Getting to Mars with REAL technology, & what's currently missing.

RobertDyck · 2018-07-20 04:28:21

SpaceNut wrote:

1. Centrifuge Accommodation Module, who will pay for it and how will it attach to ISS?

That was paid for by Italy, built by Japan, completed and waiting for launch at KSC. Obama did not authorize its launch. I think we could get Trump on-board if you emphasize that Obama screwed up. Someone (not Trump himself) will have to apologize to our international partners and beg them to repair/rebuild it. Then NASA can launch it. It was designed with a CBM hatch at each end, was to be berthed to the Harmony module (Node 2).

Wikipedia wrote:

It was built by JAXA's predecessor, NASDA, but owned by NASA, who obtained ownership of the CAM by trading in a free launch of the Japanese Experiment Module Kibo to the Station. ... It is now on display in an outdoor exhibit at the Tsukuba Space Center in Japan.

SpaceNut wrote:

2. urine processing assembly, thats the american side which fails from calcification I believe?

Yup

SpaceNut wrote:

3. CO2 electrolysis device, moxie prototype would extract O2 but it would leave co as an output leaving 1/2 the oxygen being dumped over board. Why not send that into the other waste stream recoveries to get other chemical reactions to occur to free up other oxygens and buffer gasses.

Only 80% of CO2 gets converted to CO, so only 40% of oxygen atoms are recovered. The oxygen in CO and the 20% of CO2 that still remains would be dumped overboard. Half the CO2 removed from cabin air is sent to the Sabatier reactor, where CO2 + 4 H2 → CH4 + 2 H2O. The other half of CO2 is currently dumped overboard. I'm saying recovering 40% of oxygen from that is better than 0%. If you want to send the CO/CO2 mix to another step for further recovery, fine. But we don't know how to do more, we do know how to do this. So let's do this, and GO TO MARS ALREADY! (Sorry. Not frustrated at you. Frustrated that NASA hasn't gotten the job done.)

SpaceNut wrote:

4. Operate ISS without cargo resupply for the full duration of Mars mission, That would probably lead to a better design for mars in the long run rather than trying to fix it with dead mass that we might not need for a mars duration leg.

Not sure what you mean by "dead mass".

SpaceNut wrote:

5. Operate ISS without cargo resupply for the full duration of Mars mission, That is a mass dependant problem as the more these are increased on each side of center the thicker and heavier the cable gets. Try designing the module lengths for axial rotation would make this less dependant on mass differences for center balance roaming.

"Operate ISS without cargo resupply" means to operate ISS as-is. I am not suggesting artificial gravity for ISS. I am suggesting artificial gravity for a Mars mission, a la Mars Direct.

SpaceNut wrote:

6. Require all future Mars orbiters to use aerocapture and Demonstrate a deployable heat shield on Mars: ADEPT and/or HIAD, but this needs to be done with the max mass we expect to go to mars with and work on the retropropulsion landings with that mass, with a specific mass payload that will work to mans possible dream being realized.

Mars Direct was written with the same landing system as Viking lander and Mars Phoenix. That means atmospheric entry with a heat shield, then parachute, then propulsive landing for final touch-down. Baseline design for ADEPT was 40 metric tonne payload landed on Mars. Mars Direct was designed for 28.6 metric tonne ERV and 25.2 metric tonne hab. Mars Direct would use 8.5 month transit for the ERV, 6 month transit for the hab with crew. That's why the hab would have lower landed mass. But this is well within the 40 metric tonne capacity of ADEPT. (The Case for Mars, soft cover 1997, table 4.5 on page 93.)

SpaceNut wrote:

7. Laundry machine, not sure that a washer is the only cleaning of clothing that is needed as a space suit even MCP type would before entering the air lockes need some dirt and dust removal to be done as we will not want the effects of breathing issues as we did on the moon.

Brushing off before entering the airlock sounds like a good idea. A small hand brush isn't exactly high-tech. EVA prep area would have airflow into it, so dust would not drift into the rest of the hab. Filters would remove dust before that air is returned to the hab.

SpaceNut wrote:

8. Demonstrate ISPP with a Mars sample return mission, this is the question mark as to which methods of water extraction will work with a set power/mass for intaking the co2 from the atmosphere will require.

