Moon mission today - Dragon & Mars hab

Antius · 2016-05-29 09:16:15

kbd512 wrote:

I actually think Tom is onto something here, but only for getting humans into orbit from the surface of the moon or Mars.
~100MW is required to propel a 1t payload into LEO from Earth at SL. So, on a planetary body with 1/6 to 2/5 the gravity of Earth and little to no atmosphere, is this doable with a small fusion reactor like the one Lockheed-Martin is working on?
How much power are we talking about to get a one or two person craft and perhaps 50kg worth of samples back into orbit from the surface of the moon or Mars? Let's say it's just an unpressurized capsule with thermal control for two suited astronauts and their rock collection.
How big will the frickin layzur be? If the laser is not feasible, what about HPM?
Once a capsule is in LLO or LMO, I figure our astronauts would transfer back to Earth using conventional chemical rockets. It sure would be nice to only have to carry the propellant required to land on the moon or Mars. If you use the system two or three times, it's already paid for itself in terms of the propellant for the ascent vehicle that you don't have deliver.
I haven't really thought this through. I'm just brainstorming here.

Not an easy thing to achieve over Earth-lunar distance for three reasons: (1) Gaussian beam divergence. Even a high frequency UV laser will diverge by several metres over that distance. That means a beam with an initial cross section area of 0.03m2 will spread out over 150m2 at the target; (2) At those distances, targeting needs to be very precise. If it is out by one millionth of a degree, then it misses by several metres; (3) Energy efficiency. To limit beam spreading as much as possible, high frequency (UV) lasers would be needed. Trouble is, UV lasers are at most 3% efficient and there would be reflection and re-radiation losses at the target. Infrared lasers are much more efficient, but the divergence issue would be even more of a problem.

A better solution would be to put the laser in low Earth orbit and use an efficient IR laser over the shorter distance. A booster could take the space craft to 100km (i.e. out of the atmosphere, where absorption and blooming would be a problem), at which point beamed power would do the rest.

At the target, there is an additional problem of heat transfer into the working fluid. I presume the propellant would be hydrogen, as otherwise there isn't really any performance advantage over a LOX-H2 upper stage. The receiver must be large and presumably thin to keep the weight down. It must transfer heat to the propellant at a high enough rate to generate the thrust needed to reach orbital velocity, before the craft exhausts its upward momentum. If this is too slow, the craft reenters the atmosphere before reaching orbital velocity. Not an easy problem to solve so far as I can see. I have always been sceptical that beamed power to a moving target would actually work in the real world, at least at the sort of rates that would make it useful for propulsion.

A skyhook initially looks more practical, but if the intercept velocity between the vehicle and hook is too high, acceleration would be more than any practical vehicle could withstand. A very stretchy cable would be needed to bring a craft to orbital velocity at survivable accelerations and it must be hundreds of km long. So it ends up weighing thousands of tonnes. I wonder if a cable could be made that is both elastic and electrically conducting and hence able to transfer power to an electro-thermal engine? That way, the cable can be shorter, as the vehicle provides its own acceleration. Another way of making it shorter would be to produce a sub-orbital SSTO, ie one that meets the booster phase of geeting into orbit and perhaps half the orbital velocity requirement, with a skyhook providing the rest. That way, a reusable SSTO would avoid a lot of the engineering nightmares that dog a classic LOX-H2 SSTO. It could even run on LOX-Kerosene.

There do not appear to be any easy solutions in terms of orbitally assisted takeoff.

Last edited by Antius (2016-05-29 09:47:12)

Tom Kalbfus · 2016-05-29 13:20:13

Antius wrote:

kbd512 wrote:
I actually think Tom is onto something here, but only for getting humans into orbit from the surface of the moon or Mars.
~100MW is required to propel a 1t payload into LEO from Earth at SL. So, on a planetary body with 1/6 to 2/5 the gravity of Earth and little to no atmosphere, is this doable with a small fusion reactor like the one Lockheed-Martin is working on?
How much power are we talking about to get a one or two person craft and perhaps 50kg worth of samples back into orbit from the surface of the moon or Mars? Let's say it's just an unpressurized capsule with thermal control for two suited astronauts and their rock collection.
How big will the frickin layzur be? If the laser is not feasible, what about HPM?
Once a capsule is in LLO or LMO, I figure our astronauts would transfer back to Earth using conventional chemical rockets. It sure would be nice to only have to carry the propellant required to land on the moon or Mars. If you use the system two or three times, it's already paid for itself in terms of the propellant for the ascent vehicle that you don't have deliver.
I haven't really thought this through. I'm just brainstorming here.
Not an easy thing to achieve over Earth-lunar distance for three reasons: (1) Gaussian beam divergence. Even a high frequency UV laser will diverge by several metres over that distance. That means a beam with an initial cross section area of 0.03m2 will spread out over 150m2 at the target; (2) At those distances, targeting needs to be very precise. If it is out by one millionth of a degree, then it misses by several metres; (3) Energy efficiency. To limit beam spreading as much as possible, high frequency (UV) lasers would be needed. Trouble is, UV lasers are at most 3% efficient and there would be reflection and re-radiation losses at the target. Infrared lasers are much more efficient, but the divergence issue would be even more of a problem.

