CRATS to Mars

Marsman · 2011-11-28 23:56:04

CRATS= Cheap Reliable Access To Space. (not to be confused with the NASA COTS program)

For a commercial/private funding way to send humans to Mars, the obvious answer in how to make it possible, how to make a profit is to have the mission at such a low cost that a profit can be made.

So I was doing some thinking about launch vehicles. It seems that of the 2 or 3 ways to currently create propulsion, all have limits of fuel quantity or energy sources that make the vehicle so massive, complex and costly that this challenge has never been cracked.

But what if we can remove the energy source in a rocket (electric/plasma propulsion) so that it can actually be used as a launch vehicle? Yes, the power required would be massive. But what if we could wirelessly project/beam the power into the space craft to create super thrusting electric propulsion? http://www.witricity.com/pages/application.html

Instead of needing a nuclear or fusion power plant inside the vehicle, we can have it on earth and direct the power into the craft? And what if the vehicle was already high in the atmosphere via piggy back on a jetliner or balloon when it launched?

Are there other ways to do this? What if a new super light, super strong material and reliable computer aided machining techniques could create materials and reliability robust enough to be used hundreds of times, making rockets 100% safe and efficient? Perhaps nanomaterials? Maybe more efficient mixtures of rocket fuels can be used? ALICE for example http://www.gizmag.com/nasa-eco-friendly … uel/12593/

I think a mixture approach, if used correctly, and applied to all aspects of current space launch vehicles from the smallest parts to the way it propels itself can crack this problem.

There are many myths in the CRATS area of thinking, one of which is "it will take tens of billions and decades, and possibly is against the laws of physics". We Mars advocates have heard this type of thing many time in regards to Mars missions for humans too. I believe that with small scale tests on key materials and technologies, with demonstrations, proof of concepts and critical design process, we can build a launch vehicle that will achieve CRATS in our time.

Once that happens, we can get to mars very fast, and stay there!

Waiting on NASA or governments to go to Mars is not a dream. It is an annoying, frustrating wait for what may never be, and in the end is not going to ensure a settlement of Mars or anywhere else. The private sector can get business plans to get us to Mars, as long as the vehicles are cheap enough. I know for example that The Mars Society wants humans on Mars, but I hear very little about a sustainable presence or how to make that realistic or affordable. Government paid current methods won't do it. CRATS can be achieved in 10 years from 2011. With some out of the box thinking, strategically applied. This can be done. Then Mars can be reached within 5 years or sooner.

Last edited by Marsman (2011-11-29 03:46:16)

SpaceNut · 2011-11-29 18:06:58

As posted on MarsDrive

environmentally-friendly propellant made from aluminum powder and water ice. The fuel, called ALICE, has the consistency of toothpaste with a high burn rate and achieved a maximum thrust of 650 pounds during this test. The fuel is safer to handle to traditional fuels and can be fitted into molds before being cooled to –30C 24 hours before flight.

This is a fuel of choice for a moon colony.... first experiments from this link
Lunar Soil Propellant

on the wireless power it is lessened by distance to the reciever either in electrical or in light (laser) makes no difference....

JoshNH4H · 2011-11-29 21:09:30

It seems to me that you're describing the three basic ways of powering an EtO (Earth to Orbit) rocket (to leave aside the separate challenge of non-rocket spacelaunch) as chemical, nuclear, and beamed power. I believe the general agreement is that a BDB (Big Dumb Booster) is the cheapest way to do chemical. In this case, the the BDB can be reusable or disposable, but refurbishable is generally not approved of. Then for nuclear, you make every piece of the rocket super-expensive but super-light, and reuse the rocket a thousand times. This is the logical extreme of the EELV (Evolved Expendable Launch Vehicle) concept. Generally it's supposed to be SSTO (Single Stage to Orbit). It's hard to really reach this idea with chemical propulsion.

