Let's hear your cheap launch strategies

[BenBurch]

Have we absolutely given up on the existence of gravitons?

Well, if Mass indeed does derive from the Higgs Mechanism, then you need a particle to mediate that transaction and that would be the Graviton.

But even if we can prove it is there, how can we *do* anything with that fact?

And you know, if you have a graviton, why do you need to have mass curve space-time? I've never been quite clear on that.

 

[BenBurch]

R.Mackey,

Did you ever run into Maxwell Hunter?

I've always liked his arguments in favor of developing an H2/F2-fueled launch capability.

I have had his little book "Thrust Into Space" since I was a sprout and it has guided my thinking on propulsion systems.

There are two roads to cheapness it seems to me; Big Dumb Boosters, like Sea Dragon, All-solid clusters, or OTRAG's system, OR making the smallest possible booster by using the highest possible energy chemical fuels. In the former case you build a crude but effective cheap rocket, in the latter you build a VERY complex, extremely carefully designed rocket that has to be PERFECT, but which is so much smaller than its conventional rivals that it is actually cheaper.

 

[Loss Leader]

Well, if Mass indeed does derive from the Higgs Mechanism, then you need a particle to mediate that transaction and that would be the Graviton.

But even if we can prove it is there, how can we *do* anything with that fact?

And you know, if you have a graviton, why do you need to have mass curve space-time? I've never been quite clear on that.

I don't know what the hell you're talking about. On Star Trek, they had gravitons.

 

[mhaze]

Even inhibited Nitric Acid in a pre-passivated tank scares me to death.

But less so than 100% H2O2. (BTW I made my own in a freezer. I figure I had 98% concentration... Yes, I was immortal owing to youth.)

You must be referring to a production process not a concentrating process.

 

[BenBurch]

You must be referring to a production process not a concentrating process.

No, you can make it in a domestic freezer at 20-30 below.

You start with 35% H2O2, freeze it, pour off the unfrozen liquor. Repeat with the product. You can get to a very dangerous 70% concentration with just this. I then further sparged the H2O2 using CO2 with terrible yield to get to get what I believed was 98%, but that is what I computed at the time and I was a kid...

Let me tell you a little about this stuff. I had some in a beaker and a loose hair fell in and it flashed into flame and the beaker cracked. And that beaker had just been decanted into a storage flask and only had about a ml in it.

This is when I stopped playing with H2O2.

 

[mhaze]

No, you can make it in a domestic freezer at 20-30 below.

You start with 35% H2O2, freeze it, pour off the unfrozen liquor. Repeat with the product. You can get to a very dangerous 70% concentration with just this. I then further sparged the H2O2 using CO2 with terrible yield to get to get what I believed was 98%, but that is what I computed at the time and I was a kid...

Let me tell you a little about this stuff. I had some in a beaker and a loose hair fell in and it flashed into flame and the beaker cracked. And that beaker had just been decanted into a storage flask and only had about a ml in it.

This is when I stopped playing with H2O2.

Sparging, I see now.

These are not to be done by amateurs.

The issue here was the stabilizers in the 35%.

 

[BenBurch]

These are not to be done by amateurs.

Amen.

Some day I'll tell you about the fulminating silver explosion I caused when I tried to silver a telescope mirror by the traditional method... Actually, thats all there is to tell. It went pop! and my arms were stained with black spots for weeks.

Yeah, I was stupid.

 

[R.Mackey]

R.Mackey,

Did you ever run into Maxwell Hunter?

I've always liked his arguments in favor of developing an H2/F2-fueled launch capability.

No, I'm not familiar with him. I'm not really a propulsion guy, although I am involved in some seeded-fault testing of solid and hybrid rockets this year...

I do, however, have some experience with H₂ - F₂ reactions. One of my professors at GALCIT runs a fascinating facility designed to study fluid mixing at high Reynolds numbers. Fluoride reactions are about the only chemistry that works fast enough to provide visual evidence of the effect. As a result, he kept a stock of HF gas on hand... Still not exactly what I'd call a "safe" propellant.

 

[Jimbo07]

At the risk of sounding like a broken record, I'll have to go with the space elevator.