Your forgetting something, the Ozone layer. The Earth's atmosphere is most transparent over visible wavelengths, Ozone blocks UV!

A better solution would be to put the laser in low Earth orbit and use an efficient IR laser over the shorter distance. A booster could take the space craft to 100km (i.e. out of the atmosphere, where absorption and blooming would be a problem), at which point beamed power would do the rest.

Unfortunately we don't have a Moon in low Earth orbit, and the Earth-Moon distance is only a fraction of the distance for the proposed laser sail starships to the stars.

At the target, there is an additional problem of heat transfer into the working fluid. I presume the propellant would be hydrogen, as otherwise there isn't really any performance advantage over a LOX-H2 upper stage. The receiver must be large and presumably thin to keep the weight down. It must transfer heat to the propellant at a high enough rate to generate the thrust needed to reach orbital velocity, before the craft exhausts its upward momentum. If this is too slow, the craft reenters the atmosphere before reaching orbital velocity. Not an easy problem to solve so far as I can see. I have always been sceptical that beamed power to a moving target would actually work in the real world, at least at the sort of rates that would make it useful for propulsion.
A skyhook initially looks more practical, but if the intercept velocity between the vehicle and hook is too high, acceleration would be more than any practical vehicle could withstand. A very stretchy cable would be needed to bring a craft to orbital velocity at survivable accelerations and it must be hundreds of km long. So it ends up weighing thousands of tonnes. I wonder if a cable could be made that is both elastic and electrically conducting and hence able to transfer power to an electro-thermal engine? That way, the cable can be shorter, as the vehicle provides its own acceleration. Another way of making it shorter would be to produce a sub-orbital SSTO, ie one that meets the booster phase of geeting into orbit and perhaps half the orbital velocity requirement, with a skyhook providing the rest. That way, a reusable SSTO would avoid a lot of the engineering nightmares that dog a classic LOX-H2 SSTO. It could even run on LOX-Kerosene.
There do not appear to be any easy solutions in terms of orbitally assisted takeoff.

And what would happen if we lowered a skyhook from the Moon?
Granted its not in geosynchronous orbit, but does it have to be? I'm sure a space elevator lowered from the Moon would have a very low velocity relative to the Earth's atmosphere.

GW Johnson · 2016-05-29 16:29:50

Just what do you propose to build such a thing from?

GW

Tom Kalbfus · 2016-05-29 17:07:53

The Earth-Moon L1 point would be a natural place to start, you lower one end of the cable toward the Moon and the other end toward Earth, there is just one other detail, the Moon's orbit is not completely circular.
Perigee 362,600 km
Apogee 405400 km

Difference is 42,800 km

It appears we may have to vary the length of the elevator over a period of a Month, then of course the Earth spins under it. This is similar to my 24-hour space elevator over Venus, except in this case its the Elevator that is nearly stationary and the Earth is spinning, a jet airplane should nevertheless make up the difference by flying against the Earth's spin.

RobertDyck · 2016-05-29 17:54:02

Can we get serious? Last post, previous page.

kbd512 · 2016-05-29 21:58:31

GW,

The only material I can see the stretchy lightweight tether being built from is BNNT fibers. Supposedly this is being researched to determine the feasibility of using orbital tethers for lifting lightweight satellites and manned capsules. The material has the tensile strength, low mass, and heat resistance required for the application. The research revolves around making the fibers long enough to be practical for the intended application.

Antius,

From the responses I received, I gather that everyone else is focused on whether or not we can send something all the way back to Earth or from Earth's surface to orbit without using propellant. I'm not interested in trying to do that because I don't think it's feasible. All I want to know is how much power we're talking about to send 500kg from the surface of the moon to LLO or from the surface of Mars to LMO.

From the minor amount of reading I've done on the topic, I understand why this is not currently feasible using lasers. However, our HPM technology is about two orders of magnitude more efficient than our high power laser technology.

Rob,

A fundamental problem I've seen with every architecture to be used for multiple missions to the moon and Mars, including my own, that is more involved than the flags-and-footprints that you and GW have spoken out against is that we're delivering many tons of propellant just to retrieve our explorers at the end of their surface stay.

50t of propellant for two of the tiny 2 seat MDV/MAV capsules I envisioned using and more than that for more elaborate designs. After a few missions, you can see how much delivered tonnage is lost to propellant simply to get back into orbit.