Mars Direct proposed a simple system. Freezing dry ice out of the atmosphere during Mars night when temperature is close to dry ice anyway. At dawn, close and pressure seal the canister, then heat CO2 to sublimate. Phase change will self-pressurize. That's every energy efficient. Nothing new here, it's part of Mars Direct. Bring hydrogen from Earth. Water produced by the Sabatier reactor will go to an electrolysis tank to split into hydrogen and oxygen. Recycle hydrogen, chill O2 to LOX for propellant. Do not try to use Mars ice on the first mission; that's for a later mission after the ice resource has been well quantified.

SpaceNut wrote:

9. Space toilet to Recover moisture from solid human waste, lets just call this a total waste recovery system with all forms of rubbish included as we will not want to eject it out the side of the ship and we will not have a waste ship to put it in. So lets learn to capture as much as we can from it.

On ISS, it can be put in a waste ship. In transit to Mars, it can be dumped in space, or stored until landing. On Mars it can be dumped in a pile on the surface. A permanent settlement would have a more advanced system, something you can't put on an interplanetary spacecraft. Permanent settlement could either use a composting toilet, or grey water sewage processing system. Neither recover moisture for life support; instead they provide moisture to soil for crops. A composting toilet is not compatible with hydroponics, but grey water can be used for either soil or part of the nutrient mix for hydroponics. Obviously I prefer soil because it means we don't have to manufacture nutrient solutions for hydroponics. But this is all for permanent settlement. The first mission will require something simpler. I'm recommending a toilet that recovers moisture from solid human waste.

Oldfart1939 · 2018-07-20 08:13:23

I believe I've heard Zubrin state that a modified Mars Semi Direct COULD simply bring return fuel supply and manufacture the return flight LOX, thereby simplifying things somewhat. LOX for return flight constitutes some 75% of the required mass, to my recollection?

One thing we really should emphasize is simplicity, or the "KISS" principle. What I've been trying to emphasize here is using as much COTS as possible in order to get things rolling; no "unobtanium," please!

Oldfart1939 · 2018-07-20 10:46:04

Another point we should emphasize here is NO dependence on the BFR or BFS. IMHO, those are both "off the table" for this discussion, as we're trying to lay the GROUNDWORK for those flights. Maybe this constitutes a throwback in the thinking process (hallucinations?) of some, but I prefer reality to aspirant dreams.

kbd512 · 2018-07-20 11:16:18

Dr. Zubrin's Mars Semi-Direct may be the only real way to move the first mission into the engineering realm.

The only mods I would make are as follows:

* SEP-equipped modified Orion for the interplanetary transits (miniature ITV)
* modified Dragon for the descent / surface stay / ascent only
* simple pressure-fed NTO/UDMH or NTO/MMH for Mars descent / ascent and TEI, rather than LOX/LCH4
* apart from replenishment of O2 and N2 from the Martian atmosphere to account for losses, no ISRU
* ULA's IVF-equipped ACES upper stage for TMI to increase delivered tonnage
* SEP for delivery of surface cargo modules and TEI kick stage to LMO
* surface cargo modules pre-positioned in LMO are landed AFTER Dragon
* thin film solar arrays, Sodium Nickel Chloride or solid electrolyte Lithium-ion batteries, and RTG's for electrical power

RobertDyck · 2018-07-20 11:39:48

Oldfart1939 wrote:

I believe I've heard Zubrin state that a modified Mars Semi Direct COULD simply bring return fuel supply and manufacture the return flight LOX, thereby simplifying things somewhat. LOX for return flight constitutes some 75% of the required mass, to my recollection?
One thing we really should emphasize is simplicity, or the "KISS" principle. What I've been trying to emphasize here is using as much COTS as possible in order to get things rolling; no "unobtanium," please!

But why? Fuel production is via Sabatier, which is current used on ISS for life support. Ironically LOX production is the new thing and that's the one NASA is focused on. Semi Direct uses ISPP for MAV but hauls propellant from Earth for ITV. That and increasing astronauts from 4 to 6 doubled cost. Congress wouldn't accept any cost increase. SLS is much more expensive than estimate for Ares, but still. Any unnecessary cost increase will kill it. Avoiding technology already demonstrated on ISS is unnecessary.

Oldfart1939 · 2018-07-20 12:32:00

Rob-

You must recall that the principal ingredient to the Sabatier reaction beyond CO2 is H2! Zubrin was planning initially, in Mars Direct, to bring along the necessary H2 for this use in manufacture of CH4 by the Sabatier reactor.