 

[TjW]

Mine's a little complex:
It involves a 747 or larger sized tug with a payout winch, a 10-20 km carbon-fiber cable, a high aspect ratio "launch platform", and the rocket to be launched.

The payload is placed on the launch platform, which is pulled aloft by the tug in a conventional aerotow. At the tug's service ceiling, the cable is paid out, allowing the launch platform to kite higher. If the launch platform needs additional true airspeed to climb (the indicated airspeed would be fairly low at high altitudes), the tug can turn, and the launch platform can play "crack the whip" by flying to the outside.
At maximum altitude (say, eighty to a hundred thousand feet), launch the rocket.
The cable is reeled in, and tug and platform land separately, the launch platform as a glider.

"Service ceiling" in this case would mean the altitude at which the tug's engines can still produce enough excess thrust to keep the launch platform climbing. With the cable extended, the tug could even start a shallow dive to trade off altitude for additional cable tension.

The advantage is that the engines are down where there's enough oxidizer to do some good without any terribly exotic design, while the launch platform is high enough to be out of a good portion of the atmosphere. The launch platform has some additional speed, though not much in terms of orbital velocity, and the whole assemblage can fly toward the equator during the climb to gain what advantage it can there.

 

[Myriad]

That seems unlikely. According to this calculation, the kinetic energy in Earth's rotation is ~2.5x10^29 joules:
http://en.wikipedia.org/wiki/Rotational_energy

And according to this page, annual world energy use is ~5x10^17 btus, or ~5x10^20 joules:
http://www.eia.doe.gov/oiaf/ieo/highlights.html

That is 500,000,000 years worth of energy at current rates. Even assuming massive growth in energy use, a couple of centuries would have an absolutely minuscule effect on Earth's rotation (especially since the velocity term in rotational energy is squared).

I suspect that the problem with your scheme is not in the amount of energy to be tapped .

- Dr. Trintignant

I agree that it's not the only problem. But your assessment of the effect as miniscule is optimistic. With such an abundant and clean energy source, usage would increase dramatically. Let's say a hundredfold in the first century, and another hundredfold in the next century, with no further increases after that. Now it's 50,000 years worth of energy, and you're slowing the earth's rotation by about 1 part in 1000 per century, or nearly a second per year.

By then the nuisance of perpetual timekeeping errors would have been long since adjusted to (becoming significant to scientists by the end of the first century of use) but concerns about other side effects such as complete permanent breakdown of earth's magnetic field or other geoplanetary phenomena would make this far from indefinitely "sustainable." Much of the energy harvested would then have to be budgeted (or usage greatly increased again) to power the construction of the next energy supply, such as a solar power ring. (Which is also the logical first stage in ringworld building, so it fits right in.)

Respectfully,
Myriad

 

[Jimcalagon]

Is anyone familiar with the ATO - Airship To Orbit - idea being developed by JP Airospace - www jpaerospace.com ? Here is their description of the programme...

Balloons have carried people and machines to the edge of space for over seventy years. JP Aerospace is developing
the technology to fly a balloonor more accurately, their relative, the airshipdirectly to orbit.

Flying an airship directly from the ground to orbit is not practical. An airship large enough to reach orbit would not survive the winds near the surface of the Earth. Conversely, an airship that could fly from the ground to upper
atmosphere would not be light enough to reach space. The resulting configuration is a three-part architecture for using
lighter-than-air vehicles to reach space.

The first part is an atmospheric airship. It will travel from the surface of the Earth to 140,000 feet.

The vehicle is operated by a crew of three and can be configured for cargo or passengers. This airship is a hybrid vehicle using a combination of buoyancy and aerodynamic lift to fly. It is driven by propellers designed to operate in
near vacuum.

The second part of the architecture is a suborbital space station. This is a permanent, crewed facility parked at 140,000 feet. These facilities, called Dark Sky Stations (DSS), act as the way stations to space. The DSS is the
destination of the atmospheric airship and the departure port for the orbital airship. Initially, the DSS will be the construction facility for the large orbital vehicle.