It would greatly simplify logistics if no propellant or very little propellant was required to return to orbit for departure from the moon or Mars. Everyone here has talked at length about establishing a permanent human presence on the moon and Mars. If for no other reason than building a base and eventual colonization, I would think a miniature fusion reactor would be an extraordinarily useful thing to have for that purpose and if it could also return humans to orbit that'd be the ultimate icing for that cake.

Regarding using Dragon with the Mars Direct habitat...

What's the mass of the DSH / lunar module you want to land on the moon? What does the habitat weigh without the extra EDL hardware?

What's the proposed delivery vehicle (SLS or Falcon Heavy)?

If SLS:

SLS + upper stage - Doesn't exist due to lack of funding and won't exist for at least another decade due to available funding being spent on SLS and Orion. If funding for the upper stage appears out of thin air, then we still need a lander. The Mars Direct habitat was a rather hefty payload. The lander hardware doesn't exist and won't for at least another decade because Altair was cancelled. Mythical deity of choice inserted here knows we couldn't have a craft capable of landing anywhere but Earth because someone might actually want to use it.

If Falcon Heavy:

This is doable, but requires some launch coordination unless the DSH is a lot lighter than the Mars Direct habitat. I think you're looking at three launches to do this or two if NASA pays SpaceX to develop propellant cross-feed.

RobertDyck · 2016-05-29 23:52:51

kbd512: Thank you for responding. Yes, my architecture requires SLS block 2B for delivery of the surface habitat. My idea of a surface habitat is basically the same as the Mars Direct hab. SLS block 1 will be built, and is receiving funding. The only difference between SLS block 1 and 1B is the upper stage. Block 1 uses the Delta Cryogenic Second Stage with 5 metre diametre, renamed Interim Cryogenic Upper Stage. Block 1B uses the Exploration Upper Stage. Both are receiving funding. Block 1 will be used for Orion EM1, block 1B for EM2. SLS block 2B is the came core and upper stage as block 1B, the only difference is boosters. Block 2B requires advanced boosters, either solid or liquid.

The principle purpose for this discussion thread was to work out details to launch Dragon & LM. Works out they require a single SLS block 1. Not 1B, I said block 1. It's a bit of a squeeze, will have to use all composite propellant tanks for the Dragon service module, and advanced materials such as composites for the LM, and composites for the LOI/de-orbit stage. But can be done.

Those Congress critters who support SLS should like that. And certain individuals at NASA. It means actual manifest for SLS. Again, 1 SLS block 2B for the surface habitat / base, plus 1 SLS block 1 for each Lunar mission. Multiple Lunar missions possible.

I should point out, the acronym "DSH" refers to a "Deep Space Habitat", which implies in-space use, not surface. So the Moon mission I described would not have a DSH at all. Mars would.

As for propellant: this is one reason to focus on Mars. Another is that hardware designed for Mars can be used on the Moon, but not vice-versa. That's because Mars is hard, the Moon less so. I've also said we can have American astronauts on Mars in less than 8 years, and do so within NASA's current budget. So that's within the mandate of one President. There are catches:

NASA cannot do both the Moon and Mars. Actually NASA can, but doing so would require substantial increase in budget. Congress is not willing to increase their budget that much. So within available funding, only one.
Start as soon as the new President as inaugurated. Don't wait until the second term, by then it'll be to late. If the new President does try to start something in his/her second term, it will be cancelled by the next president. Everything has been so far: Space Station Freedom, Strategic Exploration Initiative, Venture Star, Constellation, and now the Asteroid Redirect Mission has so little done that it will be cancelled.
Don't let "Old Space" companies lead. They have no intention of being effective, getting things done on time, and staying within budget. They were in the 1960s, but they were "New Space" at that time. Not now.

If you want further details of my Mars plan, it's here: Yet another Mars architecture

Tom Kalbfus · 2016-05-30 05:54:30

kbd512 wrote:

GW,
The only material I can see the stretchy lightweight tether being built from is BNNT fibers. Supposedly this is being researched to determine the feasibility of using orbital tethers for lifting lightweight satellites and manned capsules. The material has the tensile strength, low mass, and heat resistance required for the application. The research revolves around making the fibers long enough to be practical for the intended application.
Antius,
From the responses I received, I gather that everyone else is focused on whether or not we can send something all the way back to Earth or from Earth's surface to orbit without using propellant. I'm not interested in trying to do that because I don't think it's feasible. All I want to know is how much power we're talking about to send 500kg from the surface of the moon to LLO or from the surface of Mars to LMO.
From the minor amount of reading I've done on the topic, I understand why this is not currently feasible using lasers. However, our HPM technology is about two orders of magnitude more efficient than our high power laser technology.
Rob,
A fundamental problem I've seen with every architecture to be used for multiple missions to the moon and Mars, including my own, that is more involved than the flags-and-footprints that you and GW have spoken out against is that we're delivering many tons of propellant just to retrieve our explorers at the end of their surface stay.
50t of propellant for two of the tiny 2 seat MDV/MAV capsules I envisioned using and more than that for more elaborate designs. After a few missions, you can see how much delivered tonnage is lost to propellant simply to get back into orbit.
It would greatly simplify logistics if no propellant or very little propellant was required to return to orbit for departure from the moon or Mars. Everyone here has talked at length about establishing a permanent human presence on the moon and Mars. If for no other reason than building a base and eventual colonization, I would think a miniature fusion reactor would be an extraordinarily useful thing to have for that purpose and if it could also return humans to orbit that'd be the ultimate icing for that cake.
Regarding using Dragon with the Mars Direct habitat...
What's the mass of the DSH / lunar module you want to land on the moon? What does the habitat weigh without the extra EDL hardware?
What's the proposed delivery vehicle (SLS or Falcon Heavy)?
If SLS:
SLS + upper stage - Doesn't exist due to lack of funding and won't exist for at least another decade due to available funding being spent on SLS and Orion. If funding for the upper stage appears out of thin air, then we still need a lander. The Mars Direct habitat was a rather hefty payload. The lander hardware doesn't exist and won't for at least another decade because Altair was cancelled. Mythical deity of choice inserted here knows we couldn't have a craft capable of landing anywhere but Earth because someone might actually want to use it.
If Falcon Heavy:
This is doable, but requires some launch coordination unless the DSH is a lot lighter than the Mars Direct habitat. I think you're looking at three launches to do this or two if NASA pays SpaceX to develop propellant cross-feed.

A Lunar Lander isn't any big deal, we know how to build one, so it won't take a decade to build a new one, it old technology, practically 50 year old technology in fact, and its not big like a Saturn V rocket. If we really wanted to build a Lunar Lander, we could do so in a year. SpaceX could build one if it wanted! If it could land a rocket stage on a floating platform in the ocean, a Moon Lander would be easy for it to accomplish!

Tom Kalbfus · 2016-05-30 05:59:20

RobertDyck wrote:

kbd512: Thank you for responding. Yes, my architecture requires SLS block 2B for delivery of the surface habitat. My idea of a surface habitat is basically the same as the Mars Direct hab. SLS block 1 will be built, and is receiving funding. The only difference between SLS block 1 and 1B is the upper stage. Block 1 uses the Delta Cryogenic Second Stage with 5 metre diametre, renamed Interim Cryogenic Upper Stage. Block 1B uses the Exploration Upper Stage. Both are receiving funding. Block 1 will be used for Orion EM1, block 1B for EM2. SLS block 2B is the came core and upper stage as block 1B, the only difference is boosters. Block 2B requires advanced boosters, either solid or liquid.
The principle purpose for this discussion thread was to work out details to launch Dragon & LM. Works out they require a single SLS block 1. Not 1B, I said block 1. It's a bit of a squeeze, will have to use all composite propellant tanks for the Dragon service module, and advanced materials such as composites for the LM, and composites for the LOI/de-orbit stage. But can be done.
Those Congress critters who support SLS should like that. And certain individuals at NASA. It means actual manifest for SLS. Again, 1 SLS block 2B for the surface habitat / base, plus 1 SLS block 1 for each Lunar mission. Multiple Lunar missions possible.
I should point out, the acronym "DSH" refers to a "Deep Space Habitat", which implies in-space use, not surface. So the Moon mission I described would not have a DSH at all. Mars would.

The Moon's surface is in deep space, there is no difference between something on the Moon's surface and in deep space except gravity!
The vacuum found at the Moon's surface is the same vacuum that exists in deep space. The only way to avoid being in deep space while on the Moon is to burrow underground!

As for propellant: this is one reason to focus on Mars. Another is that hardware designed for Mars can be used on the Moon, but not vice-versa. That's because Mars is hard, the Moon less so. I've also said we can have American astronauts on Mars in less than 8 years, and do so within NASA's current budget. So that's within the mandate of one President. There are catches:
NASA cannot do both the Moon and Mars. Actually NASA can, but doing so would require substantial increase in budget. Congress is not willing to increase their budget that much. So within available funding, only one.
Start as soon as the new President as inaugurated. Don't wait until the second term, by then it'll be to late. If the new President does try to start something in his/her second term, it will be cancelled by the next president. Everything has been so far: Space Station Freedom, Strategic Exploration Initiative, Venture Star, Constellation, and now the Asteroid Redirect Mission has so little done that it will be cancelled.
Don't let "Old Space" companies lead. They have no intention of being effective, getting things done on time, and staying within budget. They were in the 1960s, but they were "New Space" at that time. Not now.
If you want further details of my Mars plan, it's here: Yet another Mars architecture

How do you know Congress won't increase the budget? NASA isn't exactly the largest item in the Federal budget, I think Trump stressed that he has other priorities than going to Mars, but he hasn't ruled out a Moon mission, that would be cheaper, and SpaceX could go to Mars or some other private entity. The technology is nearly there. The days of going begging to Congress to fund a Mars mission are nearly over, there is another source of funds - private investors.

