Heavy Lift an unnecessary impediment?

[rockett]

The problem with kerosene isn't storage. Kerosene stores well in space. LOX\Kerosene rocket engines generate coke. On earth this isn't a big problem because the engine is only going to be used once (or perhaps serviced then reused in an RLV). They are designed to work with the coking problem. However an engine that cokes itself up might be a poor choice for an in space engine that needs to be used many times without servicing.

Also a Kerosene first stage and hydrogen upper stages have a synergy. The hydrogen upper stage will mass less than a Kerosene one while lox\kerosene is better thrust than lox\loh. You can get better performance than each alone. LOH is expensive, but the cost of propellant is rather a small part of the whole system. A totally Kerosene rocket would have to mass more than a mixed one to do the same work or cut into payload margin.

Good point pathfinder_01. I really hadn't thought of the coking problem myself. Probably in the long run, we need to look at a lunar ice exporting business, to be processed in space as needed. I think the technology to do that is not far off, even for raw unprocessed lunar ice:

Inexpensive Metal Catalyst Can Effectively Generate Hydrogen from Water
http://www.sciencedaily.com/releases/2010/04/100430154902.htm

If in-space refueling is our goal, maybe we need to re-think our current lunar strategy:
“We’ve been there before. Buzz has been there.” - Dr Paul Spudis
http://blogs.airspacemag.com/moon/2010/04/16/“we’ve-been-there-before-buzz-has-been-there-”/
New data suggests massive lunar ice chunks
http://www.msnbc.msn.com/id/36652176/ns/technology_and_science-space/

Personally, if the above is true, I think it would be a major "tactical mistake" for our space exploration program to ignore it, and go chasing around the solar system "running on empty"....

 

[halman]

Why isn't kerosene stable in long-term storage? I really believe that hydrogen is not going to be a widely used fuel in the future, because we will be able to accomplish our goals with less esoteric propellants. We could all run our cars on nitromethanol, or whatever it is that they run in top fuel drag racing cars, but we can get by without going to that extreme. Hydrogen has been used because we have sought the absolute ultimate in performance, trying to squeeze as much payload into a rocket as possible. But that kind of philosophy is not conducive to long-term development.

The problem with kerosene isn't storage. Kerosene stores well in space. LOX\Kerosene rocket engines generate coke. On earth this isn't a big problem because the engine is only going to be used once (or perhaps serviced then reused in an RLV). They are designed to work with the coking problem. However an engine that cokes itself up might be a poor choice for an in space engine that needs to be used many times without servicing.

Also a Kerosene first stage and hydrogen upper stages have a synergy. The hydrogen upper stage will mass less than a Kerosene one while lox\kerosene is better thrust than lox\loh. You can get better performance than each alone. LOH is expensive, but the cost of propellant is rather a small part of the whole system. A totally Kerosene rocket would have to mass more than a mixed one to do the same work or cut into payload margin.

From everything I have read, hydrogen is just not going to work as a stored, on-orbit propellant, basically due to loss from evaporation. Some form of hydrocarbon is almost certainly going to be used, and coking is merely the carbon buildup associated with oxidizing a hydrocarbon in a high temperature reaction. Many people have advocated using liquid methane as a propellant, but I seem to recall reading that methane actually has more carbon atoms per molecule than kerosene does. Also, liquid methane suffers from evaporation problems as well.

But once a need exists, answers are found. Some way of dealing with coking will be discovered, or perfected, and we will move on.

To my knowledge, liquid hydrogen (LH) and liquid oxygen, (LO2) are the most powerful propellant mix generally used in rocket motors. There are some even more powerful combinations, but they involve substantial problems with handling the materials involved.

 

[halman]

As far as I know fuel depots for LEO or GEO orbit have not received serious study, because they don't save money until we have thousands of orbiting vehicles that need more fuel.

Yes, but, my argument against fuel depots is, unless you are using a technology to refill the depot that does not use fuel itself, it defeats the purpose. I can understand a fuel depot on the Moon, or on Phobos or something, anywhere you can locate the depot at the same place where the fuel is being generated. If you put the depot in low earth orbit, the fuel is presumably being sent from Earth, so you probably had to use a rocket to send it there, so, you might as well have sent a earth departure module with sufficient fuel to begin with.

