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#26 2016-05-12 17:28:29

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
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Re: On Orbit fuel depot

GW Johnson wrote:

We've had long-life propellant storage for decades with NTO and hydrazine blends.  The Russians have been transfers of these at ISS for some years now.  The tricks are figuring out how to store cryogenics for long periods,  and to transfer them.  I'm very glad to see this being worked upon. 

GW

True but they are corrosive and toxic to man....plus not as powerful as the liquid oxygen and liquifide hydrogen are.

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#27 2016-05-15 11:48:42

GW Johnson
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Re: On Orbit fuel depot

NTO-hydrazine blend,  and kerosene-nitric acid are both very storable.  The kerosene is listed as "poisonous",  but is simply not in the same practical ballpark as the other three substances.  Performance varies with chamber pressure/backpressure ratio and the length of the exit bell,  but falls in the 275-300 sec Isp range,  generally. 

LOX kerosene really isn't much better at 280-320 sec.  The LOX tends to boil off.  But it can be kept for time scales of days to weeks in a proper thermos bottle. 

LOX-LH2 is significantly better in terms of Isp:  perhaps the 370-470 range,  again depending upon chamber pressure,  backpressure,  and length of bell.  LH2 is very hard to store for very long at all (hours to a day or so),  no matter how good your thermos bottle is. 

BTW,  a real thermos bottle IS NOT a single-wall lithium-aluminum tank.  Nor is it a single-wall composite tank.  It's double wall,  with vacuum between,  and very polished metal surfaces for extreme reflectivity,  inside and out.  Plus significant external insulation and reflective surfaces.  I think you can probably really forget about 5% stage inert mass fractions with cryogenic propellants.  8-10% might be achievable for short term use.  The longer you need to store the cryo material,  especially LH2,  the heavier your rig will be,  inherently. 

If somebody ever figures out how to efficiently split water into hydrogen and oxygen with lightweight equipment,  and if somebody figures out how to liquify these efficiently and also at very light weight,  in space,  then we might store LOX and LH2 as water/ice,  and just process what we need for the next burn.  Water is VERY storable.  But I think technologies like that are still a very long way off. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#28 2016-05-15 17:14:44

Antius
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Re: On Orbit fuel depot

I can see real benefits in orbital refuelling if it becomes possible to extract gases from the rarefied atmosphere in low orbit.  That way, 5 tonnes of hydrogen lifted to orbit can be converted in 100 tonnes of NH3/O2 bipropellant.  A high ISP propulsion system is a necessary prerequisite to counter drag losses.

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#29 2016-05-19 20:35:22

SpaceNut
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Re: On Orbit fuel depot

Well is we modify a space x falcon to scoop the air on the way up an would need to not try to reuse the bottom stage we could get a 40 percent feed mass for payload to get that extra to orbit from that first stage if we store it in the second stage.....

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#30 2016-05-20 14:02:36

GW Johnson
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Re: On Orbit fuel depot

"Thin air in low orbit" is really thin.  It takes a huge scoop to offset the low density and capture any significant mass.  One of the Gemini astronauts stood up in the open hatch at only 80 miles altitude,  and felt absolutely nothing.  Yet at 80 miles,  there's enough drag to deorbit you in several days to a few weeks.  Yet you can scoop nothing,  if you can feel nothing. 

As for propulsion to offset drag of trying to scoop up mass,  well,  there's specific impulse AND there's frontal thrust density.  Impulse is worthless to you if you do not have sufficient frontal thrust density.  The forces literally have to balance.  Ignoring vehicle basic drag,  there's still the inlet momentum force of scooped material.  It is quite literally the scooped massflow multiplied by flight velocity,  in appropriate units.  To scoop up 0.01 lbm/sec (0.005 kg/sec) at 25,000 ft/sec (8 km/sec),  the momentum drag is near 8 full lb force (around 40 Newtons).  I have never heard of an ion thruster that powerful.  Not yet,  anyway.  The ones that do exist are much lower thrust and weigh hundreds of pounds,  excluding the power supply. 

To scoop that same 0.01 lbm/sec at 25,000 feet/sec velocity with a scoop 10 sq. ft (1 m^2) in area (too big to carry on current launchers) requires an ambient density near 4 x 10^-8 lbm/ft^3,  or a density ratio to sea level standard near 5 x 10^-7.  That's above 200,000 foot altitude for sure,  but probably not above 300,000 feet (60 miles,  90 km).  That's where reentry heating begins,  and where meteors just begin to burn. 

You're going to capture this air at essentially zero pressure.  Even at 200,000 feet,  the ratio of ambient pressure to sea level standard is about 2 x 10^-4.  Just what do you propose to use to compress it to a sensible pressure?  Where we can actually handle it and store it? 

And then,  you gotta liquify it.  Or else the container is just too big to carry around. 

Compression and liquifaction equipment.  Stuff like that is very heavy.  And power-consumptive.  Power supplies for them are bigger and heavier still. 

Are you really sure this is something we ought to attempt to do?