The third part of the architecture is an airship/dynamic vehicle that flies directly to orbit. In order to utilize the few molecules of gas at extreme altitudes, this craft is big. The initial test vehicle is 6,000 feet (over a mile) long. The airship uses buoyancy to climb to 200,000 feet. From there it uses electric propulsion to slowly accelerate. As it accelerate it dynamically climbs. Over several days it reaches orbital velocity.

Low cost bulk access to space

Scaleable Technology.
True reusability, multiple orbital flights before servicing.
Large structures can be placed already assembled in orbit.
Brings safety and reliability to reaching space.
Both the climb to orbit and reentry are slow controlled processes. No high reentry heating, no big fuel tanks to explode.

Opens up the solar system.

Once in orbit, the airship is a spacecraft. With its solar/electric propulsion, it can now proceed to any destination in the solar system.

It is happening now.
This is not fanciful speculation. The project is now over two decades in development with over eighty real hardware test flights and countless development tests. It is being built completely with existing technology.

It’s being built now.
The high altitude airship has been built and is awaiting test flights. Several Dark Sky Station platforms have been built and flown. Every piece of equipment for this system has been carried to 100,000 feet and tested in the environment.
The first crewed DSS is scheduled to fly in eighteen months. The ion engine 120,000 foot flight test for the orbital airship will be flown in the next five months.

It’s being paid for now.
This new way to space has not and will not require a massive pile of capital to accomplish. Each component has its own business application and funding source. It is a pay-as-you-go system. For example, funding the atmospheric
airship was provided by the Department of Defense for use as a reconnaissance vehicle. The DSS has multiple customers in the telecommunications community.

When?
We are seven years from completion.

It sounds feasible to me but then I'm not an expert.

There is a pdf detailing the program - www jpaerospace.com/atohandout.pdf

Any thoughts?

 

[R.Mackey]

140,000 feet is not "low orbit." It's well below the Karman line. While it may have the altitude to be considered "in space," it doesn't have the velocity to maintain orbit, and therefore is not "in orbit."

That's why actual satellites are higher. To stay "in orbit," they need to be going much faster. Going much faster at that altitude means tons of drag and a rapid descent back to Earth. So we boost them higher, about 400 km is the minimum.

Whether or not this concept is useful depends on what you want to do. A lot of commercial applications don't really need to be in orbit. Extreme-altitude UAVs make arguably better surveillance platforms than satellites, for instance. But this concept cannot be confused with spaceflight.

The only benefit to spaceflight would be if this "platform" could be used to launch an actual rocket. I'm skeptical of this point. Floating that much infrastructure does not sound economically feasible.

ETA: Using that plus solar-electric propulsion to float small payloads up to actual orbit is barely possible... the problem then is that to get more propulsion, you need larger solar panels. Larger panels means more drag. More drag means you need more propulsion. In other words, might be economical for a narrow range of small satellites, but will not scale to big birds.

Oh, and the type of solar-electric propulsion they're talking about doesn't work outside Earth's magnetic field.

 

[bjornart]

And supposing that someone from Earth wants to get to the launch facilities so conveniently placed on their nearest natural satellite?

Unless it's worth it to send up them up the expensive way, they'll be sod out of luck. We're at the bottom of a serious gravity well, and getting out of it is never going to be something we do cheaply.

 

[BenBurch]

What we really need is a very, very lightweight and strong superconducting electrical cable. Then your orbital vehicle is a hypertrophied resistojet with a cable reel it is playing out behind itself, and it can actually have an amazing Isp.

None of this solar butterflies nonsense!

 

[RecoveringYuppy]

140,000 feet is not "low orbit." It's well below the Karman line. While it may have the altitude to be considered "in space," it doesn't have the velocity to maintain orbit, and therefore is not "in orbit."

They referred to 140,000 feet as suborbital not low orbit. They propose launching a second craft from that station.

Oh, and the type of solar-electric propulsion they're talking about doesn't work outside Earth's magnetic field.

Where did you see enough of a description to make that judgement?

 

[R.Mackey]

They referred to 140,000 feet as suborbital not low orbit. They propose launching a second craft from that station.

My point is that the 140,000 foot platform is not really "suborbital," either. It lacks cross-range velocity. Standing on top of a 140,000-foot tower would not make one suborbital, and that's basically what this is.