I still haven't heard a good counter-argument to that.

--Brian

To my way of thinking, no launch vehicle should ever ascend any higher than Low Earth Orbit. Once there, the payload should be transferred to a specialized vehicle which will take it to its final destination. I have proposed an Orbital Transfer Vehicle for such use, to haul satellites and space station components to their intended destinations, and the OTV will have to refuel from time to time. Any mission to somewhere beyond Earth orbit should use a vehicle which is either launched empty, or assembled in LEO. Again, such a vehicle will need a source of fuel.

Launching a vehicle with enough propellant to reach its destination means either very small payloads, or enormous rockets. Sending up 30 or 40 tons of propellant on a regular basis would be a worthwhile investment, and a guaranteed market for Evolved Expendable Launch Vehicles.

 

[pathfinder_01]

Why isn't kerosene stable in long-term storage? I really believe that hydrogen is not going to be a widely used fuel in the future, because we will be able to accomplish our goals with less esoteric propellants. We could all run our cars on nitromethanol, or whatever it is that they run in top fuel drag racing cars, but we can get by without going to that extreme. Hydrogen has been used because we have sought the absolute ultimate in performance, trying to squeeze as much payload into a rocket as possible. But that kind of philosophy is not conducive to long-term development.

The problem with kerosene isn't storage. Kerosene stores well in space. LOX\Kerosene rocket engines generate coke. On earth this isn't a big problem because the engine is only going to be used once (or perhaps serviced then reused in an RLV). They are designed to work with the coking problem. However an engine that cokes itself up might be a poor choice for an in space engine that needs to be used many times without servicing.

Also a Kerosene first stage and hydrogen upper stages have a synergy. The hydrogen upper stage will mass less than a Kerosene one while lox\kerosene is better thrust than lox\loh. You can get better performance than each alone. LOH is expensive, but the cost of propellant is rather a small part of the whole system. A totally Kerosene rocket would have to mass more than a mixed one to do the same work or cut into payload margin.

From everything I have read, hydrogen is just not going to work as a stored, on-orbit propellant, basically due to loss from evaporation. Some form of hydrocarbon is almost certainly going to be used, and coking is merely the carbon buildup associated with oxidizing a hydrocarbon in a high temperature reaction. Many people have advocated using liquid methane as a propellant, but I seem to recall reading that methane actually has more carbon atoms per molecule than kerosene does. Also, liquid methane suffers from evaporation problems as well.

But once a need exists, answers are found. Some way of dealing with coking will be discovered, or perfected, and we will move on.

To my knowledge, liquid hydrogen (LH) and liquid oxygen, (LO2) are the most powerful propellant mix generally used in rocket motors. There are some even more powerful combinations, but they involve substantial problems with handling the materials involved.

LOH is the problem one. LOX and Methane are about equally hard to store but very much in the realm of possibility. Ah methane only has one carbon atom per molecule. The coke is probably due to side reactions within the kerosene molecules between carbon atoms.Methane is probably a lot "cleaner" burning. However there are lots of fuels that could be stored. The standard hypergolics might make sense, ammonia might make sense. I also agree with you about having tugs move statlights into higher orbits. The only problem is if you are using sep, the van Allen belts will slowly damage the solar panels and electronics(this might be solvable).

 

[neutrino78x]

Without a propellant depot, the Earth escape stage has to be launched fully fueled all at once. This requires, for a crewed mission, a Very Big Rocket - Saturn V or bigger.

True, but what I am saying is, if you're not going to make a Heavy Lift rocket, why would you not launch the Earth Departure Stage, fully fueled, as a separate launch, separate from the humans? The humans would go up after the thing has been assembled in space.

In other words, if you're going to Mars, you could either:

• Send up a rocket to fill the fuel depot, then send an Earth Departure Stage, and fuel it in LEO, or
• Send up an Earth Departure Stage fully fueled.

I think the second option makes more sense.

--Brian

 

[edkyle99]

Without a propellant depot, the Earth escape stage has to be launched fully fueled all at once. This requires, for a crewed mission, a Very Big Rocket - Saturn V or bigger.

True, but what I am saying is, if you're not going to make a Heavy Lift rocket, why would you not launch the Earth Departure Stage, fully fueled, as a separate launch, separate from the humans? The humans would go up after the thing has been assembled in space.