Last edited by Tom Kalbfus (2016-05-30 06:03:53)

RobertDyck · 2016-05-30 06:06:49

Tom Kalbfus wrote:

A Lunar Lander isn't any big deal, we know how to build one, so it won't take a decade to build a new one, it old technology, practically 50 year old technology in fact, and its not big like a Saturn V rocket. If we really wanted to build a Lunar Lander, we could do so in a year. SpaceX could build one if it wanted! If it could land a rocket stage on a floating platform in the ocean, a Moon Lander would be easy for it to accomplish!

You would think. And a CSM is just as easy. In fact, SpaceX has flown Dragon v1 many times now. But for some reason Lockheed-Martin ran out of money before building the service module. I flew once 5 December 2014, unmanned and with ATV-based service module, but still hasn't flown again. And Altair was part of the original Constellation, but hasn't even been started. Even if they were built, SLS block 2 is not large enough to launch both Orion and Altair. Saturn V is not large enough to lift them both in one launch.

Tom Kalbfus · 2016-05-30 06:29:29

RobertDyck wrote:

Tom Kalbfus wrote:
A Lunar Lander isn't any big deal, we know how to build one, so it won't take a decade to build a new one, it old technology, practically 50 year old technology in fact, and its not big like a Saturn V rocket. If we really wanted to build a Lunar Lander, we could do so in a year. SpaceX could build one if it wanted! If it could land a rocket stage on a floating platform in the ocean, a Moon Lander would be easy for it to accomplish!
You would think. And a CSM is just as easy. In fact, SpaceX has flown Dragon v1 many times now. But for some reason Lockheed-Martin ran out of money before building the service module. I flew once 5 December 2014, unmanned and with ATV-based service module, but still hasn't flown again. And Altair was part of the original Constellation, but hasn't even been started. Even if they were built, SLS block 2 is not large enough to launch both Orion and Altair. Saturn V is not large enough to lift them both in one launch.

I believe the plan was to launch Altair separately, it was just too big for both the command module and it to be launched with the same SLS rocket. So you launch Altair to Low Earth Orbit, and then you Launch the Orion, the two dock and then begin TLI. I think if you want a long duration mission to the Moon with more people, you need a bigger lander. Alternatively maybe you can launch the Altair to Lunar Orbit, and then send the Orion Module to Lunar orbit as well, and have a Lunar Orbit docking, I think that is doable.

I think that might be a good idea. Lets have a Lunar lander that equals the mass of the Orion, launch them both to the Moon separately, then you could launch the Hab with a third SLS. The Mass of the Hab equals that of the Orion which equals the mass of the Lunar Lander. The Hab would have the landing stage of the Lunar Lander but no ascent stage, that mass is instead devoted to the Hab to conduct a long duration mission on the Moon, the Lunar Lander is what brings the astronauts into Lunar Orbit, and the Orion is what brings them back to Earth. The astronauts can go to Lunar Orbit in either the Hab or the Orion spacecraft, they can land on the Moon's surface in either the Hab or the Lunar Lander, but only the Lunar Lander can bring them back to Lunar orbit, and only the Orion spacecraft can bring them back to Earth.

GW Johnson · 2016-05-30 11:18:57

Why not get the hab volume at lower mass, and use a Bigelow inflatable or two for the Mars or lunar surface hab? Bigelow developed these after buying the rights to NASA's "deep space hab".

GW

kbd512 · 2016-05-30 11:28:18

RobertDyck wrote:

kbd512: Thank you for responding. Yes, my architecture requires SLS block 2B for delivery of the surface habitat. My idea of a surface habitat is basically the same as the Mars Direct hab. SLS block 1 will be built, and is receiving funding. The only difference between SLS block 1 and 1B is the upper stage. Block 1 uses the Delta Cryogenic Second Stage with 5 metre diametre, renamed Interim Cryogenic Upper Stage. Block 1B uses the Exploration Upper Stage. Both are receiving funding. Block 1 will be used for Orion EM1, block 1B for EM2. SLS block 2B is the came core and upper stage as block 1B, the only difference is boosters. Block 2B requires advanced boosters, either solid or liquid.

