Boeing’s space fuel depot (PM article)

[j05h]

I actually used the "delta-V budget" article on wiki, and misread it. Looking at it again with rested eyes shows 3.77km/s from LEO to EML1. <br /><br />With a service station handling both Lunar and other (GEO, interplanetary, LEO) traffic, it might make sense. If it's just for stagign moon missions, the depot likely ends up just in LEO. <br /><br />The clowder.net map is really cool. Probably to complex a subject for kids but an interesting implementation.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[no_way]

one thing that it makes glaringly obvious: there wont be a venusian sample return mission any time soon.

 

[josh_simonson]

Most customers would be unhappy with this. Occasionally final stages fail mid-flight and the satelite has to use it's RCS system to get to the intended orbit, added weight would leave them at a lower orbit. When you're launching a multi-hundred million dollar spacecraft you want margin! <br /><br />One problem with fuel depot is that no launcher is likely to be as cheap per pound as a marginal flight of Ares V is for NASA. The marginal cost for a shuttle flight is lost in the noise in the cost of the shuttle program, the same can be expected for Ares - and Ares being unmanned won't have the same hand-wringing about whether a launch is worth risking lives for as STS does. They aren't building the heavy lift rocket to not use it.<br /><br />Alternately, if a Bigelow station were a part of the LEO depot, then crew could be launched FIRST and be able to wait for months for the lander to arrive if need be because the Orion has zero boiloff fuel. This plus the ability to store cryogenic fuels longer would significantly improve the LOM statistics for launch failure, abort/rollback and weather related problems.

 

[j05h]

I'd like to add something. <br /><br />At a certain point the fuel depot and the rocket's upper stage become indistinguishable. <br /><br />Boeing's depot uses evolved upper stages docked together. We can assume that the first depot would be dedicated stages or carry minimal payload. The proposed "Wide Body Centaur" would do these functions and be a top-of-the-line interplanetary tug. Hopefully. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[holmec]

Instead of making a "depot" they could just launch the fuel separately and have those canister modules dock (or grappled with an arm) to the TLI booster in orbit. That would seem more economical if they just want to have Ares V launch larger moon modules.<br /><br />I really don't see the point on putting extra structure in space just to hold canisters of fuel when orbital mechanics can do just that. And you wouldn't have the maintenance costs of maintaining such a structure.<br /><br />IMHO a real "depot" is only beneficial if your manufacturing fuel in space from resources in space. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[jimfromnsf]

"Vthey could just launch the fuel separately and have those canister modules dock (or grappled with an arm) to the TLI booster in orbit."<br /><br />Because that would be more complicated. The TLI booster would have more structural mass and piping to handle the tanks vs one large tank<br /><br />Also the TLI booster would have to wait for all the tanks to be delivered. <br /><br />The TLI booster just gets launched and rendezvous with the station and get refuel and then goes on. The servicing of the station with tankers is done offline

 

[holmec]

<blockquote><font class="small">In reply to:</font><hr /><p>Because that would be more complicated.<p><hr /></p></p></blockquote><br /><br />Its more complicated building a station than it is to dock. And either way your docking. Station is extra step and cost.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>The TLI booster would have more structural mass and piping to handle the tanks vs one large tank <p><hr /></p></p></blockquote><br /><br />Not much , just connectors. The booster itself ends up being small to launch since it doesn't have to take up fuel. And it can be one tank. Dock and go. Very simple. (My idea is that you take the tank with you, so TLI is launched without a tank, or small ones to get to orbit.) Also this scheme would allow to make a TLI booster that is bigger and more powerful than any before. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[cbased]

Interesting. Once I read it I had a few concerns:<br />1. Only 1 choice of fuel (LOX/LH2). Does it mean standatisation for all future spacecrafts?<br />2. How long can you store fuel until it is used? I don't know for these simple chemicals, but fuel used by Soyuz can only last for 6 months. If you can't store fuel for a long time then you have to rely on the turn-over rate.<br />3. Servicability (especially if it is placed NOT on LEO)<br /><br />So my gut feeling is that it will happen eventually but not in the nearest future.

 

[jimfromnsf]

2. There would be a cooling system for the LH2 and LO2. the Soyuz issue isn't the propellants but the propellant system. It isn't certified for longer term storage.