In other words, if you're going to Mars, you could either:

• Send up a rocket to fill the fuel depot, then send an Earth Departure Stage, and fuel it in LEO, or
• Send up an Earth Departure Stage fully fueled.

I think the second option makes more sense.

--Brian

A fully fueled departure stage for a lunar mission would account for roughly 70+% of the total LEO mass at the start of a TLI burn. It would account for an even greater percentage for a Mars mission. A Very Big Rocket, able to lift, say, 100 tonnes rather than 140 tonnes, would still be required. As I see it, NASA won't get money for even a slightly less Big rocket, and even if it does some form of propellant transfer would be needed to split the total payload mass between two rockets.

Propellant transfer is essential for future deep space exploration. NASA might as well start perfecting the technology.

- Ed Kyle

 

[neutrino78x]

A fully fueled departure stage for a lunar mission would account for roughly 70+% of the total LEO mass at the start of a TLI burn. It would account for an even greater percentage for a Mars mission.

Also, keep in mind that I assume ISRU would be used; the craft would go to Mars with only enough fuel to get there; the fuel to return would have been generated on Mars.

--Brian

 

[pathfinder_01]

Without a propellant depot, the Earth escape stage has to be launched fully fueled all at once. This requires, for a crewed mission, a Very Big Rocket - Saturn V or bigger.

True, but what I am saying is, if you're not going to make a Heavy Lift rocket, why would you not launch the Earth Departure Stage, fully fueled, as a separate launch, separate from the humans? The humans would go up after the thing has been assembled in space.

In other words, if you're going to Mars, you could either:

• Send up a rocket to fill the fuel depot, then send an Earth Departure Stage, and fuel it in LEO, or
• Send up an Earth Departure Stage fully fueled.

I think the second option makes more sense.

--Brian

Depends on the type of propellant, craft, and mission. Cryogenic propellants boil off, a depot can afford heavy insulation, an earth departure stage might not without affecting performance.

Sending it up empty could gain you more mass for the mission at a lower cost(i.e. you could short load the earth departure stage use a smaller cheaper rocket and pick up the rest in orbit). You could reuse your earth departure stage(i.e. Use to get to leo fill up use to get to EML1 fill up use to get to moon, mars). Your fully fueled earth departure stage could exceed the lifting capacity of current rockets.

 

[pathfinder_01]

A fully fueled departure stage for a lunar mission would account for roughly 70+% of the total LEO mass at the start of a TLI burn. It would account for an even greater percentage for a Mars mission.

Also, keep in mind that I assume ISRU would be used; the craft would go to Mars with only enough fuel to get there; the fuel to return would have been generated on Mars.

--Brian

The 70% he mentioned would not change by doing ISRU. The total amount of propellant would change but 70% of your mass would have to be proplent in order to do a TLI in LEO using chemical rockets. However it could be broken down in stages by using propellant transfer en route to the moon or mars.

 

[rockett]

A fully fueled departure stage for a lunar mission would account for roughly 70+% of the total LEO mass at the start of a TLI burn. It would account for an even greater percentage for a Mars mission.

Also, keep in mind that I assume ISRU would be used; the craft would go to Mars with only enough fuel to get there; the fuel to return would have been generated on Mars.

--Brian

What happens if your LH2 boils off before you get there?

 

[rockett]

Without a propellant depot, the Earth escape stage has to be launched fully fueled all at once. This requires, for a crewed mission, a Very Big Rocket - Saturn V or bigger.

True, but what I am saying is, if you're not going to make a Heavy Lift rocket, why would you not launch the Earth Departure Stage, fully fueled, as a separate launch, separate from the humans? The humans would go up after the thing has been assembled in space.

In other words, if you're going to Mars, you could either:

• Send up a rocket to fill the fuel depot, then send an Earth Departure Stage, and fuel it in LEO, or
• Send up an Earth Departure Stage fully fueled.

I think the second option makes more sense.

--Brian

Sending up an iceberg shrink-wrapped in mylar from the moon would be cheaper in the long run.