SpaceNut · 2018-07-20 16:33:20

While a Dragon capsule might be the quickest path to designing a mass lander do we really need to have a cone shaped landers for mars plus the heat shield would do nothing for landing as it needs a new first stage to be attached to get back to orbit anyways. Plus a non cone shape will provide more internal room for the long stay on the mars surface.

While the first mission might be with no demand for the use of the experiment insitu for return flight home it is the work to set up such units needed to be part of the science to ensure we can keep going with less cost in the future. Using moxie or some other means from insitu should also be part of the science to ensure future safety growth as well.

Lets see if we can narrow down the count of what we need in orbit for communications, gps and what we need on the ground for uplinks and beacons for this first mission?

We can assume that the power lander was first followed by the crew and then the cargo or should cargo go down before the crew finally goes down? Each lander could hold a single beacon, uplink repeater for surface with supplemental ones to send down to better outline the perimeter of the landing zone.

SpaceNut · 2018-07-20 17:02:10

Dry Ice collection chamber will need to be demostrated for what power levels it will require as we will want a large cooling plate that will be sealed off before morning in order to use solar direct heating and any other source to help drive it faster for additional heat sources.

Recycling should be all encompassing for H2, O2, N2, Co2 plus H2O and anything else that we can get from the rubbish but we will need to find at what mass and energy for each part to solve how far we need to go with what we bring along the way not only for a first mission but for the future ones to come as who wants a front row seat to a rubbish pile....CAll it Mount we took a dump...Not...

RobertDyck · 2018-07-20 18:40:08

Oldfart1939 wrote:

You must recall that the principal ingredient to the Sabatier reaction beyond CO2 is H2! Zubrin was planning initially, in Mars Direct, to bring along the necessary H2 for this use in manufacture of CH4 by the Sabatier reactor.

Yea, so? This is far better than hauling return propellant all the way from Earth. I have strongly argued to produce all return propellant via ISPP, not a part-way form like Mars Semi-Direct.

RobertDyck · 2018-07-20 18:51:17

Let's take a step back. NACA was founded in 1915 because industry was afraid to develop any new technology. NACA was created specifically with the mandate to develop high-risk/high-payoff technologies. It worked, aircraft technology went from canvas stretched over wooden rib biplanes to B-29 Superfortress in 27 years. NACA became NASA in 1958. Space technology developed rapidly from 1958 until Apollo, but announcement of Space Shuttle in 1969 to 1996 (27 years later), how much development? Why are you afraid of a mission plan that's 28 years old? ISPP is *NOT* radical, it's fundamental. Sabatier and water electrolysis has already been demonstrated on ISS for years.

kbd512 · 2018-07-20 19:45:13

Robert,

I agree with your arguments, but some of us don't want this to be another snow day excuse for why we're not sending people to Mars. If you take your return fuel with you for the first mission, or however many missions it takes to perfect LOX/LCH4 production on Mars, then that's one less reason why we can't go to Mars. Take the experiments with you on the first mission and try to make it work. If it doesn't work at first, then try try try again.

RobertDyck · 2018-07-20 21:44:04

kbd512,

I accept your argument. But we evaluate risk differently. When Mars Direct was first pitched to NASA in 1990, the cost estimate was $20 billion for research, development, infrastructure, and the first human mission to Mars. Plus $2 billion per mission thereafter, with one mission each time the planets align, every 26 months. Or $30 billion if they commit upfront to 7 missions, which works out to buy 6 missions, get one free. Many people in NASA got excited, but others said "Not Invented Here", so they decided to re-invent the wheel. They came up with Semi-Direct. It cost $55 billion for 7 missions. All this was in 1989 dollars to be comparable with the 90-Day Report. When Congress saw the price double without any hardware built, they balked. They were afraid certain individuals in NASA and their contractors would manipulate the mission to the full price of the 90-Day Report: $450 billion in 1989 dollars. There was no way in hell they would approve that. The largest reason Semi-Direct cost so much was hauling return propellant from Earth.

You said "some of us don't want this to be another snow day excuse for why we're not sending people to Mars". But what you're doing is already a "snow day excuse". They already used that excuse to not send humans to Mars, and you want to do it again? As long as you do that, no one will ever go to Mars. I'm trying to get people to Mars while you repeat a "snow day excuse" that has already resulted in inaction.