SLS Block 2B won't exist for another 20 years, if ever.

NASA hasn't spent a dime on advanced boosters and if advanced boosters are ever developed, you're looking at waiting until 2030 before they're available, at the earliest.

EUS won't exist as flight hardware for another 10 years, if ever. EUS has "feel good" funding allocated to it.

RobertDyck wrote:

The principle purpose for this discussion thread was to work out details to launch Dragon & LM. Works out they require a single SLS block 1. Not 1B, I said block 1. It's a bit of a squeeze, will have to use all composite propellant tanks for the Dragon service module, and advanced materials such as composites for the LM, and composites for the LOI/de-orbit stage. But can be done.

Fine, but realize these things are never going to be delivered to the moon using a paper rocket.

RobertDyck wrote:

Those Congress critters who support SLS should like that. And certain individuals at NASA. It means actual manifest for SLS. Again, 1 SLS block 2B for the surface habitat / base, plus 1 SLS block 1 for each Lunar mission. Multiple Lunar missions possible.

It doesn't matter what Congress wants. Lockheed-Martin and Boeing will continue to milk as much money as possible from the government while producing as little as is required to keep the money flowing. The next President will probably cancel both SLS and Orion for lack of progress.

RobertDyck wrote:

I should point out, the acronym "DSH" refers to a "Deep Space Habitat", which implies in-space use, not surface. So the Moon mission I described would not have a DSH at all. Mars would.

If the astronauts aren't going to land in the habitat, then we're talking about development of two different landers (humans and cargo), for which there is no funding. I'll be shocked if NASA manages to go back to the moon, or anywhere else for that matter, before 2040. I probably won't be alive to see it.

RobertDyck wrote:

As for propellant: this is one reason to focus on Mars. Another is that hardware designed for Mars can be used on the Moon, but not vice-versa. That's because Mars is hard, the Moon less so. I've also said we can have American astronauts on Mars in less than 8 years, and do so within NASA's current budget. So that's within the mandate of one President. There are catches:
NASA cannot do both the Moon and Mars. Actually NASA can, but doing so would require substantial increase in budget. Congress is not willing to increase their budget that much. So within available funding, only one.
Start as soon as the new President as inaugurated. Don't wait until the second term, by then it'll be to late. If the new President does try to start something in his/her second term, it will be cancelled by the next president. Everything has been so far: Space Station Freedom, Strategic Exploration Initiative, Venture Star, Constellation, and now the Asteroid Redirect Mission has so little done that it will be cancelled.
Don't let "Old Space" companies lead. They have no intention of being effective, getting things done on time, and staying within budget. They were in the 1960s, but they were "New Space" at that time. Not now.
If you want further details of my Mars plan, it's here: Yet another Mars architecture

Congress isn't interested in going anywhere, they're only interested in spending our money on something that gets them votes in the next election cycle. NASA has compounded the problem by not growing a pair and telling Congress and the President that they can simply keep their political nonsense out of space exploration or they can simply not have a space program. There's no point in working for an agency that is held hostage by the political whims and fancies of each successive group of elected officials.

In the span of one President's term in office, we've gone from "We're going back to the moon!" to "We're going to Mars!" to "We're going to an asteroid!" to "We're going to play with space rocks!" to "We can't get our rocket off the ground using existing STS hardware inside of a decade!". Not exactly confidence inspiring.

Propose an architecture that uses existing affordable commodity rockets (Falcon or Atlas) because that's all we have to work with.

Tom Kalbfus · 2016-05-30 17:39:16

GW Johnson wrote:

Why not get the hab volume at lower mass, and use a Bigelow inflatable or two for the Mars or lunar surface hab? Bigelow developed these after buying the rights to NASA's "deep space hab".
GW

Are you going to inflate the hab with the astronauts in it? Are you going to inflate it before or after the rocket launches?

RobertDyck · 2016-05-30 18:55:01

kbd512: Well, that's cynical. We're all critical that SLS is taking way too long, and way too expensive. But saying it won't fly at all?

kbd512 · 2016-05-30 20:18:36

RobertDyck wrote:

kbd512: Well, that's cynical. We're all critical that SLS is taking way too long, and way too expensive. But saying it won't fly at all?

I'm saying I don't think EUS will be ready for launching humans anywhere in the next decade, assuming the next administration or Congress don't pull the funding before then. SLS will fly, but there is no man rated upper stage to deliver humans anywhere farther into space than LEO. Development of any form of in-space propulsion is not the trivial task many here would make it out to be.

We have Falcon, we will have Falcon Heavy, we have Atlas, and we will have Vulcan. Those things are going to be developed and used because there are paying commercial and military customers for them.