GW

Last edited by GW Johnson (2016-05-20 14:08:44)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#31 2016-05-23 20:01:46

kbd512
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Re: On Orbit fuel depot

GW Johnson wrote:

NTO-hydrazine blend,  and kerosene-nitric acid are both very storable.  The kerosene is listed as "poisonous",  but is simply not in the same practical ballpark as the other three substances.  Performance varies with chamber pressure/backpressure ratio and the length of the exit bell,  but falls in the 275-300 sec Isp range,  generally.

What about storing xenon, argon, or krypton for electric propulsion?

GW Johnson wrote:

LOX kerosene really isn't much better at 280-320 sec.  The LOX tends to boil off.  But it can be kept for time scales of days to weeks in a proper thermos bottle.

LOX and RP-1 are more than sufficient to get us to Mars and back.  The only real issue is making RP-1 on Mars.  How do we do that?

GW Johnson wrote:

LOX-LH2 is significantly better in terms of Isp:  perhaps the 370-470 range,  again depending upon chamber pressure,  backpressure,  and length of bell.  LH2 is very hard to store for very long at all (hours to a day or so),  no matter how good your thermos bottle is.

I thought NASA's contractors were making real progress on this, or is that just PR?

GW Johnson wrote:

BTW,  a real thermos bottle IS NOT a single-wall lithium-aluminum tank.  Nor is it a single-wall composite tank.  It's double wall,  with vacuum between,  and very polished metal surfaces for extreme reflectivity,  inside and out.  Plus significant external insulation and reflective surfaces.  I think you can probably really forget about 5% stage inert mass fractions with cryogenic propellants.  8-10% might be achievable for short term use.  The longer you need to store the cryo material,  especially LH2,  the heavier your rig will be,  inherently.

Perhaps storage of hard cryogens like LH2 is still a bit beyond our capability, but we have proven that we can store LOX / LCH4 / RP-1 and either of those combinations makes pretty good rocket fuel.  Personally, I think chemical propellants are a technological dead end for in-space propulsion.

GW Johnson wrote:

If somebody ever figures out how to efficiently split water into hydrogen and oxygen with lightweight equipment,  and if somebody figures out how to liquify these efficiently and also at very light weight,  in space,  then we might store LOX and LH2 as water/ice,  and just process what we need for the next burn.  Water is VERY storable.  But I think technologies like that are still a very long way off. 

GW

Once we start using fusion for in-space propulsion, I seriously doubt fuel depots or chemical propellants will have any significant utility.  There's a substantial difference in difficulty between expelling the plasma out of a rocket nozzle and trying to contain the plasma indefinitely for power production.

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#32 2016-05-24 10:32:44

GW Johnson
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Re: On Orbit fuel depot

kbd512:

You've pretty well won me over on the used of electric propulsion,  probably solar,  for sending ahead landers,  other equipment,  and maybe even return propellants,  for manned missions to Mars.  That stuff is "slowboat" in the sense that months get added for the spiral-out and spiral-in maneuvers. 

The manned vehicle needs to get there faster to minimize risks to the crew.  Still,  mission durations get measured in years.  We cannot yet store cryogenic propellants THAT long,  so your propellants are going to be storables,  most likely MMH-NTO.  For now,  anyway.

If flown not-far-from-Hohmann min energy,  it's still near 8 months one way to and from Mars.  Doing spin gravity mitigates microgravity diseases entirely,  and greatly simplifies a lot of life support functions.  You can use water/wastewater and frozen food for solar flare shielding.  GCR is just not the threat that so many hype it up to be,  at least in the inner solar system. 

All those considerations lead me to an architecture that is manned orbit-to-orbit transports that are recovered and reused on subsequent missions.  The landers,  equipment,  and even the return propellants get sent ahead.  You just rendezvous with them at destination.  This same architecture and manned habitation design could serve to travel to any beyond-the-moon destination in the inner solar system,  not just Mars. 

Later,  when available, refit the thing with "hotter" propulsion and different propellant tanks.  Just like re-engining an old car or airplane or ship.  And,  some of the equipment you take on those first trips could be the ISRU fuel-making equipment that becomes a start on fuel depots for future trips. 

You cannot effectively meet all those needs and do all those things with the throwaway designs I keep seeing.  Building this is not building "battlestar galactica",  nor does it require gigantic launch rockets.  You just dock it together in LEO from modules we can launch,  the very same way we built ISS,  just with much cheaper launchers today. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#33 2016-05-25 08:43:40

Tom Kalbfus
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Re: On Orbit fuel depot

The ISS was built with the Shuttle and Russian launchers. We don't have the Shuttle any more, and Russia has started playing Cold War games against us. The Russians aren't the friendly partners they were when we started building the ISS. So where does that lead us. We need a new launcher anyway, we don't have the Shuttle, and we don't want to rely on the Russians anymore!

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#34 2016-05-25 11:29:20

GW Johnson
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Re: On Orbit fuel depot

Tom,  everything comprising the ISS that went up there in the shuttle could be launched today by an Atlas-5 for a factor-of-10-or-more less cost than shuttle.  That $110B station should be replaceable today for around $10B,  if launch costs are the dominant factor. 

