On Mars surface you have Mars atmosphere and Mars ice as material for various backups. In space you only have what you brought with you.

"Torching"? Slanderous words that demonstrate lack of understanding to not help your case.

kbd512 · 2015-03-17 06:11:22

RobertDyck wrote:

The next size up from Curiosity is the ERV for Mars Direct, or MAV for my mission plan. Either way, it's the component that's landed unmanned. Once that succeeds, and ISPP fills propellant tanks, then send crew.

Curiosity was ~2t and a MAV will be closer to ~40t. Kinda of a wide gap there, but ok.

RobertDyck wrote:

NASA continues to test humans in zero-G. It was tested by Mercury, Gemini, Apollo, Skylab. But they didn't stop there, they continued to test zero-G on multiple Shuttle missions. And continue to test zero-G on ISS. Shannon Lucid's response to zero-G after 6 months on Mir exactly matched prediction. How many times do we have to test the same thing? Same with landing.

Well, we're not testing the same thing. We'll have to use a very large inflatable heat shield on Mars for anything the size of the MAV. I'm confident that inflatables will work, but it's going to be an awfully expensive test. JPL says we're at least 10 years away from having the inflatable technology to land something the size of a MAV on Mars and that was in 2014, IIRC.

RobertDyck wrote:

And no, we won't use any sort of propulsion that requires spiralling out of orbit. You don't want long duration exposure to Earth's radiation belts for any craft that has humans on board. And Mars Odyssey measured interplanetary radiation during solar minimum, Curiosity measured it during solar maximum. Or close enough to minimum/maximum. The result was 2 to 3 times as much radiation as ISS. You don't want humans to experience that for any great length of time. Get through the Van Allen Belts quickly, then get to Mars quickly. For return, again dash quickly home. Long duration also has life support issues. On Mars surface you have Mars atmosphere and Mars ice as material for various backups. In space you only have what you brought with you.

There's no requirement for the crew to be aboard for the spiral out to L1. The crew can embark the MTV at L1 from a Dragon. Since NASA is so overly-concerned with radiation, we'll presume that some form of active radiation shielding will be built into the MTV. Rather than spiral in to LEO on the return flight, the same Dragon that they embarked from can return them home.

RobertDyck wrote:

"Torching"? Slanderous words that demonstrate lack of understanding to not help your case.

Most atmospheric entries require substantial thermal protection. Is that not the case here? How much thermal protection is required for aerocapture?

RobertDyck · 2015-03-17 07:23:50

No, not inflatable. I said several times, used ADEPT. NASA is already working on a carbon fibre heat shield that can be deployed like an umbrella. It's specifically designed for payloads larger than Curiosity.
YouTube: https://www.youtube.com/watch?v=LWYAryuuy_k
NASA technical report server: http://www.google.ca/url?sa=t&rct=j&q=& … XY&cad=rja

kbd512 wrote:

There's no requirement for the crew to be aboard for the spiral out to L1. The crew can embark the MTV at L1 from a Dragon. Since NASA is so overly-concerned with radiation, we'll presume that some form of active radiation shielding will be built into the MTV. Rather than spiral in to LEO on the return flight, the same Dragon that they embarked from can return them home.

Do you work for Boeing or Lockheed-Martin? Why do you obsess over stupid ideas? What are you trying to sell?

Terraformer · 2015-03-17 11:28:21

Why do you think launching from L1 is a stupid idea?

GW Johnson · 2015-03-17 15:34:32

Look, a demonstration of a new technology or hardware item is NOT (repeat NOT) the same as a ready-to-apply technology or ready-for-service hardware item. It takes a fairly extended interval of successful service before you have the confidence in it to just turn it loose and use it. (And BTW, some forms of SEP are now ready to apply!!!)

For example, the science behind, and some of the technology directly associated with, breathing pure oxygen in aircraft and spacecraft was ready in 1966. Some of the other hardware (wiring insulator materials and a slow-opening hatch) was not ready, and we killed 3 in the Apollo-1 (Apollo 204) fire because of that. There are many other examples of technologies that work in some demonstrations, but are just simply not yet ready for general application. Scramjet propulsion is one.

I understand completely that ISPP devices work fine on laboratory benchtops here on Earth, even at simulated Martian conditions. So, how good are the simulated Martian conditions? That's only the first of several questions that come to mind, derived from the school of hard knocks, guys. What we know to simulate about Martian conditions was not good enough for the design of Curiosity's wheels, apparently.

We might even get to try ISPP out in a couple of probes on Mars before we attempt to send men there. That's a tiny handful of real site conditions. But, like the Apollo hatch and wiring, we will NOT know that it works the same in all the different conditions in all the sites on Mars, including where we might really want to send crews. It'll be something idiotic like "angular dust particles that screws up the works in some ways that we just didn't anticipate". We have already run into THAT with moondust.

So, the emperor has no clothes, as I said, and I'll keep on saying it.

Take the supplies to function even if ISPP is a total failure. If it works, just accomplish more. Same for all the other technologies-that-aren't-yet-well-proven, such as the closed-loop ecology life support that still does not exist today. And astronaut food that'll last 3 years in storage, which still does not exist today. And exercise regimes that stave-off microgravity disease for 3 full years, which still do not exist today.

Failing ready-to-apply technologies in those areas, you will either (1) likely kill a crew, the most expensive thing imaginable, or (2) your mission will absolutely NOT be a minimum mass mission if you take steps to ensure their return. Packed supplies are heavy, especially canned and frozen food, which are very heavy but last for decades. Extra propellant is heavy. Artificial gravity is heavy, although it does not have to be as heavy as some folks still seem to think (we don't need giant wheels, or huge trusses driving up inert mass fractions).

Some things you just cannot avoid. Radiation shielding is heavy, there simply is no way around that. The slow drizzle of GCR really is not the issue many ballyhoo it to be. The real danger is X-class solar flares. 20 cm of water is good enough, and you only need it around the designated shelter space.

GW

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