Where did you see enough of a description to make that judgement?

I did not. I extrapolated from what else I know of solar-electric propulsion. And so, I may be wrong. Your objection is completely fair. Let me explain.

Ordinary solar-electric propulsion takes the form of an ion engine -- we just built one for the Dawn mission. Hughes and Lockheed have used them for years to boost commercial satellites in the form of xenon ion thrusters and arcjets; in the latter, monomethylhydrazine is burned and accelerated electrostatically, a mixed-mode thruster. More recently, Hall Effect thrusters are all the rage. You can burn these thrusters for weeks, building up a lot of momentum, a tiny tiny tiny bit at a time.

Now, all of these systems have high specific impulses, but very low thrust. To lift from a balloon, you're going to need a substantial amount of thrust. The minimum thrust is either equal to the spacecraft's weight (after buoyancy becomes negligible), or equal to the atmospheric drag created by the spacecraft and it's buoyancy assist -- which will be huge. Otherwise, your spacecraft has no hope of gaining altitude or gaining orbital momentum. I just don't see this happening with current ion engines, with the possible exception of the horrendously expensive VASIMIR.

So, I assume these folks -- if they're serious -- have come up with a system that essentially enhances buoyancy. They need a system with little or no reaction mass, and one that allows the spacecraft to float even higher than the balloon limit, but one that also can provide orbital momentum once the drag decreases further.

My solution is a magnetic sail, also known as tether propulsion. It can be run forever using solar power, provided your tether or wiring doesn't get hit or arc out, and provides comparable thrust to most ion systems currently in use. This approach actually does work in the solar wind as well, though it works far better in Earth's magnetic field. There have been some experiments but nothing really practical with this technology.

The text above actually does suggest ion thrusters instead, but as I stated before, I don't see this working. The consumable load would still be considerable, even if they have a very high powered ion engine in mind. On the plus side, perhaps they can recycle their helium as propellant...

I'd be interested to find out more. It seems awfully far-fetched to me, but I've been wrong before.

As always, all opinions mine alone, I do not speak for NASA, this post written on my own time with my own materials, void where prohibited, discontinue if headache persists.

 

[Gravy]

Ordinary solar-electric propulsion takes the form of an ion engine...[snip]

In fact, JP Aerospace does intend to use ion engines to get to orbit, as quoted above. (Edit: I see that you noted this)

The ion engine 120,000 foot flight test for the orbital airship will be flown in the next five months.

Allow me to coin the term "failballoon."

After poking around their site and Googling for a while, I see no data or opinions from other aerospace experts like yourself that indicate that this idea is feasible from engineering or economic standpoints. Their list of sponsors does not inspire confidence that they'll meet their 7-year projection.

Still, I enjoy learning about ambitious private projects like this, and I hope their successes and failures are educational.

 

[R.Mackey]

Still, I enjoy learning about ambitious private projects like this, and I hope their successes and failures are educational.

Absolutely. I'm glad someone is trying this, although I hope they've crunched a few numbers.

If it so happens that they have come up with an ion engine with huge ISP and raw thrust, if it works, and if it's even moderately affordable, this would be a boon to the robotic science community (my folks). I hope it works, I just know it's a tough, tough problem.

 

[Dr. Trintignant]

But your assessment of the effect as miniscule is optimistic. With such an abundant and clean energy source, usage would increase dramatically. Let's say a hundredfold in the first century, and another hundredfold in the next century, with no further increases after that.

Hmmm. Do we really have uses for a 10,000-fold increase in energy? It seems likely that there is, at most, roughly another doubling of population in store. And bringing the world up to America's energy usage gives you maybe another factor of 5. So that leaves another factor of 1,000 over and above the average American.

Is that reasonable? Maybe my imagination isn't big enough, but even assuming regular space tourism, that seems like a lot. It may even be too much for the biosphere to sustain, though I guess Trantor-style heatsinks are possible.

So maybe the most natural use for that kind of energy is off-world megaengineering. In which case, constructing the next stage in energy production would be an obvious choice.

- Dr. Trintignant