 

[EarthlingX]

http://www.spaceref.com : NASA Heavy Lift Launch System and Propulsion Technology Request for Information

Date Released: Tuesday, May 4, 2010
Source: Marshall Space Flight Center

On May 3, 2010, NASA will issue a Request for Information (RFI) seeking general information regarding potential launch or space transportation architectures (expendable, reusable, or a hybrid system) that could be utilized by multiple customers (e.g. NASA, commercial and other Government agencies). The RFI also will solicit information regarding propulsion system characteristics; technology challenges related to liquid chemical propulsion systems; as well as innovative methods to manage a heavy-lift development program to include effective and affordable business practices. The RFI will be open to the broad space community, including commercial, other Government agencies and academia. Information obtained from the RFI will be used for planning and acquisition-strategy development for current heavylift planning activities, as outlined in the Conference Report to FY 2010 Consolidated Appropriations Act (P.L. 111-117).

In the near future, NASA also is preparing to issue a Broad Agency Announcement (BAA), soliciting industry assistance in helping NASA to examine the trade space of potential heavy-lift launch and space transfer vehicle concepts. The BAA will focus on achieving affordability, operability, reliability, and commonality with multiple users (other Government, commercial, science, international partners, etc.) at the system and subsystem levels. A major thrust of this activity -- which will utilize some funds identified specifically for heavy-lift activities in the aforementioned Conference Report -- will be the development of space launch propulsion technologies.

Both procurement activities are intended to find more affordable options for a heavy-lift vehicle that could be achieved earlier than 2015 - the earliest date that the currently envisioned heavy-lift system could begin work, based on funding provided in the FY 2010 budget.

 

[MeteorWayne]

I dunno, seems to me, there will be a need to get heavy stuff into space. Without a heavy lift launcher, how do you do it??

 

[halman]

Do we send produce cross country in pickup trucks? Do we use 60,000 ton tankers to haul crude oil from the Arabian Gulf to Japan? When there is mass to move, we build big mass transports.

If we are to base our capabilities upon current demand, we will limit the future possibilities to what can be done right now. To allow for expansion of research, development, and manufacturing in space, we must make it possible to send large payloads to Low Earth Orbit. The ability will create the demand, just as the ability to build crude oil bottoms a quarter of mile long created a demand for them.

The cheapest way to send stuff to space is to send a lot of it at one time. One launch, multiple cargoes, if necessary, but big payloads. Whole space stations, Orbital Transfer Vehicles, Lunar shuttles, components for a deep space exploration vehicle, (folks, that sucker is going to be BIG, just so that the crew can get away from each other,) complete, ready to run reactors, excavators, scrapers, bulldozers, dump trucks, you name it, we will be send some up stairs someday.

A corporation interested in building a space station looks at what has gone into building the International Space Station and figures there is no way they can afford a presence in space. But when Bigelow starts building compressed space stations, which can launch on a platform capable of carrying the whole thing, with the innards on the same booster, then they will be more interested. Getting an insurance company to cover a project spanning multiple launches and on-orbit assembly is much less likely than finding coverage for a single launch which puts the whole shooting match in orbit.

Deep space exploration is going to require vehicles far larger than what we can send up in a single launch, so fueling them on-orbit is going to be a requirement. And whatever fuel is used is going to have to be stable for long periods in the space environment, or else the spacecraft is just going to float right on past whatever its destination was, with no fuel in the tanks. Several months might elapse between engine firings, during which time keeping fuel compressed is going to be prohibitive. An Orbital Transfer Vehicle is going to tank up for a number of operations, rather than for just one at a time, so, again, we need a stable fuel. Might as well send up a bunch at one time, right?

 

[Booban]

As far as I know we are not building a moon base anymore and Mars is not on the table. So why are there still plans for a heavy lift vehicle?

Can we use such a rocket and fill it up with numerous TV and weather satellites to launch them cheaply?

 

[edkyle99]

As far as I know we are not building a moon base anymore and Mars is not on the table. So why are there still plans for a heavy lift vehicle?

Can we use such a rocket and fill it up with numerous TV and weather satellites to launch them cheaply?

The President's post-Constellation plans, the long-term plans, talk about sending astronauts beyond Earth orbit toward asteroids and Mar's moons, etc. Those missions would use a super heavy lifter.

Commercial comsats typically weigh 5-6 tonnes at most. It seems unlikely that a super heavy rocket could handle such business practically, since it would need to carry a half-dozen such satellites at a time to be "full". In addition, NASA is not allowed to perform commercial satellite launches.