Flying full,  most of the Atlas-5 configurations show unit prices in the vicinity of $2500 per pound of actual delivered payload.  Shuttle was over $27,000 / lb. 

Flying full,  the promise of Falcon-Heavy is unit prices closer to only $1000/lb,  so yes,  there is a scale effect that is beneficial,  all other things equal.

With SLS,  all other things are NOT equal! 

That is a congress-mandated giant-corporate welfare program,  with the same cost-is-no-object approach that NASA has always effectively used in its launchers (look at the effects,  not the words;  words are cheap,  generally the real hardware has not been). 

NASA thinks it can launch a 70-ton SLS payload for $0.5B,  most of their critics say it'll be closer to $1B,  if not more.  Even at $0.5B/launch for flying-full at 70 metric tons,  that's about $3200/lb unit price,  worse than Atlas-5 and far worse than Falcon-Heavy.  If the critics are right,  it's closer to $6400/lb or even more. 

Why would anyone with a 50 ton or less payload item EVER want to use SLS?

If they had a 70 ton item,  the smarter thing to do is break the design into two pieces,  launch them with two Falcon-Heavies at the flying-less-than-full unit price of $1500/lb,  dock the two pieces together,  and save a real bundle. 

So,  there’s a whole lot more about cost-effectiveness than just payload capability. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#35 2016-05-25 19:56:09

SpaceNut
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Re: On Orbit fuel depot

If launch costs were the only factor then any company could build one but that is the issue as the only company close enough is the ATK/ orbital as they can build the modules empty or retrofit them with what we need and can launch them....
So lets play devils advocate and assume that they did build a station.. whom would pay for it to be done....who would pay to use it....These are the same problems with the ISS after the Nasa plus partners funding is taken out of the equation....there is no other income for its use....

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#36 2016-05-25 21:39:40

kbd512
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Re: On Orbit fuel depot

GW Johnson wrote:

kbd512:

You've pretty well won me over on the used of electric propulsion,  probably solar,  for sending ahead landers,  other equipment,  and maybe even return propellants,  for manned missions to Mars.  That stuff is "slowboat" in the sense that months get added for the spiral-out and spiral-in maneuvers.

My propellant mass, dV, and thrusting time figures for use of both chemical and electric propulsion are deliberately intended to be conservative and provide margin for human errors.  There's no point in making a determination on optimal trajectories, propellant mass, and propulsion requirements when humans are involved.  At the end of the day, electric propulsion (whether powered by solar panels or nuclear reactions) is an enabling technology for human missions within the inner solar system.

Insofar as increased transit duration is concerned, I proposed an architecture that leverages the most mature and easy-to-implement solutions that combine the use cryogenic and storable liquid propellants with electric propulsion.  The combination maximizes delivered tonnage, minimizes IMLEO requirements, and minimizes technology development requirements and associated risks.

KEN-LEO-TMI - LOX / RP-1

The cost and complexity of the most performant LOX / LH2 solutions is decidedly unattractive in terms of affordability and practicality.  If SpaceX and ULA were able to develop affordable and practical full-flow staged combustion LOX / RP-1 engines in partnership with NASA, I see little merit to further development of obscenely expensive engines like the RS-25.

TMI-LMO - SEP

Use of SEP for this phase of the transit dramatically reduces IMLEO requirements for a humans to Mars mission.  There's just not a lot of tech development required to do this when the payload masses fall between the mass of Orion's command and service modules.  Obviously aerobraking works and could be used to reduce propellant requirements, but if you're ever-so-slightly "off", kiss that expensive flight hardware and crew goodbye because the odds are pretty good that you'll never see them again.

LMO-Mars - Storable chemicals

We only need a small dV to de-orbit a small two seat capsule and storable chemicals are entirely sufficient for that purpose.

Mars-LMO - Storable chemicals

ISPP and other ISRU technologies should work just fine, but if the ISPP plant fails, you're a permanent resident.  Here again, using SEP to deliver the MAV reduces the IMLEO requirement to what a single commodity rocket can deliver.

LMO-TEI - Storable chemicals

The SEP-CTV attached to the TEI kick stage is available as a backup option for TEI.  A couple months before it's time to return to the MTV, you move in closer to the MAV launch sites and if there's any sign of problems with the kick stages, you leave a month earlier to assure crew return.

TEI-GEO or L1 - Storable chemicals

There's enough dV in the TEI kick stage for both TEI and GEO or L1 insertion.  If that fails, the MTV's integrated SEP provides backup.

Using SEP to insert multiple, small two person MTV's into LMO does away with dramatic increases in IMLEO requirements simply to deliver the total propellent quantity requirements to insert the MTV's into LMO.  The trade in transit time is a mere 30 days.  That's an entirely acceptable trade, in my mind.  My belief on this matter is that slow, controlled decelerations are better than slamming on the brakes and relying on the MTV to stop on a dime, exactly where intended.  Obviously it can be done and has been done many times, but there's no denying that sudden stops are inherently more dangerous.