The military has no interest in SLS. There's no commercial or military necessity for a rocket as massive as SLS. My critique of SLS has everything to do with its lift capability. SLS's lift capability is nowhere near enough to justify its expensive over commodity heavy lift rockets. Falcon Heavy and Vulcan Heavy can deliver the same tonnage to LEO as SLS without the upper stage. Those rockets are partially reusable, too. Absent funding for hardware to use for real space exploration, SLS has no reason to exist.

Another golden opportunity to resurrect our super heavy lift capability has been squandered by know-nothings in Congress and NASA administrators who lack the backbone to tell Congress and the President to pound sand when they're making decisions about things they know nothing about.

Ares V / SLS should've been a simple rebuild of Saturn V using its LOX / RP-1 first stage and LOX / LH2 second and third stages. The military can pay to play with large solid rockets if they want to. There is no reason that passes muster for forcing NASA to pay for a program that is primarily intended to benefit the military and not NASA. There was never any other solution that would provide the required lift capability at any lesser cost. And yes, for the money squandered we could have easily rebuilt Saturn V with modern avionics and we'd have had a functional super heavy lift rocket by now.

RobertDyck · 2016-05-30 21:08:03

Well. EUS will use 4 RL-10C engines. The upper stage of Saturn 1 used 6 RL-10A-3 engines. So this is based on Saturn technology. And one proposal for advanced boosters would use a pair of F-1B engines. That sounds like what you want.

SLS block 2 is basically Ares from Mars Direct. IIRC, according to "The Case for Mars", other engineers at Martin Marietta designed it, Dr. Zubrin worked on it, but he wasn't the primary engineer. Anyway, SLS block 2 had a core stage based on Shuttle's external tank, 5 SSME, a pair of advanced solid rocket boosters, and an upper stage with a single J-2S engine. SLS block 2 at the announcement would have a core stage based on Shuttle's external tank, 5 SSME, a pair of advanced solid rocket boosters, and an upper stage with a single J-2X engine. In 1989/1990, J-2S was the latest updated version of J-2, the engine from Saturn V's third stage. At the announcement of SLS, J-2X was the latest update. The only major difference was locating main engines under the tank. That requires modifying the Mobile Launch Platform, which would have prevented Shuttle from launching. In 1990 that just wasn't an option. So SLS block 2 is Ares.

But you want Saturn V. That would have been nice, but didn't happen.

kbd512 · 2016-05-31 02:48:09

RobertDyck wrote:

Well. EUS will use 4 RL-10C engines. The upper stage of Saturn 1 used 6 RL-10A-3 engines. So this is based on Saturn technology. And one proposal for advanced boosters would use a pair of F-1B engines. That sounds like what you want.

NASA's task was to design and build a 150t to LEO rocket. Their own reports said that that's what was required for the types of space exploration missions they wanted to do. Somehow that failed spectacularly and quickly devolved into an exercise intended to please their vendors.

RobertDyck wrote:

SLS block 2 is basically Ares from Mars Direct. IIRC, according to "The Case for Mars", other engineers at Martin Marietta designed it, Dr. Zubrin worked on it, but he wasn't the primary engineer. Anyway, SLS block 2 had a core stage based on Shuttle's external tank, 5 SSME, a pair of advanced solid rocket boosters, and an upper stage with a single J-2S engine. SLS block 2 at the announcement would have a core stage based on Shuttle's external tank, 5 SSME, a pair of advanced solid rocket boosters, and an upper stage with a single J-2X engine. In 1989/1990, J-2S was the latest updated version of J-2, the engine from Saturn V's third stage. At the announcement of SLS, J-2X was the latest update. The only major difference was locating main engines under the tank. That requires modifying the Mobile Launch Platform, which would have prevented Shuttle from launching. In 1990 that just wasn't an option. So SLS block 2 is Ares.

I want the STS hardware to be delivered to the museums, which is where it belongs, since NASA has already destroyed the infrastructure to use the STS hardware. At this point, I can think of other, better uses for NASA's budget. After more than 10 years of Apollo level funding, NASA and its contractors have produced more hot air than hardware.

I'd cut NASA's budget in half, shut down their spending projects, and get rid of their bureaucracy. Anybody who drags their feet when it comes to using new technology, is not opportunistic and frugal in purchasing of contracted services, or devises ways to expand the agency is simply shown the door. Basically, I'd refocus the agency on its core mission.

Once we've eliminated all the old ridiculous and expensive ways of doing things, maybe then we can focus on doing the things that are actually required for space exploration.

RobertDyck wrote:

But you want Saturn V. That would have been nice, but didn't happen.

I only wanted a vehicle with a 150t+ lift capability using existing hardware in less time than it took to design, build, test, and fly a Saturn V. Now I just want to stop throwing good money after bad.