 

[comga]

"fuel used by Soyuz can only last for 6 months"<br /><br />This limit is set by the corrosive nature of the fuel and oxidizer on the Soyuz. Nitric Acid IIRC, and they don't trust the valves to seal completely if bathed in this for more than six months.<br /><br />Hydrogen is an interesting, perhaps odd, choice. The standard issues remain: Extremely low temperature, and very low density. These compound because the low density means more surface for a given mass, at the same time the insulation requirements rise with the lower temperature (when compared to liquid Oxygen or say, Methane.)<br /><br />The reason you can't store the stuff in the boosters is you can't cover a booster in anywhere near good enough insulation. The Shuttle External Tank uses foam, which falls apart dangerously and is many times more thermally conductive than a properly insulated cryogenic tank. For instance, the Shuttle Power Reactant Storage Assemblies that store the liquid Oxygen and Hydrogen for the Shuttle's fuel cells are complex systems with not so great mass fractions, but can be used for several weeks of storage.

 

[cbased]

<i>the Soyuz issue isn't the propellants but the propellant system. </i><br /><br />Jim, I might be wrong, but here is a couple of links:<br />http://www.russianspaceweb.com/iss_soyuztm33.html<br /><i>The safe operation of the Soyuz vehicle is limited primarily by the lifetime of onboard batteries and the degradation cycle of the propellant for the attitude control thrusters in the spacecraft's reentry capsule.</i><br /><br />http://spaceflight.nasa.gov/station/crew/exp2/taxi2/index.html<br /><i>The Russian spacecraft is certified to remain in space no longer than six months due to the degradation of its propellant over time and space radiation hazards to the vehicle.</i><br /><br />So it could be both - propellant and the propellant system (or corrosion), but it seems like propellant IS one of the limiting factors.<br />

 

[CalliArcale]

The Soyuz uses hydrazine, a propellant widely used in spacecraft (and ICBMs) for its exceptional long-term storeability. I don't think the hydrazine and nitrogen tetroxide break down quickly enough to be a serious problem in only six months. Those articles may be saying "degradation of propellant" to avoid having to go into great detail on exactly what is degrading. I know I've only ever heard what jimfromnsf said -- that the limiting factor is the seals. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[jimfromnsf]

Comsats and some deep space probes (Galileo and Casinni) which use the same propellants, last 10 to 15 years in space

 

[MeteorWayne]

Of course they are not lifeboats for three astronauts, either. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[CalliArcale]

They're no less dependent on the propellants, though. Hydrazine is remarkable stuff. It's a great balance between energy density and storability -- plus, the hypergolic combination with nitrogen tetroxide means that you don't need a complicated ignition system. It self-ignites on contact with the oxidizer.<br /><br />Hypergolics are used in the vast majority of spacecraft (including the Space Shuttle), as cryogenics are far too volatile for most applications. You'll find them aboard a great many satellites, although ion drives are becoming increasingly popular for this application.<br /><br />Both Voyager spacecraft use <br /><br />Cassini uses monomethyl hydrazine (MMH) and nitrogen tetroxide (N2O4) for its main propulsion system. The mission is 10 years old in two weeks, and is still going strong. <img src="/images/icons/wink.gif" /> In fact, it's still in its primary mission, which means it's expected to keep going for a while yet.<br /><br />Galileo used the same propellants, and flew for almost fourteen years. There was no appreciable degradation of the propulsion system, AFAIK, but there was concern that if they didn't deorbit then, the computer could fail before they could make the critical engine burn.<br /><br />The twin Voyager spacecraft also use hydrazine, and are expected to continue operating until roughly 2020. There will still be adequate propellant for attitude control, but the thermocouples in their RTGs will no longer be able to produce enough electrical power for minimal operation of the spacecraft. The Voyagers launched in 1977, so they will be over forty years old by then. They are expected to still be using propellant, since they cannot reliably communicate with Earth otherwise. To date, they still occasionally use significant amounts of propellant; Voyager 1 used 44.72 grams of propellant the first week of August to perform a MAGROL (a maneuver used to calibrate the magnetometer readings) according to the http://voyage</safety_wrapper <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[comga]

I believe you are missing some important details. In missions like Galileo and Cassini, the fuel and oxidizer kept isolated from the main engine valves until just before they are needed for braking into orbit. The valves are not bathed in these fluids for the duration. These engines are technically not needed again after those singular events.<br /><br />Long duration spacecraft use Hydrazine as a monopropellant. You are correct in that this stuff lasts practically forever. It is not obvious what is different about their valves that they can be relied on for a decade or more, for spacecraft like Dawn and New Horizons. perhaps it is design, size, or redundancy. Perhaps it is the oxidizer.