GW Johnson wrote:

The manned vehicle needs to get there faster to minimize risks to the crew.  Still,  mission durations get measured in years.  We cannot yet store cryogenic propellants THAT long,  so your propellants are going to be storables,  most likely MMH-NTO.  For now,  anyway.

Agreed, but spending an extra month to spiral in to LMO is not a game changer after you've already spent six months in deep space.  For the people who believe in "safety", spiraling in is the "safest" way to get to LMO.  When there are no second chances to "get it right", the best approach to orbital insertion is gradual deceleration.

GW Johnson wrote:

If flown not-far-from-Hohmann min energy,  it's still near 8 months one way to and from Mars.  Doing spin gravity mitigates microgravity diseases entirely,  and greatly simplifies a lot of life support functions.  You can use water/wastewater and frozen food for solar flare shielding.  GCR is just not the threat that so many hype it up to be,  at least in the inner solar system.

To a point, for long duration space flight, AG is more of a hard requirement than radiation protection is.  You stated in another thread that we could spin a two man habitat mated to a TMI kick stage to the required RPM range without making most humans yak.  We need to try that to see how well it works.  Everyone is different, but I'm guessing that highly trained astronauts won't have any real issue with short radius spin gravity.

GW Johnson wrote:

All those considerations lead me to an architecture that is manned orbit-to-orbit transports that are recovered and reused on subsequent missions.  The landers,  equipment,  and even the return propellants get sent ahead.  You just rendezvous with them at destination.  This same architecture and manned habitation design could serve to travel to any beyond-the-moon destination in the inner solar system,  not just Mars.

Our thinking is congruent here.  I just don't believe that any craft that reenters will ever be reused without extensive refurbishment.  Regarding in-situ rendezvous, that's how we do it here on Earth.  The President may have an aircraft that carries his car with him when he visits another state or foreign country, but the rest of us just rent a car that has already been pre-positioned at our destination.  It's a matter of practicality.  Delivering absolutely everything required for a mission using a single vehicle is simply not practical here on Earth or anywhere else, for that matter.

GW Johnson wrote:

Later,  when available, refit the thing with "hotter" propulsion and different propellant tanks.  Just like re-engining an old car or airplane or ship.  And,  some of the equipment you take on those first trips could be the ISRU fuel-making equipment that becomes a start on fuel depots for future trips.

As I have determined from the process of building my own aircraft, this is often easier said than done.

GW Johnson wrote:

You cannot effectively meet all those needs and do all those things with the throwaway designs I keep seeing.  Building this is not building "battlestar galactica",  nor does it require gigantic launch rockets.  You just dock it together in LEO from modules we can launch,  the very same way we built ISS,  just with much cheaper launchers today. 

GW

Agreed.  Mega rockets and mega spacecraft cost mega bucks.  At the end of the day, there is no requirement for ridiculously large spacecraft or rockets and our pursuit of those things for its own sake has had severe negative consequences for the rest of the technology development required to achieve the goal of sending humans to another planet and then return them to Earth.

I would like to add that by using two astronaut exploration crews, there's no requirement to mate any hardware in LEO.  That's an optional extra, and an expensive one at that.

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#37 2016-05-25 22:06:30

kbd512
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Re: On Orbit fuel depot

GW Johnson wrote:

Tom,  everything comprising the ISS that went up there in the shuttle could be launched today by an Atlas-5 for a factor-of-10-or-more less cost than shuttle.  That $110B station should be replaceable today for around $10B,  if launch costs are the dominant factor. 

Flying full,  most of the Atlas-5 configurations show unit prices in the vicinity of $2500 per pound of actual delivered payload.  Shuttle was over $27,000 / lb. 

Flying full,  the promise of Falcon-Heavy is unit prices closer to only $1000/lb,  so yes,  there is a scale effect that is beneficial,  all other things equal.

With SLS,  all other things are NOT equal! 

That is a congress-mandated giant-corporate welfare program,  with the same cost-is-no-object approach that NASA has always effectively used in its launchers (look at the effects,  not the words;  words are cheap,  generally the real hardware has not been). 

NASA thinks it can launch a 70-ton SLS payload for $0.5B,  most of their critics say it'll be closer to $1B,  if not more.  Even at $0.5B/launch for flying-full at 70 metric tons,  that's about $3200/lb unit price,  worse than Atlas-5 and far worse than Falcon-Heavy.  If the critics are right,  it's closer to $6400/lb or even more. 

Why would anyone with a 50 ton or less payload item EVER want to use SLS?

If they had a 70 ton item,  the smarter thing to do is break the design into two pieces,  launch them with two Falcon-Heavies at the flying-less-than-full unit price of $1500/lb,  dock the two pieces together,  and save a real bundle. 

So,  there’s a whole lot more about cost-effectiveness than just payload capability. 