Then there's what you seem to be suggesting, which is beamed power. I don't think that electric is the right way to go on this one, because there are simply much better ways to do beamed propulsion. Electric engines are quite heavy, after all, and since you can't beam your energy directly to the ship as electricity, there is an efficiency loss. The particular power beaming method you suggested is not feasible for launch to orbit because it would also induce current in every metal objects for hundreds (thousands?) of km around. You might want to induce a current in a (superconducting if possible) loop by pointing a radio beam through it.

Anyway, it appears that BDBs can get the price down quite far; The Falcon Heavy may go for as low as $1,500/kg, and Elon thinks the price can go down, especially if he manages to make it reusable. I think that is pretty reasonable. Making it reusable undermines its BDB-ness somewhat, though it can potentially be worth it. In the near term, I think that this is the best way to reduce costs.

In the long term, I think it's a toss-up between beamed and nuclear (or other high-thrust high-Isp drives). Beamed will most likely involve lasers vaporizing a solid target to create a high-velocity exhaust stream, while high-Isp could involve nuclear or perhaps some as-yet undeveloped high energy density storage substance.

I agree with your suggestion that a reduction of the costs to orbit will enable space colonization to a huge degree; however, I'm not sure I agree with your particular proposals as to how to go about it.

I think that the costs to orbit are a large part of the reason why costs are so high. But that does not mean that reducing the cost to orbit dramatically will lead to a massive reduction in terms of cost, at least not immediately.

Zubrin talks about this a little bit in his book Entering Space. The cost of building a satellite these days can be tremendous. This was originally because launch costs were so expensive; If it's going to cost a hundred million dollars to launch your satellite, it makes a good deal of sense to spend another hundred million or two to make it last longer and to make it lighter. But now the cost of your satellite is two hundred million. Do you want to go with the 100 million dollar rocket or the 150 million dollar rocket with a better record? This way of doing business has become enshrined within NASA.

I know Marsdrive advocates a consortium style approach, and I think that this is a good idea; SpaceX came in, and then the cost to orbit dropped by a factor of ~5. MSL cost 2.5 billion dollars. Phobos-Grunt cost 160 million dollars. Phobos Grunt failed and MSL has gone completely according to plan, to date, but will it return 2.5 billion dollars worth of scientific data? Would it be more cost-effective to launch 3 Phobos Grunts in hopes that one would succeed (for a total cost probably less than $160 million each) instead of one 2.5 billion MSL?

You can't launch three Manned Mars missions and hope that one crew makes it back alive; but that kind of cost-centered thinking is what is needed more in the space industry.

Terraformer · 2011-11-30 05:08:20

Why is BDB going to reduce costs more than many smaller launch vehicles, when the latter means your fixed costs will drop arbitrarily close to zero?

JoshNH4H · 2011-11-30 09:56:38

I suppose I used BDB incorrectly (Actually, given that I was referring to a s simple chemical rocket that could be reusable and could be of any size, I should've known better).

Ideally, though, even with a big rocket the launch rate would ultimately be high enough that your fixed costs would get arbitrarily close to zero.

SpaceNut · 2011-11-30 22:47:52

One thing that is forgotten when figuring the cost per Kg or pound is the cost of the payload. Take for instence the MER rover cost 800 million for the pair with a pair of launch vehicles in the 200 million each. This makes the cost to launch a mer payload of 600 million so that mass per cost is much greater than the cost of launch vehicle into the payload mass.

JoshNH4H · 2011-12-01 10:41:36

That's very true, Spacenut. In addition to reducing launch costs we should also work on applying a BDB-type construction strategy to the payloads being launched, thus making total program costs very much reduced.

Marsman · 2011-12-04 16:39:02

Thanks for the responses guys. Well, just ideas thrown out there anyway. One thought I had was what if we could do a "Unified Combination" of technologies/systems- perhaps with BDB- A redesign which might allow a mid air launch and horizontal/vertical landing? Sort of a cross between Virgin Galactic's model and Blue Origin model but with nanotech engine materials and fuels to radically enhance strength, efficiency and safety ratings? What I see from SpaceX and these other companies is a good start, but they still don't come close to cracking this problem of CRATS.