Sabatier and space rated water electrolysis has already been demonstrated on ISS. New technology is not something to run away from. Extreme unrealistic technology is; for example VASIMR requires a nuclear reactor that provides so much power with so little mass that it just won't happen. Period. But LCH4/LOX rocket engines have already been built. Sabatier and water electrolysis is demonstrated every day on ISS. You argue for MOXIE, but that's the only technology not demonstrated in space. Well, MACDOF (Mars Atmosphere CarbonDiOxide Freezer) hasn't either, but it's so low-tech that it's a no-brainer. And MOCDOF is necessary to provide CO2 to feed into MOXIE. So you are actually arguing in favour of the only ISPP technologies not already demonstrated.

Oldfart1939 · 2018-07-20 22:08:08

One of my earlier mission architectures postulated here was an expanded Dragon, one incorporating the trunk pressurized and structurally reinforced, with additional cargo space and onboard fuel. This would be something of a short, cone plus cylinder vessel. Fold out legs for landing stability vis a vis the current Falcon 9 first stage. Several of these early Dragon landers would be fully functional fuel manufacturing plants, not intended for return to either Earth or Mars orbit. Old recycled Dragon cargo vessels. These are part of the growing Mars infrastructure. I propose using these as throwaways after having served to the ISS in prior flights.

Last edited by Oldfart1939 (2018-07-20 22:35:55)

SpaceNut · 2018-07-21 07:55:01

If we are modifying a Dragon into a mars lander why not after the capsule connect a cygnus followed by the trunk and drive portion of the cygnus into a common power system, continue with a landing stage with the legs.

This would be for a crew of 2 to land and live within on the surface.

The dragons heatshield would be removed with a sealable door in the base of the capsule to connect into the cygnus for use.

The cygnus and truck solar power unit would be redesign to maximize materials to a common supply system and still contain a section for the unpressurized cargo storeage (science equipment and other stuff).

If all we need to land is a support for 2 then a second unit of simular design would be its cargo unit for everything else that we need to set up shop on mars. If fuel for return home is in that cargo unit and its not sufficient then add another cargo lander unit we get to the fuel levels for return. Cobalance all the stuff we bring across all cargo landers and call it good.

RobertDyck · 2018-07-21 09:27:43

If anyone here has any ability to contact Donald Trump, one thing I would like to see is a last minute change of Mars 2020. It's designed as a second copy of Curiosity, so the manufacturer can sell another. It's designed to take samples, then leave them in a coconut size container on the surface of Mars in the hope that a second later rover would retrieve it. Then another mission would deliver a rocket to Mars to launch the sample container to vicinity of the Moon. Then an Orion spacecraft would go fetch it, carry it to the Deep Space Gateway. Analysis would be done on the Gateway, not Earth. This is absurd! Most likely the sample container would be left on Mars, never to be seen again. I want a lander with a smaller rover to collect samples from the immediate vicinity, a rocket contained on that lander with an Earth entry capsule like Genesis or Stardust. The Mars rocket would use ISPP. This would demonstrate ISPP, would do so quickly (launch 2020), and the mission would be self-contained to bring a Mars sample all the way back to Earth. If someone is absurdly afraid of Mars germs, I have to point out Apollo build a sample handling facility at JSC for Lunar samples. It was built with the fear of Moon germs. Of course it turned out the Moon is sterile, the only germs are ones we brought with us. But that sample examination/handling facility is still there and actively maintained; it's where Moon samples are stored. We could use that same facility to examine Mars samples. At least the samples from the robotic Sample Return mission.

SpaceNut · 2018-07-21 10:29:36

Reposted #40 in the 2020 rover topic

The capability of that mission for sample return for dragon is in post #10 via the jpl off the books of nasa work....which was a no truck landing with the legs popping through the heatshield. Of course that mission was dropped by both Space x and Nasa...