GW

Maybe we could just pay SpaceX and ULA to develop 70t+ super heavy lift rockets using existing launch vehicle families and then we might actually have certified flight hardware with that kind of lift capability sometime during this decade.  Falcon Heavy with propellant cross-feed was supposed to be capable of lifting 70t and several enlarged core diameter Atlas V variants were supposed to have similar or better lift capability.

The real question is how much more a Falcon Heavy or Atlas (or Vulcan) Heavy with propellant cross-feed would cost.  If the cost remains similar to the cost of the existing launch vehicles, the argument is even more lopsidedly in favor of commercial commodity rockets.  At some point, someone in Congress will have a random neuron collision and cancel SLS, "saving the tax payers billions" (except for the billions already squandered building the "rocket-to-nowhere").

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#38 2016-05-27 14:35:29

GW Johnson
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Re: On Orbit fuel depot

That does assume that members of congress even have two neurons to rub together.  Collectively.

GW


GW Johnson
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"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#39 2016-05-28 10:48:10

kbd512
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Re: On Orbit fuel depot

The very first time that SpaceX demonstrates reusability without any significant refurbishment, all arguments about what SLS can throw become moo points.  If a cross-feed enabled version of Falcon Heavy or Vulcan Heavy can lift 70t, there are no economic arguments remaining for this SLS nonsense when rockets that are a fraction of the price can deliver more payload in a shorter time frame.

SLS has to be killed, and will killed, and that is inevitable.  After we've done that, there's at least a chance of our manned space program moving forward.

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#40 2016-05-28 16:00:25

GW Johnson
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Re: On Orbit fuel depot

I did notice on their website that Falcon-9's payload to LEO has been increased to 22 metric tons.  Last year they were showing 13 tons.  The list price is $62M per launch.  That's for all-expendable.  Elsewhere I have seen a figure of 40% unused propellant loading required for the reuse landing of the stage.  That would cut payload to LEO drastically by an amount I do not now.

$62M/13 tons = $4.8M/ton "flying full" unit price to LEO,  before.  Same as $220/lbm.  (EDIT:  supposed to be $2200/lb,  not $220/lb) With the higher payload and the same price,  unit price is $62M/22 tons = $2.8M/ton,  same as $1300/lbm. 

Last time I calculated "flying full" unit prices for Atlas 5,  Ariane,  etc,  I got in the vicinity of $2400-2500/lbm.  So even Falcon-9 is now more-than-competitive. 

I had been using closer to $70M per 13 ton launch for Falcon-9,  based on older data.  That was about $5.3M/ton flying full,  same as $2400/lbm.  It is clear they are getting substantially cheaper to fly. 

If memory serves,  Spacex's website now projects near $85M per launch for Falcon-Heavy,  which is lower than I expected.  That's for 54 tons flying full to LEO,  I think it says,  all-expendable.  The corresponding unit prices are $1.6M/ton = $700/lbm.  With the older data,  I was getting in the $800-1000/lbm range.  Remarkable!  (EDIT:  listed price = $90M.  For 54 tons delivered,  that's $1.7M/ton = $800/lb.)

GW

Last edited by GW Johnson (2016-05-29 10:24:44)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#41 2016-05-28 20:30:30

kbd512
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Re: On Orbit fuel depot

SpaceX has truly come quite a ways in cost reduction.  I believe ULA and Blue Origin will follow suit.  Once we have two or more launch service providers competing with each other for contracts, prices will inevitably go down.  I''ll get excited when we get that cost down to $250/lb.  At that price point, these flagship missions NASA wants to pursue become much more feasible.  My hope is that eventually we'll be able to achieve economies of scale with regular reuse of a fleet of boosters.

Even at $250/lb, that's obscenely expensive LOX / LH2 or LOX / RP-1.  I can't wrap my head around a mission architecture that would cost less using propellant depots than using current electric propulsion technology.  The manned vehicles will be transferred by upper stages and the cargo need not be delivered with any great speed.

The only plausible application I can think of for using propellant depots would be in extraterrestrial mining.  We're decades away from a requirement for that.  By that time, we should have fusion powered rockets.  Nobody will be using chemical propellants for in-space propulsion when that technology becomes available.

Propellant depots were a novel idea that would've been a mission enabler once upon a time.  However, that time passed us by about two decades ago.  Now it's just a way to make missions unaffordable.

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#42 2016-05-29 10:21:17

GW Johnson
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Re: On Orbit fuel depot

Well,  if these guys actually do start recovering and reflying boosters successfully,  the price might well eventually drop near your $250/lb figure,  just at much smaller payloads than are advertised for the expendable option. Hard to say,  really.

Just thinking out loud:  Falcon-9 $62M as expendable,  wild guess $31M as recovered first stage.  Cut the 22 tons back nearer 13 as a guess.  Expendable = 1300/lb.  Recoverable = $1100.  Nope,  I don't see it happening yet,  unless they can drastically reduce the total launch price way below the current $62M.  Factor 2 ain't gonna do it. 

I'm very excited to see prices down to $2500/lb compared to $27,000/lb+ with shuttle,  and around $8,000-10,000/lb with the old boosters from the 1960's.  Seeing it drop toward $1000/lb due to Spacex's efforts is very exciting indeed.  ULA and the foreigners will have to hustle to keep up,  if they want to retain market share. 