 

[gunsandrockets]

<Long duration spacecraft use Hydrazine as a monopropellant. ><br /><br />But what about the Zvezda service module of the International Space Station?<br /><br />http://www.astronautix.com/craft/issvezda.htm<br /><br />The ISS service module not only uses hypergolic bi-propellant engines, N2O4 + UDMH I believe, but it has also been refueled mulitiple times every year by Progress cargo missions. I think the service module is expected to keep working at least until 2015!<br /><br />

 

[3488]

Galileo was nearly destroyed just prior to Jupiter Orbital Insertion by a faulty valve,<br />but fortunately it became unjammed as the main engine kicked in. If it did not,<br />the mission would have ended there & then (as the fuel & oxidiser would had met in the<br />combustion chamber in one go).<br /><br />The Galileo mission was lucky to have even returned anything from Jupiter at all. Knackered HGA, <br />faulty tape recorder, engine nearly blew up & the parachute arming switch <br />on the atmospheric probe being faulty (though the chute did open 53 seconds late).<br /><br />Instead of which, the mission under these circumstances was a huge success.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[jimfromnsf]

"In missions like Galileo and Cassini, the fuel and oxidizer kept isolated from the main engine valves until just before they are needed for braking into orbit. The valves are not bathed in these fluids for the duration. These engines are technically not needed again after those singular events. "<br /><br />Not applicable to Cassini. Its engines will and have been used multiple times. The Deep Space maneuver occured on 3 Dec 98 and Saturn Insertion burn on 1 Jul 04. Most of the TCM's (21) used the biprop engines

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>It is not obvious what is different about their valves that they can be relied on for a decade or more, for spacecraft like Dawn and New Horizons. perhaps it is design, size, or redundancy. Perhaps it is the oxidizer.<p><hr /></p></p></blockquote><br /><br />As I understand it, the difference is the engineering of the propulsion system. For Soyuz, the choice of seals that would substantially degrade over time (much longer than six months really, but they put a large safety margin in the flight rules) was driven by the fact that they are much cheaper that way, and Soyuz isn't meant to stay in orbit for years on end anyway. When the Russians build spacecraft which will stay up for years (such as the space station modules, as someone mentioned), they don't use the same parts. They design the system differently, making it heavier and more expensive but also more robust.<br /><br />And that's fine; Soyuz is meant to be expendable. <img src="/images/icons/wink.gif" /><br /><br />BTW, I seem to recall reading (warning: shaky memory ahead) that the seals in question on the Soyuz are made of natural rubber. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[holmec]

<blockquote><font class="small">In reply to:</font><hr /><p>When the Russians build spacecraft which will stay up for years <p><hr /></p></p></blockquote><br /><br />Such as Parom? <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[jimfromnsf]

Parom is a powerpoint project

 

[holmec]

They have MS PowerPoint in Russia??? <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Parom is a powerpoint project<p><hr /></p></p></blockquote><br /><br />So what. Of course its a paper project, who thinks there's one orbiting?<br /><br />BTW why don't you call it something else less Microsoft gets on to you for misusing their registered trade mark. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[CalliArcale]

We're getting a little offtopic, but yes, they do have PowerPoint in Russia. Microsoft will happily sell their software anywhere. <img src="/images/icons/wink.gif" /> In any case, I do not believe Microsoft would sue over such a trivial infringement. Some companies have fought the "verbing" of their trademarks, and the adoption of their trademarks as generic terms for the type of product, but unless it's in a situation likely to cause harm to the company, it's not generally worth the effort of suing over it. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[usn_skwerl]

like the "Superbowlâ„¢" for example? <img src="/images/icons/rolleyes.gif" /> <div class="Discussion_UserSignature"> </div>