This shows the truck which would not be able to land with a red planet sample return as jpl had run the numbers for. Of course this was using the Draco engines to slow to a landing. Something that still can be doine to make the return capsule rocket lighter when refueld for a return home.

http://spaceflight101.com/spacecraft/dragon/

Somewhat detailed drawings of the capsule
wsn.spaceflight.esa.int/docs/Factsheets/28%20SpaceXDragon%20LR.pdf

https://en.wikipedia.org/wiki/SpaceX_Dragon version cargo
https://en.wikipedia.org/wiki/Dragon_2 version crew

Looking at dragon versus the LEM
https://en.wikipedia.org/wiki/Apollo_Lunar_Module

A fully loaded cargo and fueled dragon is 12 mT at launch while the LEM was for ascent stage 4.7 mT plus descent stage 10.334 mT so a lunar lander from a dragon would also need work to make it plausable to use.

https://en.wikipedia.org/wiki/Cygnus_(spacecraft)

I would use the cygnus for any return cargo, sample return and what ever else we still need from going to the surface back to home.

Oldfart1939 · 2018-07-21 12:06:13

Rob-
It seems that NASA is still infected by the "not invented here" virus. I seriously doubt any modifications could be made to the 2020 mission at this 'late date."
SpaceNut-
Thanks for posting the diagram of the Dragon Cargo system. By reference to that illustration saves a lot of descriptive writing. Since we're talking about using a reclaimed Dragon as a throwaway, we should consider removing the Earth entry size and weight heat shield, and subsequently adding more super Draco thrusters and an inflatable re-entry heat shield in order to save weight for additional cargo. The cylindrical trunk could also be doubled in length by the simple expedient of using 2 of them stacked one atop the other configurationally. Falcon 9-style landing legs could be incorporated as well. This is how I would choose to build something w/o completely all new designs. Maybe get 12 tonnes of cargo to Martian surface? Need to do some number crunching, but think it's a possibility.

This is just "brainstorming," and more number crunching is in order. These are simply wild ideas popping out.

kbd512 · 2018-07-21 13:01:16

Robert,

NASA has already spent more than what Dr. Zubrin estimated the development work would cost just on SLS and Orion and the development work has not been completed.

The orbiter and its cargo already represented a 102t payload to LEO. No new up-rated RS-25's or SRB's were required to achieve that. All that was required to move the program forward was existing SWLT external tank and SRB technology. NASA could incrementally add more payload by reducing the inert mass of the structures over time, as development was completed. The propulsion system required to realistically send hundreds of tons of payload to Mars is electric because the NTR program was killed decades earlier.

1. electronics update with 21st century electronics - because they don't even make some of the electronics originally used
2. composite casings for the SRB's - a program nearly completed two decades earlier and then killed
3. composite tanks for the LOX and LH2 - an emerging technology only proven feasible in the past few years
4. IVF and HIAD for propulsion module recovery - another emerging technology only proven feasible in the past few years
5. aerospike nozzles for altitude compensation - on/off experimentation for decades, but it always worked

Those are the only real evolutionary performance improvements to be had over the existing design, short of designing an entirely new rocket from scratch. Well, guess what? That's exactly what they did. We still don't have a super heavy lift launch vehicle as a result because there was never enough development funding available to accelerate the development cycle. That reprise of the Apollo capsule system was an even worse idea. STS could have kept flying while the new hardware was being developed and carried the deep space hardware set into orbit, none of the jobs and irreplaceable experience flying STS/SLS hardware would've been lost, and we wouldn't have been forking over hundreds of millions of dollars to the Russians for seats aboard Soyuz.

It's almost like the entire plan, from start to finish, was a setup for failure. That's how I feel about ISPP, given present development efforts or lack thereof from lack of funding. There's no such technology suite in existence, there never has been, and unless the SLS and Orion programs are scrapped, there never will be in the next decade. If SLS and Orion were terminated, then in another decade ISPP might be feasible. Unfortunately, you can't plan a mission with paper hardware. This thread is about making lemonade since all we have to work with are lemons (existing technology set) and a tiny bit of sugar (private funding since all the sugar from Uncle Sugar went to development of unnecessary things).

RobertDyck · 2018-07-21 15:26:24

kbd512 wrote:

NASA has already spent more than what Dr. Zubrin estimated the development work would cost just on SLS and Orion and the development work has not been completed.

Do you realize how much of a condemnation that is of what NASA is doing? Do you realize it's amazing SLS and Orion haven't been killed already. They probably will be killed. Ideal is Orion flies EM1 & EM2, then never flies again.