I'm not at all sure Boeing and Lockheed-Martin will stay in the commercial space business long-term.  They've been on an easy-street gravy train for many years.  Corporate culture change is very difficult.  This isn't the commercial airplane business,  but it will have to operate like that,  if they stay in it. 

GW

Last edited by GW Johnson (2016-05-29 10:30:29)


GW Johnson
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"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#43 2016-05-31 19:43:50

SpaceNut
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Posts: 20,263

Re: On Orbit fuel depot

I wish we had a poster from Space x amoungst our topics as the questions that we need answers on are contained in how space x does business..such as Unions...personel count.. how much of the rockets components are made by space x versus how much is contracted out....

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#44 2016-05-31 22:30:49

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,280
Website

Re: On Orbit fuel depot

From their website: About SpaceX

Quick Facts about SpaceX:	| founded	| vehicles	| manifest	| employees
				| 2002		| 3		| 70+		| 4,000+

YouTube tours: (some duplicate footage)
hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=Fi9d1WVDkgejpjUoEKOg9fB6-H4 Elon Musk Tour of SpaceX 720p HD - 31:19
Published on 11 Apr 2015
SpaceX CEO and CTO Elon Musk takes us on a tour of the SpaceX Headquarters located in Hawthorne, CA , just outside of Los Angeles. Once a manufacturing site for the 747 aircraft, this 500,000 square foot facility is where SpaceX now designs and builds 80% of the Falcon line. 2010 Tour.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=kvYJbbZ0XoC5pd57oTqySvt6-eY Elon's SpaceX Tour - Engines - 4:33
Uploaded on 11 Nov 2010
SpaceX CEO and CTO Elon Musk takes us on a tour of the SpaceX Headquarters located in Hawthorne, CA , just outside of Los Angeles. Once a manufacturing site for the 747 aircraft, this 500,000 square foot facility is where SpaceX now designs and builds 80% of the Falcon line.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=Nj3cpj6PJ-t0cWyiVO3AEI3lmGw Elon Musk Take A Tour Inside The SpaceX (Get Experience A Tour At SpaceX) - 18:46
Published on 26 Apr 2016
Elon Musk Take A Tour Inside The SpaceX (Get Experience A Tour At SpaceX)

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=cbQVgL3h5yUeKam1uGsCq2q5tDM A Tour of the SpaceX Falcon 9 Launch Pad at Cape Canaveral Florida - 2:52
Published on 23 May 2012
CTTechJunkie visited the Cape Canaveral Air Force Station launch facility maintained by SpaceX. The tour was conducted a few days before the Falcon 9 rocket lifted off for the International Space Station.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=0bsgdrxHRTFdDawxqm-2BbjF8CU Elon's SpaceX Tour - Cape Canaveral Launch Site - 3:01
Uploaded on 11 Nov 2010
SpaceX CEO and CTO Elon Musk gives a tour of the new SpaceX Falcon 9 launch site at Space Launch Complex 40, Cape Canaveral AFS, Florida. Revised 11/09 with latest progress.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=sOKJNOLLrY2Z8Adea78F1G_ObL0 INSIDE SpaceX: Florida Launch Pad LC-40 & Launch Control Center tour - 1:02:05
Published on 19 May 2012
Come along as the Private Space Agency opens its facilities at Cape Canaveral Air Force Station to the Media for the first time ever.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=j23OLCaP2t-xaq4BKp1J8DggAOE SpaceX Tour - Texas Test Site - 5:13
Uploaded on 11 Nov 2010
Tom Mueller, SpaceX's VP of Propulsion, gives a tour of our Texas Test Site showing structural and propulsion test facilities in action.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=yaGG0tx1LZBFGz4cIGKRQpXgRpM Tour The SpaceX Falcon 9 Space Launch Complex 40 At Cape Canaveral - 10:21
Published on 17 Jun 2013
Tour The SpaceX Falcon 9 Space Launch Complex 40 At Cape Canaveral. SpaceX Manager SCott Henderson gives the media a short tour of the Falcon 9 launch complex. We started on the bus, and about 1/3 through the video, the bus parks on top of the launch pad and we get out to listen more and shoot photos.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=MNxNtHV_6fZmN9787YZz_NmcpyQ The Future of Design - 3:48
Published on 5 Sep 2013
SpaceX is exploring methods for engineers to accelerate their workflow by designing more directly in 3D. We are integrating breakthroughs in sensor and visualization technologies to view and modify designs more naturally and efficiently than we could using purely 2D tools. We are just beginning, but eventually hope to build the fastest route between the idea of a rocket and the reality of the factory floor. Special thanks to Leap Motion, Siemens and Oculus VR, as well as NVIDIA, Projection Design, Provision, and to everyone enabling and challenging the world to interact with technology in exciting new ways.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=3UUOH03p4J7KNVy73ptbrk0lVOg SpaceX Rocket Tank Production | Timelapse - 0:31
Published on 20 Nov 2014
Spanning nearly 1 million square feet, the SpaceX factory currently produces more rocket engines than any other U.S. manufacturer, and will eventually produce 40 rocket cores annually.