We need to focus on small scale tests on all components and materials and fuels in the range of thousands of tests, something these companies and others cannot do. One idea I came across: http://www.microlaunchers.com/ and there are others like JP Aerospace, Sea Launch, etc. Only with mass scale tests will we crack this challenge. An investment consortium would more likely invest in that kind of project which has far reaching applications versus a mission to Mars.

If a mission to Mars cost $100 Million in total, there would be no problem creating a profit/business case. How can we do this?

SpaceNut · 2011-12-04 22:26:14

I was going to meation the effects of distance to the energy recieved as a function of solar transmitted by the sun as approximately 3.846 yotta watts with Earth recieving roughly 1.361 kilowatts per square meter (kW/m²) with a panel getting 300w/m squared and Mars being much less at 140 w/m squared for the same panel on the surface..Sun to Earth rough distance 155,000,000 Km with mars at 240,000,000 Km....

I also found a microwave beamed test that indicated 84% of 30Kw at the distance of 1 mile as all that was recieved.

GW Johnson · 2011-12-05 22:42:01

Whatever basic rocket idea you use, re-usable or not, the real cost is the logistical tail behind it. NASA is famous for being expensive at $1B per shuttle launch (well, until recently, anyway). Why? It took the population of a major American city to support every launch, when you count all the contractors, subcontractors, and vendors. I bet $1B/launch didn't even cover the real costs - that's a lot of people to hire!

Now think "stick-and-rudder" into the black. Maybe a ground crew of under a dozen. You can throw the entire vehicle away and still be cheaper, if you can operate like that. But you cannot put all the bells and whistles on it. Not so extreme, but the same basic idea, is exactly why Spacex is so much cheaper than the majors. Nothing too hard to understand about that.

OK, now add real reusability, which means this thing (or "things" if multi-stage) have to take the abuses of spaceflight for years or even decades. You're going to have to build it tougher than an old boot to take that kind of abuse that long, and still keep the support crew small. There's simply no way around that dilemma. It also means you have to supply enough structure to take that kind of punishment: these 8-10% inert weight fractions I see bandied about are not even in the ballpark for a cheap system.

The most reusable, inexpensive rocket vehicle in all of history was the X-15. Its inert weight fraction (exclusive of its B-52 launcher) was 40%, which is not all that far from the typical supersonic bomber's 50-odd%, and not all that far from the B-52 itself. 3 X-15 airplanes flew 199 times over 2 decades, with only 1 complete airframe rebuild, and that was after destruction in an explosion in ground test. Nice record, for a manned rocket of 1955 design vintage.

GW Johnson

louis · 2011-12-07 19:04:32

GW Johnson wrote:

Whatever basic rocket idea you use, re-usable or not, the real cost is the logistical tail behind it. NASA is famous for being expensive at $1B per shuttle launch (well, until recently, anyway). Why? It took the population of a major American city to support every launch, when you count all the contractors, subcontractors, and vendors. I bet $1B/launch didn't even cover the real costs - that's a lot of people to hire!
Now think "stick-and-rudder" into the black. Maybe a ground crew of under a dozen. You can throw the entire vehicle away and still be cheaper, if you can operate like that. But you cannot put all the bells and whistles on it. Not so extreme, but the same basic idea, is exactly why Spacex is so much cheaper than the majors. Nothing too hard to understand about that.
OK, now add real reusability, which means this thing (or "things" if multi-stage) have to take the abuses of spaceflight for years or even decades. You're going to have to build it tougher than an old boot to take that kind of abuse that long, and still keep the support crew small. There's simply no way around that dilemma. It also means you have to supply enough structure to take that kind of punishment: these 8-10% inert weight fractions I see bandied about are not even in the ballpark for a cheap system.
The most reusable, inexpensive rocket vehicle in all of history was the X-15. Its inert weight fraction (exclusive of its B-52 launcher) was 40%, which is not all that far from the typical supersonic bomber's 50-odd%, and not all that far from the B-52 itself. 3 X-15 airplanes flew 199 times over 2 decades, with only 1 complete airframe rebuild, and that was after destruction in an explosion in ground test. Nice record, for a manned rocket of 1955 design vintage.
GW Johnson

I agree entirely about Space X. That is the way to go. Musk has essentially solved the problem of getting to Mars. He clearly intends to get there within the next 10-20 years (my money says he is thinking 15 in reality). He will soon be able to get major loads into earth orbit. I think his next level will be to master space assembly. That is the way to go: assemble small loads into larger craft.