- Ed Kyle

 

[Booban]

Thanks Ed Kyle.

Now, I thought this asteroid spaceship was going to be some kind of Orion capsule style space ship. You need a heavy lifter for that dinky capsule? http://www.enjoyspace.com/en/news/obama-targets-asteroids-and-mars.

Now, if its not that, what is this asteroid space ship? I havn't heard much on plans for this. So if it is not specified....how can there be a go ahead for a heavy lift rocket when we don't know what we are trying to lift yet. There going to make the rocket too big or too small and change design specs and everythings going to be very expensive as usual....SNAFU again!

About commercial launchings...whats wrong with launching 6 satellites at once? Arianne regularly launches 2 or even 3 at once. Surely if we launch 6 it would be much cheaper. It would be a waste to build such a rocket and not let it be used to it's full potential. What a bad idea for not letting NASA do commercial launchers, but never mind, they can sell it to another company that can.

 

[edkyle99]

Thanks Ed Kyle.

Now, I thought this asteroid spaceship was going to be some kind of Orion capsule style space ship. You need a heavy lifter for that dinky capsule? http://www.enjoyspace.com/en/news/obama-targets-asteroids-and-mars.

Now, if its not that, what is this asteroid space ship? I havn't heard much on plans for this. So if it is not specified....how can there be a go ahead for a heavy lift rocket when we don't know what we are trying to lift yet. There going to make the rocket too big or too small and change design specs and everythings going to be very expensive as usual....SNAFU again!

About commercial launchings...whats wrong with launching 6 satellites at once? Arianne regularly launches 2 or even 3 at once. Surely if we launch 6 it would be much cheaper. It would be a waste to build such a rocket and not let it be used to it's full potential. What a bad idea for not letting NASA do commercial launchers, but never mind, they can sell it to another company that can.

NASA is not a "company". It is a U.S. government agency. It once was responsible for launching commercial and government communication (and other) satellites, but that ended after the loss of Challenger. Shuttle flights could handle two or even three satellites at a time, but if a problem cropped up in one satellite or one apogee motor or one piece of payload test equipment, the whole mission could be delayed or even canceled, at great cost.

That deep-space capsule won't be "dinky". It will have to have enough delta-v to maneuver and to return to Earth. It will have to carry some type of mission module. In the end, I suspect, most deep space missions would need the 45-ish tonnes to escape velocity capability, at least, of the recently proposed shuttle-derived super-heavy-lifter.

- Ed Kyle

 

[halman]

Just because there are no immediate plans to return to the Moon, does not mean that we are not going. It merely means that we might decide not to do it in a way that is unsustainable. Again. The Constellation program ignored the fundamental difficulty in ANY space related goal, and that is getting people into space and back. Constellation would continue our primitive, wasteful methods, even taking us a big step backwards by discarding any reusability in the launch vehicle. There has been such intense focus on GOING somewhere that we have not paid any attention on how we GET there.

Somehow, I don't believe that any of the people at NASA were seriously considering sending people to Mars in an Orion capsule. The capsule was supposed to be the taxi, which would ferry the folks from Earth to their space craft, which would magically appear in Earth or Lunar orbit. Unless we have a heavy lift launcher capable of putting up large, heavy cargoes, so that we can send up the ship that the people would travel those millions of miles in.

Hopefully, we are going to stop and think a bit before we declare any major new goals for our space program. The most difficult and expensive part of a journey to anywhere is the first 180 miles, the first 5 miles per second. We have got to master that aspect of space travel, bring the costs way down, make it as reliable as airline travel, and as safe. If we do, than we are going to need heavy lift launchers in large numbers, because private industry will want to get established off-planet in a hurry.

As long as the only way that we have of getting people into space is a handful at a time, at a cost of millions of dollars each, there will be no need for heavy lift launchers.

 

[Booban]

Halman, not Mars, but it was meant to go to an asteroid. I think there is a movie somewhere about it, and calling it the Crew Exploration Vehicle.

And Constellation is old tech, but that was the whole point, old and reliable, which is better than nothing at all, which we are about to end up with.

But since Constellation is now canceled, as you point out, perhaps we should stop and think, that includes stopping any heavy lift rocket based on old tech.