hqdefault.jpg?custom=true&w=320&h=180&stc=true&jpg444=true&jpgq=90&sp=68&sigh=nInZfudqSm-cZRHl1ftKTKWuR8M Joseph Gordon-Levitt at SpaceX - 3:09
Published on 10 Feb 2014
SpaceX, Elon Musk and Mars

more tours: YouTube

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#45 2016-06-01 06:23:39

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: On Orbit fuel depot

GW Johnson wrote:

Well,  if these guys actually do start recovering and reflying boosters successfully,  the price might well eventually drop near your $250/lb figure,  just at much smaller payloads than are advertised for the expendable option. Hard to say,  really.

Just thinking out loud:  Falcon-9 $62M as expendable,  wild guess $31M as recovered first stage.  Cut the 22 tons back nearer 13 as a guess.  Expendable = 1300/lb.  Recoverable = $1100.  Nope,  I don't see it happening yet,  unless they can drastically reduce the total launch price way below the current $62M.  Factor 2 ain't gonna do it. 

I'm very excited to see prices down to $2500/lb compared to $27,000/lb+ with shuttle,  and around $8,000-10,000/lb with the old boosters from the 1960's.  Seeing it drop toward $1000/lb due to Spacex's efforts is very exciting indeed.  ULA and the foreigners will have to hustle to keep up,  if they want to retain market share. 

I'm not at all sure Boeing and Lockheed-Martin will stay in the commercial space business long-term.  They've been on an easy-street gravy train for many years.  Corporate culture change is very difficult.  This isn't the commercial airplane business,  but it will have to operate like that,  if they stay in it. 

GW

Whatever competitors drop out of the market just adds to SpaceX's profitability, but increased profitability usually increases the number of competitors in the market until an equilibrium is reached, that is how market economics typically works. Boeing is an airplane manufacturer and a military contractor, typically as such, it provides what its customer(s) ask for. Same can be said for Lockheed-Martin. In the case of their military contractor roles, if the government asks for X they provide X. Whatever the government wants, they will build for a price. The problem with these two companies is they depend on just one customer, the US government, which isn't too frugal. The US government doesn't typically shop around, they don't always go to the lowest bidder, and they have other requirements besides getting the most for its dollar spend, such as creating jobs for some influential congressman's district. SpaceX provides a launch service take it or leave it, it builds its rockets and then launches them. SpaceX doesn't depend entirely on one customer, it has several customers. This is the new business model for space launches, and it remains to be seen whether military contractors such as Boeing and Lockheed-Martin can adapt to it. As a parallel example IBM once tried to compete in the market for desk top personal computers, and it found that market not to its liking, so it stuck to big machines and consulting.

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#46 2016-06-01 10:07:58

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,146
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Re: On Orbit fuel depot

Looking back at the first post in this thread (some 9 years ago),  it seems to have started over the notion of on-orbit refueling in LEO to increase payloads sent elsewhere from LEO.  That included the moon,  as well as more distant destinations. 

Right now,  we have to launch everything from Earth,  so I don't see much difference between the fuel depot concept and the concept of on-orbit assembly by docking. 

But,  if we should learn how to make useful fuels on the moon,  the cost of doing that plus the cost of sending them to LEO from the moon,  might possibly pay off. 

As we continue to make Earth launch costs lower,  this lunar propellant manufacture notion has less potential,  unless the manufacture and return transit costs can be made very low to compete. 

Now,  if significant ice deposits really do exist on the moon,  then you can mine,  melt,  and hydrolyze them to hydrogen and oxygen.  Then you have to liquify them.  You have to fling them off the surface,  and you have to get them safely to LEO.  And you have to do this on a timescale of days,  so that boiloff losses do not defeat you.   

You do not necessarily have to send all the oxygen.  You get it at 8:1,  you need it at only 6:1 for rocket work.  The rest could supply breathing oxygen for people on the moon. 

Anybody have cheap solutions for all these processes?  If you do,  then fuel depots in LEO look to be feasible and potentially attractive.

I suppose the same considerations might apply to making propellants out of volatiles mined from "wet" asteroids.  Generally,  those are too big to direct,  so transport home would be a lot tougher than from the moon.  But that does open up the possibility of fuel depots elsewhere than LEO. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#47 2016-06-01 16:38:46

Antius
Member
From: Cumbria, UK
Registered: 2007-05-22
Posts: 1,003

Re: On Orbit fuel depot

There is fuel and there is reaction mass.  The first implies stored energy released as kinetic energy in some kind of engine.  The second is inert mass that you shoot out of an accelerator in order to exploit Newton's third law.  Any matter can be used as reaction mass provided there is enough energy to accelerate it, which there is in the form of solar power.  Most payloads delivered to orbit are accompanied by dead weight in the form of upper stages.  Dead satellites are another form of reaction mass, along with any waste from ISS.  Why not devise a plan to use this instead of going all the way to the moon?  My pet favourite idea is some form of arc jet plasma propulsion, though resistorjet and mass driver are options as well.  Basically, your fuel depot would need some means of gathering empty stages and other detritus on different orbits, grinding it into powder than can be fed into whatever type of reaction engine is being used.  The Earth's atmosphere is another source of oxidiser/propellant, although as you pointed out, there are difficulties gathering such rarefied gas and counteracting drag.