We can send lots of robot pre-missions to the designated landing area with supplies. Maybe say 8 separate missions over a period of 6 years. We can land those much more accurately than we do now with Mars GPS and transponders. As long as we get them within say 10 Kms of the landing point, that should be OK.

re the X-15 was that really "space" - I thought it was sub-space, not orbital space.

JoshNH4H · 2011-12-07 21:22:57

With regards to the X-15, it was sub-orbital and not orbital. It would be truly wonderful if could get a rocket to go into orbit that was 40% solid structure (MR 2.5), but that would require an Isp in excess of 1000 s, which is quite difficult to achieve.

I think that in the short term, I think that the best strategy to reduce costs is the free market. Have a safety/cost algorithm and use it to compare rockets, and buy the one that does the best. No exceptions.

In terms of design, in the short term I foresee a really simple BDB concept reducing cost the most, maybe at its ultimate cheapness reaching $100/kg, maybe even $50/kg. After that, I would see a more high-tech reusable SSTO vehicle. Perhaps an airbreathing skylon type concept would be a good template for this.

GW Johnson · 2011-12-07 23:15:50

Oh yes, X-15 was suborbital. But it did fly in space, it was rocket-powered, and each of the 3 airframes flew lots of times with very minimal ground support. The 40% inert fraction plus its record proves it was tougher than an old boot. (Actually, that service record is because it was tougher than an old boot.) So, that's what you want out of your BDB. 40% inert is no magic number, but I am certain the "right" number (for tougher than an old boot) is one whopping lot more than 8-10%.

There is a size effect for structures: weight (loads) scale as dimension cubed, while strengths scale only as dimension squared. Thus strength / weight ratio scales inversely with size, all other things the same. Gigantic vehicles end up in the same situation as water balloons supported by nails. An easy way to get around this is to build your gigantic stage as a cluster of much smaller tankage, and recover each of them separately. Not every tank needs its own engine, either.

The current optimal throwaway designs to LEO are two-stage rockets, with each stage around 10% inerts. The first stage delivers around 10,000 ft/sec delta-vee, more thrust-limited than Isp-limited, so kero-lox has been hard to beat for decades. The second stage operates not so vertically so it delivers the other 16-17,000 ft/sec, and is more Isp-limited than thrust-limited. Second stages are also physically smaller, so you can match or reduce diameter relative to the first stage, even with a super-low density propellant. That's why LH2-lox works so well.

Built tougher with higher inert fractions may require reverting back to three stages, in order that payload doesn't shrink to zero. That doesn't really make it much more complex (the 3-stage Minuteman was pretty simple, after all, and so was the 4-stage Scout), but by reducing the delta-vee from each stage, one can tolerate existing Isp's and thrust levels, at substantially higher inerts. Higher inerts mean tougher, which can mean smaller logistical tail (not guaranteed, it's more of a cultural change). That's how you make it cheaper, if you can really pull it off.

It's the last stage that worries me the most. I think it needs to burn three times (or even more), to achieve orbit along with the payload. That's not such a dumb, utterly-simple vehicle. That way, the payload can be completely inert dead-head cargo, and, you can ensure the last stage comes down exactly where you want it (it's the lower stage or stages that come down far downrange). I just don't yet have a clear picture of how best to survive reentry with a shape like that, and still be recoverable and reusable. Reentry is really tough. Mach 10-ish hypersonics are not all that bad. Mach 25? Really tough.

GW

GW Johnson · 2011-12-12 19:55:39

Take a look at reusable rockets under interplanetary transportation. I posted some reverse-engineering results for the Falcon-9 that apply to this discussion as well as that one.

GW

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CRATS to Mars

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