But we can't have that, too many well educated skilled folks would in the meantime have trouble finding a new job (no sympathy from the other parts of population living paycheck to paycheck at their non-government subsidized jobs).

 

[halman]

One of the problems with the Constellation program was that the Crew Exploration Vehicle was far too small to allow an extended missions, even with its Service Module. We are not going to get any useful results sending people long distances in a vehicle where they have no room to move around. Try spending a couple of weeks sitting in the front seat of a car, and then you car appreciate what I am talking about.

The Orion capsule was supposed to be the crew taxi to orbit, or to the International Space Station. A larger vehicle was to be waiting in orbit for the crew, to take them to the Moon, or some other deep space destination. The capsule would be left in orbit for the return to Earth. Without a Heavy Lift Launch Vehicle, Orion is limited to Low Earth Orbit.

 

[ZiraldoAerospace]

I am wondering why NASA doesn't just build up some old Saturn V's with current materials and tech, they could easily lift more than the originals and there were studies showing that the F-1 engines could easily withstand multiple flights, so the new ones could easily be made at least partially reusable (maybe only save the 1st stage because that is the most cost effective and easiest to pick up). We did it once, we can do it again!

 

[scottb50]

What if you could add an outer shell to a Delta IV. A very thin skin with composite ribs, Turbojet engines carry airframe weight during launch and initial climb, after the upper stage is started the wing would head down restarting engines in the mid 20's or higher. From there it's just a big plane landing, fully intact.

The upper stage could be anything from a Centaur class vehicle to a bigger Centaur with payloads from cargo to people. Use of upper stage during takeoff and orbital insertion might be considered also.

Attachment to the Delta would use existing fixtures on the rockets, used during construction, so no change has to be made. Jet engines and their fuel as well as landing gear and outer wings are carried in a sub-frame attached to the Delta IV. Autopilot or virtual flying make the most sense, for people I would probably want a crew.

Come back, go back to the Launch Pad, add a new Upper Stage, re-fuel and go. The Upper Stages get disassembled in orbit and become the building block of everything else. Fuel tanks, cargo or people use the same Modules, except for the return vehicle which would accommodate a number of people itself.

Modules could reduce the weight of the Delta IV and would be a good second step, easier to manufacture if you only make three main parts.

 

[halman]

What if you could add an outer shell to a Delta IV. A very thin skin with composite ribs, Turbojet engines carry airframe weight during launch and initial climb, after the upper stage is started the wing would head down restarting engines in the mid 20's or higher. From there it's just a big plane landing, fully intact.

The upper stage could be anything from a Centaur class vehicle to a bigger Centaur with payloads from cargo to people. Use of upper stage during takeoff and orbital insertion might be considered also.

Attachment to the Delta would use existing fixtures on the rockets, used during construction, so no change has to be made. Jet engines and their fuel as well as landing gear and outer wings are carried in a sub-frame attached to the Delta IV. Autopilot or virtual flying make the most sense, for people I would probably want a crew.

Come back, go back to the Launch Pad, add a new Upper Stage, re-fuel and go. The Upper Stages get disassembled in orbit and become the building block of everything else. Fuel tanks, cargo or people use the same Modules, except for the return vehicle which would accommodate a number of people itself.

Modules could reduce the weight of the Delta IV and would be a good second step, easier to manufacture if you only make three main parts.

Are you saying to launch the Delta IV from a wing? How much does a fully loaded and fueled Delta IV weigh? I thought that I was being ambitious advocating launching a light orbiter from a wing.

 

[scottb50]

Are you saying to launch the Delta IV from a wing? How much does a fully loaded and fueled Delta IV weigh? I thought that I was being ambitious advocating launching a light orbiter from a wing.

No, I'm saying Encase the Delta IV in an aerodynamic shell so it can be returned for re-use. Install turbo-jet engines that off-set the shells weight during initial launch and provide power for approach maneuvering and landing. With composites the shell could be kept relatively light so only two or three engines would be needed to offset the structures weight and the drag the wiing would produce. I doesn't have to be overly complex, a central structure that would carry engine, wing and landing gear loads with the Delta Common Cores mounted on top. Depending on drag the upper part of the Delta could probably remain uncovered. Once the Upper stage is released the wing would descend and start engines for approach and landing.