Last edited by Antius (2016-06-01 16:45:46)

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#48 2016-06-01 21:58:11

kbd512
Administrator
Registered: 2015-01-02
Posts: 3,838

Re: On Orbit fuel depot

Antius wrote:

There is fuel and there is reaction mass.  The first implies stored energy released as kinetic energy in some kind of engine.  The second is inert mass that you shoot out of an accelerator in order to exploit Newton's third law.  Any matter can be used as reaction mass provided there is enough energy to accelerate it, which there is in the form of solar power.  Most payloads delivered to orbit are accompanied by dead weight in the form of upper stages.  Dead satellites are another form of reaction mass, along with any waste from ISS.  Why not devise a plan to use this instead of going all the way to the moon?  My pet favourite idea is some form of arc jet plasma propulsion, though resistorjet and mass driver are options as well.  Basically, your fuel depot would need some means of gathering empty stages and other detritus on different orbits, grinding it into powder than can be fed into whatever type of reaction engine is being used.  The Earth's atmosphere is another source of oxidiser/propellant, although as you pointed out, there are difficulties gathering such rarefied gas and counteracting drag.

Antius,

The "means of gathering upper stages" is a task that Lockheed-Martin's Jupiter space tug was intended to do.

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#49 2016-06-02 05:21:26

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: On Orbit fuel depot

GW Johnson wrote:

Looking back at the first post in this thread (some 9 years ago),  it seems to have started over the notion of on-orbit refueling in LEO to increase payloads sent elsewhere from LEO.  That included the moon,  as well as more distant destinations.

 

It would be hard to get a Lunar Lander to go from Low Earth Orbit to the Lunar surface and then all the way back to Lunar orbit all in one piece and on one tank of fuel.

Right now,  we have to launch everything from Earth,  so I don't see much difference between the fuel depot concept and the concept of on-orbit assembly by docking. 

But,  if we should learn how to make useful fuels on the moon,  the cost of doing that plus the cost of sending them to LEO from the moon,  might possibly pay off.

 

To make fuel, you will need to mine the Moon, if you can mine the Moon without astronauts, there would be no reason to send the astronauts, because the automated Moon mining machines can collect all the rock samples you would want and return them to Earth. The only reason to send humans to the Moon would be to make the headlines.

As we continue to make Earth launch costs lower,  this lunar propellant manufacture notion has less potential,  unless the manufacture and return transit costs can be made very low to compete. 

Now,  if significant ice deposits really do exist on the moon,  then you can mine,  melt,  and hydrolyze them to hydrogen and oxygen.  Then you have to liquify them.  You have to fling them off the surface,  and you have to get them safely to LEO.  And you have to do this on a timescale of days,  so that boiloff losses do not defeat you.   

You do not necessarily have to send all the oxygen.  You get it at 8:1,  you need it at only 6:1 for rocket work.  The rest could supply breathing oxygen for people on the moon. 

Anybody have cheap solutions for all these processes?  If you do,  then fuel depots in LEO look to be feasible and potentially attractive.

I suppose the same considerations might apply to making propellants out of volatiles mined from "wet" asteroids.  Generally,  those are too big to direct,  so transport home would be a lot tougher than from the moon.  But that does open up the possibility of fuel depots elsewhere than LEO. 

GW

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#50 2016-06-02 05:22:38

Tom Kalbfus
Banned
Registered: 2006-08-16
Posts: 4,401

Re: On Orbit fuel depot

kbd512 wrote:
Antius wrote:

There is fuel and there is reaction mass.  The first implies stored energy released as kinetic energy in some kind of engine.  The second is inert mass that you shoot out of an accelerator in order to exploit Newton's third law.  Any matter can be used as reaction mass provided there is enough energy to accelerate it, which there is in the form of solar power.  Most payloads delivered to orbit are accompanied by dead weight in the form of upper stages.  Dead satellites are another form of reaction mass, along with any waste from ISS.  Why not devise a plan to use this instead of going all the way to the moon?  My pet favourite idea is some form of arc jet plasma propulsion, though resistorjet and mass driver are options as well.  Basically, your fuel depot would need some means of gathering empty stages and other detritus on different orbits, grinding it into powder than can be fed into whatever type of reaction engine is being used.  The Earth's atmosphere is another source of oxidiser/propellant, although as you pointed out, there are difficulties gathering such rarefied gas and counteracting drag.

Antius,

The "means of gathering upper stages" is a task that Lockheed-Martin's Jupiter space tug was intended to do.

It goes all the way to Jupiter?

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