SpaceNut · 2018-07-21 18:45:03

RobertDyck I do not think that we are against the use of the SLS but even if that does launch on time every time it is the cost that will not be wanted for all of the materials that we need for a mars mission.
Use it sparingly for the things that are beyond a falcon heavy launch capability and then lets go to mars.

SpaceNut · 2018-07-21 19:22:52

Compact and Lightweight Sabatier Reactor for Carbon

http://www.digipac.ca/chemical/mtom/con … batier.htm
http://www.digipac.ca/chemical/mtom/con … atier2.htm

http://www.pennenergy.com/articles/penn … ction.html

We know the process and the work that nasa is doing to lower the power, pressure and heat of reaction but for all its worth there is not COTS vendors to which we can send.

kbd512 · 2018-07-21 19:44:31

Robert,

In a word, yes.

If I was put in charge of the SLS program and all the constraints about which engines and contractors to use were placed upon my team, my top priorities would've been thus:

1. upgrade the electronics, because the older stuff was dangerous to use
2. demo the basic vehicle using the existing infrastructure / SWLT / SRB technology that was in use at that time
3. repair or upgrade the integration facilities, as required
4. implement the common sense cost savings measures you outlined for STS as interim solutions until its retirement and apply them to SLS
5. develop a coherent upgrade path for the new vehicle that took existing infrastructure and engine technology into account

Here's what didn't happen:

1. priority wasn't given to designing a usable vehicle with the existing infrastructure
* the Shuttle-C design work was at an advanced stage of development decades ago, so that should've been the baseline
* there was never any requirement for a new capsule program that never had the volume required for deep space operations
2. the reversion to using hard alloy in the tank and the switch to friction stir welding jigs didn't save any time or money
* experimentally demonstrated and proven to work at significant scale are two entirely different things, as GW would say
3. facilities repair and upgrade was almost an afterthought that came years after the SLS program began
* the new vehicle was too heavy for the existing MLP to handle
* none of the VAB equipment worked with the new vehicle
* none of the launch pad equipment worked with the new vehicle
4. the engineers knew there was never a path to a 125t payload capability without adding a 5th RS-25
* 3 engines was too few, 4 engines was doable, but 5 engines was too many - no logic there at all
* RL-10's don't produce enough thrust to achieve optimal payload capability
* the modernized J-2X engine was developed specifically for the upper stages, so that should've been the baseline
* the use of 5 segment SRB's was another needless de-facto engine development program
5. none of the technologies that came along or already existed were incorporated into the development program, except as afterthoughts
* since the rocket was intended from the outset to be expendable, it made far more sense to develop the use of highly automated fabrication methods and cheap materials like carbon and glue
* high quality forged steel and aluminum components with weeks to months of machining are absurdly expensive, whereas composites are fabricated with robots in days to a week or so and there's three to five machine watchers watching the robot work instead of a small army, mostly feeding in more materials and clearing malfunctions, whereas metalworking is an inherently labor intensive process for low production rate items
* the weight savings from using composite casings for the SRB's and composite propellant tanks had a nearly direct correlation with increased payload and this was known for at least two decades
* shockingly, the robotically fabricated and non-autoclaved composite tanks actually held pressure with LN2, LOX, LH2, LCH4, RP1, and performed far better than anyone expected

Basically, I would've taken the development of the technology set to its zenith in a logical incremental progression. The first step is always creation of a working prototype. There still isn't any and the damage to the one functional prototype means further delays. The second step is a reduction in structural mass, fabrication time, and thus marginal production cost. The third step is retrieval of the engines to further reduce marginal operating cost. The final step is further refinement of the basic engine technology. We would've had an operational vehicle by now, not as performant as some would like, but something is still something and nothing is still nothing.

This stuff is really frustrating to me. It's like watching a slow motion train wreck and being able to do nothing about it.

SpaceNut · 2018-07-21 20:29:09

well Shuttle C -Z were all flavor various of the basic orbitor less crew cabin, altered cargo bay, and in the long run the shuttlke titles still required the same amount of standing army to maintain so it never would have been a cost saver.
I agree that Nasa keeps throughing away each launch platform reinventing what it once had each time and its taking long to do it each time as well sionce the knowlegde base of the past is disappearing as they age rapidly.
Even the contract players in the ULA, Boeing and Lockheed are not producing a product very fast as well. In fact a new launcher is quite a long time in the wings before it can launch.