RobertDyck · 2016-05-31 05:46:43

When Shuttle was flying, many members of the Mars Society called for its cancellation. They believed cancelling Shuttle would free funds for Mars. Now we have no Shuttle, and no mission to Mars. I fear if you cancel succeed in convincing Congress to cancel SLS, we still won't have any money for Mars. All you're doing is destroy, gain nothing.

SLS can lift 150t; with liquid boosters that have 2 F-1B engines each, plus an upper stage with one or two J-2X engines. Studies show the Exploration Upper Stage cannot lift as much weight to LEO, but can lift as much or more to TLI or TMI. Saturn V is dead, won't be revived. Why not lobby for liquid boosters?

Tom Kalbfus · 2016-05-31 17:17:11

RobertDyck wrote:

When Shuttle was flying, many members of the Mars Society called for its cancellation. They believed cancelling Shuttle would free funds for Mars. Now we have no Shuttle, and no mission to Mars. I fear if you cancel succeed in convincing Congress to cancel SLS, we still won't have any money for Mars. All you're doing is destroy, gain nothing.
SLS can lift 150t; with liquid boosters that have 2 F-1B engines each, plus an upper stage with one or two J-2X engines. Studies show the Exploration Upper Stage cannot lift as much weight to LEO, but can lift as much or more to TLI or TMI. Saturn V is dead, won't be revived. Why not lobby for liquid boosters?

What you suggest is physically impossible, it takes more energy to accelerate a given mass to TLI than it does to lift it merely to LEO.

RobertDyck · 2016-05-31 21:06:37

SLS block 2: core stage with 5 SSME, upper stage with J-2X, advanced solid rocket motors = 130t to LEO
SLS block 2: 5 SSME, J-2X, advanced liquid boosters with 2 F-1B engines per booster = 150t to LEO
SLS block 2B: 4 SSME, EUS, advanced liquid boosters = 130.7t to LEO

SpaceNut posted this image in another thread:

Tom Kalbfus · 2016-06-01 05:56:18

What you were suggesting was that the booster could send more mass to TLI than to Low Earth Orbit, I find that hard to believe. Any Rocket that can send 150 tons to trans lunar injection can also leave that 150 tons in low earth orbit.

RobertDyck · 2016-06-01 06:57:18

Tom: Try reading the posts before responding.

kbd512 · 2016-06-01 08:44:04

RobertDyck wrote:

SLS block 2: core stage with 5 SSME, upper stage with J-2X, advanced solid rocket motors = 130t to LEO

Complete core stage redesign

RobertDyck wrote:

SLS block 2: 5 SSME, J-2X, advanced liquid boosters with 2 F-1B engines per booster = 150t to LEO

Complete core stage redesign

Redesign of EUS to use a J-2X instead of RL-10's

Not enough space on the pad for the tail service masts for the F-1B's (NASA's engineers said this, not me)

RobertDyck wrote:

SLS block 2B: 4 SSME, EUS, advanced liquid boosters = 130.7t to LEO

Not enough space on the pad for the tail service masts for the F-1B's (NASA's engineers said this, not me)

This is why I said 115t is the max lift capability of SLS. That's with advanced solid boosters and EUS. It might still be possible to hit the lift capability target (125t) with composite tanks since structural mass fraction considerably affects the lift capability of low-Isp chemical rockets.

The core stage design clearly did not take the reduced (125t) ultimate target lift into account. At the outset of the process, the rocket must be designed for the desired lift capability required by the missions to be executed. It can't be an afterthought. There's only so much additional capability to be squeezed out of existing designs, and at enormous expense.

RobertDyck · 2016-06-01 09:16:05

kbd512 wrote:

Not enough space on the pad for the tail service masts for the F-1B's (NASA's engineers said this, not me)

So don't build separate service masts. Saturn V used a Mobile Launcher (ML), which was a platform with service mast mounted on the platform. Shuttle used a Mobile Launch Platform (MLP), no service mast on the platform at all. KSC removed the static service structure and rotating service structure from the launch pads, so the pad could be flexible to handle different launch vehicles. They expect the service mast to be mounted on the Mobile Launcher. But you don't need a separate tower for each booster. Just run a propellant feed hose from one single common mast to tanks for each stage/booster.

Look at the service mast for Atlas V. It's a lot simpler. It's made of steel I-beams instead of truss because it tilts back before launch.

SpaceX uses a truss structure, but their's isn't just a service mast, it's a "hard back" that lifts the rocket from horizontal to vertical. That's done when propellant tanks are empty. The hard back isn't strong enough to lift it when tanks are full. But it shows a truss can rotate back.

Service mast for a crew launch vehicle will require an elevator to lift crew to the capsule. But you don't need a service mast as huge as the one for Saturn V. And you certainly don't need a separate service mast for each booster.

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