RobertDyck · 2018-07-22 06:28:14

kbd512 wrote:

This stuff is really frustrating to me. It's like watching a slow motion train wreck and being able to do nothing about it.

I feel your pain. Yes, a lot of this stuff should have been done. But it wasn't. Now we need to stop concocting excuses and get the job done.

You mentioned Shuttle-C. If you read "The Case for Mars", engineers at Martin-Marietta looked at ways to get astronauts to Mars. One launch vehicle they looked at was Shuttle-C. An obvious out-growth of the Space Shuttle. But it wasn't powerful enough, so they expanded the upper stage. Since Zubrin was involved in that, they called it Shuttle-Z. That still wasn't powerful enough, so they redesigned the launch vehicle, making the LOX tank a cylinder so they could stack an upper stage on top instead of side-mounted, which meant they needed an engine pod for the main engines. The result was Ares.

Ares was designed to launch from the same MLP as Shuttle. Main engine exhaust was the same location, so no new hole had to be cut. Cutting a new hole would compromise structure, so the existing hole for Shuttle main engine exhaust would have to be filled in. As you pointed out, ensuring MLP could support the weight was a concern, so it's more complicated that just filling in a hole; the structure had to be reinforced. But with Ares, that wasn't necessary. I believe VAB facilities were sufficient for Ares; after all they were originally designed for Saturn V.

We could go on and on. However, at this point I'm going to focus on what needs to get done. If you take the time from the 1961 announcement that Saturn C5 would carry astronauts to the Moon until the first unmanned test launch of Saturn V (Apollo 4), the count the same number of days from the joint NASA-Senate announcement of SLS, the first test launch should have occurred December 10, 2017. It's overdue. If you take the cost of developing Saturn V, not all of Apollo, just Saturn V, then apply inflation from those years until today, SLS has already cost more. It's overdue and over budget. Yet, when the President asked for humans to orbit the Moon in 2019, NASA refused. They claimed they needed more money yet. Copious gobs of cash. We need a President who has the balls to fire a few key people; many of us thought Donald Trump was that President. Yes, we can have EM1 in 2018, and EM2 in 2019. It only takes a NASA manager willing to do it.

SLS is built from a combination of Shuttle and Saturn parts. SLS should have cost less money and take less time, but it has already cost more money (after inflation) and more time. It's absurd! They had delayed EM1 from December 2017 to the winter of 2018, but when Donald Trump asked to have astronauts orbit the Moon in 2019, they delayed EM1 even further. He wanted results so the held SLS hostage, demanding more money more money more money more money.

You mentioned carbon fibre composite SRBs. Ok, I won't argue. However, I still believe Liquid Rocket Boosters using F-1B engines are far better. Let's skip Advanced SRB all together, build liquid boosters with F-1B.

GW Johnson · 2018-07-22 09:31:03

There's a very good reason they keep going back to solid boosters to get these big designs off the pad. The solid offers more thrust from the same size frontal blockage area than any other type of rocket. Period.

This comes about from F = CF Pc At. It's the same class of Pc's solid or liquid. That means its the same class of CF's, which depend primarily on Pc/Pambient. That leaves At.

If you look at the size of a solid's throat area At compared to the size of the motor, it's just way-to-hell-and-gone larger than anything you can do with a liquid, even clustered liquids.

That's more thrust, by far. Exactly what you need right off the pad when you are heaviest. The lower Isp just means you stage them off sooner, when you are lighter and don't need them anymore.

Why is that so hard to understand?

Can solids be made reliable? YES. The makers do that every day with military products that are safe enough to fire off a pylon under a wing. Note that NASA is not involved with those designs they way they were with the SRB's that killed a shuttle crew.

EDIT: to amplify what I said about solids and CF's, the area ratio typical for a sea-level-launchable design is about 9. That is exit area/throat area. The corresponding diameter ratio is about 3.

Look at the exit areas of the nozzles. On a solid, there is one big exit, about the same size as the blockage area diameter. That means the throat diameter is about 1/3 the blockage diameter and the throat area/blockage area is about 1/9.

About the best area coverage you get in a clustered liquid first stage would be 50% of the base area is exit area. That means the throat area is 1/18 the blockage area, or less. That's HALF or less the thrust potential of a solid of the same diameter blockage.

END EDIT

GW

Last edited by GW Johnson (2018-07-22 10:25:26)

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